Umbra SAR Constellation

Quick facts

Overview

Related Resources

Summary

Mission Capabilities

Each Umbra satellite houses a centre-fed parabolic mesh reflector SAR antenna, designed for high bandwidth and efficiency in order to operate seamlessly from data tasking to delivery. The planned full constellation will harmonise 32 SAR sensors operating in low Earth orbit (LEO) to support critical and persistent observation of the Earth for sectors including intelligence, defence, emergency response, disasters, urban planning, and maritime.

Performance Specifications

The satellites prioritise two imaging modes: Spotlight mode, which facilitates high resolution, multi-look SAR imagery; and Extended Dwell mode, designed for extended observations of fixed targets. Extended Dwell mode facilitates additional imaging capabilities including SAR video, low-noise, and Colour Sub-aperture imagery. Both imaging modes capture 5 km x 5 km scenes as standard, with resolutions as low as 0.25 m.

The Umbra SAR satellites orbit in a Sun-synchronous orbit of 560 km altitude and 97.4-degree inclination. The high agility of the satellites allows for revisit periods less than one hour for latitude bands ± 67 degrees.

Space and Hardware Components

The high agility and dwell capabilities of the Umbra SAR satellites is a result of their ability to squint - the steering of a radar beam to cover different perspectives. Each microsatellite features a 70 kg mass, five year design life, and fits on an Evolved Expendable Launch Vehicle, or EELV, Secondary Payload Adapter (ESPA).

Overview

Umbra is a US-based commercial space company, established in 2015, that offers vertically-integrated services to governments and commercial partners through high spatial and temporal resolution SAR imagery, as well as custom mission solutions. Umbra develops and operates a synthetic aperture radar (SAR) constellation that can deliver high quality SAR imagery for commercial and government customers for rapid, actionable insights. The constellation facilitates critical and persistent monitoring applications across intelligence, defence, emergency response, disasters, urban planning, and maritime domains. 1) 2) 17)

The Umbra constellation is planned to contain 32 satellites, with its first, Umbra-01 launching in June 2021. SAR instruments use a powerful active remote sensing technology that can image through the cover of night, clouds, smoke, and rain, unlike optical instruments which are limited to unobstructed sunlit conditions. This grants SAR imagery the capability to monitor changes persistently and reliably. 3) 16)

Spacecraft

Each Umbra SAR spacecraft has a mass of 70 kg, a five-year design life, and is designed to fit on an Evolved Expendable Launch Vehicle, or EELV, Secondary Payload Adapter (ESPA) ring, making the satellites suitable for rideshare missions at low cost. The satellites have a small stowed size, and a large deployable antenna with high bandwidth, efficiency, and resolution. 2)

The Umbra spacecraft have high agility due to their ability to squint, which involves angling the radar beam to make observations from different perspectives. Squinting permits sustained focused observations of a particular target or scene. 4)

Launch

Orbit

The Umbra SAR constellation orbits in a Sun-synchronous, 560 km orbit, inclined at 97.4 degrees. Umbra achieves an approximate repeat cycle of seven days. Despite this repeat capacity, the satellites’ ability to squint permits observations outside of the observation track, and a rapid revisit time around the globe. 2)

Mission Status

• July 31, 2024: Umbra announced a new service dedicated to developing SAR satellites for customers, leveraging the company’s ‘vertically integrated’ structure. Umbra’s Mission Solutions line aims to offer custom satellite solutions ranging from satellite platforms and payloads to full constellations. 6)
• April 30, 2024: Umbra progressed to phase II of the Defense Advanced Research Projects Agency (DARPA) Distributed Radar Image Formation Technology (DRIFT) programme. The programme aims to advance satellites flying formation and data collection techniques with Umbra SAR satellites. Developments in Umbra’s SAR capabilities offer the US Government with new radar opportunities and applications. 7) 8)

Phase II of the programme will involve a multi-month data collection campaign, consisting of bistatic and multistatic datasets for DARPA analysis. Phase II will conclude with a dedicated in-orbit demonstration of Umbra’s multistatic capabilities.

• March 7, 2024: Umbra announced the upcoming release of bistatic SAR imagery, from the constellation’s first tandem pair of satellites, Umbra-07 and -08, which launched in November 2023. Umbra plans to release the remainder of the planned 32-satellite constellation in pairs, which would form a cluster formation capable of multistatic SAR imaging. These enhanced capabilities will serve applications for surveillance, elevation modelling, high resolution imaging, and moving target indication. 9)

Bistatic SAR involves using a spatial separation between the instrument’s transmitter and receiver, which reduces the risks of jamming and creates interferometric applications, known as InSAR. InSAR is a crucial tool for monitoring dynamic events like Earthquakes and for automatic target detection and classification. 10)

Read more about InSAR here.

• March 1, 2024: Umbra announced the free and public release of over 3,000 SAR images in the last year. Since the company’s Open Data Programme’s launch in March 2023, over $4 million of SAR imagery has been released to the public for free. 11)
• October 2, 2023: Umbra was selected as a provider for NASA’s Commercial Satellite Data Acquisition (CSDA) programme, in a five-year contract to acquire SAR data for NASA research. Umbra offers the highest commercially-available SAR imagery, providing NASA with all-weather and time imagery for augmentation with NASA’s existing data collection. 12)
• September 4, 2023: Umbra announced a new partnership with European Space Imaging (EUSI), to develop high resolution optical and SAR European remote sensing products. Optical and SAR imagery around Europe and North Africa at 30 cm and 25 cm resolutions, respectively, can be accessed from one source. EUSI can now harmonise optical and SAR data to guarantee acquisitions irrespective of weather or time of day. This collaboration will develop the companies’ capabilities for emergency response, maritime, and defence applications. 13)
• August 7, 2023: Umbra acquires the highest resolution commercial SAR satellite image, at an astonishing 16 cm x 16 cm. This resolution (as of August 2023) will permit observations of the Earth’s surface details with unparalleled accuracy. 14)

• April 18, 2023: Umbra released first light imagery from Umbra-06, which was acquired less than 48 hours after launch. 15)

• June 25, 2021: Umbra successfully launched the constellation’s first satellite, Umbra-01, initially named the Umbra SAR 2001 radar-imaging microsatellite, onboard SpaceX’s Falcon 9 Transporter-2 mission. The mission launched from Cape Canaveral, Florida. 16)

Sensor Complement

Synthetic Aperture Radar (SAR) System

Umbra’s SAR instrumentation is designed for high spatial and temporal resolution imaging applications, which requires a high bandwidth and efficiency in order to operate seamlessly from tasking to delivery. Specifications for the constellation’s SAR instrument are presented in Table 4 below.

Imaging Modes

The Umbra SAR Constellation features imaging modes suited to a variety of observations, with a number of modes in development that will expand the constellation’s capabilities. 3)

Spotlight Imaging

Spotlight imaging is a SAR imaging mode commonly used to make high spatial resolution observations, whereby the beam direction is focused onto the target area as the spacecraft moves in orbit. This mode permits the extraction of fine topographical details from a scene, as the spacecraft squints at a desired viewing angle. The dwell time is governed by the desired ground plane resolution. A longer dwell creates a longer synthetic aperture and therefore a better resolution. 3) 20)

The standard scene size for Umbra spotlight imagery is 5 km x 5 km, with an additional 10 km x 10 km extended scene size product. A typical Spotlight observation will consist of either single, two, or multiple ‘looks’ - the number of acquisitions gathered as the satellite squints over a target. Spotlight imagery is offered at resolutions between 0.25 and 1 m, at either HH or VV polarisations.

Extended Dwell Imaging

Umbra’s Extended Dwell data product is an extension of the Spotlight imaging mode that tracks a fixed scene for a longer period of time to generate a range of SAR imagery formats. Such imagery includes Dwell Spotlight, a low-noise and high resolution image; Colour Sub-Aperture, a processed image that utilises the unique reflectance spectral fingerprints of man-made objects; and SAR video, a collection of SAR images acquired during an extended dwell observation. 4)

The standard scene size for extended dwell is 5 km x 5 km, at 1 m resolution and either HH or VV polarisation.

Future Imaging Modes

Umbra also plans to implement imaging further imaging modes to the constellation, including Stripmap, Mosaic, and Scan. Stripmap mode is geared towards gathering imagery across wide swaths, up to hundreds of square kilometres while maintaining high resolution. 3)

Mosaic imagery will enable Spotlight imagery to be stitched together to form a large and contiguous scene. This mode will facilitate observations over large areas at no resolution cost.

Scan mode is designed for observations covering large areas at a lower resolution, suitable for oceanography and ship monitoring applications.

Ground Segment

Umbra SAR Data Products

Umbra intends to provide only SAR data products, not insights and analytics.

Umbra offers a wide range of levels and formats of SAR data products, which are described in detail in the Umbra Product Specification Guide. Umbra data can be tasked and acquired through the company’s Canopy tool. 5)

Alternatively, freely available SAR data can be accessed through the company’s Open data programme, which consists of multi-looked spotlight observations of over 1000 locations.

The data products offered by Umbra are broadly classified into Detected and Complex products. Detected products solely use the radar signal amplitude, which defines the strength of pixel values in a greyscale image - the most common SAR visualisation. Complex products make use of the phase of a radar signal for interferometric techniques and applications like InSAR. 3)

References  

1) “Umbra Satellites,” Umbra Product Guide, URL: https://help.umbra.space/product-guide/umbra-satellites 

2) “Umbra Product Guide,” URL: https://help.umbra.space/product-guide

3) Garcia LP, Furano G, Ghiglione M, Zancan V, Imbembo E, Ilioudis C, Clemente C, Trucco P. Advancements in on-board processing of synthetic aperture radar (SAR) data: enhancing efficiency and real-time capabilities. IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing. 2024 Jun 3.

4) “Umbra Products,” Umbra Product Guide, URL: https://help.umbra.space/product-guide/umbra-products

5) “Umbra launches worlds most capable commercial radar-imaging satellite,” Umbra Press Release, June 25, 2021, URL: https://umbra.space/blog/umbra-launches-worlds-most-capable-commercial-radar-imaging-satellite/

6) “Dwell Overview,” Umbra Remote Sensing, URL: https://umbra.space/remote-sensing/dwell/

7) “Satellite: UMBRA,” WMO OSCAR, URL: https://space.oscar.wmo.int/satellites/view/umbra

8) “Krebs, Gunter D, “Umbra-SAR 2001,” Gunter's Space Page, Retrieved August 16, 2024, from https://space.skyrocket.de/doc_sdat/umbra-sar-2001.htm

9) “Umbra offers the world’s most capable SAR satellites to customers,” Umbra Press Release, July 31, 2024, URL: https://umbra.space/blog/umbra-offers-the-worlds-most-capable-sar-satellites-to-customers/

10) Gierull CH, “Bistatic synthetic aperture radar,” Defence R&D Canada - Ottawa, November 2004, URL: https://people.ece.ubc.ca/~yewn/papers/DRDCbistatic.pdf

11) “DARPA selects Umbra for their DRIFT program,” Umbra Press release, May 22, 2023, URL: https://umbra.space/blog/darpa-selects-umbra-for-their-drift-program/

12) “Umbra Unveils Bistatic SAR Data from its Tandem Pair of Satellites,” Umbra Press release, March 7, 2024, URL: https://umbra.space/blog/umbra-unveils-bistatic-sar-data-from-its-tandem-pair-of-satellites/ 

13) Gierull CH, “Bistatic synthetic aperture radar,” Defence R&D Canada - Ottawa, November 2004, URL: https://people.ece.ubc.ca/~yewn/papers/DRDCbistatic.pdf 

14) “Umbra Releases Over $4 Million in Free SAR Data,” Umbra Press Release, March 1, 2024, URL: https://umbra.space/blog/umbra-releases-over-4-million-in-free-sar-data/ 

15) “NASA selects Umbra for its CSDA Program,” Umbra Press Release, October 3, 2023, URL: https://umbra.space/blog/nasa-selects-umbra-for-its-csda-program/ 

16) “Umbra partners with EUSI to offer SAR imagery to European remote sensing projects,” Umbra Press Release, September 4, 2023, URL: https://umbra.space/blog/eusi-partners-with-umbra-to-offer-sar-imagery-to-european-remote-sensing-projects/ 

17) “Umbra Space releases highest resolution commercial satellite image,” Umbra Press Release, August 7, 2023, URL: https://umbra.space/blog/umbra-generates-the-highest-resolution-commercial-satellite-image-ever-released/ 

18) “Umbra achieves first light in under 48 hours,” Umbra Press Release, April 18, 2023, URL: https://umbra.space/blog/umbra-achieves-first-light-in-under-48-hours/ 

19) Lacomme et al, “Electronically Steered Antennas,” Air and Spaceborne Radar Systems, William Andrew Publishing, 2001, Pages 457-467, URL: https://doi.org/10.1016/B978-189112113-5.50028-0 

20) “Canopy,” Umbra Canopy, URL: https://docs.canopy.umbra.space/docs/introduction