Space

The announcement was made in late July when former Industry Minister Kenneth Clarke stated “the scale of funding required to develop Hotol or any similar concept to eventual production would be far too great for the UK to contemplate on a national basis, particularly since only a relatively small number of such launch vehicles is likely to be required. I have therefore concluded that any further development must take place on the basis of international collaboration. The Government will be supporting efforts by UK companies to find suitable collaborators but will not be providing any further financial support in the foreseeable future”.

This exercise was very unfortunate as the UK government has effectively damaged the credibility of the project by demonstrating its view that the project is not a worthwhile investment, in spite of the UK’s leading position in this area of powerplant design. Both RR and BAe have indicated their belief that the programme cannot survive without funding by the UK government. This situation was further exacerbated by the secrecy surrounding the RB545 powerplant which was at the time of writing still classified and therefore not available for release to foreign manufacturers. Industry sources in the UK suggest that the MoD is reviewing this situation.

The comment which must be made here is that the British Government has yet again displayed its technologically myopic attitude which has claimed many victims over the last four decades. One need only to examine the TSR. 2 programme where a technically viable project was killed off with the justification that a replacement (the US F-111) could be purchased at a lower cost. That did not eventuate and the UK suffered a painful gap in capability for more than a decade. Needless to say this will now occur with Hotol as Britain over the next two decades will have great difficulty in becoming involved in any orbital processing of high value added products-this being one of the major targets in the current view of early 21st century space activity.

Outlook for NASA Shuttle-C Unmanned Heavy Booster Increasingly Favourable

On the other side of the Atlantic· the Americans have been reviewing their Shuttle-C proposal very carefully. The Shuttle-C is conceptually analogous to the Russian Energia booster and uses Shuttle SRMs, main fuel tank and engines all mated to an expendable cargo pod.

The problems that are being foreseen in the US are due to a shortage of heavy lift capacity resulting from reduced Shuttle launch frequency, this in turn resulting from post Challenger disaster proced real changes and the shortage of propellant following the destruction of one of the larger production facilities.

The proposed USAF Advanced Launch System is receding !nto the future as it becomes more an advanced technology vehicle. The planned NASA Space Station would eat up available Shuttle payloads at a very high rate, conversely use of the Shuttle concurrently for other programmes will severely limit the rate of construction of the Space Station. With a practical payload limit of 48,000lb (22,000kg) the Shuttle is not seen as providing the best utilisation of projected propellant resources per launch; a semi expendable vehicle like the Shuttle-C offers a much higher fraction of payload to orbit per launch.

Phase 1 Shuttle-C studies carried out over the last year indicated that the packaging of existing Shuttle hardware into the new pod would not present major difficulties. Martin Marietta and Rockwell have been awarded recent Phase 2 study contracts worth US$1Om planned to cover the next financial year.

The projected design of the Shuttle-C would use either two or three Space Shuttle Main Engines (SSME) and two standard Rocket Motors (SRM) providing a range of payload to orbit options; two SSMEs at 100% nominal thrust lifting 100,000lb to the nominal 220nm altitude Space Station orbit, three SSMEs at 100% nominal thrust lifting 155,000lb (70,000kg) to the same orbit or three SSMEs at 104% nominal thrust lifting 178,000lb (81,000kg) to a 110nm equatorial orbit. This is performance in the class of the Saturn V which lifted the Apollo programme. Were NASA to use the planned Advanced Shuttle Solid Rocket Motors this payload would increase to 190,000lb (86,000kg).

NASA would use SSMEs which have exceeded their safe life as powerplants for manned vehicles recovering the residual value of the engines as one shot expendables. Greater than expected engine wear has led to a policy of using SSMEs for only ten launches rather than the earlier planned twenty launches this will result in a sufficient supply of out of life SSMEs to support three or four Shuttle-C launches annually by the early 1990s. Furthermore the Shuttle-C could absorb existing stocks of older revision SRMs which are now considered to be unsafe for manned launches.

Studies have suggested that five Shuttle-C launches could reduce the number of Shuttle launches required to assemble the Space Station from twenty down to seven. In this scenario the vehicle offers a high payoff, its otherwise high incremental cost per launch of US$235m makes it impractical for use as a general purpose heavy lift booster.

In an unrelated move a NASA internal study has proposed the use of the Shuttle in unmanned fully automated launches with the objective of using up stocks of older revision SRMs. This approach would apparently save US$20-40m per launch although with the penalty of having to modify the Orbiter with a braking parachute. Understandably this proposal has drawn considerable criticism_ as unmanned flights would greatly increase the risk of losing another Shuttle; there is no substitute for a crew to intelligently manage difficulties with onboard systems.

The Shuttle programme will have hopefully resumed by the time this issue is read. At the time of writing NASA had finally committed to a launch date of the 29th September. Mission 26 will involve the launch of a 45,000lb tracking and data relay satellite with its inertial upper stage. NASA has also recently revised its Shuttle launch schedule for the next five years with seven missions planned for 1989, ten for 1990 and a total of 50 planned for the half decade.

The revised schedule has had to accommodate a number of time critical missions while allowing for the unfortunate slippages. These missions include the Magellan Venus radar mapping probe, the recovery of the long duration exposure facility, the Galileo Jupiter orbiter, the Teal Ruby infra-red imaging satellite, SOi’s Starlab and a fourth TORS satellite. NASA’s space telescope has been delayed to February 1990 or later, a four year lag behind the originally envisaged schedule.