Descent & landing systems for re-entry vehicles aim at a well controlled way of (almost) undamaged recovery of the vehicle and its payload. This can be achieved through use of either parachutes or parafoils. Parachutes can provide a simple and reliable way of descent and landing but with relatively high vertical speed and possible wide landing range. Parafoils on the other hand, can be very accurate and are capable of reducing vertical speed to almost zero. Both techniques have been mastered by Dutch Space including re-entry trajectory calculations/simulations, application of different parachute/parafoil designs for multiple deployment stages and for various types of vehicles (capsules, bi-cones, slender bodies), system control, accommodation and interfaces, and solutions for different kind of landing sites (water, land).
X-38 parafoil free flight
Experience with descent & landing comes from early involvement in studies for Crew Return Vehicle / Crew Transport Vehicle (CRV/CTV) Recovery Systems. Dutch Space performed a feasibility study on different CRV/CTV concepts, followed by an in-depth concept design for both the descent and the landing systems. This included requirements identification and evaluation, concept generation, system sizing and finally a more detailed concept design. Parachute descent simulations were part of these studies.
Another milestone has been the participation in an ESA/NASA Parafoil Technology Demonstrator (PTD) programme concerning feasibility of the application of controllable parafoils for re-entry vehicles. Dutch Space' responsibility was primarily focused on development of the electronic control system and participation in the test programme. The PTD project under the responsibility of (former) DASA developed a parafoil/payload system for payloads up to 3200 kg with a manual and autonomous guidance system.
Based on this experience, follow-on developments in the field of descent & landing have been performed for launcher and defence applications being the Ariane 5 Booster Recovery System . For this system, Dutch Space has established close working relations with parachute suppliers in Russia, W-Europe and the US.
Renewed activities in the field of re-entry vehicles include a study of the design of the descent & landing system of EXPERT, an ESA aerodynamic re-entry test bed designated to have its first flight in 2008. The system will consist of a 3-stage parachute system, the first to be deployed at hypersonic speed. Landing will be at a few m/s vertical speed enabling survival of the vehicle except for the nose.
Ariane 5 Booster Recovery parachute during drop test in Russia
In parallel, concept studies are being performed for descent & landing systems for Human Transportation Systems (ISS return and space exploration) and an Atmospheric Re-entry Experimental Vehicle as an intermediate step towards a reusable future launcher.
Main activities for these studies are to evaluate the recovery strategy and subsequently find the system level constraints and functional requirements for a descent & landing systems including mission profile and main interfaces to other systems (structure, GNC, pyro trigger). Different types of systems (parachute or parafoil, water or land landing) for different vehicle concepts are then traded against e.g. reliability, landing accuracy/cross range, mass/volume, reusability and other. Best concepts will be selected for detailed design in follow-on projects.