Demonstration of orbital rendezvous and docking of micro-satellites using satellite navigation is being planned by Surrey Satellite Technology (SSTL) for 2007. Use of the US global positioning system or other constellations would remove the need for bulky inertial navigation systems on spacecraft.
For micro-satellites, GPS receivers have the advantage of being as small as credit cards. These can provide positioning accuracy of about 15m (50ft).
SSTL is working on further miniaturisation so that an equally small unit could receive more than one GPS signal and provide an accuracy down to 5m. This level of accuracy would enable docking manoeuvres.
The flight to test GPS-based in-space navigation is planned for 2007 aboard a Russian rocket that is to launch five 150kg (330lb) spacecraft under a separate contract. There is enough payload capacity for a sixth 150kg vehicle or several spacecraft each weighing less.
"We are just working out now how big the spacecraft would be and whether it should be a 1kg Palmsat or a 6kg Snap-1-sized craft, which would be better for docking," says Dr Stuart Eves, principal engineer at SSTL.
ROB COPPINGER / LONDON
Source: Flight International
