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

[j.divelbiss at att.net]

those pics are too cool Ron.

Phobos is one strange moon.

thanx,

John

 
-------------- 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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