Six days after launch, shuttle mission STS-100 continues according to
plan. On Monday, Shuttle astronauts, including the European Space Agency’s
Umberto Guidoni, used Endeavour’s robot arm to lift the Italian-built
Raffaello module from the shuttle cargo bay and dock it with the
International Space Station. Yesterday, the space station crew activated
the module — which carries up to nine tonnes of cargo to and from the
station — and checked out its Environmental Control and Life Support
Subsystem, provided by the ESA.

You can watch the highlights of yesterday’s activities in the video
highlights and put your questions on Europe and the ISS to ESA’s experts in
the live web chat this afternoon. 16:00 to 17:00 CET (14:00 to 15:00 GMT).

Today, the station crew — Commander Yury Usachev and astronauts James Voss
and Susan Helms — will begin to transfer equipment and experiment racks
from Raffaello to the ISS. Thanks to the ECLSS they will work in shirt-
sleeve comfort, but for the time being they will be on their own. Although
Endeavour is still firmly docked with the station and astronaut Umberto
Guidoni will supervise the unloading by radio link, the Shuttle is
operating at a lower air pressure than the ISS and right now the hatch
between the two is sealed.

The pressure differential is necessary because of the series of EVAs that
Shuttle astronauts have been making in order to install new station
equipment, especially the Canadarm robotic arm they successfully fitted
yesterday. Lower air pressure aboard the Shuttle makes the business of
suiting up and unsuiting quicker and less wasteful of on-board oxygen
supplies.The reduction in pressure makes no difference to the crew’s
breathing: as overall pressure falls, the proportion of oxygen is increased
to compensate. Low air pressure is even more important for spacewalking
astronauts. “Normal” air pressure would make their spacesuits hopelessly
stiff and unmanageable. But after Endeavour’s EVAs are complete, the
Shuttle will match pressure with the station and the two crews will once
more be able to share the same space.

Endeavour’s schedule allows for a maximum of three EVAs. But yesterday’s
intense activity — astronauts Chris Hadfield and Scott Parazynski were at
work for almost 8 hours — went so well that the third EVA will probably
be unnecessary. Pressures will be equalized some time today and the
Shuttle crew will help Usachev, Voss and Helms with their unloading and
restowing of Raffaello’s contents until the time comes to undock on 28
April. The Canadarm was given its first test after installation yesterday
when it lifted the pallet on which it had been carried to orbit from the
Shuttle cargo bay to a parking space close to the station. Today, the
Canadarm will “pass” the pallet to the Shuttle’s own robotic arm.

“Pallet” is actually quite a misleading name. The device has nothing in
common with the wooden pack-and stack units used by fork-lift trucks on
Earth. It is a sophisticated payload carrier, and one with a long history.
Back in the 1980s, when the European Space Agency built the pressurized
modules for the Spacelab programme, it also built the unpressurized
payload carriers without which the crewed modules would have been useless.

The two Spacelabs have long since been retired (one of them is now on
display in Bremen; the other is in Washington’s Smithsonian Museum). But
the unpressurized modules, the humble pallets are still at work on the
ISS. Raffaello and the other MPLMs are often described as “space moving
vans”. If so, then the pallets are the pick-up trucks, robust and long-

Related News

* What is the MPLM?

* Vital link between Earth and orbit

Related Links

* Discussion Forum

* Chat room

* Guidoni mission highlights

ESA astronaut Umberto Guidoni enters the International Space Station for the
first time, 23 April 2001.