Landsat-9Spacecraft Launch Mission Status Sensor Complement Ground Segment References
Landsat-9 — a partnership between NASA and USGS (U.S. Geological Survey) — will continue the Landsat program's critical role in monitoring, understanding and managing the land resources needed to sustain human life. Today's increased rates of global land cover and land use change have profound consequences for weather and climate change, ecosystem function and services, carbon cycling and sequestration, resource management, the national and global economy, human health, and society. 1) 2) 3) 4)
Landsat is the only U.S. satellite system designed and operated to repeatedly observe the global land surface at a moderate scale that shows both natural and human-induced change.
Figure 1: Timeline of the Landsat program, starting with the launch of Landsat-1. Landsat-9, slated to launch in September 2021, will continue the legacy of the Landsat program (image credit: NASA)
• In 2016, the Landsat-9 project has been fast-tracked for a December 2020 launch (initially planned for 2023) .The risk reduction of a Landsat data gap is a high priority of the U.S. Sustainable Land Imaging Program. Landsat-9 will be a rebuild of Landsat-8 so it can be launched as soon as possible. 5)
- Hence, NASA HQ amended direction in response to FY16 appropriations and associated congressional language targeting a 2020 launch (Ref. 2).
- In January 2016, the project has been directed to pursue the earliest possible launch date within the spending authority provided in FY16.
- Project has $100M in Congressionally directed spending authority for FY16: $58M of unspent carryover from FY15, $42M in new FY16 funding.
- Substantial progress in FY16 is required for maintaining CY2020 LRD (Launch Readiness Date).
According to Jeff Masek, the project scientist: "With a launch in 2020, Landsat-9 will propel the program into the next half-century of global observations. That's the hallmark of Landsat: the longer the satellites view the Earth, the more phenomena you can observe and understand."
Landsat-9, like Landsat-8, will have a higher imaging capacity than past Landsat missions, allowing more valuable data to be added to the Landsat's global land archive.
Landsat-8, after collecting data for 3.5 years, has already added over 827,000 images to the archive—this represents 12.5 percent of the entire 44-year Landsat data collection—and each day Landsat-8 adds another ~700 new scenes. Landsat-9, like Landsat-8, will be both radiometrically and geometrically better than earlier generation Landsats.
Landsat-9 is essential for informed land use decisions:
Landsat-9 will extend our ability to measure changes on the global land surface at a scale where we can separate human and natural causes of change. When land use and resource availability issues arise, Landsat-9 will help decision makers make informed management decisions. Landsat-9 will thus contribute a critical component to the international strategy for monitoring the health and state of the Earth.
Landsat users can now take advantage of more frequent observations (every 8 days using two satellites). Applications such as weekly tropical deforestation alerts, water quality monitoring, and crop condition reports are now feasible with the constellation.
With increased activity in international and commercial remote sensing, Landsat has emerged as a cornerstone of the global constellation of imagers. The science quality of the Landsat archive, including careful calibration, allows it to serve as a "gold standard" for studies harmonizing multiple sources of satellite imagery.
Landsat-9 will enable informed decision support for key areas such as:
• Tropical deforestation and global forest dynamics: the Landsat archive provides an impartial and unbiased record of Earth's forests for world governments and resource organizations to verify claims of environmental protection and carbon storage.
• Urban expansion: the Landsat record helps us visualize the impact of humankind's convergence on urban centers and to understand the environmental consequences.
• Water use: Landsat-9 will be an invaluable tool for managing water in areas such as the Western U.S. where water is scarce and water usage between agriculture, industry, and residential needs is very competitive.
• Coral reef degradation: Landsat has helped enable global monitoring of Earth's reefs.
• Glacier and ice-shelf retreat: the Landsat archive chronicles changes to 98 percent of Earth's glaciers, and Landsat-9 will continue monitoring them into the future.
• Natural and man-made disasters: Landsat data are regularly used as part of the International Disaster Charter, mapping disaster impacts to save lives.
• Climate change: Landsat data provide a direct view of how almost five decades of climate change have affected Earth's surface and biology.
Some background: Already in April 2015, NASA and the U.S. Geological Survey (USGS) have started work on Landsat- 9, planned to launch in 2023, to extend the Earth-observing program's record of land images to half a century. 6)
Landsat is a remarkably successful partnership," said Sarah Ryker, USGS deputy associate director for climate and land use change, Reston, Virginia. "Last year the White House found that GPS, weather satellites, and Landsat are the three most critical types of Earth-orbiting assets for civil applications, because they're used by many economic sectors and fields of research. Having Landsat-9 in progress, and a long-term commitment to sustainable land imaging, is great for natural resource science and for data-driven industries such as precision agriculture and insurance."
NASA's Goddard Space Flight Center in Greenbelt, Maryland, will lead development of the Landsat-9 flight segment. Goddard will also build the TIRS-2 (Thermal Infrared Sensor-2), which will be similar to the TIRS that the center built for Landsat-8. The new improved TIRS will have a five-year design lifetime, compared to the three-year design lifetime of the sensor on Landsat-8.
With decades of observations, scientists can tease out subtle changes in ecosystems, the effects of climate change on permafrost, changes in farming technologies, and many other activities that alter the landscape.
SLI (Sustainable Land Imaging) 2016-2035:
President Obama's NASA budgets of FY14 and FY15 called for design and initiation of an affordable, sustained,Land Imaging Satellite System (with USGS) to extend the Landsat data record for decades –not just the "next mission". 7)
The SLI program will enable the development of a multi-decade, spaceborne system that will provide users worldwide with high-quality, global, land-imaging measurements that are compatible with the existing 44-year Landsat data record. Landsat-9 is the latest satellite in the Landsat series — it will continue Landsat's irreplaceable record of Earth's land surface upon its 2020 launch. To reduce the build time and a risk of a gap in observations, Landsat-9 will largely replicate its predecessor Landsat-8.
Table 1: Landsat program on-orbit status as of July 2015
Legend to Figure 1:
- a) Limited data of Landsat-4 due to transmitter failure soon after launch. Only 45,172 Landsat-4 TM (Thematic Mapper) scenes from 1982-1993 are available for science users ~10 scenes/day (versus 725 scenes/day from Landsat-8)
- b) Data coverage of Landsat-5 is limited to CONUS (Continental US) and international ground station sites after a transmitter failure in 1987; the MSC (Multispectral Scanner) turned off in August 1995.
- c) Degraded performance due to SLC (Scan Line Corrector) failure in May 2003.
Landsat-9 mission objectives:
• Collect and archive moderate-resolution, reflective and emissive multispectral image data affording seasonal coverage of the global land mass for a period of no less than five years.
• Ensure that Landsat-9 data are sufficiently consistent with data from the earlier Landsat missions, in terms of acquisition geometry, acquisition rates, calibration, coverage characteristics, spectral and spatial characteristics, output product quality, and data availability to permit studies of land cover and land use change over multi-decadal period.
• Distribute standard Landsat-9 data products to users on a nondiscriminatory basis and at no cost to the users.
The Landsat-9 satellite will be constructed at Northrop Grumman Innovation Systems (formerly Orbital ATK in Gilbert, AZ), NASA awarded a contract in October 2016. 8) Landsat-9 is based on the company's LEOStarTM-3 platform, the medium-class LEO (Low Earth Orbit) spacecraft successfully flown on Landsat-8 and NASA's Fermi and Swift Gamma-ray astrophysics observatories. Landsat-9 will be designed, manufactured and tested by Orbital ATK's Space Systems Group at its facilities in Gilbert, Arizona, the same location and production team that executed the Landsat-8 program. Orbital ATK will also support launch, early orbit operations and on-orbit check-out of the observatory, which is scheduled for launch in December of 2020. 9) 10)
Figure 2: Artist's rendering of the Landsat-9 spacecraft (image credit: NASA)
Project development status
• September 21, 2021: The Landsat-9 observatory has been mounted on top of a United Launch Alliance Atlas 5 rocket in California for liftoff Sept. 27, continuing an unbroken record of Earth observations to track urban sprawl, water usage, tropical deforestation, retreating glaciers, and more over the last half-century. 11)
Figure 3: The Landsat 9 Earth observation satellite inside the payload fairing of an Atlas 5 rocket at Vandenberg Space Force Base (image credit: NASA)
• August 31, 2021: A one-week delay in the launch of the next Landsat satellite on an Atlas 5 is the result of a ripple effect in the supply chain caused by increased demand for liquid oxygen to treat COVID-19 patients. 12)
- NASA announced Aug. 27 that the launch of Landsat 9 on an Atlas 5 from Vandenberg Space Force Base in California had slipped a week, from Sept. 16 to no earlier than Sept. 23, because "pandemic demands for medical liquid oxygen have impacted the delivery of the needed liquid nitrogen supply." Liquid nitrogen, or LN2, is used to create gaseous nitrogen needed to support launch site activities.
- During an Aug. 31 virtual news briefing about the upcoming launch, Del Jenstrom, NASA Landsat-9 project manager, said the issue was not an overall lack of liquid nitrogen but instead a transportation issue.
- "There's plenty of liquid nitrogen in the Los Angeles area. The problem is they need some trucks to bring it up to Vandenberg," he said. "Because of the pandemic, from what we understand, liquid oxygen deliveries have been paying much higher premiums than liquid nitrogen deliveries, and LN2 trucks have been converted to carry liquid oxygen."
- Jenstrom said that the Defense Logistics Agency (DLA) informed the project Aug. 23 that liquid nitrogen supplies at the base were "critically low" and could not support upcoming prelaunch test activities or the launch itself. That prompted NASA Deputy Administrator Pam Melroy to contact senior DLA officials to discuss ways to restore the base's nitrogen supply.
- Airgas, the company that handles the nitrogen supply at Vandenberg, is bringing in "a dozen or so" liquid nitrogen tankers from the Gulf Coast temporarily to increase deliveries. "We're seeing a substantial increase of the number of LN2 deliveries to the base right now," he said, "and as far as we know, based on latest reports, we're on track to support our launch on Sept. 23."
- Supply chain issues related directly or indirectly to liquid oxygen, which is used by hospitals as the oxygen source for ventilators, came to light recently when Gwynne Shotwell, president and chief operating officer of SpaceX, mentioned them during a panel discussion at the 36th Space Symposium in Colorado Springs Aug. 24.
- "We're actually going to be impacted this year with the lack of liquid oxygen for launch," she said. "We certainly are going to make sure the hospitals are going to have the oxygen that they need, but for anybody who has liquid oxygen to spare, send me an email."
- At that time, Tory Bruno, chief executive of United Launch Alliance, hinted at a problem getting liquid nitrogen to Vandenberg to support the upcoming Landsat-9 launch. "Working that situation now," Bruno said.
- The next launch planned for Vandenberg is not the Atlas 5 launch of Landsat-9. Instead, Firefly Aerospace has scheduled the inaugural launch of its Alpha rocket from the base on Sept. 2, during a four-hour window that opens at 9 p.m. Eastern. Company spokesperson Kim Jennett told SpaceNews Aug. 31 the launch remains on schedule and is not affected by any liquid nitrogen or other supply issues.
- Liquid oxygen supply chain problems extend beyond the United States. Dmitry Rogozin, head of Roscosmos, tweeted Aug. 29 that Roscosmos had for months been transferring "almost all" of the oxygen produced by its various enterprises to hospitals. That has postponed testing of rocket engines, he claimed.
• August 16, 2021: Landsat-9, a joint NASA and U.S. Geological Survey satellite mission, is scheduled to launch Thursday, Sept. 16, from Vandenberg Space Force Base in California. To help the media and public learn more about the project and its near 50-year history, NASA has launched a new interactive website: http://www.nasa.gov/landsat9 13)
- The Landsat Program missions changed the field of Earth science when the Landsat 1 satellite launched in 1972. In 2008, the program created new opportunities for research around the world when it made decades of Landsat data available to the public for free.
- The Landsat-9 satellite continues the program's critical role in monitoring, understanding, and managing land resources – agricultural crops, water, and forests – needed to sustain human life.
- Landsat's data of Earth's surface as seen from space have transformed scientists' understanding of regional, national, and global-scale changes in land use and land cover, providing information for sectors including agriculture, forestry, urbanization, hydrology, and homeland security and disaster mitigation. Landsat-9 will continue this record of monitoring key natural and economic resources, as well as global environmental changes into the future.
- Once fully commissioned in orbit after launch, Landsat-9 will replace Landsat-7 and join its sister satellite, Landsat-8. Together, they will collect images that capture Earth's land surfaces every eight days.
- Landsat-9 uses similar instrument technology to Landsat-8. Carrying two sensors, the Operational Land Imager-2 (OLI-2), built by Ball Aerospace & Technologies Corporation, and the Thermal Infrared Sensor-2 (TIRS-2), built at NASA's Goddard Space Flight Center in Greenbelt, Maryland, it will detect the reflected light and heat emitted from Earth's surface across the visible, near infrared, shortwave infrared, and thermal infrared wavelengths.
- The instruments will capture more than 700 new images daily across 11 wavelengths at 30-meter resolution. This resolution is fine enough to detect even small agricultural fields, buildings, forest stands, and lakes, while still providing a broad enough swath to cover large areas of terrain. With its 11 wavelengths, the instruments will capture information about Earth, including data related to coastal waters, forests, healthy and unhealthy plants, and wildfire scars in the visible light to thermal infrared ranges.
- United Launch Alliance is the spacecraft provider for Landsat-9's launch. Northrop Grumman built the Landsat-9 spacecraft, integrated it with instruments, and tested the observatory.
- The U.S. Geological Survey Earth Resources Observation and Science Center will operate the mission and manage the ground system, including maintaining the Landsat archive.
- To date, more than 18,000 peer-reviewed research papers have used Landsat data, and many public and private programs use it to support agriculture, forest management, urban development, wildfire-damaged vegetation recovery, and many more applications.
• August 1, 2021: Landsat-9 is in its final preparations for launch from Vandenberg Space Force Base on 16 September 2021. It has completed its environmental testing at Northrop Grumman Space (NGSP) in Gilbert, Arizona and has been transported to its California launch site. It will be launched into a 705 km orbit replacing Landsat-7 to provide 8-day Earth land mass coverage in concert with Landsat-8. Landsat-8 carries the first Operational Land Imager (OLI) and the Thermal Infrared Sensor (TIRS); Landsat-9 carries the second of each: OLI-2 and TIRS-2. Once launched it will undergo a 90-day activation, checkout, characterization and calibration, a.k.a. commissioning phase before transitioning to operations. For a several-day period during this commissioning phase, Landsat-9 will under-fly Landsat-8, allowing near simultaneous data collection by both sensors of common Earth targets. These data will be used to compare the radiometric calibrations of the instruments and allow for adjustments of processing parameters to provide more consistent data products. 14)
• August 14, 2020: Landsat is the only U.S. satellite system designed and operated to repeatedly observe the global land surface at a moderate scale that shows both natural and human-induced change. 15) 16)
- Since reducing the risk of a Landsat data gap is a high priority of the U.S. Sustainable Land Imaging Program, Landsat-9 has a design very similar to Landsat-8's; allowing the Landsat-9 build and launch to be expedited.
- Landsat-9, slated for a Mid-2021 launch, will join Landsat-8 in orbit; the satellite orbits will be 8 days out of phase. Landsat 9 will replace Landsat-7 (launched in 1999), taking its place in orbit (8 days out of phase with Landsat-8). The combined Landsat-8 + Landsat-9 revisit time for data collection with be every 8 days, like it currently is for Landsat-8 + Landsat-7.
- Landsat-9, like Landsat-8, will have a higher imaging capacity than past Landsats, allowing more valuable data to be added to the Landsat's global land archive.
- Landsat-8, after collecting data for 7 years, has added over 1.6 million images to the archive and each day Landsat-8 adds another ~700 new scenes.
- Landsat-9, like Landsat-8, will be both radiometrically and geometrically better than earlier generation Landsats.
Figure 4: The data contributions of each Landsat satellite to the USGS Landsat data archive as of Sept. 30, 2019. For Landsats 4 and 5, the darker color on the bars represents Multispectral Scanner System data and the lighter color is Thematic Mapper data collected by the mission (image credit: NASA)
• April 3, 2020: Landsat-9 has successfully passed its Mission Operations Review. Together, NASA and USGS demonstrated that the Landsat-9 ground system and mission operation preparations are highly mature. The maturity of the Landsat-9 ground system and mission operation development significantly exceeds the requirements of the Mission Operations Review, putting the Landsat-9 mission well on track to complete remaining preparations prior to launch. 17) 18)
- The Mission Operations Review panel lauded the Landsat-9 mission for the excellent joint agency teamwork between NASA and USGS, the exceptional quality of presentation materials, and the team's creative and flexible responses in the face of major challenges, including the COVID-19 pandemic.
- Both Landsat-9 Project Managers, Del Jenstrom (NASA) and Brian Sauer (USGS), extended their praise and appreciation to the Landsat-9 ground system and mission operations readiness team for their work that led to a highly successful review performance.
- The joint NASA/USGS Landsat 9 mission continues the nearly 50-year Landsat data record, providing actionable information to resource managers and policymakers around the world. In 2021, Landsat-9 will join Landsat-8 in orbit and the two satellites will work together to record the condition of Earth's ever-changing land surface, enabling scientists and others to monitor crops and algal blooms, to assess deforestation trends and urban growth, and to aid disaster management.
• January 9, 2020: Landsat 9's two science instruments are now attached to the spacecraft, bringing the mission one step closer to launch. In late December, the Operational Land Imager 2 (OLI-2) and the Thermal Infrared Sensor 2 (TIRS-2) were both mechanically integrated on to the spacecraft bus at Northrop Grumman in Gilbert, Arizona. 19)
Figure 5: Engineers work on the newly integrated Landsat 9 satellite in a cleanroom at the Northrop Grumman facility in Gilbert, Arizona. In December, the team attached Landsat 9's two instruments: OLI-2 (left) and TIRS-2 (right) to the spacecraft bus at the bottom of the image. The two instruments are covered to protect them from contaminants ( image credit: Northrop Grumman)
- Engineers will next work on the electrical integration of the instruments, which includes getting power to the instruments and incorporating the satellite's data-handling hardware.
• September 27, 2019: The Landsat-9 instrument that will help scientists detect deforestation, monitor crops and track potentially toxic algal blooms, among many other uses, is now built, tested, and in place to be assembled onto the spacecraft. 20)
- OLI-2 (Operational Land Imager 2) will detect visible and infrared light from Earth's surface, providing data on our changing planet. Like its predecessor that launched in 2013 on the Landsat-8 satellite, OLI-2 contains thousands of sensors that view a swath of Earth's surface in nine spectral bands, optimized to detect different features on the surface.
Figure 6: OLI-2 is shown in this photo at Ball Aerospace in Boulder, Colorado, where it was built and tested. On Sept. 18 it was trucked from Boulder to the Northrop Grumman facility in Gilbert, Arizona, arriving the next day. At Northrop Grumman, engineers will assemble and then test the complete Landsat 9 spacecraft with OLI-2 and another instrument, TIRS-2 (Thermal Infrared Sensor-2), which was built at NASA's Goddard Space Flight Center in Greenbelt, Maryland (image credit: Ball Aerospace, Alex Turner)
Figure 7: The Landsat-9 instrument that will help scientists detect deforestation, monitor crops and track potentially toxic algal blooms, among many other uses, is now built, tested, and in place to be assembled onto the spacecraft. The Operational Land Imager 2, or OLI-2, will detect visible and infrared light from Earth's surface, providing data on our changing planet (video credit: NASA Goddard, Scientific Visualization Studio)
• August 23, 2019: This month, TIRS-2 successfully passed the stringent 12-week testing process at NASA's Goddard Space Flight Center in Greenbelt, Maryland. It was shipped to Northrop Grumman's facility in Arizona, where it and the OLI-2 (Operational Land Imager-2) will be assembled onto the Landsat-9 spacecraft. Landsat-9 is a joint effort of NASA and the U.S. Geological Survey. 21)
Figure 8: Engineers pose with the TIRS-2 instrument, which was built and tested at NASA Goddard (image credit: NASA)
Figure 9: From orbit aboard the Landsat-9 satellite, the TIRS-2 (Thermal Infrared Sensor-2) will measure the temperature of Earth's land surfaces, detecting everything from a smoldering wildfire, to the amount of irrigation used on crop fields, to wispy clouds that are all but invisible to other instruments. First, however, it had to survive tests that simulated the harsh environment of space (video credit: NASA Goddard, Published on Aug 23, 2019)
- Like digital cameras on a smart phone, the TIRS-2 instrument is an imager, said Joel McCorkel, the instrument's deputy project scientist. But while a camera detects light reflected off an object, TIRS-2 detects the thermal energy that an object emits. The hotter a surface is, the more energy the instrument will detect. And since TIRS-2 is a highly-calibrated scientific instrument, not a camera, it provides data that researchers can use to investigate key questions about our home planet.
- TIRS-2 is designed to work in the same way as the first TIRS instrument, which launched on Landsat-8 in 2013 and is still collecting important data on Earth's surface temperature. But the latest version has a couple improvements.
- "The beauty of TIRS-2, is that we had TIRS data from up in orbit and were able to look at what worked, and how we could mitigate what didn't work," said Melody Djam, TIRS-2 instrument deputy project manager at Goddard.
- The TIRS-2 team incorporated a new optical component to shield the instrument's sensor from stray light that had caused problems on the original instrument, requiring software fixes. The first TIRS was also designed, constructed, and integrated in less than three years – which is an incredibly quick turnaround for a satellite's instrument – and so it was only required to last three years. TIRS-2, however, is designed with redundant electronics and other components in order to last at least five years.
- IRS-2 has about 10 main components, and each one was built and tested individually before engineers brought everything together to ensure the instrument worked, Djam said. The engineering team, which included as many as 250 people, then tested the whole instrument both in the clean room, as well as in environmental chambers that simulate the launch and space environments.
- With round-the-clock shifts and successful tests, the team delivered the instrument more than two weeks ahead of its target date. TIRS-2 passed its pre-ship review on Aug. 12 and was trucked to Gilbert, Arizona in two shipments. At the Northrop Grumman facility, the team will reassemble it, test it, and make sure everything is ready to integrate the instrument with the Landsat 9 spacecraft this fall.
Taking Earth's temperatures from orbit
- Landsat satellites have been observing Earth since 1972, building the longest continuous record from space of the planet's forests, farms, cities, and other surfaces. Starting with Landsat-4 and continuing through the first TIRS instrument on Landsat-8, the satellites have carried instruments that can detect thermal energy as well as visible and infrared light – and water managers and others have put these observations to work.
- "Landsat's thermal data is critical for tracking water use in the western United States, where rainfall can be short in supply and managing water resources is critical to ensuring a sustainable supply for farmers, cities, and natural ecosystems," said Bruce Cook, Landsat-9 deputy project scientist at Goddard.
- When plants take up water from the soil, they ‘sweat' it out as they undergo transpiration, cooling them down just as sweating cools people down. By measuring the temperature of growing plants and soils that are cooled by transpiration and evaporation, respectively, Landsat users can create maps that quantify water use and consumption. The accuracy of these maps is increased by TIRS' two thermal bands, which allows researchers to subtract out the effect of atmospheric constituents better than with the single-band thermal data from previous Landsat instruments.
- TIRS also works "behind the scenes" to detect clouds that are difficult to sense with visible data alone, which makes it an important filter for scientists constructing Landsat time series to record disturbances and changes in land cover over time.
- "With TIRS, scientists can better identify clouds, remove those data, and focus on the real land surface," said McCorkel. "This increases the efficiency of their study and the accuracy of their science, whether they're looking at a plot of land or a continent."
• On June 6, 2018, Northrop Grumman Corporation announced it has closed the acquisition of Orbital ATK Inc. ("Orbital ATK"), a global leader in aerospace and defense technologies. Orbital ATK is now Northrop Grumman Innovation Systems, a new, fourth business sector. — Hence, the Landsat-9 spacecraft development news are now going to be reported under the label of Northrop Grumman. 22)
• May 23, 2018: Landsat-9 will continue the Landsat program's critical role in monitoring, understanding and managing the land resources needed to sustain human life. To do so, Landsat-9 will carry two science instruments: the Operational Land Imager 2 (OLI-2) and the Thermal Infrared Sensor 2 (TIRS-2). 23)
Figure 10: Ball Aerospace technicians prepare to install the focal plane assembly, a 14-module detector array, into the OLI-2 (Operational Land Imager 2), one of the key science instruments for Landsat-9 (image credit: Ball Aerospace)
• April 25, 2018: The Landsat-9 Mission Critical Design Review was held April 17-20, 2018 at NASA/GSFC (Goddard Space Flight Center), Greenbelt, MD. NASA and USGS scientists and engineers provided the Standing Review Board (SRB) a status on all segments including the spacecraft, instruments, launch vehicle, and ground system to date. 24)
- The SRB had high praise for the accomplishments and the strengths of the Landsat-9 project team. Highlights noted included the high degree of experience and expertise throughout the project, the close working relationship among agency team members, the project's strong technical maturity, the cost and schedule performance to date, the maturity of plans going forward, and exemplary use of lessons learned. The SRB assigned one request for action (RFA) related to USGS funding reserve levels.
• April 10, 2018: The USGS and NASA held a Landsat-9 Ground System Preliminary Design Review (GPDR) on March 20-22, 2018 in Sioux Falls, South Dakota. The GPDR, which contains the Data Processing and Archive System (DPAS), Ground Network Element (GNE) and Landsat Multi-Satellite Operations Center (LMOC) components, demonstrated that the proposed design of each component satisfies the required functional and performance requirements to continue the Landsat-9 development process. 25)
- With the GPDR a success, the Ground System can now proceed to the Critical Design Review, which is planned for Fall 2018 – continuing to ensure the Landsat-9 mission remains on schedule for a launch readiness date of December 2020.
• March 15, 2018: Northrop Grumman (former Orbital ATK) has been given approval to begin building the NASA Landsat-9 spacecraft after completing a comprehensive design review of the mission. Northrop Grumman is designing and manufacturing the satellite, integrating two science instruments, and supporting launch, early orbit operations and on-orbit check-out of the observatory. 26)
- Representatives from NASA and Northrop Grumman successfully completed a rigorous Critical Design Review (CDR) demonstrating that the program meets all technical performance measures and requirements. The execution of the design review enables the program to effectively transition into manufacturing and prepare for the assembly, test and launch operations phase of the mission. The Landsat-9 spacecraft will be manufactured and tested at the company's Gilbert, Arizona, facility and is currently planned for launch in late 2020. The spacecraft will be operated by the U.S. Geological Survey once in orbit.
- The Critical Design Review took place February 26 through March 1 at Northrop Grumman's facility in Gilbert, Arizona. Landsat-9 will extend the length of the overall Landsat series to half a century, providing the longest continuous record of the Earth's surface as seen from space. Northrop Grumman has built three other Landsat satellites, including Landsat-8, which was launched in 2013, and is providing high quality images in quantities that surpass mission requirements.
• February 14, 2018: Ball Aerospace delivered the TIRS-2 Flight Cryocooler for the Landsat-9 TIRS-2 (Thermal Infrared Sensor-2) instrument ahead of schedule to NASA/GSFC (Goddard Space Flight Center). Achieving this milestone early will allow GSFC additional time and options during the instrument integration and test phase. 27)
- For more than 45 years, Landsat Earth-observing satellite missions have gathered multispectral imagery from space, helping scientists understand the impacts of human activity and natural events on our planet through constant monitoring of land changes. The TIRS-2 instrument aboard Landsat-9 will provide two-band thermal imaging data to measure surface temperature and track land and water usage. The Ball-built cryocooler on the instrument enables TIRS-2 to cool the focal plane and the surrounding enclosure to maintain the sensitivity needed for imaging.
- The TIRS-2 Flight Cryocooler is based upon a Ball family of Stirling Cryocoolers, which are the nation's largest capacity, highest efficiency cryocoolers on orbit to date. The two-stage Flight Cryocooler consists of two CCEs (Cryogenic Control Electronics), one RSE (Redundancy Switch Electronics), a TMU (Thermo Mechanical Unit) and a flight harness set. For TIRS-2, Ball developed redundant electronics and incorporated many design and manufacturing improvements to simplify the fabrication and assembly process.
• December 19, 2017: The USGS and NASA have selected a new Landsat science team, whose primary responsibility is to conduct Landsat-based scientific research and engineering studies, develop useful data products and applications and share the results of its work with the USGS, NASA and others — members will serve a five-year term from 2018 to 2023. 28) 29)
- The new team will conduct scientific research on technical issues critical to the success of the overall Landsat mission, including topics related to data acquisition, product access and formats, new science datasets, practical data applications to be derived from an operational system and other science opportunities for new and past-generation Landsat data.
- Members will evaluate the quality of data when Landsat 9 is launched, which is estimated for December 2020, and help ensure that Landsat 9 data can be successfully integrated into the overall Landsat record. They will also be on the ground floor of discussions for future Landsat missions. In addition, the new team may be called on to assess the viability of Landsat 7 data for scientific or operational purposes as the satellite nears its nineteenth year in orbit. They will also be responsible for looking at opportunities to develop new and advanced applications of Landsat data.
- Previous Landsat Science Teams helped increase the ease of use and expand the utility of Landsat data for users across the nation; greatly increased the size of the Landsat archive by transferring historical data held by international cooperators; and advanced the breadth and accuracy of applications of the 45-year Landsat record.
Table 2: The 2018-2023 USGS-NASA Landsat Science Team members and their areas of study
• December 7, 2017: Landsat-9 has entered its implementation phase, or "Phase C" of its project lifecycle after successfully passing Key Decision Point C (KDP-C). The Landsat-9 project team garnered high praise from NASA Headquarters' APMC (Agency Program Management Council) for the project's exemplary mission formulation performance and for the lockstep collaboration with its partner agency, the U.S. Geologic Survey. 30)
- The implementation phase of the Landsat-9 project lifecycle will be dominated by the fabrication and testing of the Landsat-9 instruments and spacecraft; this phase will last approximately 24 months and will be followed by the observatory integration phase.
Mission Schedule and Lifecycle (Figure 11): NASA-managed satellite builds have a mission lifecycle that is divided into incremental phases. Phase A is concept and technology development; Phase B is preliminary design and technology completion; Phase C is final design and fabrication; Phase D is system assembly, integration/testing, and launch readiness; Phase E starts after on-orbit operational checkout and ends at the mission's operational end. 32)
• September 24, 2017: The USGS awarded the prime contract to General Dynamics Mission Systems, with a.i. solutions as one of the subcontractors. Under this contract, General Dynamics will continue to operate Landsat-8 from the existing mission operations center at the GSFC (Goddard Space Flight Center) and will begin design and integration of a new Landsat Multi-satellite Operations Center at GSFC. 33)
- Under the requirements of the contract, a.i. solutions will provide key flight dynamics and mission planning for the ongoing Landsat-8 mission, develop the flight dynamics component of the ground system that will launch and operate on Landsat-9 as well as transition Landsat-8 to the new flight dynamics system once complete.
• September 18, 2017: The Landsat-9 satellite mission team completed a successful Mission PDR (Preliminary Design Review) last week. During the review, the mission team demonstrated to an independent Standing Review Board that all design plans for the Landsat-9 mission are both sound and well integrated. - The PDR is the last milestone before the major Key Decision Point C, scheduled for December 2017, after which the mission officially enters its implementation phase. The review took place from September 12-15 at NASA's Goddard Space Flight Center in Greenbelt, Maryland. 34)
• August 10, 2017: The Landsat-9 spacecraft passed an important progress evaluation milestone in mid-July. The PDR (Preliminary Design Review) for the Orbital ATK-sourced spacecraft was held from July 18–20 in Gilbert, Arizona at the satellite fabricator's facility. 35)
- NASA concluded that the Landsat 9 spacecraft is on track and meeting all of the system and schedule requirements needed for the mission's planned December 2020 launch.
• February 28, 2017: The Landsat-9 TIRS-2 (Thermal Infrared Sensor-2) team at the NASA/GSFC (Goddard Space Flight Center) has successfully completed their ICDR (Instrument Critical Design Review). 36)
• February 27, 2017: USGS and NASA officials will participate in the Landsat-9 SSRR (Spacecraft System Requirements Review) February 28 and March 1 at the Orbital ATK facility in Gilbert, Arizona. 37)
- An independent panel will review the work of the spacecraft vendor to understand system requirements in a number of areas, including being able to control the orientation of Landsat 9 through attitude control, how much redundancy is built into the spacecraft, and how much fuel will be onboard.
- Reviewers will also look at fault management capabilities, which include hardware and software features used to address any potential problems that may arise in orbit. This is the final such review before full-scale spacecraft design and development begins.
• On November 30 – December 1, 2016, USGS EROS hosted the Landsat-9 GSRR (Ground System Requirements Review) in Sioux Falls, SD. This was the first in a series of major project reviews for Landsat-9, which is scheduled for launch December 2020. The GSRR included presentations given to a joint NASA/USGS review panel on the proposed components of the Landsat-9 Ground System. At the conclusion of the review, the panel approved the Landsat-9 Ground System team to proceed to the PDR (Preliminary Design Review) stage. 38)
• Oct. 25, 2016: NASA has awarded a delivery order under the Rapid Spacecraft Acquisition III (Rapid III) contract to Orbital ATK for the Landsat 9 spacecraft. This contract is a 5-year, firm fixed-price delivery order for the purchase of the Landsat-9 spacecraft in the amount of $129.9 million. Orbital will design and fabricate the spacecraft, integrate the mission's two government-furnished instruments, and conduct satellite-level testing, in-orbit satellite checkout, and mission operations support. The work will be performed at the contractor's facilities and at the launch site at Vandenberg Air Force Base in California. 39)
• May 17, 2016: NASA has awarded a sole source contract to BATC (Ball Aerospace and Technology Corporation) of Boulder, Colorado, for the TIRS-2 (Thermal Infrared Sensor-2) instrument Cryocooler for Landsat-9. 40) — TIRS-2 is being upgraded to a Class B instrument, with additional steps being taken to fix the straylight issue affecting the Landsat-8 TIRS instrument.
• On March 4, 2015, the Landsat-9 project was officially directed to initiate activities with strong support from Administration, Congress, NASA, and USGS (Ref. 2).
Figure 12: Overview of spectral band coverage in various missions (HyspIRI, Sentinel-2 of ESA, Landsat-8 and Landsat-7 (image credit: NASA)
What Makes Landsat-9 a Science-Grade Satellite?
Scientific studies rely on science-grade instruments—instruments that record information reliably and accurately. Studying long-term changes to Earth's surface requires carefully calibrated observations to measure subtle changes occurring over decades. The Landsat-9 mission will extend the data record of Earth observations and advance the scientific study of land change and land use into the next half-century. Consistency in Landsat's spatial resolution, calibration, and spectral characteristics over four decades allows long-term, consistent comparisons of historical and current data.
1) Spectral Coverage: For a science-grade instrument, the ability to have broad spectral coverage—the ability to see parts of the light spectrum beyond the visible and VNIR (Near Infrared ) — is essential. Landsat-9 will collect data in three shortwave infrared bands and two thermal infrared bands, in addition to VNIR. These longer wavelength bands play a vital role in water use measurements (evapotransporation), fire scar mapping, volcanic lava flow mapping, and other indices used for land use monitoring.
Because of optical diffraction, the ability to image features at longer wavelengths requires progressively larger telescope apertures. In addition, multiple types of detectors (or even separate instruments) may be required to cover the full spectral range. Thermal detectors must be cooled to very low temperatures (-150º C) in order to be sensitive to the low radiance levels emitted at normal Earth temperatures, which in turn necessitates coolers that can cool to cryogenic temperatures.
2) Accuracy: Radiometric resolution and geometric fidelity: We use the term "science-grade" a lot when describing Landsat's instruments. What we mean by this is that the data collected by Landsat satellites have very strict levels of accuracy that they must live up to—the radiation measurements must be reliable for each of the Landsat spectral bands.
This reliability is what makes comparisons of Landsat data day-to-day, year-to-year and sensor-to-sensor possible. To do scientific research you need to know you can make accurate comparisons.
Radiometric resolution is the ability to measure small differences in radiation over a wide range of brightness levels and geometric fidelity is the ability to know exactly where any given pixel is located. Large optics help by mitigating stray light and ensuring focal plane uniformity (i.e. sameness across the field of the tens-of-thousands of detectors which the telescope focuses light on) to avoid skewed measurements.
The Landsat-9 instruments provide radiometric calibration via onboard sources (blackbody, lamps) and a solar-diffuser system for the reflective bands. Additionally, every full Moon, Landsat-9 (like Landsat-8) will be turned toward the Moon to scan the distant lunar surface multiple times. Since the Moon has no atmosphere, it is the perfect consistent source of light to measure–like a gray card for calibrating a camera's exposure. Data from the Moon is used to both complement and corroborate the results from the other on-board calibration activities.
3) Redundancy: Live long and be precise: Landsat-9 must have sufficient redundancy to ensure the collection of science-grade data over a 5-year mission life. This means that many critical components have a redundant counterpart to minimize the risk of a single point failure. For example, Class B missions like Landsat-9 typically have two of almost every kind of electronics on board (e.g., spacecraft computers, communications electronics, attitude control electronics, instrument control electronics), extra reaction wheels, and extra thrusters. In the event that some primary piece of equipment on the satellite experiences an anomaly that impacts its performance, ground controllers can switch over to the backup unit on the satellite to do the job. But implementing redundancy comes at the expense of higher cost and longer development time, and it also tends to make things bigger and heavier. So a critical element of mission design is performing detailed reliability and risk assessments to determine where redundancy might be most beneficial, and then implementing redundancy as efficiently as possible to provide the needed level of reliability.
Launch: Landsat-9, a NASA satellite built to monitor the Earth's land surface, successfully launched on 27 September 2021 at 2:12 p.m. EDT (18:12 UTC) from Vandenberg Space Force Base in California. 41)
A joint mission with the U.S. Geological Survey (USGS), Landsat-9 lifted off on a United Launch Alliance Atlas V rocket from Vandenberg's Space Launch Complex 3E. Norway's Svalbard satellite-monitoring ground station acquired signals from the spacecraft about 83 minutes after launch. Landsat-9 is performing as expected as it travels to its final orbital altitude of 438 miles (705 km).
"Today's successful launch is a major milestone in the nearly 50-year joint partnership between USGS and NASA who, for decades, have partnered to collect valuable scientific information and use that data to shape policy with the utmost scientific integrity," said Secretary of the Interior Deb Haaland. "As the impacts of the climate crisis intensify in the United States and across the globe, Landsat 9 will provide data and imagery to help make science-based decisions on key issues including water use, wildfire impacts, coral reef degradation, glacier and ice-shelf retreat, and tropical deforestation."
Secondary (or rideshare) payloads: Four CubeSats for NASA's 37th Educational Launch of Nanosatellites (ELaNa 37) mission and the Mission Manifest Office at the U.S. Space Force Space Systems Command will begin separating from Centaur at approximately T+plus 2 hours, 14 minutes. The CubeSats are carried on the Evolved Expendable Launch Vehicle Secondary Payload Adapter (ESPA) Flight System, or EFS. It is a ring positioned below the Landsat-9 and above the top of Centaur carrying the four science and national security CubeSats. 42)
ULA's four-meter-diameter metallic payload fairing, built at the company's facility in Harlingen, Tex., protects Landsat-9 and the CubeSats during ascent through Earth's atmosphere. The longest of available Atlas V four-meter fairings will be used, known as the Extra Extended Payload Fairing (XEPF).
• CUTE (Colorado Ultraviolet Transit Experiment), a 6U CubeSat astronomy mission of the University of Colorado at Boulder, Boulder, Colorado.
• CuPID (Cusp Plasma Imaging Detector), a 6U CubeSat space weather science mission of Boston University, Boston Massachusetts.
• CM1 (Cesium Mission 1) of CesiumAstro with two 6U CubeSats (CM1 and CM2), a technology demonstration mission.
Figure 13: The United Launch Alliance (ULA) Atlas V rocket with the Landsat 9 satellite onboard launches, Monday, Sept. 27, 2021, from Space Launch Complex 3 at Vandenberg Space Force Base in California. The Landsat 9 satellite is a joint NASA/U.S. Geological Survey mission that will continue the legacy of monitoring Earth's land and coastal regions (image credit: NASA/Bill Ingalls)
Orbit of Landsat-9: Sun-synchronous near-circular orbit, altitude = 705 km, inclination = 98.2º, period = 99 minutes, repeat coverage = 16 days. The Landsat-9 satellite will be in coplanar orbit with Landsat-8, 180º apart. This reduces the repeat coverage to 8 days.
Figure 14: Flight profile of the Landsat-9 mission (image credit: ULA) 43)
Orbit of secondary (or rideshare) payloads: After deployment of Landsat-9, the Centaur stage will reignite its engine two times to maneuver into a different orbit for separation of four small CubeSat rideshare payloads. The CubeSats will be delivered into a near-circular sun-synchronous orbit of 550 km altitude with an inclination of 97.6º.
After launch, Landsat-9 will move into the current orbit of Landsat-7, which has sufficient fuel to operate into 2021, and will subsequently be decommissioned. Landsat-9 will image the Earth every 16days in an 8-day offset with Landsat-8. Landsat-9 will collect as many as 750scenes per day, and with Landsat-8, the two satellites will add nearly 1,500 new scenes a day to the USGS Landsat archive. Landsat9 will increase the volume of the USGS archive by imaging all global landmasses and near-shore coastal regions, including islands at solar elevation angles greater than 5º that were not always routinely collected prior to Landsat-8 (Ref. 31).
• May 11, 2022: Four years ago this month, Hawaii's youngest and most active volcano experienced its biggest eruption in at least 200 years. The Lower East Rift Zone (LERZ) eruption at Kilauea, which began on May 3, 2018, destroyed 700 buildings and prompted the evacuation of thousands of residents. Scientists are still studying the eruption and its effects. 44)
- The 2018 eruption was large on a global scale, not just for Hawaii. Kilauea emitted up to 1.4 km3 (about 0.34 cubic miles) of lava in just four months. By comparison, the eruption from the Pu'u'o'o vent on the Middle East Rift Zone—which started in 1983 and continued for 35 years—emitted 4.4 km3 (1.1 cubic miles) of lava and destroyed 215 structures.
- The 2018 LERZ eruption also drastically changed the volcano's magma plumbing system. It ended the eruption from the Pu'u'o'o vent, the longest-running eruption in the world. And it collapsed the floor of the Halema‘uma‘u summit crater, lowering it by more than 500 meters (1,600 feet) and draining the lava lake that had pooled in the summit crater since 2008.
- The lava lake was replaced by a water lake in July 2019, an event unprecedented in the historic record. Over the next year and a half, water slowly filled the crater to a depth of about 50 meters (160 feet).
- The water lake was of special interest to scientists because Kilauea has an unusual history of both effusive and explosive eruptions. The latter are usually more violent and destructive, and they are often driven by the interaction of magma with water—a fact that kept volcano observers extra attentive to activity. However, in December 2020, a new phase of eruptive activity began with an influx of lava into the crater that boiled off the water lake in a few hours. That eruption started a new lava lake and continued until May 2021. The latest eruption started in September 2021 and continues today.
Figure 15: The image was acquired on April 15, 2022, by the Operational Land Imager-2 (OLI-2) on Landsat 9. The image includes a combination of visible and infrared light (bands 6-5-3), which helps distinguish the heat signature of the lava (image credit: NASA Earth Observatory image by Lauren Dauphin, using Landsat data from the U.S. Geological Survey. Story by Sara E. Pratt)
• April 13, 2022: Visit a seafood restaurant in western Washington and you will likely see Dungeness crab on the menu. The crustacean got its name from a small town on the north coast of the Olympic Peninsula, where the species was first commercially fished in the mid-1800s. But there is more to the area than just crabs. It is also the site of the longest sand spit in the United States. 45)
Figure 16: The town, the bay, the spit, and its lighthouse—all named Dungeness—are visible in this image, acquired on April 6, 2022, with the Operational Land Imager-2 (OLI-2) on Landsat-9. Before the arrival of Europeans, the S'Klallam indigenous people had named the spit Tsi-tsa-kwick and the bay Tses-kut. British explorer George Vancouver dubbed the area New Dungeness in 1792 because he thought it resembled the Dungeness headland in the English Channel (image credit: NASA Earth Observatory image by Lauren Dauphin, using Landsat data from the U.S. Geological Survey. Story by Kathryn Hansen)
- According to David Parks, a geologist with Washington's Department of Natural Resources, the spit began forming about 5,000 years ago after glacial ice retreated and sea levels stabilized. Sediments naturally erode from bluffs southwest of the spit, drift in the water parallel to the shore, and feed the spit. Scientists estimate that between 1855 and 1985, the spit grew by about 14 feet (4 meters) per year. The spit now measures about 5 miles (8 km) long.
- "Dungeness Spit is a dynamic landform," Parks said. Year-to-year changes are most obvious at spit's eastern end, where the amount of growth reflects the amount of sediment supplied to the spit from the bluffs. (These changes are not especially apparent at the resolution of Landsat satellites.) In some years, storms cause water to temporarily breach the spit, although gaps quickly fill in with new sediment.
Figure 17: The landform is sustained by a steady supply of sediment from nearby bluffs (photo courtesy of David Parks/Washington DNR)
- Sediment can naturally erode from the Dungeness bluffs because they are relatively unarmored--the practice of using huge, car-sized rocks to control erosion. Sediments from bluff erosion provide just the right habitat for the spawning of forage fish—the small fish that become prey for salmon, birds, and whales. Forage fish depend on shorelines with small grains of sand and gravel to deposit their eggs. Armoring a bluff can cause the adjacent beach to become dominated by larger rocks unsuitable for spawning.
- Sediments from erosion are also important for sustaining the spit. "If bluff erosion is limited by shoreline armoring, Dungeness Spit will begin to erode very quickly. That erosion has the potential to impact the Dungeness National Wildlife Refuge and all the resources within Dungeness Bay," Parks said. "Dungeness Spit shelters Dungeness Bay, which has extensive eelgrass beds that support a great variety of marine species including Pacific Herring, and of course, Dungeness crab."
• April 11, 2022: Just over three months into 2022, Sydney, Australia, has already received a year's worth of rain. The recent deluge brought more flooding to the already rain-soaked southern and central coasts of New South Wales, prompting evacuations. 46)
Figure 18: Yet another extreme precipitation event sent rivers out of their banks, inundating coastal towns and prompting evacuations. The ground was saturated and rivers were swollen when the Operational Land Imager-2 (OLI-2) on Landsat-9 acquired these images on April 4, 2022. The ongoing impacts of flooding can be seen in the muddy rivers, inundated land, and sediment plumes draining from rivers along the coast (image credit: NASA Earth Observatory image by Joshua Stevens, using Landsat data from the U.S. Geological Survey. Story by Sara E. Pratt)
Figure 19: On April 7, torrential downpours brought a month's worth of precipitation—more than 100 mm (4 inches) —to parts of the city. The storm pushed rain gauges past 1,223 mm (48 inches) for the year, leaving them 10 mm (0.4 inches) above the mean annual rainfall in early April
- Near the top of image 18, north of Newcastle, a large lobe of brown floodwater has inundated the Hunter Wetlands. A plume of sediment can also be seen discharging from the mouth of the Hunter River and flowing along the beach in Worimi National Park. Sydney and its harbor can be seen at the bottom left of the image. North of Sydney are the brown, sediment-laden waters of the Hawkesbury River, which is seen in more detail in the image of Figure 19.
- The Hawkesbury River originates to the west, where the Colo and Nepean rivers join. Areas of the Hawkesbury-Nepean Valley were some of the hardest hit in the March 2022 floods, which left thousands of homes damaged and uninhabitable.
- Several climate systems influence Australia's weather. The El Niño Southern Oscillation (ENSO), a coupled atmospheric and ocean circulation pattern in the tropical Pacific. It is currently in its La Niña phase, which typically brings more rain and cooler temperatures to eastern Australia. The Southern Annular Mode (SAM) describes the north or south movement of strong westerly winds in the Southern Hemisphere. With the winds farther south, the SAM has recently been in a positive phase, which increases rainfall in eastern Australia in the summer. The interaction of the two climate modes exacerbates the amount of moisture in the atmosphere available for precipitation, according to research by team at Australian National University, CSIRO, and the University of New South Wales.
- The extreme precipitation in the summer of 2021–22 comes after a three-decade period when southeastern Australia has seen an overall decline in rainfall, according to Australia's Bureau of Meteorology. However, the distribution of rainfall throughout the year has also changed, with summer rains intensifying, winter rains decreasing, and the intensity of short-duration, heavy rainfall increasing.
• March 27, 2022: Providencia is officially a territory of Colombia, though it sits closer to the Nicaraguan coast. Spanning about 17 square kilometers (7 square miles), the island is part of the San Andres archipelago; a small footbridge connects neighboring Santa Catalina Island. The island is one of the centerpieces of the Seaflower Biosphere Reserve, a UNESCO Marine Protected Area noted for its marine biodiversity. The peaks at the center of the island are remnants of an ancient volcano. 47)
- Providencia is officially a territory of Colombia, though it sits closer to the Nicaraguan coast. Spanning about 17 km2 (7 square miles), the island is part of the San Andres archipelago; a small footbridge connects neighboring Santa Catalina Island. The island is one of the centerpieces of the Seaflower Biosphere Reserve, a UNESCO Marine Protected Area noted for its marine biodiversity. The peaks at the center of the island are remnants of an ancient volcano.
- Not much has been written about the indigenous history of the island, but Europeans arrived around the start of the 17th century. Dutch pirates were the first of many generations of privateers to use the island as a safe harbor and launching point for raids on Central America and the Caribbean Islands. In 1631, English pilgrims arrived on the Seaflower (a sister ship to the Mayflower) with hopes for more agricultural success than their fellows to the north in Plymouth, Massachusetts.
- But it was not long before the island was also forcibly populated with indentured servants and slaves. It also wasn't long before Providencia became the site of one of the first known slave rebellions in a British colony. Eventually, control of the island was taken by the Spanish, and then again by pirates such as Henry Morgan. Today, the island is populated by about 5,000 people scattered among seven main villages, with the economy driven by fishing, farming, and limited tourism.
- The volcanic island is surrounded by reefs, and the varying water depths nearby have led some people to call the surrounding area the ‘sea of seven colors.' Old Providence McBean Lagoon is the centerpiece of a national nature park with tropical dry forests and mangroves onshore, and coral reefs, cays, and lagoons offshore. More than 150 bird species have been reported in the park, including frigate birds. Between April and June, the island pauses for a vast migration of black land crabs (Gecarcinus ruricola), which march down from the central hills toward the sea to lay their eggs.
- Late in 2020, Providencia was severely damaged by category 5 Hurricane Iota, an intense storm that wiped out most of the island's homes and infrastructure. By November 2021, about half of the homes had been rebuilt, and local leaders were hoping to re-open the island to tourism sometime in 2022.
Figure 20: Once a sanctuary for pilgrims and privateers, the Caribbean island is now a refuge for a quiet Caribbean life and raw natural beauty.. Situated in the southwestern Caribbean Sea, Providencia was once an island sanctuary for pilgrims and privateers. Today, it is mostly a refuge of quieter Caribbean life amid raw natural beauty. The Operational Land Imager-2 (OLI-2) on Landsat-9 acquired this image of it on January 9, 2022 (image credit: NASA Earth Observatory image by Joshua Stevens, using Landsat data from the U.S. Geological Survey. Story by Michael Carlowicz)
• March 21, 2022: For at least a thousand years, humans have been the biggest agent of geologic change on the planet. Through agriculture and mining—and the resultant erosion they cause—humans move more earth than all natural agents of erosion (wind, water, and ice) combined. 48)
- In Scotland's West Lothian region, roughly halfway between Edinburgh and Glasgow, the effects of more than a century of mining are still highly visible in the form of 19 large spoils heaps. Locally called bings, these piles of waste rock are remnants of shale mining that occurred between 1851 and 1963. The tallest bing rises 95 meters (310 feet) above the surrounding land.
- Construction of the Five Sisters, also called the Westwood Bing, began during World War II. It owes its large size and unique five-fingered shape to the introduction of motorized conveyor belts and carts on rails to haul and tip the spoils. This mechanization produced longer, higher, and steeper bings.
- The shale became a valuable fuel source when Scottish chemist James Young discovered and patented a process to distil kerosene, or paraffin oil, from the oily rocks. Kerosene was a welcome replacement for whale oil, which was then the primary source of lamp fuel.
- The oil shales formed during the Carboniferous Period, about 340 million years ago, when Scotland lay near the equator. The land that would become West Lothian was then a shallow coastal plain that periodically flooded. This formed an ancient lake that was cut off from mixing with the ocean. When that happened, ancient Lake Cadell stratified, and massive algal blooms thrived in the oxygenated surface waters. When the algae died, it sank to the oxygen-starved lake bottom, where it built up thick mud deposits. Over time, this organic-rich mud was buried, compressed, and heated, forming oil shales.
- Since the mining era ended here in the 1960s, efforts to manage and remediate the bings have varied depending on their ownership and soil chemistry. Early attempts to beautify some with ornamental plantings often failed to take root. Later attempts, focusing on the unique ecology of the sites, helped cultivate more biodiverse ecosystems that have been turned into parks and recreational spaces. The bings, once seen as a blight on the land, are now distinctive local landmarks, as well cultural and historical attractions on West Lothian's Shale Trail, a walking and cycling route.
Figure 21: One of the largest bings in area is the Five Sisters Bing in the village of West Calder south of Blackburn. The bing, which rises to a height of 73 meters (240 feet), is shown in this image acquired on March 8, 2022, by the Operational Land Imager-2 (OLI-2) on Landsat 9 (image credit: NASA Earth Observatory image by Joshua Stevens, using Landsat data from the U.S. Geological Survey. Story by Sara E. Pratt)
• February 25, 2022: Another blast of winter weather passed over the eastern United States in mid-February 2022. Though the storm was less substantial than the nor'easter in January, it managed to drop enough snow to accent parts of the Appalachian Mountains. 49)
- According to the National Weather Service, snowfall on February 13 was the heaviest in Rockbridge and Bath counties, where as much as 5 inches (13 cm) had accumulated. Warm ground caused some of the snow to melt away by the afternoon, but cold air temperatures over the next few days helped some snow persist through February 15, when Landsat 9 passed over. The ground appears bare in the town of Goshen and along some of the river valleys.
Figure 22: This image, acquired on February 15, 2022, by the Operational Land Imager-2 (OLI-2) on Landsat 9, shows the snowy ridges and valleys in western Virginia (image credit: NASA Earth Observatory images by Joshua Stevens, using Landsat data from the U.S. Geological Survey. Story by Kathryn Hansen)
- Areas to the north also received a dusting of white. This image shows Jennings Randolph Lake, located about 100 miles (160 km) north of Goshen. The lake spans a 5.5-mile length of the North Branch of the Potomac River, along the border of Maryland and West Virginia. The lake formed following construction of a dam in 1982. The dam was designed to control flooding, dilute pollution downstream, supply drinking to the Washington D.C. area during drought, and provide recreation.
- The climate in this part of the Appalachians is generally less harsh than areas in the northern part of the range. Still, winter can bring cold temperatures and heavy snowfall. Notice that almost half of the reservoir is frozen over.
Figure 23: Part of the Shenandoah Valley is visible in the southeast (image credit: NASA Earth Observatory)
• February 25, 2022: To celebrate the recent data release from Landsat-9, this week we take a closer look at a part of Washington state – the northwesternmost state of the US – through the lens of Landsat-9. 50)
- Data from Landsat-9, which was launched in September 2021, is now publicly available for users and researchers across the world. The satellite will continue the programme's critical role in monitoring, understanding and managing the land resources needed to sustain human life.
- A partnership between NASA and the US Geological Survey, the satellite carries two science instruments, the Operational Land Imager 2 (OLI-2) and the Thermal Infrared Sensor 2 (TIRS-2). The OLI–2 captures observations of the Earth's surface in visible, near-infrared, and shortwave-infrared bands, and TIRS-2 measures thermal infrared radiation, or heat, emitted from Earth's surface.
- Columbia River, the largest river in the Pacific Northwest, is visible in the top of the image in black. The river rises in the Rocky Mountains of British Columbia, Canada, flows through Washington and Oregon, before emptying into the Pacific Ocean. The river is one of the world's greatest sources of hydroelectric power and, with its tributaries, represents a third of the potential hydropower of the United States.
- As water absorbs a fair amount of radiation, water bodies, such as the Columbia River, appear black in the image. However certain icy water bodies dotted in the left of the image can be seen in turquoise as ice reflects less in the near-infrared channel than in the visible part of the spectrum.
- The Landsat series is part of ESA's Third-Party Missions programme which consists of almost 50 satellite missions, and also forms part of ESA's Heritage Space programme.
Figure 24: This false-colour image, captured on 12 February 2022 by Landsat-9, has been processed using the satellite's near-infrared channel. This channel is frequently used to highlight vegetation, which is particularly evident in the lower half of the image. Fields that are currently cultivated can be seen in bright red, while unvegetated areas appear in green and brown. Circular shapes, predominantly in the bottom-left, are centre-pivot irrigation fields – where equipment rotates around a central pivot and crops are watered with sprinklers. Washington is a leading agricultural state, with the top crops being apples, milk, potatoes and wheat. This image is also featured on the Earth from Space video programme (image credit: USGS/NASA Landsat/ESA)
• February 20, 2022: The Willamette Valley in Oregon is rich with farms and orchards, home to 70 percent of the state's population, and dotted with more than 500 wineries. But all of that can disappear under a blanket of white when the valley fills in with fog, as it has several times in recent weeks. 51)
- Fog is common in the region in the autumn and winter, as moist Pacific air moves inland, cools, and sinks into the vast valley between the Cascade Mountains and the Oregon Coast Range. As that air gives up its heat to the upper atmosphere, the layer near the surface becomes saturated and essentially forms clouds at ground level.
- Such fog has been locked in the Willamette Valley for several long stretches in January and February 2022 due to temperature inversions, where warm air high in the atmosphere moved in over the cooler, denser air in the lowlands. Normally, temperatures are warmer at the land surface, cooling higher up in the sky. This allows for most of the rising air and pollutants to continue to disperse out into the atmosphere. But an inversion acts like an atmospheric "lid" that can trap moisture and air pollution in a valley for days.
- Fog is essentially a low-lying cloud composed of tiny water droplets suspended in the air. As nights lengthen with the season, the atmosphere has more time to cool down and approach the dew point—the temperature at which the air becomes saturated and water vapor condenses into fog. Since cold, moist air is denser than warm air, it sinks and drains into valleys, meaning fog develops there first. Many valleys like the Willamette also have rivers and streams that amplify the fog with a ready supply of moisture.
- Fog can pose serious risks for drivers. Fog-related traffic accidents typically cause more deaths in the United States each year than other high-profile weather events like heat waves, tornadoes, and floods, according to data from the National Weather Service and the Federal Highway Administration. The foggiest parts of the United States, including Oregon, see dense fog at least 40 days per year.
- Oregon has already seen at least three extended periods of valley fog in 2022, as observed by the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA's Terra satellite from February 8-12, January 22-29, and January 14-17.
Figure 25: On February 10, 2022, the Operational Land Imager-2 (OLI-2) on Landsat-9 acquired this natural image of fog in the Willamette Valley (image credit: NASA Earth Observatory images by Joshua Stevens, using Landsat data from the U.S. Geological Survey. Story by Michael Carlowicz and Adam Voiland)
Figure 26: This is a false-color view of thick fog in the Willamette Valley. The false-color image was composed from SWIR (Shortwave infrared, near-Infrared), and red light (OLI-2 bands 6-5-4). Scientists turn to these wavelengths to distinguish clouds (white and pink) from snow and ice (cyan), image credit: NASA Earth Observatory
• February 18, 2022: Amidst a record-setting heatwave and ongoing drought, northeastern Argentina has been experiencing widespread wildfires. In late January 2022, more than a thousand fires were burning around Corrientes province, a predominantly rural and agricultural region that has seen little to no rain in two months. Since the fires began in December, more than 520,000 hectares (1.3 million acres) have burned, killing wildlife and livestock, decimating pasturelands, and destroying crops such as yerba mate and rice. 52)
- On February 7, 2022, the governor of Corrientes declared a state of emergency and an agricultural disaster, retroactive to January 1. The same day, the National Institute of Agricultural Technology (INTA) estimated that the fires had affected roughly 6 percent of the province, which lies between the Paraná and Uruguay rivers near the border with Paraguay.
- Drought began in November 2021 and has continued into February, as Argentina experiences its second La Niña summer. During La Niña events, clouds and rainfall become more sporadic over the central and eastern Pacific Ocean, which can lead to dry conditions in Brazil, Argentina, and other parts of South America. Corrientes, which normally averages 162 millimeters (6.5 inches) of rain during February, has received less than 20 millimeters (1 inch) so far, according to the National Meteorological Service (SMN).
- The dry conditions have been exacerbated by extreme heat across central South America, as temperatures repeatedly approached or surpassed 40° Celsius (104° Fahrenheit). On January 11, ground stations in Buenos Aires recorded a temperature of 41.1°C (106°F)—the city's second-hottest day on record, according to SMN.
- On February 10, Argentina's Secretary of Environmental Control and Monitoring travelled to Corrientes to announce a coordinated response with provincial and local authorities to provide more equipment, including hydrant planes, helicopters, firefighters, and support personnel to help fight the fires.
Figure 27: The images, acquired by the Operational Land Imager-2 (OLI-2) on Landsat-9 on February 16, 2022, show the scorched fields and heavy smoke from the multiple wildfires still burning near Iberá National Park (image credit: NASA Earth Observatory images by Lauren Dauphin, using Landsat data from the U.S. Geological Survey. Story by Sara E. Pratt)
Figure 28: Detail image of Landsat-9 observed on 16 February 2022 (image credit: NASA Earth Observatory)
• February 12, 2022: Passes will be flying this weekend in Los Angeles at the Super Bowl, one of the most watched sporting events each year in the United States. Earlier this week, one of the science community's newest satellites also flew over LA, continuing 50 years of watching the city—and the planet—from above. 53)
- NASA launched Landsat-9 in September 2021 from the Vandenberg Space Force Base, about 150 miles (240 km) up the road from Los Angeles. The satellite took its "first light" images on October 31, and mission operators have since been testing the satellite's systems and subsystems and calibrating its instruments. In late January 2022, NASA transferred operation of Landsat-9 to the U.S. Geological Survey (USGS).
- On February 10, USGS announced that Landsat-9 data is now available for free download from EarthExplorer, Machine to Machine (M2M), and LandsatLook. Since October 31, 2021, Landsat 9 has collected more than 57,000 images of Earth. The images will be processed, archived, and distributed from the USGS Earth Resources Observation and Science Center.
Figure 29: On February 7, 2022, the Operational Land Imager-2 (OLI-2) on Landsat-9 acquired these natural-color views of the Los Angeles area. The Super Bowl, the championship of American football, will be played in SoFi Stadium in Inglewood, California. It will be the eighth time the Los Angeles area has hosted the Super Bowl, but the first since 1993 (image credit: NASA Earth Observatory images by Joshua Stevens, using Landsat data from the U.S. Geological Survey. Story by Michael Carlowicz)
Figure 30: Detail image of LA showing the SoFi Stadium (NASA Earth Observatory)
- Landsat-9 carries two main instruments: OLI-2, which detects visible, near-infrared, and shortwave-infrared light in nine wavelengths, and the Thermal Infrared Sensor 2 (TIRS-2), which detects thermal radiation in two wavelengths used to measure Earth's surface temperatures. The new satellite and instruments are quite similar in design to Landsat 8, which was launched in 2013 and remains in orbit. Together the satellites will collect approximately 1,500 images of Earth's surface every day, observing the entire planet every eight days.
- Landsat-9 features several improvements, including higher radiometric resolution, allowing OLI-2 to detect more subtle differences in surface features, especially over darker areas like water or dense forests. With 14-bit radiometric resolution, Landsat 9 can differentiate more than 16,000 shades of a given wavelength; Landsat-8 provides 12-bit data and 4,096 shades. Landsat-7, the satellite being replaced, detects only 256 shades with its 8-bit resolution.
Figure 31: This image was acquired on February 7 with the TIRS-2 instrument on Landsat-9. It shows land surface temperatures just before a winter heat wave hit Southern California. Temperatures have been 15 to 20 degrees Fahrenheit (8º to 11º Celsius) above normal this week in many parts of California, and several towns and cities (including Burbank) set new daily temperature records in February. The National Weather Service declared a heat advisory for February 9–13. Some forecasters are suggesting this Super Bowl could see some of the warmest game-time temperatures on record (image credit: NASA Earth Observatory)
• November 5, 2021: Landsat-9, a joint mission between NASA and the U.S. Geological Survey (USGS) that launched Sept. 27, 2021, has collected its first light images of Earth. 54)
- The images, all acquired Oct. 31, are available online. They provide a preview of how the mission will help people manage vital natural resources and understand the impacts of climate change, adding to Landsat's unparalleled data record that spans nearly 50 years of space-based Earth observation.
- "Landsat-9's first images capture critical observations about our changing planet and will advance this joint mission of NASA and the U.S. Geological Survey that provides critical data about Earth's landscapes and coastlines seen from space," said NASA Administrator Bill Nelson. "This program has the proven power to not only improve lives but also save lives. NASA will continue to work with USGS to strengthen and improve accessibility to Landsat data so decision makers in America – and around the world – better understand the devastation of the climate crisis, manage agricultural practices, preserve precious resources and respond more effectively to natural disasters."
- These first light images shows Detroit, Michigan, with neighboring Lake St. Clair, the intersection of cities and beaches along a changing Florida coastline and images from Navajo Country in Arizona that will add to the wealth of data helping us monitor crop health and manage irrigation water. The new images also provided data about the changing landscapes of the Himalayas in High Mountain Asia and the coastal islands and shorelines of Northern Australia.
- Landsat-9 is similar in design to its predecessor, Landsat-8, which was launched in 2013 and remains in orbit, but features several improvements. The new satellite transmits data with higher radiometric resolution back down to Earth, allowing it to detect more subtle differences, especially over darker areas like water or dense forests. For example, Landsat-9 can differentiate more than 16,000 shades of a given wavelength color; Landsat-7, the satellite being replaced, detects only 256 shades. This increased sensitivity will allow Landsat users to see much more subtle changes than ever before.
- "First light is a big milestone for Landsat users – it's the first chance to really see the kind of quality that Landsat-9 provides. And they look fantastic," said Jeff Masek NASA's Landsat-9 project scientist at Goddard Space Flight Center. "When we have Landsat-9 operating in coordination with Landsat-8, it's going to be this wealth of data, allowing us to monitor changes to our home planet every eight days."
- Landsat 9 carries two instruments that capture imagery: OLI-2 (Operational Land Imager- 2 ), which detects visible, near-infrared and shortwave-infrared light in nine wavelengths, and TIRS-2 (Thermal Infrared Sensor-2), which detects thermal radiation in two wavelengths to measure Earth's surface temperatures and its changes.
- These instruments will provide Landsat-9 users with essential information about crop health, irrigation use, water quality, wildfire severity, deforestation, glacial retreat, urban expansion, and more.
- "The data and images from Landsat-9 are expanding our capability to see how Earth has changed over decades", said Karen St. Germain, Earth Science Division director at NASA Headquarters in Washington. "In a changing climate, continuous and free access to Landsat data, and the other data in NASA's Earth observing fleet, helps data users, including city planners, farmers and scientists, plan for the future."
- NASA's Landsat-9 team is conducting a 100-day check-out period that involves testing the satellite's systems and subsystems and calibrating its instruments in preparation for handing the mission over to USGS in January. USGS will operate Landsat-9 along with Landsat-8, and together the two satellites will collect approximately 1,500 images of Earth's surface every day, covering the globe every eight days.
- "The incredible first pictures from the Landsat 9 satellite are a glimpse into the data that will help us make science-based decisions on key issues including water use, wildfire impacts, coral reef degradation, glacier and ice-shelf retreat and tropical deforestation," said USGS Acting Director Dr. David Applegate. "This historic moment is the culmination of our long partnership with NASA on Landsat-9's development, launch and initial operations, which will better support environmental sustainability, climate change resiliency and economic growth – all while expanding an unparalleled record of Earth's changing landscapes."
- Landsat-9 data will be available to the public, for free, from USGS's website once the satellite begins normal operations.
- NASA manages the Landsat-9 mission development. Teams from NASA's Goddard Space Flight Center in Greenbelt, Maryland, also built and tested the TIRS-2 instrument. NASA's Launch Services Program, based at the agency's Kennedy Space Center in Florida, managed the mission's launch. The USGS Earth Resources Observation and Science (EROS) Center will operate the mission and manage the ground system, including maintaining the Landsat archive. Ball Aerospace in Boulder, Colorado, built and tested the OLI-2 instrument. United Launch Alliance is the rocket provider for Landsat-9's launch. Northrop Grumman in Gilbert, Arizona, built the Landsat- 9 spacecraft, integrated it with instruments, and tested it.
Figure 32: The first image collected by Landsat-9, on Oct. 31, 2021, shows remote coastal islands and inlets of the Kimberly region of Western Australia. In the top middle section of the image, the Mitchell River carves through sandstone, while to the left Bigge Island and the Coronation Islands stand out in the Indian Ocean. Australia is a major international partner of the Landsat-9 program, and operates one of the Landsat Ground Network stations in Alice Springs (image credit: NASA/USGS, Michael Bock)
Figure 33: The city of Kathmandu, Nepal, seen at the bottom left of this Landsat-9 image, lies in a valley south of the Himalayan Mountains between Nepal and China. Glaciers, and the lakes formed by glacial meltwater, are visible in the top middle of this image. In High Mountain Asia, many communities rely on meltwater from glaciers – and Landsat can help track how those glaciers are changing in a warming climate. Previous studies with Landsat have documented shrinkage of Himalayan glaciers, as well as changing lake levels the adjacent Tibetan plateau. From Oct. 31, 2021, the first day of data collection for Landsat-9 (image credit:NASA/USGS, Michael Bock)
Figure 34: Landsat 9 carries two instruments designed to work together to capture a broad range of wavelengths: OLI-2 (Operational Land Imager-2), which detects nine different wavelengths of visible, near-infrared and shortwave-infrared light; and TIRS-2 (Thermal Infrared Sensor-2), which detects two wavelengths of thermal radiation to measure slight changes in temperature. Data from both instruments are shown in the two pairs in this image. — The top left shows snow and glaciers in the Himalayan mountains, leading to the flat Tibetan Plateau to the north. The top right shows the same area in thermal data from the TIRS-2 instrument. Blue-white color indicates relatively cooler surface temperatures, while orange-red indicates warmer surface temperatures. — The bottom left shows the brown and green rectangles of farm fields in southern Ontario, sandwiched between Lake Erie and Lake St. Clair. The white and grey rectangles in the bottom of the image are produce greenhouses, which show up as blue-ish (relatively cooler) spots in the TIRS-2 image on the right (image credit: NASA/USGS)
Figure 35: Sediments swirl in Lake Erie and Lake St. Clair in this Landsat 9 image of both Detroit, Michigan, and Windsor, Ontario, from Oct. 31, 2021. The Great Lakes serve as sources of freshwater, recreational activity, transport, and habitat for the upper-midwestern United States, and water quality remains a high priority. In warmer months, Landsat-9 observes swirls of green algae which can become harmful algal blooms. Landsat-9 will be able to help scientists and resource managers identify those blooms early, identifying areas to test further (image credit: NASA/USGS, Michael Bock)
Sensor complement (OLI-2, TIRS-2)
The two NASA science instruments are OLI-2 and TIRS-2. OLI-2 is being constructed by BATC (Ball Aerospace & Technology Corp.), while TIRS-2 is being developed by NASA's Goddard Space Flight Center.
Landsat-9 will fly near-identical copies of the OLI (Operational Land Imager) and TIRS (Thermal Infrared Sensor) instruments that were flown on Landsat-8. The TIRS instrument will be upgraded to a risk class B implementation, whereas no changes are planned for OLI. With respect to the Landsat-9 project, these instruments will be referred to as OLI-2 and TIRS-2.
In the four+ decades since Landsat-1 launched, the spectral bands of the Landsat satellites have evolved. Landsat-9, like Landsat-8, has the most evolved of the Landsat spectral bands. 55)
In 1972, Landsat-1 launched with a three-band RBV (Return Beam Vidicon) camera system and a secondary four-band digital MSS (Multispectral Scanner System). The MSS with its scanning mirror whisking back and forth to create an image, seemed to many researchers of the period the antithesis of the high quality camera systems traditionally used in aerial studies. But the secondary MSS instrument proved itself the imaging powerhouse producing superior data. But the four-band MSS was spectrally coarse; it essentially mimicked the color infrared films that became widely used during WWII (World War II).
For follow-on sensors, Landsat management brought together scientists from diverse fields to discuss and recommend spectral channels most useful for answering questions in their research areas. These discussions informed the more sophisticated TM (Thematic Mapper) sensor with its seven spectral bands that flew on the Landsat missions-4 and -5. The Landsat TM band placement has subsequently guided all successive Landsat sensors and is is also echoed in almost all modern passive remote sensing systems—domestic, international, public, commercial, and even those circling about other planets.
Figure 36: MSS aboard Landsats 1–5 had four bands. TM (Thematic Mapper) aboard Landsats-4 & -5 had seven bands. Landsat-7's ETM+ (Enhanced Thematic Mapper Plus) has 8 bands and Landsats-8 &-9 have 11 bands. The atmospheric transmission values for this graphic were calculated using MODTRAN for a summertime mid-latitude hazy atmosphere (circa 5 km visibility), image credit: NASA
Today, Landsat-8 has and Landsat-9 will have eleven spectral bands acquired by the OLI/TIRS and OLI-2 / TIRS-2 instruments, respectively. These new bands help scientists measure high, thin clouds and water quality.
The previous generation sensor, ETM+, supports 8-bit data products, which means means the brightest to the darkest pixels are discriminated with 256 data values. The greater sensitivity of OLI, OLI-2, TIRS, and TIRS-2 instruments allow the signal to be discriminated over 4096 data values (12 bits), and the range has been increased to prevent saturation of very bright targets such as snow.
Table 3: Specification of the OLI-2 and TIRS-2 spectral band requirements
OLI-2 (Operational Land Imager-2)
OLI-2 will continue observations in the visible, near infrared, and shortwave infrared portions of the electromagnetic spectrum and includes two new spectral bands, one of which is designed to support monitoring of coastal waters and the other to detect previously hard to see cirrus clouds that can otherwise unknowingly impact the signal from the Earth's surface in the other spectral bands. 56)
The spatial resolution of its images will be 15 m for the panchromatic band and 30 m for the multispectral bands. The image swath will be 185 km wide, covering wide areas of the Earth's landscape while providing sufficient resolution to distinguish land cover features like urban centers, farms, and forests. Landsat-9's near-polar orbit precesses at the same rate the Earth rotates around the sun, allowing the entire Earth to fall within view every 16 days at the same local solar time.
OLI-2 will, to the extent possible, be a copy of OLI for Landsat-9 to maintain data continuity with Landsat-8 and to minimize cost and risk (Ref. 2).
Figure 37: A diagram of OLI-2 showing its main components (image credit: NASA)
Instrument design: The OLI-2 is a pushbroom sensor. Its focal plane features long arrays of photosensitive detectors. Incident radiation is focused onto the focal plane by a four-mirror anastigmatic telescope. OLI-2 has a 15ºFOV covering a 185 km across-track ground swath.
Landsat-9's photosensitive detectors are divided into 14 modules. There are ~7000 across-track detectors for each OLI-2 spectral band, except the 15 m panchromatic band that has 13,000 detectors. Each spectral band has a specific filter; together the filters are arranged like a "butcher-block" over each module's detector array. The visible and near-infrared detectors are made from Silicon PIN (SiPIN). The shortwave infrared detectors are made from Mercury–Cadmium–Telluride (MgCdTe).
The OLI-2 telescope will view the Earth through its Earth-view baffle. There is a shutter wheel assembly between the Earth-view baffle and the aperture stop. Light enters the telescope via a hole in the shutter wheel during nominal observations. The solar-view baffle is occasionally pointed at the sun so that a diffuser panel can reflect solar illumination into the telescope for calibration purposes. Two lamp assemblies with six small lamps each inside an integrating hemisphere can illuminate the full OLI-2 focal plane through the telescope with the shutter closed as another component of the OLI-2 calibration subsystem.
Figure 38: Drawing of the OLI-2 focal plane showing the 14 detector modules; the "butcher-block" filters are the striped black boxes where the upper and lower detector modules meet (image credit: BATC)
TIRS-2 (Thermal Infrared Sensor-2)
TIRS-2 will be a rebuild of the Landsat-8 TIRS except TIRS-2 will be upgraded to Risk Class B for Landsat-9. The primary Risk Class B improvements are (Ref. 2):
• Redundant MEBs (Main Electronics Boxes)
• Redundant CCEs (Cryocooler Electronics)
• Redundant RSEs (Switch Electronics).
Other TIRS-2 improvements:
• Improved stray light performance through improved telescope baffling
• Improved position encoder for scene select mirror to address problematic encoder on Landsa- 8 TIRS
• Improved thermal blanketing to better protect from micrometeorite impact; in accordance with new GSFC guidelines.
The TIRS-2 instrument is a two-band thermal imaging sensor with a push broom sensor (like OLI-2). Its focal plane has long arrays of photosensitive detectors.
The instrument features a four-element refractive telescope that focuses an f/1.64 beam of thermal radiation onto a focal plane that is cryogenically cooled. TIRS-2 has a 15º FOV to match the 185 km across-track swath of OLI-2. The TIRS-2 focal plane holds three modules with QWIP (Quantum Well Infrared Photodetector) arrays arranged in an alternating pattern along the focal plane centerline.
Spectral filters cover each focal plane module to create TIRS-2's two specified bandwidths. Each QWIP array is 640 detectors long in cross-track allowing for overlap between the arrays to produce an effective linear array of 1850 pixels spanning across the 185 km ground swath.
The FOV is flipped between nadir (Earth) and both an internal blackbody and a deep space view used for on-orbit radiometric calibration using a mirror controlled by a scene select mechanism. This allows the view to be changed without changing the nominal Earth-viewing attitude of the Landsat-9 spacecraft.
A two-stage mechanical cryocooler will cool TIRS-2's focal plane. This permits the QWIP detectors to function at their required temperature of 43 K (-230° C). There will be two radiators mounted to the side of the TIRS-2 instrument structure. One dissipates heat from the cryocooler and the other passively maintains a constant TIRS-2 telescope temperature of 185 K (-88° C).
Figure 39: A diagram of TIRS-2 showing its main components (image credit: NASA)
Figure 40: Left: The TIRS-2 focal plane: the 3 squares in the center of the circuit board are QWIPs. Each QWIP can measure 327,680 pixels. The QWIPs on TIRS-2 will detect two narrow segments of the thermal infrared spectrum. Right: The TIRS-2 cryocooler will look like the one above (image credit: NASA)
On November 30 – December 1, 2016, the USGS EROS hosted the Landsat-9 GSRR (Ground System Requirements Review) in Sioux Falls, SD (South Dakota). This was the first in a series of major project reviews for Landsat-9, which is scheduled for launch in December 2020. The GSRR included presentations given to a joint NASA/USGS review panel on the proposed components of the Landsat-9 Ground System. At the conclusion of the review, the panel approved the Landsat-9 Ground System team to proceed to the PDR (Preliminary Design Review) stage. 57)
Figure 41: Landsat-9 operations concept architecture - identical to Landsat-8 (image credit: USGS)
The ground segment consists of the following elements (Ref. 3):
1) MOC (Mission Operations Center) with the following functions: Command & telemetry, Trending & analysis, Flight dynamics, Science acquisition planning, Primary and backup MOCs at GSFC.
- FOT (Flight Operations Team) performs mission planning and scheduling, command and control, health and status monitoring, orbit and attitude maintenance, mission data management.
- NASA provides MOC and BMOC facility at GSFC as well as NASA institutional services (SN, NEN, NISN, FDF) through on-orbit acceptance.
2) Operations Flight Operations Team:
- NASA leads (USGS supports) mission operations readiness activities, pre-launch, launch and early orbit activities.
- USGS leads operations following on-orbit acceptance.
3) DPAS (Data Processing and Archive System) with the following functions: Provides data ingest, product generation, & image assessment/processing, User Portal web interface for data discovery, product selection & ordering (for Cal/Val), & product distribution Storage and archive services.
- DPAS facility at USGS EROS Center.
4) GNE (Ground Network Element) with the following functions: Ground stations/antennas for X-band image & S-band telemetry data downlink; Generation of S-band command uplink.
- LGN (Landsat Ground Network) stations provide X- and S-band communications with the Observatory.
- LGN stations in Sioux Falls, SD; Fairbanks, AK; and Svalbard, Norway.
- DCRS (Data Collection and Routing Subsystem) gathers mission data from LGN stations into complete intervals to transfer to the DPAS.
Figure 42: USGS/EROS facilities in Sioux Falls, SD (image credit: USGS)
Development status of Landsat-9 Ground Segment
• February 19, 2019: The Landsat-9 Ground System development team members executed the first of a series of GRTs (Ground Readiness Tests) this week as they successfully simulated the communication of command and telemetry data between the GNE (Ground Network Element) at EROS and the LMOC (Landsat Multi-Satellite Operations Center) at the Goddard Space Flight Center. 58)
- In what was called GRT One, ground system engineers and operations team members used simulators to test the ability of the LMOC system and GNE system to talk with each other, communicating both simulated commands for actions by the spacecraft, but also retrieving and sharing with each other simulated telemetry data related to the health and safety of the satellite.
- The GNE is the element of the ground system that includes the hardware, software, and networks necessary to receive data from the spacecraft. It relies on a variety of ground stations around the globe to assist with those communications, though this week's test focused only on the station at EROS and the LMOC.
- The LMOC is an element of the ground system as well. It receives and monitors spacecraft telemetry, ensures its health and safety, and sends commands to the satellite. While the LMOC utilizes some of the Landsat-8 software subsystems, the LMOC is new, and this initial test is a significant accomplishment for the incremental delivery of the Landsat-9 ground system.
- That the exercise was a success didn't surprise Brian Sauer, the USGS EROS Landsat-9 Project Manager. A significant amount of effort and preparation went into the test. The two elements conducted lower-level tests to verify their associated requirements. Following element tests, the system was installed into the operations environment, and L-9 Ground System staff conducted a series of Interface Connectivity Tests to ensure the systems could communicate with each other, commands could be sent, and data were able to flow. That was followed by several dry runs in January, and a Test Readiness Review conducted Feb. 8, Sauer said.
- "We know what requirements are supposed to be verified from the tests, and we completed dry runs for the tests. So, if the run for the record (for the GRT) would not have been a success, that would have been a surprise," he said.
- The test wasn't only about verification; it was also an early training opportunity for staff members who will operate the system. The test is conducted by ground system Integration and Test (I&T) engineers and executed by the staff who will operate the system when interfacing with the satellite. In fact, to the extent possible, it follows the "test as you fly" principle—operators run the system as they would when the spacecraft is in flight.
- GRT One also included Quality Assurance monitors who ensured that processes and procedures were correctly followed for the test, and that documentation was appropriate for those processes and procedures.
- Sauer said GRT One only covered initial commanding and did not include the full command suite. The additional tests will take place in upcoming GRTs, the next which is penciled in now for August. GRTs are expected to be ongoing for the next 14 months, he said. "The success of this GRT truly is a credit to the all of the people on the Landsat-9 Ground System team," Sauer said. "Contractors, government, everyone... it really is a team effort."
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The information compiled and edited in this article was provided by Herbert J. Kramer from his documentation of: "Observation of the Earth and Its Environment: Survey of Missions and Sensors" (Springer Verlag) as well as many other sources after the publication of the 4th edition in 2002. - Comments and corrections to this article are always welcome for further updates (email@example.com).
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