Space Forum / Astronomy / April 2005

ESA News
http://www.esa.int

29 April 2005

Mars Express radar to be deployed in May

Following green light for the deployment of ESA's Mars Express radar,
given in February this year, the radar booms are now planned to be
deployed in the first half of May.

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.

Before each deployment, the spacecraft will be placed in a 'robust'
attitude control mode, which will allow it to tumble freely while the
boom extends before regaining standard pointing to the Sun and Earth.

After each deployment, the control team will conduct a full assessment
of the spacecraft status before a decision is taken to proceed with the
next phase.

The result of each deployment can be assessed only after a series of
tests, each taking few days. After the deployment of the three booms,
ESA engineers will start the analysis of the complete behaviour of the
satellite to be able to confirm the overall success of the operation.

The current schedule is subject to changes, because the timing of the
complex series of operations cannot be all fixed beforehand. A status
report will follow in due course.

Once the deployment is complete, MARSIS will undergo three weeks of
commissioning before the start of actual science investigations, ready
for when one of the prime regions of interest for radar observations
comes into the right position through the natural evolution of the
spacecraft's orbit.

The MARSIS instrument was developed by the University of Rome, Italy, in
partnership with NASA's Jet Propulsion Laboratory (JPL) in Pasadena,
California, USA.

For more information please contact:

Fred Jansen, ESA Mars Express Mission Manager
E-mail: fjansen @ rssd.esa.int

More about...

* Mars Express overview
  http://www.esa.int/esaSC/120379_index_0_m.html
* Looking at Mars
  http://www.esa.int/SPECIALS/Mars_Express/index.html

Related articles

* Green light for deployment of ESA's Mars Express radar
  http://www.esa.int/esaCP/SEM42PXEM4E_index_0.html
* Mars Express latest findings give hints about water loss in the
Martian atmosphere
  http://www.esa.int/esaCP/SEM75BADFZD_index_0.html
* Chances of life are linked to water
  http://www.esa.int/esaSC/SEMN3AR1VED_index_0.html
* Water on early Mars?
  http://www.esa.int/SPECIALS/Mars_Express/SEMKK75V9ED_0.html
* Orbiter instruments
  http://www.esa.int/SPECIALS/Mars_Express/SEMUC75V9ED_0.html

IMAGE CAPTIONS:

[Image 1:
http://www.esa.int/esaCP/SEMH4Q2IU7E_index_1.html]
The Mars Advanced Radar for Subsurface and Ionospheric Sounding (MARSIS)
on board ESA's Mars Express will employ ground-penetrating radar to map
underground water (if it exists) on Mars.

Low-frequency waves will be directed towards the planet from a 40-metre
long antenna which will be unfurled after Mars Express goes into orbit.
The radio waves will be reflected from any surface they encounter.

In most cases this will be the surface of Mars, but because low
frequencies are used, a significant fraction will travel through the
crust to encounter further layers of different material - perhaps even
water.

Analysis of the echoes produced will reveal much about the composition
of the top five kilometres of the crust.

[Image 2:
http://www.esa.int/esaCP/SEMH4Q2IU7E_index_1.html#subhead1]
MARSIS main antenna during Mars Express payload tests. One of the two
main radar booms is shown here, a 20-metre long hollow cylinder, of 2.5
centimetres diameter, folded up in a box like a concertina (accordion).
When the box is opened, the elastic energy of the compressed glass-fibre
booms will let them unfold like a jack-in-the-box.

Credits: Universität der Bundeswehr - München