Featured Research

from universities, journals, and other organizations

Mars Express Phobos flyby a success: Unlocking mystery of 'second generation' moons

Date:
March 4, 2010
Source:
European Space Agency
Summary:
Mars Express encountered Phobos March 3, smoothly skimming past at just 67 km, the closest any artificial object has ever approached Mars' enigmatic moon. The data collected could help unlock the origin of not just Phobos but other "second generation" moons.

This image of Phobos’s surface was obtained by the Super Resolution Channel (or SRC, a part of the High Resolution Stereo Camera experiment) on board ESA’s Mars Express on 3 August 2008 (orbit 5889). The distance from the moon’s centre was 656 km, and the image resolution is 6 m/pixel. The original image has been corrected for mirror distortion.
Credit: ESA/ DLR/ FU Berlin (G. Neukum)

Mars Express encountered Phobos March 3, smoothly skimming past at just 67 km, the closest any man-made object has ever approached Mars' enigmatic moon. The data collected could help unlock the origin of not just Phobos but other 'second generation' moons.

Something is not right about Phobos. It looks like a solid object but previous flybys have shown that it is not dense enough to be solid all the way through. Instead, it must be 25-35% porous. This has led planetary scientists to believe that it is little more than a 'rubble pile' circling Mars. Such a rubble pile would be composed of blocks both large and small resting together, with possibly large spaces between them where they do not fit easily together.

The flyby was close enough to give scientists their most exquisite data yet about the gravitational field of Phobos. Mars Express locked onto the radio signal from Earth at around 21:20 CET (20:20 UT). The radio frequency oscillators on the ground are 100 000 times more stable than those on the spacecraft, so for this experiment, which required the best precision possible, the signal was sent up to Mars Express and then returned by the spacecraft to the ground.

The radio waves travel at the speed of light and took 6 minutes 34 seconds to travel from Earth to the spacecraft. So the round trip time was 13 minutes 8 seconds. Once the signal was received back at Earth, it was clearly strong and good. So strong that radio amateurs were also able to lock onto the signal, although their equipment would not be able to detect the subtle variations induced by the gravity of Phobos.

Now that the data are all collected, the analysis can begin. First will be an estimate of the density variation across the moon. This will tell scientists just how much of Phobos' interior is likely to be composed of voids.

"Phobos is probably a second-generation Solar System object," says Martin Pätzold, Universitat Koln, Cologne, Germany, and Principal Investigator of the Mars Radio Science (MaRS) experiment. Second generation means that it coalesced in orbit after Mars formed, rather than forming concurrently out of the same birth cloud as the Red Planet. There are other moons around other planets where this is thought to have been the case too, such as Amalthea around Jupiter.

Whatever the precise origin, Phobos will eventually crumble back into this disrupted state. It is gradually spiralling towards Mars and will eventually be pulled apart. "It came from debris, it will return to debris," says Pätzold. In the meantime, it is there to be studied and explored.

The flyby was just one of a campaign of 12 Mars Express flybys taking place in February and March 2010. For the previous two, the radar was working, attempting to probe beneath the surface of the moon, looking for reflections from structures inside. In the coming flybys, the Mars Express camera will take over, providing high resolution pictures of the moon's surface.


Story Source:

The above story is based on materials provided by European Space Agency. Note: Materials may be edited for content and length.


Cite This Page:

European Space Agency. "Mars Express Phobos flyby a success: Unlocking mystery of 'second generation' moons." ScienceDaily. ScienceDaily, 4 March 2010. <www.sciencedaily.com/releases/2010/03/100304112239.htm>.
European Space Agency. (2010, March 4). Mars Express Phobos flyby a success: Unlocking mystery of 'second generation' moons. ScienceDaily. Retrieved April 23, 2014 from www.sciencedaily.com/releases/2010/03/100304112239.htm
European Space Agency. "Mars Express Phobos flyby a success: Unlocking mystery of 'second generation' moons." ScienceDaily. www.sciencedaily.com/releases/2010/03/100304112239.htm (accessed April 23, 2014).

Share This



More Space & Time News

Wednesday, April 23, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Nuclear-Level Asteroids Might Be More Common Than We Realize

Nuclear-Level Asteroids Might Be More Common Than We Realize

Newsy (Apr. 23, 2014) — The B612 Foundation says asteroids strike Earth much more often than previously thought, and are hoping to build an early warning system. Video provided by Newsy
Powered by NewsLook.com
NASA Chief Outlines Plan for Human Mission to Mars

NASA Chief Outlines Plan for Human Mission to Mars

AFP (Apr. 22, 2014) — NASA administrator Charles Bolden, speaking at the 'Human to Mars Summit' in Washington, says that learning more about the Red Planet can help answer the 'fundamental question' of 'life beyond Earth'. Duration: 00:48 Video provided by AFP
Powered by NewsLook.com
Nasa Gives You An Excuse to Post a Selfie on Earth Day

Nasa Gives You An Excuse to Post a Selfie on Earth Day

TheStreet (Apr. 22, 2014) — NASA is inviting all social media users to take a selfie of themselves alongside nature and to post it to Twitter, Facebook, Flickr, Instagram, or Google Plus with the hashtag #globalselfie. NASA's goal is to crowd-source a collection of snapshots of the earth, ground-up, that will be used to create one "unique mosaic of the Blue Marble." This image will be available to all in May. Since this is probably one of the few times posting a selfie to Twitter won't be embarrassing, we suggest you give it a go for a good cause. Video provided by TheStreet
Powered by NewsLook.com
SpaceX's Dragon Spacecraft Captured by International Space Station

SpaceX's Dragon Spacecraft Captured by International Space Station

Reuters - US Online Video (Apr. 20, 2014) — SpaceX's unmanned Dragon spacecraft makes a scheduled Easter Sunday rendezvous with the International Space Station. Rough Cut (no reporter narration). Video provided by Reuters
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