Jacques van Oene
June 22nd 05, 03:04 PM
N° 34-2005 - Paris, 22 June 2005
Mars Express radar ready to work
MARSIS, the Mars Advanced Radar for Subsurface and Ionosphere Sounding
onboard ESA's Mars Express orbiter, is now fully deployed, has undergone its
first checkout and is ready to start operations around the Red Planet. With
this radar, the Mars Express orbiter at last has its full complement of
instruments available to probe the planet's atmosphere, surface and
subsurface structure.
MARSIS consists of three antennas: two 'dipole' booms 20 metres long, and
one 7-metre 'monopole' boom oriented perpendicular to the first two. Its
importance is that it is the first- ever means of looking at what may lie
below the surface of Mars.
The delicate three-stage phase of radar boom deployment, and all the
following tests to verify spacecraft integrity, took place between 2 May and
19 June. Deployment of the first boom was completed on 10 May. That boom,
initially stuck in unlocked mode, was later released by exploiting solar
heating of its hinges.
Taking advantage of the lessons learnt from that first boom-deployment, the
second 20-metre boom was successfully deployed on 14 June. Subsequently,
ESA's ground team at the European Space Operations Centre (ESOC) in
Darmstadt, Germany, commanded the non-critical deployment of the third boom
on 17 June, which proceeded smoothly as planned.
MARSIS's ability to transmit radio waves in space was tried out for the
first time on 19 June, when the instrument was switched on and performed a
successful transmission test.
The instrument works by sending a coded stream of radio waves towards Mars
at night, and analysing their distinctive echoes. From this, scientists can
then make deductions about the surface and subsurface structure. The key
search is for water. But MARSIS's capabilities do not stop there. The same
methods can also be used by dayto probe the structure of the upper
atmosphere.
Before starting its scientific observations, MARSIS has to undergo its
commissioning phase. This is a routine procedure for any spacecraft
instrument, necessary to test its performance in orbit using real targets in
situ. In this case, the commissioning will last about ten days, or 38
spacecraft orbital passes, starting on 23 June and ending on 4 July.
During the commissioning phase, MARSIS will be pointed straight down (nadir
pointing mode) to look at Mars from those parts of the elliptical orbit
where the spacecraft is closest to the surface (around the pericentre).
During this phase, it will cover the areas of Mars between 15° S and 70° N
latitude. This includes interesting features such as the northern plains and
the Tharsis region, so there is a small chance of exciting discoveries being
made early on.
On 4 July, when the commissioning operations end, MARSIS will start its
nominal science observations. In the initial phase, it will operate in
survey mode. It will make observations of the Martian globe's night-side.
This is favourable to deep subsurface sounding, because during the night the
ionosphere of Mars does not interfere with the lower-frequency signals
needed by the instrument to penetrate the planet's surface, down to a depth
of 5 kilometres.
Through to mid-July, the radar will look at all Martian longitudes between
30° S and 60° N latitude, in nadir pointing mode. This area, which includes
the smooth northern plains, may have once contained large amounts of water.
The MARSIS operation altitudes are up to 800 kilometres for subsurface
sounding and up to 1200 kilometres for studying the ionosphere. From
mid-July, the orbit's closest approach point will enter the day-side of Mars
and stay there until December. In this phase, using higher frequency radio
waves, the instrument will continue shallow probing of the subsurface and
start atmospheric sounding.
"Overcoming all the technical challenges to operate an instrument like
MARSIS, which had never flown in space before this mission, has been made
possible thanks to magnificent cooperation between experts on both sides of
the Atlantic," said Professor David Southwood, ESA's Science Programme
Director. "The effort is indeed worthwhile as, with MARSIS now at work,
whatever we find, we are moving into new territory; ESA's Mars Express is
now well and truly one of the most important scientific missions to Mars to
date," he concluded.
Note to editors
The MARSIS instrument was developed by the University of Rome, Italy, in
partnership with NASA's Jet Propulsion Laboratory (JPL) in Pasadena,
California. The instrument team is led by Professor Giovanni Picardi. It is
the first instrument to actually look below the surface of Mars, using low
frequency microwaves reflected by the different layers of matter. Among its
primary objectives are the attempt to detect underground water ice and the
characterisation of terrains underneath layers of sediment. In addition,
MARSIS will conduct large-scale altimetry mapping and provide data on the
planet's ionosphere, as this electrically-charged region of the upper
atmosphere reflects radio waves too.
Mars Express was launched on 2 June 2003 and reached the Red Planet on
Christmas Day that same year. MARSIS was planned to deploy its three antenna
booms in April 2004, towards the end of the orbiter's commissioning phase.
Computer simulations pointed to a risk that the booms could lash back and
harm the spacecraft and its instruments during deployment. ESA therefore
delayed deployment until the boom supplier (JPL) and the spacecraft prime
contractor (Astrium, France) together with ESA's experts had conducted
further analyses and simulations of boom behaviour during deployment and the
possible impact on the spacecraft. Once the magnitude of the risk involved
had been assessed and the relevant mitigation scenarios defined, ESA decided
to proceed with releasing the MARSIS antennas in May 2005.
For more information contact:
Fred Jansen
ESA, Mars Express Mission Manager
E-mail: fjansen @ rssd.esa.int
Agustin Chicarro
ESA, Mars Express Project Scientist
E-Mail : agustin.chicarro @ esa.int
ESA Media Relations Division
Tel. :+33(0)1.53.69.7155
Fax : +33(0)1.53.69.7690
--
--------------
Jacques :-)
www.spacepatches.info
Mars Express radar ready to work
MARSIS, the Mars Advanced Radar for Subsurface and Ionosphere Sounding
onboard ESA's Mars Express orbiter, is now fully deployed, has undergone its
first checkout and is ready to start operations around the Red Planet. With
this radar, the Mars Express orbiter at last has its full complement of
instruments available to probe the planet's atmosphere, surface and
subsurface structure.
MARSIS consists of three antennas: two 'dipole' booms 20 metres long, and
one 7-metre 'monopole' boom oriented perpendicular to the first two. Its
importance is that it is the first- ever means of looking at what may lie
below the surface of Mars.
The delicate three-stage phase of radar boom deployment, and all the
following tests to verify spacecraft integrity, took place between 2 May and
19 June. Deployment of the first boom was completed on 10 May. That boom,
initially stuck in unlocked mode, was later released by exploiting solar
heating of its hinges.
Taking advantage of the lessons learnt from that first boom-deployment, the
second 20-metre boom was successfully deployed on 14 June. Subsequently,
ESA's ground team at the European Space Operations Centre (ESOC) in
Darmstadt, Germany, commanded the non-critical deployment of the third boom
on 17 June, which proceeded smoothly as planned.
MARSIS's ability to transmit radio waves in space was tried out for the
first time on 19 June, when the instrument was switched on and performed a
successful transmission test.
The instrument works by sending a coded stream of radio waves towards Mars
at night, and analysing their distinctive echoes. From this, scientists can
then make deductions about the surface and subsurface structure. The key
search is for water. But MARSIS's capabilities do not stop there. The same
methods can also be used by dayto probe the structure of the upper
atmosphere.
Before starting its scientific observations, MARSIS has to undergo its
commissioning phase. This is a routine procedure for any spacecraft
instrument, necessary to test its performance in orbit using real targets in
situ. In this case, the commissioning will last about ten days, or 38
spacecraft orbital passes, starting on 23 June and ending on 4 July.
During the commissioning phase, MARSIS will be pointed straight down (nadir
pointing mode) to look at Mars from those parts of the elliptical orbit
where the spacecraft is closest to the surface (around the pericentre).
During this phase, it will cover the areas of Mars between 15° S and 70° N
latitude. This includes interesting features such as the northern plains and
the Tharsis region, so there is a small chance of exciting discoveries being
made early on.
On 4 July, when the commissioning operations end, MARSIS will start its
nominal science observations. In the initial phase, it will operate in
survey mode. It will make observations of the Martian globe's night-side.
This is favourable to deep subsurface sounding, because during the night the
ionosphere of Mars does not interfere with the lower-frequency signals
needed by the instrument to penetrate the planet's surface, down to a depth
of 5 kilometres.
Through to mid-July, the radar will look at all Martian longitudes between
30° S and 60° N latitude, in nadir pointing mode. This area, which includes
the smooth northern plains, may have once contained large amounts of water.
The MARSIS operation altitudes are up to 800 kilometres for subsurface
sounding and up to 1200 kilometres for studying the ionosphere. From
mid-July, the orbit's closest approach point will enter the day-side of Mars
and stay there until December. In this phase, using higher frequency radio
waves, the instrument will continue shallow probing of the subsurface and
start atmospheric sounding.
"Overcoming all the technical challenges to operate an instrument like
MARSIS, which had never flown in space before this mission, has been made
possible thanks to magnificent cooperation between experts on both sides of
the Atlantic," said Professor David Southwood, ESA's Science Programme
Director. "The effort is indeed worthwhile as, with MARSIS now at work,
whatever we find, we are moving into new territory; ESA's Mars Express is
now well and truly one of the most important scientific missions to Mars to
date," he concluded.
Note to editors
The MARSIS instrument was developed by the University of Rome, Italy, in
partnership with NASA's Jet Propulsion Laboratory (JPL) in Pasadena,
California. The instrument team is led by Professor Giovanni Picardi. It is
the first instrument to actually look below the surface of Mars, using low
frequency microwaves reflected by the different layers of matter. Among its
primary objectives are the attempt to detect underground water ice and the
characterisation of terrains underneath layers of sediment. In addition,
MARSIS will conduct large-scale altimetry mapping and provide data on the
planet's ionosphere, as this electrically-charged region of the upper
atmosphere reflects radio waves too.
Mars Express was launched on 2 June 2003 and reached the Red Planet on
Christmas Day that same year. MARSIS was planned to deploy its three antenna
booms in April 2004, towards the end of the orbiter's commissioning phase.
Computer simulations pointed to a risk that the booms could lash back and
harm the spacecraft and its instruments during deployment. ESA therefore
delayed deployment until the boom supplier (JPL) and the spacecraft prime
contractor (Astrium, France) together with ESA's experts had conducted
further analyses and simulations of boom behaviour during deployment and the
possible impact on the spacecraft. Once the magnitude of the risk involved
had been assessed and the relevant mitigation scenarios defined, ESA decided
to proceed with releasing the MARSIS antennas in May 2005.
For more information contact:
Fred Jansen
ESA, Mars Express Mission Manager
E-mail: fjansen @ rssd.esa.int
Agustin Chicarro
ESA, Mars Express Project Scientist
E-Mail : agustin.chicarro @ esa.int
ESA Media Relations Division
Tel. :+33(0)1.53.69.7155
Fax : +33(0)1.53.69.7690
--
--------------
Jacques :-)
www.spacepatches.info