EO satellites outlive their design
Friday, September 30. 2011
Nigeriasat-1 and UK-DMC-1, part of the Disaster Monitoring Constellation coordinated by DMCii, have this week reached their 8th operational year in orbit. Launched on September the 27th 2003 from the Plesetsk Cosmodrome on board a Kosmos 3-M rocket, Nigeriasat-1 and UK-DMC-1 have been providing imagery to their respective operators, NASRDA in Abuja, Nigeria and SSTL in Guildford, Surrey for the last 8 years.
UK-DMC-1 moved to adapter before launch
In addition to its remote sensing payload, UK-DMC-1 also carries three experimental payloads which have in their own ways proven to be revolutionary: The Cisco router in Low Earth Orbit (CLEO) was a pioneering implemention of an internet link in space. Working together, NASA Glenn Research Center, SSTL and Cisco Systems used UK-DMC-1 to demonstrate a prototype of the future Interplanetary Internet - being the first to evaluate the delay-tolerant networking bundle protocol in space.
The GPS Reflectometry experiment was the first dedicated experiment to demonstrate the feasibility of using GPS and GNSS reflections off the surface of the Earth to measure geophysical parameters, such as the roughness of the ocean surface. For the first time, spaceborne reflections were received from reflections off sea, ice, snow and land. A follow-on instrument has recently been designed and will be flying on TechDemoSat-1. The water Resistojet experiment was the first flight of this kind of technology. Water based propulsion avoids the complications and infrastructure required in using hazardous propellants at high pressures, and results in a useful level of thrust and efficiency at a very low cost.
SSTL prepares all its missions for End of Mission as a precautionary measure. UK-DMC-1 initiated its preparations in September 2010 and Nigeriasat-1 in June this year, which meant using up the remaining propellant to passivate the satellites. Using up the propellant also lowers the orbit and is an efficient way of reducing their remaining time in orbit. Since this work was completed, both satellites have continued their respective missions and will continue to provide imagery until End of Mission. The first satellite in the constellation Alsat-1, which was built by SSTL for the Algerian Space Agency (ASAL) and launched in 2002, completed its mission last year having exceeded its original 5-year design lifetime by 50% to a remarkable 7 years and 9 months.
