The DLR Institute of Space Systems is strongly contributing to Europe’s effort to make space launch more competitive, flexible, and sustainable. Re-usable launch stages are a key part of that strategy – they reduce costs, lower launch cadence barriers, and strengthen European independence in space access.
vertical take-off and horizontal landing (VTHL), similar to the US Space Shuttle
vertical take-off and vertical landing (VTLV), similar to what Space X and Blue Origin have successfully demonstrate.
These two ways are complementary, as they answer different needs, depending on architecture and ground segment available to launch vehicles.
For these reasons, DLR took the decision to develop, mature and demonstrate key technologies and operations that are the stepping stone for future implementation on European launch vehicles for both VTHL with the ReFEx project and for VTVL with the CALLISTO project.
This is providing to DLR a worldwide almost unique know-how and expertise, that will be leveraged for future launch vehicles in Germany and in Europe. Both projects are coordinated by the institute of Space Systems in Bremen and involves several of its departments.
CALLISTO: Cooperative Action Leading to Launcher Innovation in Stage Toss-back Operations
Team: DLR (Germany), JAXA (Japan), CNES (France), plus a broad European and Japanese industrial base subcontracted.
Goal: Demonstrate the technology and operations needed to bring a rocket stage back vertically to its launch site, to relaunch it, and to operate it cost‑effectively.
2. Vehicle Chracteristics
Feature
Detail
Height
13 m
Diameter
1.1 m
Launch mass
~4 t
Reusability
Up to 10 flights with the same vehicle
Payload
Hundreds of sensors (no satellite)
Propulsion
JAXA‑developed RSR engine – 46 kN thrust, LH₂/LOX, deep throttling, re‑ignition (derived from the engine used on the successful demonstration of JAXA RV-X vehicle)
Carbon Fiber ogive equipped with a global navigation satellite system antenna.
Vehicle Equipment Bay
Mostly metally structure accommodating tha major part of avionics but also the reaction control system and the aerodynamic control system.
Cryogenic tank
Insulated and equipped Liquid-hydrogen tank design, leveraging DLR’s long-standing cryogenic propellant management experience.
Landing system
The design has been made possible by a unique set of tools validated by years of testing and simulation of landing sequence supported by the Landing and Mobility Test Facility of the Institute of Space Systems.
Flight-control
Aerodynamic control with 4 deployable, electromechanical fins.
Location: Kourou, French Guiana (same pad that once hosted the CNES Diamant B launcher in the 1970s).
Mission: Five flight classes, each adding complexity, with the final class emulating an operational VTVL stage. Incremental approach will be applied to reduce the risk to loosethe vehicle.
5. Learning & Impact
Knowledge gain: Significant technical and operational know-how has already been acquired during the pre-flight phases.
Advantage for European launcher sector: These insights will feed into future Europeanlaunch vehicles, helping to reduce costs, improve reliability, and accelerate re-usabilitytimelines.
Advantage for the general public: Cost reduction of European access to space will further ease the use of space based or space-assisted European sovereign service bythe general public
With CALLISTO, DLR engineers, in collaboration with the French space agency CNES and the Japanese space agency JAXA, are developing a demonstrator that can take off vertically and land in the same orientation (Vertical Take-off, Vertical Landing (VTLT)). CALLISTO is controlled with the aid of aerodynamic control surfaces in a phase without an engine, in which a transition from supersonic to subsonic flows takes place. The engine is then ignited again to decelerate CALLISTO. The landing system absorbs the remaining kinetic energy so that CALLISTO can perform a safe and stable landing.
Video: CALLISTO (engl.)
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Video: CALLISTO (engl.)
With CALLISTO, DLR engineers, in collaboration with the French space agency CNES and the Japanese space agency JAXA, are developing a demonstrator that can take off vertically and land in the same orientation (Vertical Take-off, Vertical Landing (VTLT)). CALLISTO is controlled with the aid of aerodynamic control surfaces in a phase without an engine, in which a transition from supersonic to subsonic flows takes place. The engine is then ignited again to decelerate CALLISTO. The landing system absorbs the remaining kinetic energy so that CALLISTO can perform a safe and stable landing.
