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TOPIC: Mars Express


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RE: Marsis Deployment
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Mars Express will be made ready for the second boom antenna’s deployment starting June 13 2005.
The antenna will be unfolded over a two-day period starting June 15.
The Marsis radar will spend the next five months taking readings mainly of Mars’ atmosphere rather than peering deep beneath its surface. Between now and November the lighting conditions due to the satellite’s orbit are not favourable to take subsurface readings.
Deployment of the second 20-meter boom also will allow ESA ground controllers to fly the satellite in its normal mode.
Since the first boom’s deployment, Mars Express has been kept in “robust” mode to compensate for the minor disequilibrium resulting from having only one of the two unfolded.


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L

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RE: MARSIS antenna boom
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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.


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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.

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L

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RE: Mars Express
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Thanks to a manoeuvre performed on 10 May 2005 at 20:20 CET, ESA flight controllers have successfully completed the deployment of the first boom of the MARSIS radar on board ESA's Mars Express spacecraft.
After the start of the deployment of the first 20-metre boom on 4 May, analysis by flight controllers at ESA’s European Space Operations Centre, Darmstadt, Germany, had shown that although 12 out of the 13 boom segments were in place, one of the outermost segments, possibly No. 10, had deployed but was not locked into position.
Deployment of the second (20 m) and third (7 m) booms was suspended pending a full analysis and assessment of the situation.
As prolonged storage in the cold conditions of outer space could affect the fibreglass and Kevlar material of the boom, the mission team decided to ‘slew’ (or swing) the 680 kg spacecraft so that the Sun would heat the cold side of the boom. It was hoped that as the cold side expanded in the heat, it would force the unlocked segment into place.
After an hour, Mars Express was pointed back to Earth, and contact re-established at 04:50 CET on 11 May. A detailed analysis of the data received showed that all segments had successfully locked and Boom 1 was fully deployed.
The operations to deploy the remaining two booms could be resumed in a few weeks, after a thorough analysis and investigation of the Boom 1 deployment characteristics.
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.


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The primary antenna will beam radio waves towards the surface of the Red Planet, some of which will penetrate the crust, probing the composition of the hidden layers of rock and possibly water.
The experiment can function without its third, 7m-long (23ft) "monopole" boom, but this component will help investigators verify whether reflected radio waves are really coming from beneath the surface or simply bouncing off the surface further away from Mars Express.

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The deployment of the second antenna boom of the Mars Express Sub-Surface Sounding Radar Altimeter (MARSIS) science experiment has been delayed pending investigation of an anomaly found during deployment of the first antenna boom.
The anomaly was discovered on 7 May towards the end of the first deployment operations.
Mission controllers were able to determine that 12 of the 13 boom segments of Boom 1 were correctly locked into position. However, one of the final segments, possibly No. 10, had deployed but was not positively locked into position.
It was determined that deployment of the second boom should be delayed in order to determine what implications the anomaly in the first boom may have on the conditions for deploying the second.


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The Mars Express spacecraft has deployed the first of three booms that comprise its Marsis radar, which is to look for water within the Red Planet. At 1430 GMT on 4th May, a command was sent to release the boom, which forms one half of Marsis' primary antenna. The primary antenna's second boom is now due to be deployed on Sunday.


Once the deployment is successful, the Mars Express MARSIS radar will enable the first European spacecraft to orbit Mars to complement its study of the planet’s atmosphere and surface.



MARSIS (Mars Advanced Radar for Subsurface and Ionosphere Sounding instrument) is the first antenna of its kind which was also designed to actually look below the surface of Mars at the different layers of material, most notably for water.
The deployment of the three MARSIS radar booms is an operation which will take place in three phases, in a window spanning from 2 to 12 May 2005. These operations will be initiated and monitored from ESA’s European Space Operations Centre (ESOC) in Darmstadt, Germany.
Each boom will be deployed separately, with the two 20-metre ‘dipole’ booms to be unfurled first and the 7-metre ‘monopole’ boom to follow a few days later.

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-- Edited by Blobrana at 19:29, 2005-05-05

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