ISS work to proceed as USA fails to secure further European Space Agency funding

The Space Shuttle Atlantis STS 104 is set to attach the $164 million airlock module to the International Space Station in a mission that has been held up by software problems.

Atlantis will be launched from the Kennedy Space Center on 12 July. It will attach the module using the Space Station Remote Manipulator System (SSRMS) twin robot arm, which has been cleared of the major software problem that had put the mission in doubt (Flight International, 19-25 June).

Atlantis must launch by 17 July before the sun's position relative to the ISS creates temperatures too high for the attached orbiter to endure, otherwise it will be delayed by about two weeks.

The green light for STS 104 came after successful checks of the cumbersome SSRMS. The 6,500kg (14,320lb) airlock module cannot be attached to the ISS without the SSRMS as the Shuttle's own RMS cannot reach the docking location.

Software problems were experienced with the SSRMS soon after it was attached to the ISS in April and it had been recently restricted by faulty software on a back-up unit on the shoulder of one of the unit's twin arms. The risk was that during the transfer of the airlock the 15.5m (51ft) long SSRMS would fail, stranding the module. The problem was traced to a suspect computer chip in the shoulder joint electronics and a software patch was developed to bypass this.

The ISS crew carried out a dry run of the airlock transfer last month, operating the SSRMS as they will during the real manoeuvre.

Meanwhile, Discovery STS 105 was scheduled to be rolled out to another pad on 27 June in readiness for its 5 August launch to the ISS to exchange crews and deliver and return cargo.

US Congressmen visiting last month's Paris air show failed to persuade the European Space Agency (ESA) to pay more money for its participation in the ISS. Italy is, however, keen to build the habitation module independently of ESA membership and also assist in developing a crew rescue vehicle to enable the ISS to have its anticipated six-person crew. The failure to secure additional European funding comes as NASA moves to appoint an external team of scientists to conduct a detailed review of the ISS after its $4 billion cost overrun and subsequent cuts by President Bush, reducing the crew to three and science work by 40%. The US General Accounting Office has also launched an investigation into ISS cost overruns. Tommy Holloway, NASA's ISS manager, concedes that if the ISS cannot accommodate six crew, international partners could pull out of the project.

Source: Flight International