Now docking: A fridge-freezer in outer space

The most ambitious and technically complex series of space missions since the Moon landings 30 years ago was scheduled to begin in earnest at 2am this morning with the docking of the third module of the international space station.

The most ambitious and technically complex series of space missions since the Moon landings 30 years ago was scheduled to begin in earnest at 2am this morning with the docking of the third module of the international space station.

The Russian Zvezda module will allow the embryonic station to be permanently inhabited. Three crew members - two Russians and an American - are expected early in November to become the first to live on the orbiting platform.

Over the next five years, 40 space flights carrying hundreds of tons of supplies and equipment will enable a succession of astronauts to put together one of the most expensive - and remote -- projects in history,estimated to end up costing at least $60bn (£40bn).

Two Russian cosmonauts were standing by last night in case the automatic docking procedures failed to hitch the Zvezda module to the rest of the two-module Zarya station. They have been trained for a quick launch and rendezvous to perform a manual docking within the next two weeks.

At 43ft long and weighing 42,000 pounds, the Zvezda module contains everything necessary for a long spell in space - radio communications with ground control, living quarters with a kitchen table and fridge-freezer, exercise equipment, toilet and computers.

Eighteen of the 40 flights needed to build the space station have been pencilled in for between now and October 2001, involving the American space shuttle and the powerful Russian Proton rocket.

The American National Aeronautics and Space Administration (Nasa) believes the shuttle missions will be some of the most complicated the agency has undertaken. "What we're facing is probably the most challenging and difficult series of missions since we landed man on the Moon," said a spokesman.

The political stakes are huge, with Al Gore, the US Vice-President, backing the venture, which should come to fruition during his presidency if he is elected later this year.

As the Zvezda module was launched from Kazakhstan earlier this month, Mr Gore said: "Once the international space station becomes fully operational, it promises to deliver enormous benefits to Americans in the form of increased scientific research and development opportunities."

Although 19 nations, including Britain, are involved in building the station, America is shouldering the lion's share of costs, with Russia struggling to meet the timetable for its own substantial commitments.

A key moment will come on 30 October when the first three crew to live in the station will be launched in a Soyuz rocket.The veteran US astronaut Bill Shepherd will be joined by Yuri Gidzenko and Sergei Krikalev, who was on board Mir in 1991 when the break-up of theSoviet Union began. Once the Zvezda module is permanently manned, a series of shuttle missions will enable the crew to begin assembling the 100 individual components of the space station, due to be finished by the end of 2005.

Weighing 450 tons, the complete station will include six laboratories. Its volume will be roughly equal to the passenger cabin of a jumbo jet.

One of the last modules to be attached will be a second accommodation vehicle, which will enable seven astronauts to work and live in space for up to six months at a time. These American-made quarters are expected to be far more comfortable than Zvezda.

Scientists will use the station for a series of experiments, including investigations into:

* Protein crystals, which will enable medical researchers to understand viruses and enzymes and perhaps enable them to design better drugs;

* Tissue cultures, where living cells are grown at low gravityto produce better ways of testing new treatments for cancer;

* Life in low gravity, exploring the effects on the human body of long periods in space, already known to affect the growth of bones and muscles;

* Flames and fluids, which behave differently in low gravity and could be used to explore ways of making new materials, such as metal alloys, and;

* Observations of Earth and space from the comfort and stability of a permanently manned space station.

Despite Nasa's insistence that the station will provide valuable new scientific information, many other scientists, including Britain's Astronomer Royal, Sir Martin Rees, have criticised the project's price. They believe unmanned missions could be more valuable at a fraction of the cost. "The project has more to do with superpower politics than science," said a British space scientist.