With less than three months to go before Rosetta lifts off
from Kourou spaceport in French Guiana, engineers from ESA,
Alenia and Astrium are working feverishly to ensure that
Europe’s comet chaser meets its narrow launch window in
January 2003.
Two major milestones in the extended Rosetta launch
campaign have been successfully completed in recent weeks,
and the project team is delighted with the progress that
has been made since the 3-tonne spacecraft was delivered
to Kourou in early September.
Once Rosetta had been set up in its launch configuration
(without the solar arrays and high-gain antenna) and
passed a leak test of its propulsion system, experts
installed the final versions of the flight software and
validated its electrical systems.
This was followed by the Final Acceptance Test, in which
engineers in the payload preparation facility at Kourou
worked around the clock for eight days to carry out
extensive checks of Rosetta’s computer ‘brain’ to verify
that the spacecraft was responding as it should.
“This was the last full functional test of the
spacecraft, including its payload, before liftoff,” said
Claude Berner, Rosetta Payload and Operations Manager.
“It was a critical moment, but the test was successfully
completed on schedule. We will not carry out another
full functional test until after the launch.”
Confident that all was well with their deep-space
explorer, the Rosetta team then conducted a complex
system validation test with colleagues at the European
Space Operations Centre (ESOC) in Darmstadt, Germany.
During a transatlantic link up that lasted almost
round-the-clock for 96 hours, specialists at ESOC checked
that they could communicate with the spacecraft in real
time as Rosetta responded to a series of commands.
“The test was extremely successful,” commented Paolo
Ferri, Rosetta Operations Manager at ESOC. “We spent
about 78 hours out of the 96 hour period sending
commands, and every day we finished within half an
hour of the scheduled time.”
“We tried to operate the spacecraft in a realistic
manner,” he explained. “Members of the experiment teams
were present in ESOC to study the results as we commanded
all of the experiments both in sequence — one after the
other — and then several at a time.”
One of the most important aspects of the long-distance
trial was the attempt to simulate the operations that
would take place immediately after launch.
“At the beginning of the test, we asked the Kourou crew
to put the spacecraft into the configuration it will
have just before launch,” said Ferri. “Immediately
after they manually triggered the separation switches
(simulating the spacecraft separation from the Ariane
launcher) we took control and ran through the same
sequence that we will follow on 13 January. It was a
very real simulation of the first day and a half of
Rosetta’s mission.”
“Although this was a very important test, it is just
part of the training and validation procedures we have
been practising since September 2002 and that we will
continue until launch,” he added. “This involves
simulating all of the early phases of the mission and
rehearsing possible failure situations.”
With these two potential stumbling blocks out of the
way, Rosetta’s launch campaign is well on the way
towards completion. Over the next few weeks, the
spacecraft will assume its final flight configuration
as the huge solar arrays and dish-shaped high gain
antenna are installed. In late November, after a final
‘go-no go’ test, the spacecraft will be fuelled and
placed under wraps prior to mating with its Ariane 5
upper stage.
USEFUL LINKS FOR THIS STORY
* More about Rosetta
IMAGE CAPTION:
[Image 1:
http://sci.esa.int/content/searchimage/searchresult.cfm?aid=13&cid=12&oid=30847&
ooid=30848]
[Image 2:
http://sci.esa.int/content/searchimage/searchresult.cfm?aid=13&cid=12&oid=30847&
ooid=30851]
Rosetta’s team ensuring that the instruments Lander, Cosima,
Alice and Rosina respond to commands.
