Space

The Morton Thiokol SRB in its current modified version will be used through to 1997 by which time it will be phased out in favour of a new Advanced Solid Rocket Motor (ASRM). The ASRM is planned for initial use in 1994 through to 201O; at a projected launch rate of 12 per annum, this will require the purchase of 380 ASRMs.

The ASRM will be designed for higher reliability than the existing SRBs, with fewer parts and improved field joints (Uoint failure was responsible for the loss of the Challenger) while providing sufficient additional thrust to lift 12,000lb more payload to orbit without the current need to run the main engines at 109% of the nominal throttle setting. This practice, not surprisingly, tends to wear out the engines.

Interestingly Morton Thiokol have dropped out of the competition which at this stage involves three contractor groups – Aerojet/Lockheed, Martin-Marietta/Hercules/Atlantic Research and United Technologies. While Morton Thiokol’s withdrawal has not been attributed to political prejudice as a result of the company’s involvement in the Shuttle 51L disaster, it still has outstanding orders for 160 existing design SRBs to be used until 1997. The loss in lift capacity resulting from the reduced Shuttle launch rates will be compensated for by an increase in the use of Expendable Launch Vehicles (ELV) amounting to a rate of 30 per annum over the next five years. This is meant to clear the current backlog while providing a buffer against further grounding of the Shuttle.

The largest ELV programme in the US at this stage is the Titan 4. The USAF has ordered 23 vehicles to be used with the Centaur or Inertial Upper Stage, although some may be used for large low orbit payloads. Follow on orders will involve another 25 Titan 4s with the expectation of two launch sites being required at Vanderberg in California and Canaveral in Florida.

The Titan 4 is an upgrade of the existing Titan 34D with stretched first and second stages, seven segment solid boosters and a large 200 inch diameter payload bay fairing which can accommodate the Boeing IUS or the GD G Prime Centaur upper stage.

The inevitable increase in ELV launch capacity is stimulating a lot of activity by suppliers and potential suppliers. One of the more interesting proposals appearing over the last few months was the Orbital Sciences/Hercules Pegasus winged booster. A fully commercial venture, the 40,000lb three stage Pegasus would be lifted to 40,000ft by a large aircraft (B-52 for tests) and launched much like the 1960’s X-15 rocket aircraft. Using its first stage and wing, it would climb at Mach 8 + along a shallow trajectory to cca 200,000ft where burnout and jettisoning of the stage and wing occur. From that point the Pegasus behaves much like a conventional booster. The Pegasus will lift a 600-900Ib payload to low orbit in a 72 inch long (1. 83m) and 46 inch (1. 17m) diameter payload shroud. The Pegasus may also be used to acquire data to support X-30 NASP development.

Magellan Venus Probe Planned for Early 1989 Shuttle Launch

The first NASA planetary probe in over a decade is being prepared for an April or May launch next year on Shuttle flights STS-29 or STS-30. Magellan is a radar mapper which will map 90% of the Venusian surface at a resolution better than 0. 5km. The thick and hot Venusian carbon dioxide atmosphere presents optical mapping of the surface completely while the high surface temperature will fry a landing probe in a matter of minutes. The Magellan probe will fly an elliptical orbit mapping and recording during the low altitude portion of the orbit and transmitting recorded data to Earth during the high altitude portion of the orbit.

New Ariane 4 Elv Successfully Launched

The new heavy lift Ariane 4 was successfully launched from Kourou on the 15th June this year. The Ariane 4 is a major upgrade of the earlier Ariane 1 to 3 ELVs with a stretched first stage, structurally improved second and third stages, a new equipment bay and enlarged payload fairing. Various mixes of solid and liquid strap on boosters are available to provide various lift capabilities.

On its· first flight the ELV lifted three satellites, the ESA Meteosat P2 weather satellite, the Amsat amateur radio satellite and the Pan American Satellite PAS-1 communications satellite.

Arianespace are now committed to a production run of 50 vehicles with firm orders for 21 vehicles mainly by European organisations. The Ariane 4 will supplant earlier models becoming the ESA’s workhorse until the new Ariane 5 becomes available in the mid 1990s. Nine launches are planned for next year and this rate may be sustained. Arianespace apparently expect to capture a large part of the ELV market over the next decade and thus believe their investment will pay off handsomely.

At least six versions of the ELV will be available. The AR40 will be a core Ariane 4 vehicle without strap on boosters and capable of lifting a 1,900kg payload to geostationary transfer orbit (GTO), the AR42P will lift 2,600kg using two solid strap ons, the AR44P will lift 3,000kg with four solid strap ons, the AR42L will lift 3,200kg with two liquid strap ons and the AR44L will lift 4,200kg with four liquid strap ons. The sixth version is the AR44LP with two liquid and two solid strap on boosters; this version was used for the first flight to qualify the solid and liquid strap on boosters. The liquid strap ons use Viking 6 engine derived from the core vehicle’s Viking 5 burning 3,900kg of N2O4 oxidiser and UH25 propellant.

Aussat-B Contract Awarded to Hughes

The next generation Aussat-B communications satellite contract was awarded to Hugi Ies in preference to three other contenders British Aerospace/Matra,Ford Aerospace/Mitsubishi and General Electric. The decision has apparently resulted in some upset as the Hughes bid was rumoured to involve the use of a Chinese Long March ELV. The entry of the Chinese and Russians to the world commercial ELV market has had less impact than originally envisaged as most Western governments have banned their use to avoid the risk of Warpac nations acquiring state of ttie art Western technology. The new generation Aussat will provide mobile satellite communication services in addition to broadcasting and communication services. Provisions have been made for transmission of services to New Zealand if appropriate.

In an unrelated move Aussat has expressed its support for the Australian Spaceport Group which is seeking to build the Cape York spaceport. ASG is a consortium formed by Martin-Marietta, Bond Corporation, Comalco and BHP who seek to compete with the Queensland Government award of the spaceport feasibility contract to the Cape York Space Agency Pty Ltd.