Atmospheric Reentry Demonstrator

Reaching a recorded altitude of 830 km, the ARD performed a guided reentry back to Earth before splashing down relatively close to its intended target point in the Pacific Ocean after one hour and 41 minutes of flight.

The ARD and IVX demonstrators are intended to serve as developmental stepping stones towards a vehicle called Space Rider, meant to be the first of a series of production-standard spaceplanes.

[1][2] The prime contractor selected to perform the ARD's development and construction was French aerospace company Aérospatiale (which later merged into the multinational EADS – SPACE Transportation group).

[1] During 1995 and 1996, multiple development studies exploring concepts for the shape of such a vehicle were conducted; ultimately, it was decided to adopt a configuration that resembled the classical manned Apollo capsule which had been previously operated by NASA.

[2] The experience and data obtained through ARD and IVX demonstrators are serving as developmental stepping stones towards a vehicle called Space Rider.

These rocket thrusters, each typically generating 400-N of thrust, were arranged in a blow-down configuration and positioned so that three units provide pitch control, two for roll and two for yaw.

[2] During reentry, the ARD's head shield loses only 0.5 mm of its thickness, keeping its aerodynamic shape relatively constant, which in turn simplifies the flight control algorithms.

[2] The vehicle is equipped with a Descent Recovery System (DRS), deployed prior to splashdown in order to limit the impact loads and to ensure its flotation for up to 36 hours.

However, the ARD was designed to be tolerant to instances of GPS failure; this is achieved via a series of control loop algorithms that verify the GPS-derived data to be within a pre-established ‘credibility window’, defined by the inertial navigation readings.

[1] During the vehicle's sole mission, it continuously recorded and transmitted to the ground in excess of 200 critical parameters that were used to analyse the ARD's flight performance as well as the behaviour of the equipment on board.

[1] Issues highlighted during analysis included the role of design uncertainties having led to difficulties in observing some physical phenomena such as real gas effects, addressing aerothermal environment characterization was also hindered due to the premature failure of some thermocouples.

Overall, the flight was stated to have brought a great amount of high quality aerodynamic information back which, amongst other benefits, served to confirm and enhance the capabilities of ground-based prediction tools.

[1] Since its retrieval and the conclusion of post-mission examination, the sole ARD vehicle itself has been preserved and has become a publicly-accessible exhibit at the European Space Research and Technology Centre in Noordwijk, Netherlands.