SNAP and Tsinghua

We developed our own nanosatellite - SNAP, through a series of student research projects. A flight opportunity presented itself along with the launch of the Chinese microsatellite Tsinghua-1.


The Tsinghua-1 satellite was a 50 kg microsatellite that was carrying an experimental imaging system. SNAP, on the other hand, was a technology demonstrator satellite that could show a small 6.5 kg satellite capable of three axis pointing, having its own GPS navigation system and a small butane based propulsion system.

The opportunity afforded by the dual launch of these two satellites allowed the Astrodynamics group to consider a rendezvous experiment where the SNAP satellite could use its propulsive capability to catch up with the Chinese microsatellite and image it from close proximity using its novel CMOS based vision system.

The two satellites were launched in June 2000 on a Russian launcher. Shortly after separation the SNAP vision system automatically imaged the launcher and Tsinghua-1 microsatellite, which was still attached. This launch date was around the time of Solar maximum, and so we anticipated a significant atmospheric drag on the satellites. Since SNAP was so much lighter, there was a differential loss in altitude of the nanosatellite which also needed to be compensated for by the propulsion system.

This would be a world first demonstrating formation flying and proximity manoeuvres between two satellites in orbit. While there had been much interest in the possibility of satellites orbiting together, a demonstration of the technology was yet to be made.


Unfortunately, the experimental propulsion system on SNAP exhausted its propellant tank before the rendezvous could take place and there was no longer any means of sustaining SNAP's orbit. The differential drag then caused SNAP's altitude to drop relative to that of Tsinghua and the satellites started once again to recede from each other.

While this experiment failed to demonstrate proximity operations, it did demonstrate the technologies needed for such a formation flying experiment and using subsequent technological improvements we could today perform this experiment very satisfactorily.

Further information can be found on our Astrodynamics page.