Atmospheric Reentry Demonstrator

The Advanced Reentry Demonstrator (ARD) was a European Space Agency (ESA) suborbital reentry vehicle. It was developed and operated for experimental purposes, specifically to validate the multiple reentry technologies integrated upon it and the vehicle's overall design, as well as to gain greater insight into the various phenomenon encountered during reentry.

The ARD only performed a single spaceflight. On 21 October 1998, the vehicle was launched upon the third flight of the Ariane 5 expendable launch system. Reaching a recorded altitude of 830 km, the ARD was 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. Following its recovery and subsequent analysis, the vehicle was found to have performed well, the nose cone and heat shield thermal protection having remaining in a ideal state and having remained completely airtight and perfectly intact.

The ARD held the distinction of being the very first guided sub-orbital reentry vehicle to be manufactured, launched and recovered by Europe. One of the core purposes of the mission was the gathering of knowledge that could be subsequently used during the development of future re-entry vehicles and precise landing capabilities. In the aftermath of the programme, the ESA decided to embark on a follow-up reentry demonstrator, known as the IXV. This vehicle underwent its first successful test flight during February 2015.

Development

The Atmospheric Reentry Demonstrator (ARD) was developed and operated as a cooperative civilian space programme under the oversight of the European Space Agency (ESA); it fell within the agency's Manned Space Transportation Program (MSTP) framework. Under this framework, the programme was pursued with a pair of expressed principal objectives. First, the ESA was keen to perform a demonstration of the ability of the European space industry to design and produce low-cost reentry vehicles, as well as its ability to handle the critical mission phases involved in their operation, such as sub-orbital flight, reentry and vehicle recovery. In addition, the ARD was equipped with a comprehensive suite of on-board sensors and recording equipment so that detailed measurements could be captured throughout its testing; the ESA recognised that the exploration of the various phenomena involved in the vehicle's successive phases of flight would be of high value and that the data gained would be subsequently catalogued and harnessed in the course of further programmes, especially future reentry vehicles.

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).

Design

The ARD has a classical Apollo capsule design and was packed with the most advanced technologies to test and qualify new technologies and flight control capabilities for atmospheric reentry and landing. During the vehicle's sole mission, it recorded and transmitted to the ground more than 200 critical parameters for analysis of the flight and behaviour of onboard equipment.

Operational history

The ARD only performed a single spaceflight. On 21 October 1998, the ARD was launched upon the third flight of the Ariane 5 expendable launch system. It was released shortly after separation of the launcher's cryogenic main stage (at an altitude of about 216 km) 12 minutes after lift-off from the Guiana Space Centre, Europe's spaceport in Kourou, French Guiana. The ARD attained a recorded altitude of 830 km, after which a guided reentry into the atmosphere was conducted. It splashed down to within 4.9 km of its target point in the Pacific Ocean between the Marquesas Islands and Hawaii after one hour and 41 minutes of flight.

The ARD was recovered roughly five hours following splash down. Following recovery, the vehicle was transported back to Europe and subject to detailed technical analysis in order to acquire more information on its performance. Engineers analysing data from its sub-orbital flight reported that all the capsule's systems had performed well and according to expectations; analysis of the craft's real-time telemetry broadcast during the flight had also reported that all electrical equipment and propulsion systems functioned nominally. Telemetry systems and reception stations had all performed well, and the onboard GPS receiver worked satisfactorily during the entire flight except, as expected, during black-out in reentry.

During reentry, the heat shield temperature reached a recorded peak temperature of 900°C; nevertheless, both the vehicle's cone and heat shield thermal protection were found in a perfect state following its retrieval. Throughout the flight, the ARD had remained completely airtight and perfectly intact. The ARD itself has been preserved and has since become an exhibit at the European Space Research and Technology Centre in Noordwijk, Netherlands.

See also

• IXV, follow-up ESA reentry demonstrator, tested in February 2015.
• OREX, equivalent Japanese demonstrator from 1994, developed and flown by NASDA
• CARE, experimental test vehicle for the ISRO Orbital Vehicle launched on 18 December 2014 atop GSLV Mk III LVM 3X

References

• EADS ARD web page
• ESA ACRV review
• ARD drop test from a stratospheric balloon performed in Southern Italy in 1996