Tim Furniss/LONDON
The STS93 Space Shuttle mission to deploy the Chandra X-ray telescope has been cleared to fly on 22 July. The much-delayed Columbia launch has been put on hold because of concerns about its Boeing inertial upper stage (IUS) after a similar stage failed during a US Air Force Titan IVB launch in April, stranding an early warning satellite in a useless orbit.
Although NASA has cleared its IUS, further launches of the unit - and of those with a Centaur upper stage, or other upper stages using Pratt & Whitney RL-10 engines - will be delayed until full investigations have been completed by the USAF, Boeing and Lockheed Martin into the Titan IV/IUS and Titan IV Centaur and Delta III failures which took place in April and May (Flight International, 12-18 May).
The Chandra - formerly known as the X-Ray Astrophysics Facility and part of the NASA Great Observatory series - and its IUS stage will be close to the limits for the Columbia's payload capacity. The spacecraft and stage, weighing 19,960kg (44,000lb), will fill almost the entire length of the payload bay.
The Columbia's full payload limit to low inclination orbit is 21,140kg. Because of these limitations, the STS93 crew is reduced to the basic five and the flight will last only five days.
Meanwhile, Space Shuttle STS96 Discovery docked with the International Space Station (ISS) on 29 May. And it was confirmed that Russia's Zvezda Service Module is scheduled for a 12 November launch, with the first occupation crew to be launched in March next year.
The STS96's astronauts, Dan Barry and Tamara Jernigan, completed a 6h spacewalk on 30 May, only to have it extended by a further 2h in the unpressurised airlock, while Jernigan struggled to connect her suit to an airlock umbilical.
The astronauts fitted a 95kg crane, with a 1.5m boom that can be extended to 2.7m, to the outside of the Unity node module. The crew also removed parts of a similar Russian crane, to be completed on the side of the Zarya control module on a future mission.
On 31 May, the STS96 crew entered the ISS to repair a communications system, replace faulty battery chargers and to unload more than 2t of equipment. They also installed foam mufflers over noisy fans. The Zarya module was so noisy - 72dB - that the crew had to wear earplugs.
The STS96 crew was scheduled to undock from the ISS on 3 June and return to earth on 6 June. Another Shuttle logistics mission to the ISS is due in December.
Source: Flight International
