Featured Research

from universities, journals, and other organizations

Five Giant Impact Basins Reveal The Ancient Equator Of Mars

Date:
April 19, 2005
Source:
American Geophysical Union
Summary:
A Canadian researcher has calculated the location of Mars' ancient poles, based upon the location of five giant impact basins on the planet's surface. This suggests that the projectiles that caused the basins originated with a single source, an asteroid that disintegrated when it approached too close to Mars, and that the impacts trace the Martian equator at the time of impact.

WASHINGTON - Since the time billions of years ago when Mars was formed, it has never been a spherically symmetric planet, nor is it composed of similar materials throughout, say scientists who have studied the planet. Since its formation, it has changed its shape, for example, through the development of the Tharsis bulge, an eight kilometer [five mile] high feature that covers one-sixth of the Martian surface, and through volcanic activity. As a result of these and other factors, its polar axis has not been stable relative to surface features and is known to have wandered through the eons as Mars rotated around it and revolved around the Sun.

Now, a Canadian researcher has calculated the location of Mars' ancient poles, based upon the location of five giant impact basins on the planet's surface. Jafar Arkani-Hamed of McGill University in Montreal, Quebec, has determined that these five basins, named Argyre, Hellas, Isidis, Thaumasia, and Utopia, all lie along the arc of a great circle. This suggests that the projectiles that caused the basins originated with a single source and that the impacts trace the Martian equator at the time of impact, which was prior to the development of the Tharsis bulge, he says.

Writing in the Journal of Geophysical Research (Planets), Arkani-Hamed calculates that the source of the five projectiles was an asteroid that had been circling the Sun in the same plane as Mars and most of the other planets. At one point, it passed close to the planet, until the force of Martian gravity surpassed the tensile strength of the asteroid, at which point it fragmented. The five large fragments would have remained in the same plane, that of Mars' then-equator. They hit in different spots around the Martian globe, due to Mars' rotation on its then-axis and the differing lengths of time the fragments took before impacting on Mars.

Arkani-Hamed describes the locations of the resulting basins, only three of which are well preserved. The two others have been detected by analysis of Martian gravitational anomalies. The great circle they describe on the Martian surface has its center at latitude -30 and longitude 175. By realigning the map of Mars with that spot as the south pole, the great circle marks the ancient equator.

Arkani-Hamed estimates that the mass of the asteroid captured by Mars was about one percent of that of Earth's Moon. Its diameter was in the range of 800 to 1,000 kilometers [500 to 600 miles], depending upon its density, which cannot be determined.

The significance of Arkani-Hamed's findings, if borne out by further research, is that the extent of presumed underground water on Mars would have to be reassessed. "The region near the present equator was at the pole when running water most likely existed," he said in a statement. "As surface water diminished, the polar caps remained the main source of water that most likely penetrated to deeper strata and has remained as permafrost, underlain by a thick groundwater reservoir. This is important for future manned missions to Mars."

###

The research was supported by the Natural Sciences and Engineering Research Council (NSERC) of Canada.


Story Source:

The above story is based on materials provided by American Geophysical Union. Note: Materials may be edited for content and length.


Cite This Page:

American Geophysical Union. "Five Giant Impact Basins Reveal The Ancient Equator Of Mars." ScienceDaily. ScienceDaily, 19 April 2005. <www.sciencedaily.com/releases/2005/04/050418203556.htm>.
American Geophysical Union. (2005, April 19). Five Giant Impact Basins Reveal The Ancient Equator Of Mars. ScienceDaily. Retrieved August 28, 2014 from www.sciencedaily.com/releases/2005/04/050418203556.htm
American Geophysical Union. "Five Giant Impact Basins Reveal The Ancient Equator Of Mars." ScienceDaily. www.sciencedaily.com/releases/2005/04/050418203556.htm (accessed August 28, 2014).

Share This




More Space & Time News

Thursday, August 28, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Experiment Tests Whether Universe Is Actually A Hologram

Experiment Tests Whether Universe Is Actually A Hologram

Newsy (Aug. 27, 2014) Researchers at Fermilab are using a device called "The Holometer" to test whether our universe is actually a 2-D hologram that just seems 3-D. Video provided by Newsy
Powered by NewsLook.com
SpaceX’s Falcon 9 Rocket Explodes After Liftoff

SpaceX’s Falcon 9 Rocket Explodes After Liftoff

Newsy (Aug. 23, 2014) The private spaceflight company says it is preparing a thorough investigation into Friday's mishap. Video provided by Newsy
Powered by NewsLook.com
Did Russia Really Find Plankton On The ISS? NASA Not So Sure

Did Russia Really Find Plankton On The ISS? NASA Not So Sure

Newsy (Aug. 21, 2014) Russian cosmonauts say they've found evidence of sea plankton on the International Space Station's windows. NASA is a little more skeptical. Video provided by Newsy
Powered by NewsLook.com
Space to Ground: Hello Georges

Space to Ground: Hello Georges

NASA (Aug. 18, 2014) Europe's ATV-5 delivers new science and the crew tests smart SPHERES. Questions or comments? Use #spacetoground to talk to us. Video provided by NASA
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins