COPPER (Close Orbiting Propellant Plume and Elemental Recognition) CubeSat
COPPER is a CubeSat mission of SSRL (Space Systems Research Laboratory) at Saint Louis University (SLU), Saint Louis, MO, USA. The purpose of the COPPER experiment is to study the use of a microbolometer array in LEO (Low Earth Orbit) for taking infrared images of propulsion system plumes as well as Earth's atmospheric and oceanic conditions. The goals are to: 1) 2)
• Imaging mission: Flight-test the abilities of a commercially available compact uncooled microbolometer array to take infrared images of Earth’s oceans and atmosphere.
• Radiation mission: Improve the predictive performance modeling of radiation effects on small, modern space electronics devices by collecting radiation particle collision data from electronics monitoring experiments and relaying the data to the ground.
SSRL participated with the COPPER mission in the UNP-6 (University Nanosat Program) competition in January 2011. It was not selected for flight in the UNP-6 program, but it was accepted in NASA's ELaNa-4 launch services program.
The ISDE (Institute for Space and Defense Electronics) at Vanderbilt University (Nashville, TN) has partnered with SSRL (Space Systems Research Laboratory) at SLU to develop Argus, a proposed flight program of perhaps a dozen CubeSat-class spacecraft spanning many years and several launches. The Argus collaboration between SSRL and ISDE is based on overlapping interests: SSRL in space systems engineering research and education, ISDE in radiation-effects modeling and in space-qualifying modern electronics.
The goal of the Argus program is to fly an array of radiation-effects modeling experiments; on-orbit event rates will be compared against ground predictions to help calibrate new predictive models developed at ISDE. Argus leverages COTS (Commercial-off-the-Shelf) CubeSat systems and the extremely simple payload requirements to field a set of very low-cost, very automated passive platforms developed by students at both institutions. 3)
1) The first Argus pathfinder mission is COPPER, carrying a demonstration version of the flight systems (manifested for a 2012 launch)
2) Argus-High, a 2U CubeSat mission, is intended for 550-800 km operations (2013 delivery date)
3) Argus-GTO, a 6U CubeSat mission,will be operating in a geostationary transfer orbit (planned launch in 2014).
The payload-bus interface as well as the spacecraft-ground interface have been designed intentionally to maximize the ability of each institution to meet its objectives.
Radiation-effects modeling: The qualification of advanced integrated circuits (ICs) for spaceflight applications is one of the most significant challenges faced by spacecraft designers. Historically, radiation effects on ICs are determined using ground-based radiation sources; response models are developed from those data and are used to predict the effects of space radiation exposure. This analysis is becoming more and more difficult to implement for several reasons, including:
• The details of the ground test and modeling techniques used by most engineers were developed in the 1980s based on assumptions appropriate for technologies of the time. Recently these techniques have failed to provide accurate reliability and survivability estimates for modern technologies, e.g., Figure 1, yielding predictions that could overestimate or underestimate on-orbit error rates by orders of magnitude. This problem is not restricted to a single radiation environment or device.
Figure 1: Comparison of predicted, observed and adjusted SEU rates for the MESSENGER mission (image credit: ISDE, SSRL)
• Because of increases in IC complexity, ground-based radiation tests of modern ICs are very costly and often result in very limited information about the reliability and survivability of a component. For example, a NASA paper 4) stated that a complete heavy ion SEEs (Single Event Effects) test on a modern memory would take more than 40 days per mode; this device had more than 68 different modes. This type of test requires an unrealistic 7.6 years to perform, and incurs a cost of >$46 M just for the radiation source. The conclusion from  is that exhaustive ground-based radiation-effects testing of modern complex ICs is simply not possible. Engineers are forced to design mission-specific radiation tests, in order to reduce the test matrix and costs dramatically. Radiation effects tests using the smaller test matrix still take months to execute and cost on the order of $400,000, and importantly they are less rigorous. Thus, the mission assumes risk that can’t be completely quantified.
The Argus program is envisioned as more than one or two flights; rather, it is to be a sustained campaign of space experiments spanning many years and many launches. The scope of the project is for a dozen or more satellites to be launched over 6-10 years. No such campaign has been attempted previously by a university program (Ref. 3).
Argus concept of operations:
The success of this campaign hinges on the simplicity of the operations concept. The radiation-effects modeling experiments operate continuously and require neither active pointing control nor real-time monitoring from the ground. Although the payloads are monitored continuously to detect radiation events, science data is generated only when an event occurs; depending on the devices being tested, there may be minutes to hours to days between events. Therefore, the data collection requirements are very modest, and there are no time-critical events; it is sufficient that on-board science data “eventually” be relayed to the ground.
Figure 2: Concept of operations of the Argus program (image credit: SSRL, ISDE)
As shown in Figure 2, the fleet of Argus spacecraft will be operated as a network of automated remote-monitoring stations. Spacecraft will be launched as secondaries on any available launch meeting the science orbit profile (typically, above 550 km with inclinations consistent with the ground station network). The spacecraft will be ejected from the P-POD canister and immediately enter safe mode. Once mission control makes contact with the spacecraft and verifies nominal operations, the mission will immediately enter science capture mode; the payloads will be activated and monitored for radiation events. Spacecraft are passively stabilized (if they are stabilized at all) and powered via static solar arrays (nominally body-mounted).
The science mission data consists of the time-tagged radiation event logs: the details of the event plus a state-of-health snapshot (e.g., attitude, thermal state, power consumption); the total data capture for an event is on the order of 1 kbit, with an expectation of only a handful of events per day. Additional engineering housekeeping data will be on the same order of magnitude.
The only way for a team of student volunteers to manage simultaneously between three and twelve satellites is to migrate most operations functions on-board the spacecraft. While the FCC (Federal Communications Commission) regulations require an uplink capability (so that a runaway transmitter can be shut off), Argus vehicles are designed to be contacted rarely, if ever. Again, operational simplicity makes this possible. “Safe mode” on an Argus spacecraft consists of powering down the payloads; there are no other devices to disable, and there is no active attitude control system to manage. On-board telemetry monitoring will respond to threatening conditions such as low battery voltage by entering safe mode and notifying ground operations via the beacon network. In addition, hardware will be designed with latch-up protection and software will include error detection and correction capabilities.
A distributed network of receive-only ground stations will be utilized to capture mission data; this will be similar to the stations currently used by Santa Clara University’s DRCN (Distributed Robotic Control Network) to monitor the NASA/ARC GeneSat/PharmaSat family of CubeSats. The passive receiving stations utilize fixed wide-beam antennas and a remotely-programmable receiver. The stations maintain their own database of spacecraft and orbital elements, and automatically tune to the appropriate frequency to monitor spacecraft as they fly overhead. All received data is logged and automatically relayed over the internet to mission control.
As an event is detected on-board the satellite, the science data processor will automatically assign it a time-tag and a unique serial number. All events will be stored in on-board memory, and the most-recent 24 events will be stored in a communication downlink buffer; data in that buffer will be broadcast on a repeating loop of roughly 1-second data bursts every 5 seconds. Thus, the entire data log will be broadcast every two minutes. Assuming four receive stations distributed across the continental United States and Hawaii, this communications scheme would result in more than 75 complete buffer downlinks per day. As long as there are less than 24 events per day, this communications scheme guarantees that many copies of the science data will be downlinked, allowing for bit-error corrections to be performed on the ground by comparison of each buffer report.
This method is capable of handling more than 24 events per day, but with less certainty that any one event will be broadcast while the Argus vehicle is over a receive station. Still, automated ground station software in mission control will note the skipped serial numbers as the data is received from the receive station network; the missing events will be noted, and at the next convenient pass, ground operators can manually connect to the satellite and retrieve those events from on-board storage.
The timing of beacon broadcasts, the size of the buffer and other communication parameters will be adjustable on-orbit, and thus the architecture can be adjusted based on actual event rates and ground station distribution. The timing of beacons can also be adjusted to account for multiple Argus spacecraft in nearby orbits that might be jamming one another’s transmissions.
Argus spacecraft will be operated until they de-orbit or until on-board components fail. The spacecraft will comply with the U.S. government requirement to de-orbit within 25 years of the end of the mission. The means for de-orbit will vary based on orbit altitude, but may include items such as deployable or inflatable drag panels; the first Argus will use fold-out drag panels. Active systems such as on-board propulsion will be avoided due to the cost and complexity of such systems, and because propulsion systems require much more intensive pre-flight verification in order to fly as a secondary. Any de-orbit mechanism will be activated at the beginning of the mission to ensure that de-orbit is still achieved in the event of a premature on-board system failure.
In summary - the Argus program meets an important need in the space industry: improving our understanding of the effects of radiation on space electronics. Because of CubeSats and their many opportunities for low-cost launch, it is now possible to consider serial spaceflight experimentation in the same way that we think of aircraft flight testing or repeated balloon experimentation. Argus is one such concept, depending on reflights of radiation-effects modeling experiments to advance scientific understanding in the field.
Each Argus vehicle is scoped to fly as a secondary payload; the CubeSat system was selected as the baseline to maximize the possible launches. P-PODs (and their Japanese/Canadian/European analogs) have flown on multiple rockets operated by the US, Russia, India, Japan and Europe. The CubeSat platform is the most cost-effective, schedule-effective means of flying Argus payloads.
At present, the only way for a dozen Argus spacecraft to be launched is if NASA continues to support its ELaNa program, and if the SSRL/ISDE team succeeds in being selected. It is anticipated, however, that after COPPER and Argus-High fly (see below), subsequent Argus missions may also be able to secure flights through the DoD STP (Space Test Program) on the merits of more advanced Independence payloads.
The COPPER mission is SLU's first student-built 1U CubeSat with a 2 W nominal average daily power and mass 1.3 kg. SCARAB (SLU Core Aerospace Research Application Bus) is the 1U CubeSat bus. SCARAB consists of the following elements: 5)
• The PIC24-based CubeSat Kit microcontroller
• The Clyde Space 1U EPS w/Lithium-polymer battery
• Spectrolab triple-junction CIC solar cells (body-mounted)
• The AstroDev Helium-100 UHF/VHF transceiver.
Figure 3: Photo of the COPPER EM (Engineering Model), image credit: SSRL
Figure 4: Schematic view of the COPPER data flow (image credit: SLU, Ref. 2)
Figure 5: Photo of the COPPER CubeSat (image credit: SLU)
Launch: The COPPER CubeSat was launched on Nov. 20, 2013 (01:15:00) as a secondary payload on the ORS-3 (Operationally Responsive Space-3) mission, a joint initiative of several agencies within DoD (Department of Defense). The ORS Office at Kirtland AFB is the manager of the ORS program. The launch site was MARS (Mid-Atlantic Regional Spaceport), located at NASA's Wallops Flight Facility,Wallops Island, VA. The launch vehicle was a Minotaur-1 of OSC (Orbital Sciences Corporation). 6) 7)
Note: The ELaNa-4 CubeSats were originally manifested on the Falcon-9 CRS-2 flight (launch of CRS-2 on March 1, 2013). However, when NASA received word that the P-PODs on CRS-2 needed to be de-manifested, NASA's LSP (Launch Services Program) immediately started looking for other opportunities to launch this complement of CubeSats as soon as possible. 8) 9) 10)
Orbit: Near-circular orbit, altitude of 500 km, inclination = 40.5º.
Secondary Payloads: The secondary technology payloads on this flight consist of 26 experiments comprised of free-flying systems and non-separating components (2 experiments). ORS-3 will employ CubeSat wafer adapters, which enable secondary payloads to take advantage of excess lift capacity unavailable to the primary trial. 11) 12)
NASA's LSP (Launch Services Program) ELaNa-4 (Educational Launch of Nanosatellite-4) will launch eight more educational CubeSat missions. The ELaNa-4 CubeSats were originally manifest on the Falcon-9 CRS-2 flight. When NASA received word that the P-PODs on CRS-2 needed to be de-manifested, LSP immediately started looking for other opportunities to launch this complement of CubeSats as soon as possible. 13)
Table 1: ORS-3 manifested CubeSats & Experiments (Ref. 10)
ORS and CubeStack: 14)
• ORS (Operationally Responsive Space) partnered with NASA/ARC and AFRL to develop & produce the CubeStack
• Multi CubeSat adapter provides “Low Maintenance” tertiary canisterized ride capability
• ORS-3 Mission: Will fly 2 CubeStacks in November 2013. This represents the largest multi-mission launch using a Minotaur I launch vehicle (26 free flyers, 2 experiments).
Figure 6: Illustration of the CubeStack, (consisting of wafers) configuration (image credit: ORS, Ref. 10)
The CubeStack adapter structure is a design by LoadPath and Moog CSA Engineering. 15)
• March 2014: Unfortunately, the project was unable to receive any signals from COPPER. There is still a small possibility that the spacecraft will recover, but it is currently nonoperational. 16)
Sensor/experiment complement: (Tau, Commodore)
The COPPER payload project has the goal of developing a satellite payload for the expressed purpose of taking low-cost infrared images on-orbit.
Tau LWIR camera:
The primary instrument on COPPER is the Tau camera of FLIR Commercial Vision Systems, Inc., Goleta, CA, USA. Tau is a compact uncooled microbolometer array sensitive in the 7-13 µm LWIR band. This will be the first orbital flight of the Tau. In addition to characterizing the Tau’s performance for Earth observation, the project is interested in using the Tau to observe the separation sequence from the launch vehicle. The project assumes that the Tau will capture evidence of thruster plume firing as the plumes interact with the plasma bubble around the vehicles. 17) 18)
Figure 7: Photo of the Tau camera (image credit: FLIR)
FLIR’s Tau is the smallest, lightest, lowest power, longwave thermal camera core in its class. Its fusion of small size, light weight, miniscule power consumption, and outstanding imaging performance makes Tau the ideal thermal camera core for the most demanding applications.
The infrared camera used onboard COPPER is a FLIR Tau 320 uncooled microbolometer array. The Tau camera has a mass of ~70 gram with low power consumption (< 1 W at 5 V). The primary goal of the camera will be imaging Earth; images will be stored on-board to be downlinked to the ground during a station pass. The camera is sensitive in the LWIR (Long Wave Infrared) radiation spectrum, with wavelengths ranging from 7.5 - 13.5 µm. The operating temperature of this camera is -10ºC to +60º C. The camera is rated to withstand a70 g pulse shock and 4.3 g rms random vibration over 8 hours in 3 axes.
Figure 8: Specification of the Tau camera (image credit: FLIR)
Commodore is a radiation experiment of ISDE. The objective of the Commodore payload is to flight-test the bus interface, storage and monitoring electronics that will form the template for ISDE Argus payloads. Commodore is a very small printed circuit board (roughly 40 mm x 80 mm useful area) with two main features: the experiment-management electronics and the experiments themselves. The experiment manager is the interface between the spacecraft bus and the experiments; it performs all payload operations and responds to bus commands. The manager monitors all experiments and captures event data locally.
The Commodore experiment is a set of SRAM memory devices, nominally below the 20 nm scale; the memory will be written in a known matter, and then the state of memory will be periodically polled to look for events. As events occur, they will be time-tagged and stored locally.
The Commodore manager interacts with the COPPER CPU via the standard I2C protocol. The COPPER bus has the ability to activate or deactivate Commodore for power management purposes; similarly, it can adjust the duty cycle of memory monitoring and other operations. When over a ground station, the CPU will retrieve science data from Commodore and downlink.
2) Steve Massey, “COPPER: IR Imaging and Radiation Studies,” Summer CubeSat Developer's Workshop, USU, Logan, UT, August 6-7, 2011, URL: http://mstl.atl.calpoly.edu/~bklofas/Presentations/SummerWorkshop2011/Massey_COPPER.pdf
3) Michael Swartwout, Sanjay Jayaram, Robert Reed, Robert Weller, “Argus: A Flight Campaign for Modeling the Effects of Space Radiation on Modern Electronics,” Proceedings of the 2012 IEEE Aerospace Conference, Big Sky Montana, USA, March 3-10, 2012
4) Kenneth A. LaBel, “Memory Overview-Technologies and Needs,” 2010 NEPP (NASA Electronic Parts and Packaging )Program, Electronics Technology Workshop, Greenbelt, MD, USA, June 23, 2010
6) “Orbital Successfully Launches Minotaur I Rocket Supporting ORS-3 Mission for the U.S. Air Force,” Orbital, Nov. 19, 2013, URL: http://www.orbital.com/NewsInfo/release.asp?prid=1876
7) Patrick Blau, “Minotaur I successfully launches STPSat-3 & record load of 28 CubeSats,” Spaceflight 101, Nov. 20, 2013, URL: http://www.spaceflight101.com/minotaur-i-ors-3-launch-updates.html
8) Garrett Lee Skrobot, Roland Coelho, “ELaNa – Educational Launch of Nanosatellite Providing Routine RideShare Opportunities,” Proceedings of the 26th Annual AIAA/USU Conference on Small Satellites, Logan, Utah, USA, August 13-16, 2012, paper: SSC12-V-5
9) Garret Skrobot, “ELaNA - Educational Launch of Nanosatellite,” 8th Annual CubeSat Developers’ Workshop, CalPoly, San Luis Obispo, CA, USA, April 20-22, 2011, URL: http://mstl.atl.calpoly.edu/~bklofas/Presentations/DevelopersWorkshop2011/21_Skrobot_ELaNa.pdf
10) Peter Wegner, “ORS Program Status,” Reinventing Space Conference, El Segundo, CA, USA, May 7-10, 2012, URL: http://www.responsivespace.com/.../Dr.%20Peter%20Wegner.pdf
11) Peter Wegner, “ORS Program Status,” Reinventing Space Conference, El Segundo, CA, USA, May 7-10, 2012, URL: http://www.responsivespace.com/.../Dr.%20Peter%20Wegner.pdf
12) Joe Maly, “ESPA CubeSat Accommodations and Qualification of 6U Mount (SUM),” 10th Annual CubeSat Developer’s Workshop, Cal Poly State University, San Luis Obispo, CA, USA, April 24-25, 2013, URL: http://www.cubesat.org/images/stories/workshop_media/DevelopersWorkshop2013/Maly_MoogCSA_ESPA-SUM.pdf
13) Garrett Lee Skrobot, Roland Coelho, “ELaNa – Educational Launch of Nanosatellite Providing Routine RideShare Opportunities,” Proceedings of the 26th Annual AIAA/USU Conference on Small Satellites, Logan, Utah, USA, August 13-16, 2012, paper: SSC12-V-5
14) “CubeStack: CubeSat Space Access,” 9th Annual Spring CubeSat Developers’ Workshop, Cal Poly State University, San Luis Obispo, CA, USA, April 18-20, 2012, URL: http://mstl.atl.calpoly.edu/~bklofas/Presentations/DevelopersWorkshop2012/Maly_CubeStack.pdf
15) Joe Maly, “6U Mount for CubeSats on ESPA,” CubeSat 9th Annual Summer Workshop, Logan UT, USA, August 11-12, 2012, URL: http://mstl.atl.calpoly.edu/~bklofas/Presentations/SummerWorkshop2012/Maly_6U_ESPA_Mount.pdf
16) Information provided by Michael A. Swartwout, Saint Louis University.
17) M. Swartwout, S. Jayaram, “The Argus Mission: Detecting Thruster Plumes for Space Situational Awareness”, Proceedings of the 2011 IEEE Aerospace Conference, Big Sky, Montana, USA, March 5-12, 2011
18) “Tau™ - The Smallest, Lightest, Lowest-Power IR Camera Core – Period,” URL: http://www.flir.com/uploadedfiles/Eurasia/MMC/Cores/CC_0013_EN.pdf
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.