R3 – 28 October 1971

R3 was dispatched to Australia early in 1971, and the second stage arrived at Woomera on 26 July, followed by the first stage on 17 August. Static firing of the second stage occurred on 1 September, and the two stages and the back-up satellite had been assembled by 1 October. The complete vehicle was given a static firing test on 8 October, and the flight model satellite was fitted by 22 October. A decision was made to delay the launch until 26 October, but systems checking delayed the launch further.

Derek Mack, one of the Saunders Roe launch team (Saunders Roe had by then become the British Hovercraft Corporation), remembers the morning of 28 October as a cool, fresh Australian spring day, with clear skies. The overnight crew had filled the HTP tanks and adjusted the kerosene levels, as well as arming the many pyrotechnic systems on the vehicle. The gantry was wheeled back at 11:00, but there was some alarm when the Attitude Reference Unit, which steers the vehicle, began to give erratic signals. There was relief when it was realised that this was due to the vehicle swaying gently in the light breeze. The vehicle lifted off smoothly, and the various telemetry stations north of Woomera reported that all events had been successful. However, this did not yet mean that the launch had been successful: it was only when the global satellite station at Fairbanks reported an operational signal from a satellite on a frequency of 137 MHz that the team knew that they had an orbiting satellite. The party could begin, but there was a sour taste to it.

R3 launched the Prospero satellite (X3) into orbit on 28 October 1971, in a text book launch.19 The programme had meanwhile been cancelled by an announcement in Parliament by the new Minister at the Department of Trade and Industry, Frederick Corfield, on 29 July 1971. The teams that had built Black Arrow and launched it were out of a job.

Prospero had a mass of 66 kg, and was launched into an orbit of perigee 557 km, apogee 1,598 km, and an inclination to the equator of 82°. It is still in orbit. It carried four experiments:

(a) To determine the thermal stability of a number of new surface finishes.

(b) To determine the behaviour of new silicon solar cells.

(c) An experiment in hybrid electronic assemblies.

(d) An experiment by Birmingham University to determine the flux of micro meteorites.

The satellite was formed from eight faces covered with 3,000 solar cells. Since the spacecraft would be in the earth’s shadow for part of its orbit, rechargeable batteries were also carried.

The flight sequence for the Prospero satellite launch was:

Event Time (seconds)

Lift-off 0

First stage engine shut down (HTP depleted) 126.9 Stage separation/second stage ignition 133.5

Inter stage bay separation 139.1

Payload fairing separation 180.0

Second stage shut down (HTP depleted) 256.9

Pressurise attitude control system 262.5

Spin-up rockets 575.0

Stage separation 577.0

Third stage ignition 590.0

Payload separation 710.1

The fifth vehicle, R4, was never fired, and is now on display in the Science Museum, London.