Paul Stephens, DMCii Marketing Director has written an article for Earth Imaging Journal (EIJ) this month which discusses the application of small satellite constellations for remote sensing.

Paul discusses the application of cost effective small satellites in earth observation and the development of a commercial earth observation market by DMCii and privately funded satellites such as the RapidEye constellation.

If you're interested, why not take a look at the EIJ website

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.

When making our blog entries we are always on the "look out" for interesting and unusual satellite applications. Well, this week we have something "completely different"! Eagle Island, in the Chagos Archipelago, is overrun by rats! And it's all thanks to the human population that inhabited the island until 1935. Before that coconuts where farmed to provide oil, principally for lamps, but with electricity becoming widely available the economics of transporting the commodity from Eagle Island just didn't stack up. So the Island was left to return to nature - the problem was the rats stayed and truly made the island their home!

Now Eagle Island, at 5 x 0.5 km is the second largest in the archipelago after Diego Garcia and the only island in the Great Chagos Bank to be infested by the Black Rat (other rat-infested islands occur in other island groups of the archipelago, and Diego Garcia is also heavily infested). Our friends the rats are seemingly preventing the breeding of seabirds which on other islands within the group are prolific, providing some of the most valuable seabird breeding areas in the entire Indian Ocean despite the tiny sizes of these islands. The rats were also maintaining a less than desirable vegetation state by preventing the regeneration of indigenous species and by feeding on the eggs and hatchlings of nesting marine turtles. There are no land birds on the island, probably in large part due to the rat presence. Anyway, that's all changing now and we can measure this by using satellite imagery.

So how were the rats controlled? Firstly a baiting grid 30 x 30m was established across the entire island based on lines cut by hand through the dense vegetation by the eleven expedition members over a 6 week period during April this year. These provided an excellent opportunity to conduct a Rapid Assessment Survey of the state of the environment of the entire island surface using the resulting 2,844 grid points as recording stations. Ten parameters including the type of vegetation were recorded at each station by four expedition members. This data is now being mapped and together with other expedition results will be the subject of a "state of the environment" report later in the year.

Satellite imagery has been difficult to come by, not least because there is seemingly little of general interest to the world on tiny uninhabited islands in the middle of the Indian Ocean. As the result satellites are rarely focused - if at all - on the island, and any resulting images are almost unobtainable. The CHRIS images from the Surrey Space Centre will accurately compare images taken in April this year with those due to be taken in October. The CHRIS images will also high quality maps for conservation management purposes.

Results of the assessments will be used in assisting future management processes in this far-flung location, part of the British Indian Ocean Territory (BIOT), not least in monitoring the effects of the rat eradication and any other interventions to be made in future conservation.

So it's bad news for the rats but good news for the Island's environment and sea bird colonies.