[meteorite-list] Mars Express Image: Martian Moon Phobos in Detail

From: j.divelbiss_at_att.net <j.divelbiss_at_meteoritecentral.com>
Date: Thu Nov 11 18:24:13 2004
Message-ID: <111120042324.25941.4193F49800086C680000655521602810609C9C070D040A90070BD206_at_att.net>

those pics are too cool Ron.

Phobos is one strange moon.



-------------- Original message from Ron Baalke <baalke_at_zagami.jpl.nasa.gov>: --------------

> http://www.esa.int/export/SPECIALS/Mars_Express/SEM21TVJD1E_0.html
> Martian moon Phobos in detail
> European Space Agency
> Mars Express
> 11 November 2004
> These images, taken by the High Resolution Stereo Camera (HRSC) on board
> ESA's Mars Express spacecraft, are Europe's highest-resolution pictures
> so far of the Martian moon Phobos.
> These HRSC images show new detail that will keep planetary scientists
> busy for years, working to unravel the mysteries of this moon. The
> images show the Mars-facing side of the moon, taken from a distance of
> less than 200 kilometres with a resolution of about seven metres per
> pixel during orbit 756.
> Images of Phobos as shown here had already been taken at lower
> resolution in previous orbits (413, 649, 682, 715 and 748). In the
> coming months, these first pictures will be followed by a series of
> images taken in subsequent fly-bys.
> Collection of Phobos images from different orbit passes
> The Mars Express spacecraft periodically passes near Phobos about one
> hour before it flies at an altitude of only 270 kilometres above the
> Martian surface, just above the atmosphere. Within minutes, the orbiting
> spacecraft turns from its attitude where it points at Mars to train its
> camera on this little world.
> The HRSC provided an unprecedented near-simultaneous group of 10
> different images of the surface, enabling the moon's shape, topography,
> colour, "regolith" light-scattering properties, and rotational and
> orbital states to be determined. The regolith is the small-grained
> material covering most non-icy planetary bodies, resulting from multiple
> impacts on the body's surface.
> Phobos in 3D
> These images have surpassed all previous images from other missions in
> continuous coverage of the illuminated surface, not blurred and at the
> highest resolution. The US Viking Orbiter obtained a few small areas
> sampled at an even higher resolution of a few metres per pixel, but
> these were not so sharp due to the close and fast fly-by.
> The global "groove" network is seen in sufficient detail to cover the
> Mars-facing surface continuously from near the equator up to the north
> pole with regular spacing between the grooves. It now may be possible to
> determine whether the grooves existed before the large cratering events,
> and exist deep within Phobos, or came after the cratering events and
> were superimposed on them.
> Much more detail is seen inside the various-sized craters, showing some
> with marked albedo variations. Some craters have dark materials near the
> crater floors, some have regolith that slid down the crater walls, and
> some have very dark ejecta, possibly some of the darkest material in our
> Solar System.
> Phobos in black and white, close-up
> This tiny moon is thought to be in a "death spiral", slowly orbiting
> toward the surface of Mars. Here, Phobos was found to be about five
> kilometres ahead of its predicted orbital position. This could be an
> indication of an increased orbital speed associated with its secular
> acceleration, causing the moon to spiral in toward Mars.
> Eventually Phobos could be torn apart by Martian gravity and become a
> short-lived ring around Mars, or even impact on the surface. This orbit
> will be studied in more detail over the lifetime of the Mars Express.
> The 3D anaglyph image was generated from a combination of the nadir and
> the blue channel. The colour image was calculated from the three colour
> channels and the nadir channel. Due to geometric reasons the scale bar
> is only valid for the centre of the image.
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Received on Thu 11 Nov 2004 06:24:09 PM PST

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