Newsgroup: it.scienza.astronomia
Titolo: Disco verde per il radar MARSIS

Ciao a tutti!
Buone notizie oggi: l'ESA, dopo 8 mesi di simulazioni al computer, ha 
dato l'ok all'apertura del radar MARSIS, che per possibili problemi con 
dispositivi di rilascio, era stato lasciato chiuso per quasi un anno.
Finalmente potranno iniziare i "sondaggi" per cercare tracce di acqua 
nel sottosuolo marziano e lo studio della ionosfera del pianeta rosso.
Finalmente!
Riporto qui sotto la notizia in lingua inglese
***
N° 08-2005 - Paris, 8 February 2005
Green light for deployment of ESA's Mars Express radar
The European Space Agency has given the green light for the MARSIS radar on
board its Mars Express spacecraft to be deployed during the first week of
May. Assuming that this operation is successful, the radar will finally
start the search for subsurface water reservoirs and studies of the Martian
ionosphere.
ESA's decision to deploy MARSIS follows eight months of intensive computer
simulations and technical investigations on both sides of the Atlantic.
These were to assess possible harmful boom configurations during deployment
and to determine any effects on the spacecraft and its scientific
instruments.
The three radar booms of MARSIS were initially to have been deployed in
April 2004, towards the end of the Mars Express instrument commissioning
phase. They consist of a pair of 20-metre hollow cylinders, each 2.5
centimetres in diameter, and a 7-metre boom. No satisfactory ground test of
deployment in flight conditions was possible, so that verification of the
booms' performance had to rely on computer simulation. Just prior to their
scheduled release, improved  computer simulations carried out by the
manufacturer, Astro Aerospace (California), revealed the possibility of a
whiplash effect before they locked in their final outstretched positions, so
that they might hit the spacecraft.
Following advice from NASA's Jet Propulsion Laboratory (JPL), which
contributed the boom system to the Italian-led MARSIS radar instrument, and
the Mars Express science team,  ESA put an immediate hold on deployment
until a complete understanding of the dynamics was obtained. JPL led a
comprehensive investigation, including simulations, theoretical studies and
tests on representative booms, the latter to assess potential aging of the
boom material. European experts, from ESA and the former spacecraft prime
contractor, Astrium SAS, France, worked closely with JPL throughout the
entire investigation. An independent engineering review board, composed of
ESA and industry experts, met in January to evaluate the findings and advise
on 'if and when' to proceed with deployment.
The ESA review board, at its final meeting on 25 January, recommended
deployment of the MARSIS booms. The rationale for the decision was based on
the results of the analyses, which showed the possible impact scenarios, the
amount of energy involved, the nature of the materials, and the physical
conditions in space. The board concluded that the risk of an impact on the
spacecraft could not be ruled out, but that the impact energy would be low
and the probability of a severe failure was very small.
One credible failure case is that an antenna boom could become blocked
during deployment, either by itself or by the spacecraft. Although means are
available to unblock a deployment, in the worst case MARSIS would have to be
considered partially or completely lost. However, the analyses have shown
that the Mars Express control systems would be able to cope with such a
configuration and minimise the consequences for the other scientific
instruments.
The ESA board recommended planning the deployment for the week beginning 2
May. However, should the remaining preparations proceed faster than planned,
it might be feasible to start deployment during the week beginning 25 April.
An early deployment is scientifically desirable, as the evolution of the
Mars Express orbit will allow radar measurements of the most interesting
scientific regions on Mars to start in May 2005.
If, as expected, the deployment is successful, MARSIS will probe the secrets
of Mars's subsurface at least until 30 November 2005, the nominal end date
of Mars Express operations, and beyond if the mission is further extended.
Note to editors
Mars Express was launched on 2 June 2003 and reached the planet on 25
December 2003. Since entering its operational orbit on 28 January 2004, it
has been performing studies and global mapping of the atmosphere and
surface, analysing their chemical composition, and delivering amazing images
of Martian landscapes.
For more information please contact:
ESA Communication Department
Media Relations Office
Paris, France
Tel: +33(0)15369 7155
Fax: 
+33(0)1 5369 7690
Rudolf Schmidt, ESA Mars Express Project Manager
Noordwijk, The Netherlands
Tel: 
+31 71 565 3603
For more information about the Mars Express mission visit:
http://mars.esa.int
For more information about the Science Programme visit :
http://www.esa.int/science
-- 
Marco Zambianchi
Gruppo Astrofili DEEP SPACE Lecco
Italian Space Society Member
British Interplanetary Society Member

 ha scritto nel messaggio 
news:36rlk8F...@individual.net...


 
Entro fine maggio 2005


 > April.
[snip]
Ciao,
-- 
      Ermanno Polli   (INFN-LNF)
    user:      hostname:  subdomain:  domain:  country:
ermanno.polli    N/A        lnf         infn     it


Sorry.  Ho un po' la testa tra le nuvole.