Cape Canaveral, Florida  - Astronauts have to plan ahead.

Without a hardware store in orbit, the International Space Station has long relied on US space shuttles to haul up the large parts needed to assemble the laboratory in low-Earth orbit. But that delivery service is about to screech to a halt when NASA retires the ageing space shuttle fleet at the end of 2010.

The loss of the shuttles and their "space truck" capabilities will force astronauts to hop rides to the station on Russian Soyuz space capsules, which can taxi humans to orbit and back but are too small for the large equipment that has been integral to the space station.

The space shuttle Atlantis is set to blast off Monday on a mission that is part of NASA's effort to stock up the ISS reserves ahead of the inevitable deadline.

"It's been the workhorse of just getting the big parts up, at least on the US and international partner side," Atlantis commander Charlie Hobaugh said of the shuttle in a NASA published interview.

Atlantis' six-member crew will deliver two platforms full of 12,360 kilogrammes of spare parts, which will be installed on the outside of the station. The so-called Express Logistics Carriers contain all kinds of crucial parts, such as gyroscopes that help keep the ISS at the proper altitude in space, an extra hand for the station's robotic arm, a gas tank for providing oxygen to the airlock during spacewalks and parts for the station's cooling system.

The first of several flights devoted largely to spare parts, this mission is carrying the highest-priority items.

"The components we have left are basically just coming up now for the long haul," Hobaugh said. "I mean, the station itself right now is an incredible vehicle. We just need to provide its sustainment so these last few missions ... but we were essentially the beginning of the sustainment of the long-term life of the station."

The flight is also the last time the shuttle will be used to take an ISS crew member back to Earth. US astronaut Nicole Stott has been living aboard the ISS for three months.

During the 11-day flight, astronauts will conduct three six-hour spacewalks to transfer spare parts and prepare for the installation of new modules.

The first spacewalk set for Thursday will focus on transferring a spare antenna, attaching power for heaters and lubricating the Japanese robotic arm. A spacewalk on November 21 involves installing part of a project to monitor ships at sea and a separate device to measure the electric charge on the station in its interaction with plasma in orbit. The third, final spacewalk will install gas tanks full of oxygen outside the station.

There are just five more shuttle flights remaining after the upcoming Atlantis mission, as NASA races to complete the station, with the next launch slated in February to deliver the last US module.

With the retirement deadline fast approaching, NASA is at work on developing the next generation spacecraft with an eye on returning humans to the moon or travelling to Mars and beyond. It will carry the crew on top of the rocket in a configuration that recalls the Apollo moon missions and which engineers say is safer than the space shuttle design, following the explosion of the Columbia in 2003.

But there will be a years-long gap during the development of the new craft, leaving US astronauts dependent on Russian flights and causing much consternation among policymakers.

However an independent review committee convened by the Obama administration to evaluate all US manned spaceflight said the space- shuttle programme will likely need to be extended into 2011, in what it dubs a more realistic time frame to complete the remaining scheduled flights to the ISS. It also looked at other ways to shorten the gap between the end of the shuttle and deployment of the new Orion spacecraft.

But all this may be just a pipedream as the overall conclusion of the panel was that the goals of exploring the moon and deeper into space are impossible given current funding constraints. (IANS)