Perimeter Railway for ISS; HETE-1 Comes Down

Quirk writes "The Sydney Morning Herald is touting the mission to start construction of an orbiting railway. Space Shuttle Atlantis will carry the astronauts who will initiate the planned 107 meter rail line along the outside of the International Space Station. The remote controlled train will move at speeds of 2.5 centimeters a second and be able to carry more than 20 tonnes of cargo. Construction is projected for completion in 2004." And B3avis followed up with news about the HETE re-entry: "The pieces of the HETE-1 spacecraft seem to have crashed somewhere in the Himalayas. "The final notification from Space Command indicates that the debris re-entered at 31.5 degrees North and 92.4 degrees East." says NASA. And they should know."

Comments

cm/s - mph

[mberman]

In case anyone's wondering, 2.5 cm/s is about 1/20 mph...so it takes a while for this thing to get anywhere.

ISS Railway Links

[Quirk]

Here are a few more links that provide greater detail.

http://spaceflight.nasa.gov/spacenews/releases/200 2/02-58.html

http://www.spacedaily.com/news/iss-02c.html?astron omylinks

Re:Purpose

[Merik]

from NASA "Also, STS-110 spacewalkers will install the Mobile Transporter, which will later be attached to a base system that will allow the station's robotic arm to ride along the truss to perform assembly and maintenance work"

Basically this is to allow automated construction of the IIS as it grows in size. That site also mentions they are installing a new expansion hub,to which new modules are attached (maybe by the robotic arm)

Why 20 tons?

[zardor]

The reason for the 20 ton mass requirement is due to the fact that the train track will be expected to 'build itself'. As new sections of the truss are brought up in the shuttle payload bay (each massing about 14,000 kg), they need to be attached to the ends of the truss already in place. The shuttle robot arm won't be able to reach that far out, so the station's robot arm (with one end on the 'train') will chug out along the rails on top of the truss, then lock itself down, grab the payload from the shuttle, and swing it accros and attach it onto the end of the truss. Repeat eight times (with eight shuttle flights, and lots of spanner weilding astronouts to bolt it together), and the truss is completed by 2004 or so.
Also, a lot of very heavy equipment is mounted in/on the truss (things like storage batteries for example), and these need to be replaced every so often, so the train will be used for that also.
Regarding the water, the US considers it a waste product, and actually dumps quite a lot of it from the US lab on the station. (quite a lot of it builds as condensation from the people on board, several liters per person per day). The Russians on the other hand, consider it a resource, and pump the 'waste' water from their AirConditioner into a electrolosis unit which electrically splits off the oxygen for breathing purposes. In any case the condensed water would not be safe for drinking, but fresh drinking water is supplied by the shuttle, as a by-product of the shuttle fuel cells. (Cyrogenic H2 + 02 = lots of electricty + pure water) The shuttle actually produces a *lot* of water, but dosn't really carry much into orbit to start with!