At U.K.-based Surrey Satellite Technology Ltd. (SSTL), a number of earth observation (EO) projects are underway. The largest involves five microsatellites for the $100 million Rapideye constellation being constructed for Germany-based Rapideye AG, by MDA of Canada, according to David Frampton, SSTL marketing and communications manager. Each of the 150 kg microsatellites provides 6.5-meter ground sample distance (GSD) 6-band multispectural earth observation images primarily for agricultural and cartographic information services.

"During the past four years, SSTL has seen a dramatic increase in EO demand. Approximately 70 percent of current production is devoted to EO spacecraft," says Frampton. "The affordability of constellations allows revisit times to be more frequent (now daily, but it could be even more often) and this has lead to the reality of persistent monitoring being made possible at a reasonable cost."

By vastly reducing project costs, SSTL has enabled Algeria and Nigeria, for example, to develop and deploy their own EO satellites. Both countries are members of the five- nation consortium that sustains the Disaster Monitoring Constellation (DMC). SSTL is managing DMC ground station development, training, spacecraft design and manufacture as well as launch procurement at a reduced rate. DMC was first established in order to provide individual countries with disaster monitoring through coordination and constellation management for applications using EO satellites.

SSTL has also established a new enterprise called DMC International Imaging (DMCII). Via DMCII, international data and commercial sales opportunities will be pursued. The latest meeting of the members of the DMC consortium was held (passive voice) in Beijing in November; the terms for the supply DMCII commercial data were agreed (passive) upon.

"DMCII will fund selected shared activities for the benefit of the consortium such as marketing and promotions, data quality initiatives and infrastructure development through data sales," says Frampton.

"Satellite design and production quality must not be confused with image quality. SSTL has its expertise in the manufacture of low-cost small satellites and we are only now getting down to the 2.5-meter GSD arena. Very expensive, high-resolution imaging is also available, but at a greatly increased price, and more often than not, without the earth coverage to make it of global benefit," adds Frampton.

SSTL is developing the fifth satellite for the DMC for China. This will have two cameras providing 32-meter 3-band multispectral and 4-meter GSD panchromatic images. This satellite is under construction at SSTL and launch is scheduled for mid-2005 on a Russian Cosmos rocket from Plesetsk Cosmodrome.

"The 32-meter camera image swath width will be 600 km so that the constellation revisit time for a given location will be at least every 24 hours. The benefits for a daily revisit as opposed to two weeks from other satellites means that crop growth and environmental issues such as flooding, fires or landslips can be tracked and managed around the world as they happen," says Frampton.

In addition, SSTL is developing the Topsat satellite platform for the U.K. government. This will be a 2.5-meter GSD satellite for varying applications worth approximately US$7.5 million. The launch is scheduled for mid-2005 also on a Russian Cosmos rocket from Plesetsk Cosmodrome.

A number of low-cost instruments are being developed in conjunction with the Planetary Environments Group and the Remote Sensing Group at the Surrey Space Center, which is part of the University of Surrey.

"These instrument concepts have a direct relevance to SSTL’s future business plans. These include miniature un-cooled thermal infrared imagers, which have application to fire detection, volcanology and ocean current monitoring; ultra-violet radiometers for atmospheric research — observing ozone and other trace gasses; and imaging spectrometers for planetary exploration," says Frampton. "The thermal imager is in an advanced state of development and it is expected to be one of the instruments added to the next generation of DMC spacecrafts."

Whereas five years ago, SSTL satellites had data transfer rates of just 76 kbs; today transfers at 40, 80 or even 100 mbs are feasible.

"Obviously, this means the image quality is much improved, and this trend will only continue. Lifespan of the satellites is also improving due to improved efficiency in the design, resulting in longer term business cases," says Frampton. "The ability to deliver imagery on an ever more frequent and timely basis is having a huge impact for disaster monitoring and businesses such as crop management."

"Besides embracing increasingly advanced sensors and systems to allow the tracking of more than just raw images, the issue of synchronization of the satellite constellation itself, let alone with other technologies, is a key concern," adds Frampton. "In order for a multinational EO constellation such as the DMC to work, it requires the positioning of the satellites in the right orbit so that the revisit times are consistent, along with the development of the systems to allow for the sharing of imagery among all the DMC members."