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(meteorobs) [ASTRO] Rosetta Structural Thermal Model Is 'All Shook Up'


Rosetta is the futuristic asteroid AND comet rendezvous mission.

Lew

------- Forwarded Message


From: Ron Baalke <BAALKE@KELVIN.JPL.NASAdot gov>
Date: Tue, 22 Feb 2000 4:00:17 GMT
Subject: [ASTRO] Rosetta Structural Thermal Model Is 'All Shook Up'

ESA Science News
http://sci.esa.int

21 Feb 2000

Rosetta STM is 'all shook up'

The test programme of the Rosetta Structural Thermal Model (STM)
continues to go with a bang. At the end of last week, the STM underwent
a series of shocking experiences in order to check its ability to survive
the rough treatment that will be meted out during launch. This was
followed today by a deployment test of a giant solar array.

The first of the STM's trials to be carried out last week was the so-called
'shogun' test. This was a joint operation by technicians from CNES,
Arianespace, and ESA's European Space Research and Technology Centre
(ESTEC) in The Netherlands. (Arianespace operates the Ariane 5 launch
vehicle that will send Rosetta on its way to Comet Wirtanen in 2003.)

The shogun test was a simulation of the shock transmitted to the
spacecraft when its protective fairing separates from the rocket's upper
stage. Using a copy of the actual spacecraft adapter which will attach
Rosetta to the upper stage, a set of pyrotechnic devices was attached
around the underside of the adapter. With all staff withdrawn to safe
positions behind protective glass, these explosive charges were set off
instantaneously to rupture the aluminium plate on the adapter.

"It only lasted a millisecond, but it went off with quite a loud crack,"
commented Rosetta Assembly and Integration Verification Engineer Alan
Moseley.

The next day, the STM was subjected to a 'clamp band separation test'.
The clamp band is a metal strip that attaches the launch adapter to the
spacecraft. After checking that the clamp band fitted properly, technicians
once again had to discover whether its explosive separation would damage
Rosetta. This time, two pyrotechnic charges were set off. As the band was
split in two, both sections were pushed away from the spacecraft interface
by springs and caught by special 'catcher' brackets.

"Although the tests themselves were extremely short, the shocks imparted
to the STM were quite severe. The detailed analysis of the impact on the
spacecraft's units will data take several days, to come to a realistic
conclusion," said J. C. Salvignol, Rosetta mechanical systems engineer.

"I'm pleased to say that the STM passed both tests without any damage,"
added his colleague, Jacques Cand=E9.

Today saw the deployment test for one of Rosetta's 16 metre-long solar
arrays. These enormous arrays are needed because Rosetta will be operating
at five times the Earth's distance from the Sun, where levels of sunlight are
only 4% those on our planet. Rosetta will be making history as the first
spacecraft ever to use solar arrays to generate electrical power during a
deep space mission beyond the asteroid belt.

The check-out began when six 'thermal knives' were used to melt through
the attachments which held the array to the side of the spacecraft. Using
a special jig, springs on the giant panel caused it to slowly open out to its
full, impressive length. After 3 minutes 47 seconds, the array was fully
extended, allowing engineers to check its alignment and condition.

Later in the day, yet another shock test took place. This time, the dish-
shaped high-gain antenna was shaken by three pyrotechnic devices which
exploded one after another. During a subsequent performance check of the
antenna motor, the dish was successfully moved more than 40 degrees
from its fixed position.

"Once again, everything was nominal," declared a highly satisfied Alan
Moseley.

USEFUL LINKS FOR THIS STORY

* More about Rosetta
  http://sci.esa.int/rosetta

IMAGE CAPTION:
[http://sci.esa.int/missions/image.cfm?TypeID=3D11&ContentID=3D9471&table=
=3DContentTable]

Structural Thermal Model (STM) of the Rosetta spacecraft in the
ESA/ESTEC test centre.

------- End of Forwarded Message


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