Sunday, July 18, 2010

Martian Mantles

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

  • 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.


Subscribe to this thread:

Add a comment

More by Jim Nintzel

Staff Pick

Carnival of Illusion: Magic, Mystery & Oooh La La!

Carnival of Illusion conjures an evening of old-world magic by blending their international travel theme with all… More

@ Scottish Rite Grand Parlour Saturdays, 5:30 p.m., Sat., Oct. 3, 8 p.m. and Saturdays, 5 & 8 p.m. Continues through April 22 160 South Scott Ave

» More Picks

Submit an Event Listing

Popular Content

  1. The Weekly List: 25 Things To Do In Tucson In The Next 10 Days (The Range: The Tucson Weekly's Daily Dispatch)
  2. Win Tickets to the Chiles, Chocolate & Day of the Dead Festival (The Range: The Tucson Weekly's Daily Dispatch)
  3. We Made One-Fifth of a Lotería Deck For You (The Range: The Tucson Weekly's Daily Dispatch)
  4. Quick Bites: Halloween, Japanese-Style (The Range: The Tucson Weekly's Daily Dispatch)
  5. Cinema Clips: A Man Called Ove (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