CALLISTO is a reusable demonstrator for a vertical take-off and vertical landing (VTVL) rocket stage.
The introduction of reusability for launcher systems could make it possible to reduce launch costs and
enhance the versatility of the launcher system. The project aims at improving the knowledge of VTVL
rocket stages and demonstrating the capabilities and technologies required for developing and exploiting
an operational, reusable vertical take-off and vertical landing rocket stage. Test flight results will also be
used to optimise the design of a future reusable operational space transportation system.
The CALLISTO vehicle itself is single stage and is operated using cryogenic oxygen (LOx) and hydrogen (LH2).
The engine can be throttled so as to enable precise, soft landings. At least five different missions are to be
flown using the same vehicle from Europe’s Spaceport in French Guiana.
An incremental test plan will make it possible – in the concluding flights – to achieve flight conditions that
are relevant to an operational VTVL rocket stage. In particular, the engine performs a boost after a large
change of CALLISTO’s attitude, and the trajectory is modified in order to reach the landing site. CALLISTO is
then guided using aerodynamic control surfaces during a non-powered phase featuring a transition from
supersonic to subsonic flow conditions. Finally, the CALLISTO engine will re-ignite and decelerate the vehicle.
The landing system will thus be able to absorb the remaining kinetic energy, enabling CALLISTO to perform
a safe and stable landing. The demonstrator will then be prepared for the next flight