Thursday, March 8, 2012

Dust Devils on Mars

Posted By on Thu, Mar 8, 2012 at 4:00 PM

If you think it's been windy in these parts in recent days: The UA's HiRISE camera aboard the Mars Reconnaissance Orbiter has captured this shot of a half-mile-tall dust devil skirting across the surface of the Red Planet.

HiRISE's Paul Geissler tells us:


A towering dust devil casts a serpentine shadow over the Martian surface in this stunning, late springtime image of Amazonis Planitia.

The length of the shadow indicates that the dust plume reaches more than 800 meters, or half a mile, in height. The tail of the plume does not trace the path of the dust devil, which had been following a steady course towards the southeast and left a bright track behind it.

The delicate arc in the plume was produced by a westerly breeze at about a 250-meter height that blew the top of the plume towards the east. The westerly winds and the draw of warmth to the south combine to guide dust devils along southeast trending paths, as indicated by the tracks of many previous dust-devils. The dust plume itself is about 30 meters in diameter.

Numerous bright tracks trend from northwest to southeast. It is interesting to see that these tracks are bright, whereas dust-devil tracks elsewhere on Mars are usually dark. Dark tracks are believed to form where bright dust is lifted from the surface by dust devils, revealing a darker substrate.

Here in Amazonis, the dust cover is too thick to be penetrated by such scouring. A blanket of bright dust was deposited over this region recently, just before the arrival of MRO, so the surface dust here can still be moved. Perhaps the bright tracks form when the settled dust is stirred up by the strong winds generated by the dust devils (tangential wind speeds of up to 70 miles per hour have been recorded in HiRISE images of other dust devils).

It's also interesting that this image was taken during the time of year when Mars is farthest from the Sun. Just as on Earth, Martian winds are powered by solar heating. Exposure to the sun's rays should be at a minimum during this season, yet even now, dust devils act relentlessly to clean the surface of freshly deposited dust, a little at a time.

Tags: , , , , , ,

Comments

Subscribe to this thread:

Add a comment

Previously in the Range

More by Jim Nintzel

  • Zona Politics: Your Primary Election Round-Up!

    • Aug 27, 2016
  • The Skinny

    Secret emails, fear of a bugged office, 911 calls: the greatest hits of Pima County Supervisor Ally Miller
    • Aug 25, 2016
  • The Skinny

    Kirkpatrick continues her effort to link McCain to Trump, while McCain links Kirkpatrick to Hillary.
    • Aug 18, 2016
  • More »

Staff Pick

Barbara Brandel: Paintings on Display

Barbara Brandel’s paintings will be on display September 1-30, 2016, during regular library hours.… More

@ Joel D. Valdez Main Library Mondays-Thursdays, 9 a.m.-6 p.m., Fridays, 9 a.m.-5 p.m., Saturdays, 10 a.m.-5 p.m. and Sundays, 1-5 p.m. Continues through Sept. 25 101 N. Stone Ave.

» More Picks

Submit an Event Listing

Popular Content

  1. Zona Politics: Your Primary Election Round-Up! (The Range: The Tucson Weekly's Daily Dispatch)
  2. Cinema Clips: Southside with You (The Range: The Tucson Weekly's Daily Dispatch)
  3. Independent Distillery to Release Its First Batch of Handcrafted Spirits (The Range: The Tucson Weekly's Daily Dispatch)
  4. World View Case Moves Forward After Motion Denied (The Range: The Tucson Weekly's Daily Dispatch)
  5. Casa Video Top 10 (The Range: The Tucson Weekly's Daily Dispatch)

© 2016 Tucson Weekly | 7225 Mona Lisa Rd. Ste. 125, Tucson AZ 85741 | (520) 797-4384 | Powered by Foundation