Tim Furniss/LONDON


The Proton launch of the Russian Zvezda service module to the International Space Station (ISS), planned for 12 November, has been put back to between 26 December and 16 January, with more delays possible.

Although Russian launch site testing of the module has been slower than intended, the main reason for the delay is NASA's Space Shuttle fleet wire-insulation problems and difficulties in getting follow-on US ISS hardware ready for launch. NASA is experiencing computer software problems, particularly with the US Laboratory Module and software due to be loaded on to the Zvezda after it has been launched. In addition, the discovery of a leak in an orbital manoeuvring system valve on the orbiter Discovery has added further delays to Space Shuttle missions, which will have an adverse affect on ISS service and non-ISS missions. The Space Shuttle flight backlog for next year is building.

The delay in the Zvezda launch will lessen the gap (previously two months) before the flight of the Space Shuttle Atlantis STS101 to equip the module for operations. This flight has been pushed into late next January or early February from an original November launch date. Only after this can the next Atlantis mission - STS92 - be attempted about two months later. This mission, to conduct a major assembly of more equipment for the ISS, is over two years late.

The first expedition crew to operate on the ISS - due for launch next March - should not be aboard until STS92 has completed its work, so a delay to this flight is also likely. Some ISS hardware that was to have flown next year will not be added to the ISS until 2001.

The Zvezda launch delay will enable the module to dock to the ISS in daylight, rather than in darkness - which would have occurred during a November launch - and to avoid that month's Leonid meteor shower. The extra time will also allow Russia to concentrate on the final Soyuz mission to prepare the Mir space station for de-orbiting. Any further delays to the Zvezda launch could result in Russia keeping the Soyuz crew on board Mir beyond next March.

In addition to ISS service missions, the Discovery's third Hubble Space Telescope servicing mission, planned for 12 November, will be delayed and is likely to be the last Shuttle mission this year.

The Endeavour STS99 radar topography mission could slip to January.

Source: Flight International