PARIS - Europe's large unmanned space tug
is undergoing final preparations for a maiden flight to the International Space
Station sometime between Feb. 22 and March 9, with docking at the station
likely to occur during windows of March 15-19 or March 30-April 5, program
managers said Tuesday.
At a
briefing at European Space Agency (ESA) headquarters here, ESA and industry
officials said the Automated
Transfer Vehicle (ATV), has passed most of its key pre-launch milestones at
Europe's Guiana Space Center spaceport in French Guiana.
The ATV is
designed to carry food, water, fuel and other supplies to the space station
once every 18 months or so. It will also reboost the station into its operating
orbit. Flying at between 217 and 267 miles (350 and 430 km) in altitude, the
station gradually loses altitude because of the force of the Earth's gravity
and because of atmospheric drag at that altitude.
The ATV has
three times the cargo capacity of Russia's Progress vehicle and is being
developed by ESA as part of a barter arrangement with NASA. Instead of paying
cash for its share of the station's common operating costs, and also to secure
additional astronaut access, ESA is providing ATV and other gear.
So far, ESA
nations have spent some 1.3 billion euros ($1.9 billion) on developing the ATV,
a figure that includes the first launch. The agency currently plans to build
four other ATVs, with the second due for launch in 2010 - assuming the first
flight occurs without a hitch.
For
this first ATV, called Jules Verne, ESA, NASA and Russia's Roskosmos space
agency have agreed on a go-slow approach as the 42,108-pound (19,100-kg) tug,
operating automatically, nears the station and docks to it.
To be sure
the vehicle responds to commands, it will be ordered to stop at various
distances from the station, then withdraw and wait for further instructions.
Program
managers estimate that following ATV's launch aboard a specially designed
European Ariane 5 rocket, it will take about 10 days for the vehicle to climb
to the station's orbiting altitude.
Depending
on the traffic at the station, ATV may be sent into a parking orbit to wait for
the U.S. space shuttle, or a Russian Progress vehicle, or a Russian Soyuz
manned capsule to complete its mission at the station and depart.
John
Ellwood, ESA's ATV mission manager, said ATV operations require the use of
NASA's Tracking and Data Relay Satellite System, TDRSS, whose capacity will be
fully used during shuttle launches. The next shuttle launch, of Europe's
Columbus space station laboratory, is currently scheduled for Feb. 7.
ATV's need
for TDRSS is minimal if the vehicle is parked at a safe distance from the
station while waiting for a docking opportunity, Ellwood said, meaning that the
launch date is not directly dependent on whether the Feb.
7 shuttle launch is further delayed.
In addition
to needing to steer clear of other traffic to and from the station, ATV's
rendezvous and docking schedule is governed by the position of the sun relative
to both ATV and the station, Ellwood said.
ATV's final
approach to the station is guided by lasers. Ellwood said mission managers want
to avoid having direct sunlight in front of the vehicle as it chases the
station to avoid confusing the laser guidance.
In
addition, the station's astronauts will be monitoring the approach of ATV using
a small camera mounted on board the station. To maintain a clear view, the
maneuver must occur when the sun is not shining directly into the camera,
Ellwood said.
advertisement
