This Echo is READ ONLY !   NO Un-Authorized Messages Please!
 ~~~~~~~~~~~~~~~~~~~~~~~~   ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

ESA Science News
29 Oct 2002

Success for Rosetta's transatlantic link

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 http://sci.esa.int/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.

http://sci.esa.int/content/news/index.cfm?aid=13&cid=36&oid=30847

-END OF FILE-
=============

---