Launch date looms for space module

China hopes to resume its nascent effort to build a space station with the launch next week of an orbiting laboratory module that scientists hope will provide a training platform for space rendezvous.

The China National Space Administration (CNSA) announced on its website yesterday plans to send its Tiangong - or 'heavenly palace' - module into orbit from the Jiuquan Satellite Launch Centre in Gansu .

But the launch - scheduled for a window between Tuesday and the following Friday - has been delayed for more than a month as investigators scrambled to figure out what caused another rocket to veer off course and fail last month during a satellite launch.

That LM-2 rocket was similar to the model that CNSA hopes to use to launch the Tiangong module into orbit. Authorities feared the expensive module, a core component of a planned mid-sized orbiting laboratory, could also be lost, if the problem went unresolved.

A panel of experts assigned to investigate the August 18 failure traced the problem to small secondary thruster used to control the rocket's ascent, Xinhua reported.

The thruster apparently lost connection with its servo, an automatic error correction device, and misfired, sending the rocket off course, said the project operator, the China Aerospace Science and Technology Corporation. Similar vernier engines appeared in older rockets, such as the US Atlas-family of space-launch vehicles, but have since been abandoned by Nasa.

Chinese space authorities did not release details about the connection failure, but they said they had come up with a solution to strengthen the suspect component on similar rockets, including the LM-2 that will launch the Tiangong module.

A spokesman for the manned space programme admitted in a statement yesterday that the Tiangong team had been under pressure to meet the launch deadline, but said they had applied patches to the rocket to prevent similar glitches.

The spokesman said authorities were treating Tiangong as a stepping stone to the construction of a permanent, full-scale space station.

'Tiangong's key mission is to provide a target for other spacecraft to practice rendezvous,' he said. 'It will provide some experience for the construction of a space station.'

The module consists of a short, thick cylinder with a docking platform at either end. It has two chambers, one to provide short-term quarters for astronauts and another to house its propulsion system and electricity supply.

Three manned or unmanned Shenzhou spacecraft will be launched to dock with Tiangong. All trips must completed within the Tiangong's intended two-year lifespan. Tiangong weighs just eight tonnes, far less than the International Space Station, which weighs more than 400 tonnes. Any heavier and it would exceed the maximum payload of Chinese rockets.

China hopes to significantly improve its lift capacity by the time it plans to begin formal construction of a full-sized space station in 2020. The construction of a new launch centre in Wenchang, Hainan, and the introduction of the LM-5 series rockets will boost payloads to more than 50 tonnes.