[meteorite-list] Mars Express Acquires Sharpest Images of MartianMoon Phobos

From: Jeff Kuyken <info_at_meteoritecentral.com>
Date: Fri, 1 Aug 2008 16:48:10 +1000
Message-ID: <62A514E1F7B947B38A8AA23FFA0030E9_at_JeffPC>

Absolutely stunning!!! Thanks for the post Ron.

Cheers,

Jeff


----- Original Message -----
From: "Ron Baalke" <baalke at zagami.jpl.nasa.gov>
To: "Meteorite Mailing List" <meteorite-list at meteoritecentral.com>
Sent: Friday, August 01, 2008 9:06 AM
Subject: [meteorite-list] Mars Express Acquires Sharpest Images of
MartianMoon Phobos


>
> http://www.esa.int/esaCP/SEM5H48N9JF_index_0.html
>
> Mars Express acquires sharpest images of martian moon Phobos
> European Space Agency
> 30 July 2008
>
> Mars Express closed in on the intriguing martian moon Phobos at 6:49 CEST
> [0449 UTC] on 23 July, flying past at 3 km/s, only 93 km from the moon.
> The
> ESA spacecraft's fly-bys of the moon have returned its most detailed
> full-disc images ever, also in 3-D, using the High Resolution Stereo
> Camera
> on board.
>
> Phobos is what scientists call a 'small irregular body'. Measuring 27 km x
> 22 km x 19 km, it is one of the least reflective objects in the Solar
> System, thought to be a capture-asteroid or a remnant of the material that
> formed the planets.
>
> The best images of Phobos ever
>
> The HRSC images, which are still under processing, form a bounty for
> scientists studying Phobos. They are a result of observations carried out
> over several close fly-bys of the martian moon, performed over the past
> three weeks. At their best, the pictures have a resolution of 3.7 m/pixel
> and are taken in five channels (in the stereo channel) for images in 3-D
> and
> (in the photometric channels) to perform analyses of the physical
> properties
> of the surface.
>
> The images obtained by several other spacecraft so far have either been of
> a
> lower resolution, or not available in 3D and have not covered the entire
> disc of Phobos. This is also the first time that portions of the far-side
> of
> the moon have been imaged in such high resolution (Phobos always faces
> Mars
> on the same side).
>
> Scientific bounty
>
> In observing Phobos, Mars Express benefits from its highly elliptical
> orbit
> which takes it from a closest distance of 270 km from the planet to a
> maximum of 10 000 km (from the centre of Mars), crossing the 9000 km orbit
> of the martian moon. Mars Express imaged the far-side of Phobos (with
> respect to Mars) for the first time after NASA's Viking mission, by flying
> outside the spacecraft's orbit around Mars.
>
> Phobos-Grunt (Phobos soil), a Russian sample-return mission, is due to for
> launch in 2009. It is expected to land on the far-side of Phobos at a
> region
> between 5 deg south to 5 deg north, and 230 deg west to 235 deg west. This
> region was last imaged in the 1970s by the Viking orbiters.
>
> The HRSC observations have been awaited eagerly to better assess and
> characterise the choice of the landing site.
>
> The moon's remarkably grooved surface can be seen in the pictures quite
> clearly. The origin of these grooves is still debated. It is not known
> whether they are produced by ejecta thrown up from impacts on Mars, or if
> they result from the surface regolith, or soil, slipping into internal
> fissures.
>
> In this image, at least two families of grooves with distinct orientations
> can be seen along with an elongated crater.
>
> The stereo observations (resolution 3.7 m/pixel) are important for
> structural analysis and they will be used to derive a digital terrain
> model
> (a 3-D map of the surface that includes elevation data). The extra
> photometric channels (at 7.4 m/pixel) make it possible to study the
> properties of the Phobos regolith at micron to millimetre scales.
>
> An operational challenge
>
> Managing the close fly-bys was an operational challenge, made possible by
> spacecraft operations engineers and scientists who worked together to
> specially optimise Mars Express's trajectory and obtain the best possible
> views.
>
> The observation made use of a spacecraft slew, a special manoeuvre whereby
> the body of the spacecraft is rotated against the direction of motion, to
> effectively lower the speed at which the target passes in the field of
> view
> of the camera. This makes it possible to avoid blurring of the pictures
> despite the high fly-by velocities, whilst maintaining acceptable exposure
> time.
>
> The HRSC Super Resolution Channel (SRC) also observed during this close
> fly-by, with a nominal resolution of 90 cm/pixel. As expected, despite the
> slew, some residual motion blur has crept into the image, but much detail
> is
> expected to be recovered after further processing.
>
> In the days running up to the observation, the primary star-tracker - a
> navigation device that helps the spacecraft point its instruments at the
> target accurately - experienced some temporary difficulty in recognising
> the
> star constellations in its field of view, leaving the spacecraft operating
> on its secondary system. Concerned that this might affect this critical
> observation, the team at ESA's European Space Operations Centre (ESOC) in
> Darmstadt, Germany, worked intensely to recover the primary system and
> were
> able to switch back successfully two days before the fly-by.
>
> Notes for editors:
>
> The Principal Investigator (PI) for the HRSC experiment on ESA's Mars
> Express is Prof. Dr Gerhard Neukum, who also designed the camera
> technically. The HRSC science team consists of 45 Co-Investigators from 32
> institutions located in 10 nations. The camera was developed at the German
> Aerospace Center (DLR) under the PI in cooperation with industrial
> partners
> (EADS Astrium, Lewicki Microelectronic GmbH and Jena-Optronik GmbH). It is
> operated through ESA/ESOC by the DLR Institute of Planetary Research,
> where
> systematic processing of the image data is carried out. The scenes shown
> here were processed by the PI group at the Institute for Geosciences of
> the
> Freie Universitaet Berlin in cooperation with the DLR Institute of
> Planetary
> Research, Berlin.
>
> [NOTE: Images and weblinks supporting this release are available at
> http://www.esa.int/esaCP/SEM5H48N9JF_index_1.html ]
>
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Received on Fri 01 Aug 2008 02:48:10 AM PDT