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March 15, 2010 | 12
On March 3 the European Space Agency's Mars Express orbiter passed within 67 kilometers of the Martian moon Phobos, the closest a spacecraft has ever skimmed the larger of Mars's two diminutive oddball satellites. Only 27 kilometers long at its lengthiest dimension, Phobos is a misshapen lump that may be a captured asteroid.
Mars Express is engaged in a series of 12 Phobos flybys that began in February and will end March 26. The photograph above comes from a March 7 pass, when the spacecraft came within about 100 kilometers of Phobos; the closer approach of March 3 took Mars Express past the moon's nightside to gather data, albeit limiting its value as a photo opportunity.
The Russian Phobos–Grunt lander, scheduled to lift off in 2011, is designed to return soil samples that should help uncover Phobos's origin. The proposed landing area for Phobos Grunt is on the rightmost visible edge of the moon in this photograph, about one third of the way up from the bottom.
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12 Comments
Add CommentI think this moon's irregular shape is more the result of its limited mass rather than an indicator of its origin. It is gravitation that tends to produce spherical objects, given sufficient mass.
Reply | Report Abuse | Link to thisI think all object are just as irregular, it's just as they increase in volume they appear smoother because the scale of the irregularities does not change. (Imagine a swarm of Phobos massing about the same as Mars coming together - their irregularities would remain the same on the surface, while being crushed into an average on the interior.)
Reply | Report Abuse | Link to thisSo, a chemical composition will be a vastly superior method of gaging the object's origin(s).
There are strings of grooves and craters in a linear pattern. Any theories as to how they came to be?
Reply | Report Abuse | Link to thisSkepticalThinker - Interesting counterpoint, from a fractal perspective. However, I think that small scale irregularities are allowed by local gravitational affects, but at large scales the gravitational affects of discrete, dense masses tend to produce spherical objects. Of course, this tendency can still be overcome by external forces to produce at least temporary irregularities.
Reply | Report Abuse | Link to thisSkepticalThinker - You're absolutely correct - a detailed compositional analysis is necessary to better determine its origin.
Reply | Report Abuse | Link to thisj.quasimodo - Very good point. Interestingly the grooves seem to be regionally parallel, but then they also intersect in the photo. I don't know, but it does suggest an eventful history.
Reply | Report Abuse | Link to thiswww.holyconservancy.org/images/MOON/PHOB/MAPhobosUprite.png
Reply | Report Abuse | Link to thisIf you flip this image about 80 degrees, there are people standing up.
Ooops! Bad link.
Reply | Report Abuse | Link to thishttp://www.holyconservancy.org/images/MARS/PHOB/MAPhobosUprite.png
If you flip this image about 80 degrees, there are people standing up, there.
EmilyCragg - I didn't see anyone I recognized...
Reply | Report Abuse | Link to thisDoes anyone else think that Phobos looks like it was created in water?? It appears to be built up in layers, at least to me.? Just a thought................?
Reply | Report Abuse | Link to thishinoon42 - From this view it seems that the parallel surface features could be stratified deposition layers. In that case, I'd expect the surface features on two hemispheres would parallel each other. Unfortunately, this view only shows one of those hemispheres, but I wouldn't expect it to have been built up from mineral deposits sinking in water or any other fluid.
Reply | Report Abuse | Link to thisj.quasimodo - The linear features are somewhat reminiscent of features on Jupiter's moon Europa, although the are much better aligned.
Reply | Report Abuse | Link to thisI'd guess the might be produced by gravitational 'tidal' forces imposed the geology of Phobos by Mars.