[meteorite-list] Mars Express to Rendezvous with Phobos
From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Wed, 16 Jul 2008 18:30:19 -0700 (PDT)
Mars Express to rendezvous with Martian moon
European Space Agency
16 July 2008
Scientists and engineers are preparing ESA's Mars Express for a pair of
close fly-bys of the Martian moon Phobos. Passing within 100 km of the
surface, Mars Express will conduct some of the most detailed investigations
of the moon to date.
The series of fly-bys will take place between 12 July and 3 August. During
the second encounter, the spacecraft will fly within 273 km of the surface.
Six days later, Mars Express will close to within just 97 km.
Although the Red Planet itself has been studied in detail, very little is
known about the origins of its moons, Phobos and Deimos. It is unclear if
the moons are actually asteroids that were captured by Mars's gravity and
never left its orbit. Another possibility is that Phobos and Deimos are
actually surviving planetesimals, bodies which formed the planets of the
Solar System. They may also be remnants of an impact of a large object on
As Mars Express closes-in on Phobos, the data gathered will help scientists
answer these questions.
Mars Express has flown close to Phobos in the past, but this is the first
time that the spacecraft will be less than 100 km from the moon. To achieve
this proximity to Phobos, spacecraft operations engineers and scientists
have been working together to optimise the trajectory of Mars Express to
obtain optimum science results -- this is not the case for routine fly-bys.
As it flies by at a distance of 97 km, Mars Express will image areas of
Phobos that have never been glimpsed before. The High-Resolution Stereo
Camera (HRSC) on board the orbiter will take pictures of the moon's surface
with the highest resolution possible, in colour, and in 3-D.
The data obtained will be added to a digital terrain model (DTM). This DTM
will help scientists visualise what it would be like to stand on the moon's
surface by calculating its topography, or the elevation of its surface.
The camera may also capture an image of the intended landing site for
Russia's Phobos-Grunt mission, due for launch in 2009. The manoeuvres
required to observe this site are an operational challenge, and the activity
involves close cooperation between ESA mission scientists, the flight
control team and flight dynamics specialists.
The Visible and Infrared Mineralogical Mapping Spectrometer, OMEGA, the
Planetary Fourier Spectrometer, PFS, and the Ultraviolet and Infrared
Atmospheric Spectrometer, SPICAM, will also gather details on the surface
composition, geochemistry and temperature of Phobos.
The Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) will
collect information during two flybys (23 and 28 July) on the topography of
the moon's surface and on the structure of its interior.
The Energetic neutral atoms analyser, ASPERA will study the environment
around Phobos, in particular the plasma that surrounds the moon and also the
interaction of the moon with the solar wind.
During the second fly-by, all efforts will be concentrated on accurately
determining the mass of the moon using the Mars Radio Science experiment
The upcoming fly-bys
Date Altitude at closest approach
12 July 563 km
17 July 273 km
23 July 97 km
28 July 361 km
3 August 664 km
For more information:
Agustin Chicarro, ESA Mars Express Project Scientist
E-mail: Agustin.Chicarro _at_ esa.int
Olivier Witasse, ESA Mars Express Deputy Project Scientist
Email: Olivier.Witasse _at_ esa.int
[NOTE: Images and weblinks supporting this release are available at
Received on Wed 16 Jul 2008 09:30:19 PM PDT