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This image from NASA’s Mars Reconnaissance Orbiter shows gullies near the edge of Hale crater on southern Mars.

Martian gullies carved into hill slopes and the walls of impact craters were discovered several years ago. On Earth, gullies usually form through the action of liquid water — long thought to be absent on the Martian surface. Whether liquid water carves gullies under today’s cold and dry conditions on Mars is a major question that planetary scientists are trying to answer.

Gullies at this site are especially interesting because scientists recently discovered actively changing examples at similar locations. Images separated by several years showed changes in the appearance of some of these gullies. Today, planetary scientists are using the HiRISE camera on MRO to examine gullies such as the one in this image for change that might provide a clue about whether liquid water occurs on the surface of Mars. The view covers an area about 1 kilometer, or 0.6 mile, across and was taken on Aug. 3, 2009.

h/t: nasa.gov

Grant Brissey covered everything from hard news and technology, to music, film, and visual arts during his time working for The Stranger. Grant's work has also appeared at Geekwire, and in Billboard,...

9 replies on “Today in Outer Space”

  1. I see an alluvial fan in the lower right. Cool!

    I think these could be, geologically speaking, recent (within the last few thousand years, but not last week). I’m thinking some type of repeated flooding events rather than streams that flow consistently, like in the desert here on Earth.

    Either that, or the aliens did a likeness of Wilfred Brimley on the surface of Mars. That would be cool, too.

  2. I’m no expert on this stuff by any strech of the imagination, but wouldn’t wind do the same thing? I know that there is a thin atmosphere on Mars.

  3. Along the same lines, the Cassini probe seems to have seen the lakes at Titan’s poles drying up and then reforming — observable methane weather, in only a thirtieth of a Titan year!

    Messenger sent back a great departing pic from its pure gravitic flyby of Mercury, showing a never before spotted northern impact crater (relatively recent) that sprayed material over nearly the entire planet!

    Cassini also seems to have found more evidence of a ring around Saturn’s moon Rhea, a line of material that followed its equator in a UV view of the moon.

    And speaking of moons, LCROSS will smash into ours in a couple of days…

  5. Grant @4, get up early (it will impact at 4:30 AM our time) and try to get clear of the city lights — NASA is recommending a 10″ or larger scope to watch. Details here:

    http://lcross.arc.nasa.gov/observation/a…

    There may be other local events, but NASA has a viewing party listed on the LCROSS site in Tacoma:

    “The Tacoma Astronomical Society will be hosting an LCROSS Breakfast Bash at the Pacific Lutheran University Observatory from 3:45 am PDT to 30 minutes post impact. We will stream NASA LCROSS footage as well as our own images from the 16″ W.M. Keck Observatory.”

    http://www.nasa.gov/mission_pages/LCROSS…

  9. @2, from an abstract submitted to the American Geophysical Union:

    “Bright gully deposits imaged by the Mars Orbiter Camera at other locations were initially interpreted as evidence for water on the surface in recent years. One of these bright gully deposits was modeled and it was found that, although water could not be ruled out in the formation of the studied bright gully deposits, dry flow was sufficient to create them. HiRISE has imaged several other unmodified bright gully deposits around Mars, most of which occur on steep slopes (26-35°) in fresh craters. The slopes of one section of Hale Crater with bright gully deposits are closer to 19-20°, which suggests that it would be difficult for a dry debris flow to form the bright gully deposits.”

    So there’s mostly just theories so far. There is wind on Mars, that kicks up almost planet-wide dust storms. Here’s some dust devils caught on camera at Gusev Crater by the Opportunity Rover:

    http://a52.g.akamaitech.net/f/52/827/1d/…

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