Celebrating a decade in space, we take a closer look at the hyperspectral imager CHRIS and how gazing at Earth from different angles and with a large number of programmable spectral bands has made all the difference for a fantastic range of scientific studies, from classifying plants to mapping the submerged shoreline.

CHRIS is the innovative hyperspectral imager payload on the European Space Agency (ESA) microsatellite Proba-1 - that started its life as a technology demonstration satellite, but turned into an Earth observation mission serving the scientific society. Its agility makes PROBA-1 different to most Earth-observing missions, with the satellite platform and payload working as one.

Guided by a star tracker, the microsatellite spins its reaction wheels to roll 25 degrees off-nadir across track directions, and 56 degrees along-track. This means that CHRIS can acquire five different views of the same target at different viewing angles. It’s these different angles that the scientists find valuable, as they can capture or avoid reflections and look at differences in colour.

“Say you’re looking at a sunflower on the ground,” explains Mike Cutter of SSTL’s Optical Payloads Group, which developed CHRIS and oversees its operation. “You’ll see a different mix of colours depending on where you’re stood, as well as the growing season and time of day: the yellow canopy, green stalk and leaves, brown soil, sun glint or shadows. The same is true when observing from orbit. This offers a way of giving much more accurate classification of vegetation and canopy covers, such as the tree species within forests.”

Continue reading "CHRIS: 10 years of science innovation"

The Compact High Resolution Imaging Spectrometer (CHRIS) recently captured telling images of red toxic sludge following the Ajka alumina plant accident in Devecser, Hungary that has recently been widely reported in the media. Unlike many satellite images of flooding disasters, there is no need to highlight the affected area in the image afterwards as the red sludge clearly stands out from the surrounding landscape.

Emergency monitoring is just one of the applications that the high-resolution CHRIS imager has been used for during the past 9 years. In fact, today marks the 9th birthday of the CHRIS imager which was launched on-board the European Space Agency’s PROBA-1 mission in October 2001. The hyperspectral data from CHRIS remains in high demand from the international scientific community and its rich, high-resolution imagery is used for precision farming, air quality assessment and seabed classification and much, much more.

The image above was acquired on October 14th, showing the extent of the disaster in great detail. Not bad for a nine year old!

The toxic sludge spill followed a collapsed reservoir on October 4 and initially affected about 40 square kilometres of land. Read more about the accident on BBC’s website.

SSTL is celebrating the 8th year in orbit of the high resolution CHRIS Imager, which was launched on-board the European Space Agency’s PROBA-1 mission, in October 2001.

The Compact High Resolution Imaging Spectrometer (CHRIS) is a highly versatile hyperspectral system that was developed by SSTL’s Optical Payload Group. CHRIS was one of many instruments on-board the mission, with the others including a Space Radiation Environment Monitor (SREM) and a Payload Autonomous Star Sensor (PASS).

CHRIS offers the highest spatial resolution of any hyperspectral system currently in orbit and can provide simultaneous images of the Earth in 19 wavebands. This allows for many features of the images it produces to be identified and analysed.

This high resolution imager enables ESA’s Proba-1 mission to acquire detailed images of the Earth. The result – stunning images of natural and urban phenomena.



Many more images can be seen on ESA’s website including that of the Mauna Kea Volcano, Hawaii and Tokyo.

CHRIS can be used for many applications, including precision farming, disaster monitoring, air quality assessment and seabed classification, and has proved so successful that it has paved the way for advanced sibling CHRIS-2, which allows for other valuable applications to be addressed, including mineralogy and pollution monitoring.

The CHRIS Imager is not the only family to have grown, as the ESA’s Proba-1 mission has now been joined in orbit by Proba-2, which was successfully launched yesterday.

In addition to SSTL's CHRIS hyperspectral imager, ESA's 8-year old PROBA-1 mission has been continuing to depend on a number of sub-systems provided by SSTL (incorporating contributions from Space Innovations Limited). These include the power system, communications system, AOCS sensors, the Data Handling System computer and the SGR-20 Space GPS receiver. All systems remain fully operational in the primary chain of the satellite and have served to enable the extended life imagery capture from the CHRIS and HRC payloads.

CHRIS may in fact have had no choice but to remain onboard PROBA, but as a highly successful and popular satellite payload Compact High Resolution Imaging Spectrometer has much to celebrate - not least a new addition to the family!

The scientific community is celebrating 7 years of high resolution hyperspectral satellite imagery from the multi-spectral payload imager. The instrument has been so successful that an advanced variant (CHRIS-2) is under development, offering new functionality for Earth observation missions in a wide range of applications in resource monitoring and mapping, environmental science and security.

CHRIS was developed by SSTL's Optical Payload Group (formerly Sira Space Group), and placed into orbit in October 2001 on the PROBA mission developed by the European Space Agency (ESA). The sophisticated optical earth imaging instrument recently passed its 7th year in orbit as the highest resolution civil hyperspectral instrument in space.

Data from CHRIS has been highly successful in development of new Earth observation applications, and is supporting 94 international Principal Investigators (PIs), acquiring images from over 240 sites in 43 countries for diverse scientific research.

Dr. Mike Cutter, SSTL Optical Payloads Group explained the importance and value of such instrumentation,

Hyperspectral instruments have been widely used on aircraft for mineral prospecting and resource management and the CHRIS instruments enable this capability to be used on a national and continental scale, which is critical both for efficient management of natural resources and for providing the information to determine the effects of climate change and mitigation measures.

SSTL’s subsidiary DMCii schedules and processes images captured by CHRIS for ESA. The data from the mission then used in a wide range of applications including land cover assessment, resource management, deforestation and forest management, precision farming, aerosol monitoring and water quality assessment. The mission also supports International Charter: Space and Major Disasters campaigns by providing high resolution optical imagery of disaster affected areas.

The CHRIS hyperspectral images have been in high demand over the past 7 years, and the PROBA / CHRIS mission has pioneered and validated techniques for future scientific and commercial imaging spectrometer missions. Another reason for the scientific demand is that images can be acquired at 5 different view angles for each site, on a single over pass, allowing both spectral and directional signatures to be captured.

The new, more advanced CHRIS-2 instrument expands upon this unique capability by including the short wave infra-red band (SWIR), which allows further valuable applications to be addressed including mineralogy, prospecting, crop health and pollution monitoring.

Hyperspectral imagers split the available light from a scene into a large range of channels, providing detailed information about the imagery content. Whereas the CHRIS instrument provided up to 62 channels in the visible band, the CHRIS-2 instrument extends this capability to over 200 bands, including the short-wave infra-red bands (SWIR). Placing such an instrument on a spacecraft provides global reach and supports national and international routine imaging campaigns efficiently.

SSTL will provide the CHRIS-2 instrument on future Earth observation missions like PROBA or as a stand-alone payload for integration with third party satellite platforms.