Sunday, July 18, 2010

Martian Mantles

Posted By on Sun, Jul 18, 2010 at 9:21 PM

PSP_002917_2175.jpg
  • NASA/JPL/University of Arizona

A new batch of photos from the UA's HiRISE camera aboard the Mars Reconnaissance Orbiter are available here.

HiRISE team member Kelly Kolb tells us about the above shot:

A northern mid-latitude scene consisting of craters, intercrater plains, and mantled material is visible in this HiRISE image.

The mantled material seen here covers much of the middle latitudes in both hemispheres of Mars; it has been visibly removed in some locations. It's called "mantled" because it looks as if

it's just draped over, or mantling, the topography underneath.

The mantled material is what causes the craters to have a muted, softened appearance. It's thought to be ice-rich material deposited in a climate different from that of today.

The mantled unit is dissected here, meaning that is not pristine and has likely undergone modification since it was originally laid down. The intercrater plains have a pitted texture full resolution thought to be caused by water ice sublimating and leaving depressions behind.

Unlike that of Earth, the obliquity (tilt of the planet's rotation axis) of Mars changes wildly. Earth has the Moon to keep its axis stable, but Mars' satellites, Phobos and Deimos, are not massive enough to do the same.

Today Mars' obliquity (25.19 degrees) is similar to that of Earth's (23.45 degrees), but this has not always been the case. As the obliquity changes, the portions of Mars that receive the most sunlight shift. During periods of high obliquity, polar regions receive the most sunlight. This causes polar ices, including water ice and carbon dioxide ice, to sublimate (evaporate) into the atmosphere. They would then potentially be re-deposited in the mid-latitudes, similar to where this image is located. It is believed that this process is responsible for the mid-latitude mantled unit.

Comments

Subscribe to this thread:

Add a comment

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

Porter Hall Gallery: Sightlines, a Group Show Courtesy of Etherton Gallery

The Porter Hall Gallery is pleased to welcome Sightlines, a group photography show courtesy of Etherton Gallery,… More

@ Tucson Botanical Gardens Aug. 1-Sept. 30, 8:30 a.m.-4:30 p.m. 2150 N. Alvernon Way.

» 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. Win Tickets To See Colvin & Earle (The Range: The Tucson Weekly's Daily Dispatch)
  5. World View Case Moves Forward After Motion Denied (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