Green light for the deployment of the second MARSIS boom (Forwarded)

ESA News
http://www,esa,int

7 June 2005

Green light for the deployment of the second MARSIS boom

Following in-depth analyses performed after the deployment of the first MARSIS
antenna boom on board Mars Express, ESA has decided to proceed with the
deployment of the second 20-metre antenna boom.

The full operation will be performed during a time frame starting 13 June and
nominally ending on 21 June.

A delay in the execution of the second boom deployment was necessary, due to
problems encountered with the first deployment in early May this year. During the
deployment, one of the antenna hinges (the tenth) got stuck in an unlocked position.
Analysis of data obtained from earlier ground testing suggested a potential solution.

The Mars Express spacecraft control team at ESA's Spacecraft Operations Centre
(ESOC) succeeded in unblocking the hinge by exposing the cold side of the boom
to the Sun. This warmed the hinges and the boom quickly became unstuck. In the
end, the first boom deployment was completed on 10 May.

The lessons learnt during the first boom deployment were used to run new simulations
and determine a new deployment scenario for the second boom. This scenario
contains an additional sun-heating phase, to get the best possible thermal conditions
for all hinges.

The deployment of the third (7-metre) third MARSIS boom is not considered critical.
It will be commanded only once the ESA ground control team have re-acquired signal
from the spacecraft, and made sure with a sequence of tests that the second boom is
correctly locked into position and the spacecraft is well under control.

After this event MARSIS, the Mars Express Sub-Surface Radar Altimeter, will enter into
a commissioning phase for the next few weeks, before starting to look at Mars's
ionosphere during martian daylight, and to probe down below the Martian surface
during the martian night.

For more information please contact:

Fred Jansen
Mars Express mission manager
fjansen @ rssd.esa.int

Related articles

* Looking at Mars
http://www.esa.int/SPECIALS/Mars_Express/index.html
* First MARSIS boom successfully deployed
http://www.esa.int/esaCP/SEMY3R5TI8E_index_0.html
* Deployment of second MARSIS boom delayed
http://www.esa.int/esaCP/SEMQGXY5D8E_index_0.html
* Mars Express radar to be deployed in May
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* Green light for deployment of ESA's Mars Express radar
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* Water on early Mars?
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IMAGE CAPTIONS:
[http://www.esa.int/esaCP/SEMSL01DU8E_index_1.html]
2nd MARSIS antenna to be deployed next week

The 2nd antenna of the Mars Express radar MARSIS (indicated by the red
arrow) is due to be deployed in mid-June 2005.

The Mars Express Sub-Surface Sounding Radar Altimeter (MARSIS) experiment
is to map the Martian sub-surface structure to a depth of a few kilometres. The
instrument's 40-metre long antenna booms will send low frequency radio waves
towards the planet, which will be reflected from any surface they encounter.

MARSIS is one of the seven science experiments carried on board Mars Express,
one of the most successful missions ever flown to the Red Planet. Mars Express
was launched on 2 June 2003 and entered Mars orbit in December 2003.