Spacecraft Ready to 'Skim' Mars Moon Phobos

On Thursday (Jan. 14), the European Space Agency's Mars Express orbiter is set to pay Phobos a visit in what will be the mission's closest flyby of the Martian moon this year.

UPDATE (Jan. 15): According to a Twitter update on Thursday, the Mars Express orbiter successfully completed its Phobos flyby. "Today's #Phobos flyby complete. Science data will come down from #MarsExpress in the next few days," -- @ESAOperations.

On Thursday (Jan. 14), the European Space Agency's Mars Express orbiter is set to pay Phobos a visit in what will be the mission's closest flyby of the Martian moon this year.

Flyby will occur at 16:00:21 UTC (10 a.m. EST) when the mission will come within 53 kilometers (33 miles) of Mars' largest moon. According to a Mars Express blog update, in the nearly-60 planned Phobos flybys this year, this event is a "real skimmer" (the other flybys will come no closer than a few hundred miles), allowing mission scientists to carry out some invaluable science.

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Principally, key scientific instruments, including the High Resolution Stereo Camera (HRSC), will be able to view a region of the moon that has been poorly observed in the past.

"This flyby will provide very good viewing, within 1,000 km (620 miles), of an area previously not seen well," said ESA's Mars Express project scientist Dmitri Titov. "HRSC will be taking images; the MARSIS radar and the ASPERA-3 particle instrument will operate as well to sound the subsurface and plasma environment of the moon."

Within the flyby region is the proposed landing site for the future Russian lander and sample-return mission, Phobos Grunt. The mission was first launched in 2011, but failed when the spacecraft became stranded in low-Earth orbit and ultimately reentered the atmosphere. It is hoped that a repeat attempt may happen by 2026.

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"This flyby is important as it will allow us to finally view this area on Phobos that has yet to be seen at high resolution and excellent lighting," said Thomas Duxbury, professor in planetary science at George Mason University, Va.

In addition, the incredibly close encounter will cause Phobos' weak gravitational field to slightly alter Mars Express' orbital trajectory. In 2013, another close flyby (passing within 45 km or 28 miles) allowed scientists to detect the gravitational deflection so a precise measurement of Phobos' mass and average density could be arrived at. Thursday's flyby will be used to confirm and tightly refine these measurements.

Mars Will Become a Ringed Planet When Phobos Dies

These observations will add to the growing wealth of information about the irregularly-shaped moon that only measures 22 miles across at its widest section. Recently, new theories as to the origin of Phobos' trademark lines and likely doomed future have seen the headlines. Through tidal sheer with Mars, the moon is expected to be pulled apart in less than 40 million years, likely creating a ring system that could persist in Mars orbit for a few million years more.

For more about this fascinating flyby, read Wednesday's mission blog update.

The High Resolution Stereo Camera (HRSC) onboard the ESA spacecraft Mars Express took this image of Phobos using the HRSC nadir channel on March 7, 2010.

The realism of "The Martian" is getting the attention of NASA -- and not only because of what fictional NASA astronaut Mark Watney (Matt Damon) does on the surface. The agency has released several photographs showing real-life locations related to Watney's journey as he tries to get home to Earth. Also, the European Space Agency put out a map showing where Watney moved around on the surface (which we have put last in case you are worried about any spoilers.) Read on to see some of the places Watney had to think about when surviving on Mars.

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Watney's journey begins in Acidalia Planitia, the landing site for his mission (Ares 3). Inside the crater you can see deposits that were blown there by the wind. Think about it -- as Watney and his crew moved around the crater, every place they went to, they were the first to put bootprints in that sand. The University of Arizona's HiRISE camera aboard the Mars Reconnaissance Orbiter helped gather data for this picture. "We can’t see the Ares 3 habitat because it arrives sometime in the future, so this is the 'before' image,"

joked the HiRISE website

earlier this year.

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While we think of Mars as a place devoid of humans, we've sent several landing missions over the years. It turns out that Ares 3 is not so far away from the landing site of

NASA Pathfinder

and its rover, Sojourner -- the first rover to explore Mars in 1997. This image shows portions of the craft after it was deployed, such as the airbags and possibly parts of the heat shield. Since Pathfinder, NASA has sent three more rovers to the surface:

Opportunity (2004), Spirit (2004)



(2012). Opportunity and Curiosity are still working on the surface. The European Space Agency plans to send its first rover to Mars as part of the

2018 ExoMars mission


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As the name "Ares 3" implies, the Ares program is just one of a series of missions to Mars. Ares 4 is the next one, targeting a famous crater on the Martian surface: Schiaparelli Crater. Nearly 300 miles (500 kilometers) across, it's hard to get the entire thing into one high-resolution image, so this is just a portion of it taken with HiRISE. According to NASA, the agency has

avoided dusty regions

like this for two reasons: the dust gets very warm during the day and cold at night (hard on equipment) and it's hard to know if there's anything interesting geologically in the bedrock underneath.

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Here's a challenge about moving around on Mars: it's really hard to judge distance, because there are no familiar human markings to help us find our way around. Astronauts faced this challenge on the moon, and as Watney uses his rover on the surface, he has to be similarly careful not to go in the wrong direction or overstretch his rover's battery. Mawrth Crater is one of the landmarks Watney plots. "The crater rim is not very distinct, and from the Martian surface it would be quite difficult to tell that you are even on the rim of a crater,"

NASA says


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The Opportunity rover (which landed in 2004) is somewhat close to where Watney is moving around. It's possible that Watney draws inspiration from the plucky machine, which is still working well on Mars long past its original 90-Martian-day expiry date. Among Opportunity's major milestones: driving

more than a marathon's worth of distance on Mars,

finding extensive evidence of water around its landing site and beyond, and

exploring the rim of a large crater

called Endeavour.

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While we initially could imagine craters as simple excavations of the surface, the Martian weather makes them far more complex than that. This is a

close-up view of Becquerel Crater

, somewhat near where Watney was moving on the surface. These thick deposits would be made either by water (in the ancient past, when Mars was wetter) or wind, based on what we know of similar processes on Earth. You don't see a lot of craters here because the deposits are so thin that the wind can easily erase any craters in the surface.

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Here you can see Watney's journey across the surface of Mars, as mapped by the European Space Agency (and German Space Agency, DLR) based on imagery from the Mars Express spacecraft. The colors represent different heights of features on the Martian surface, with blue being lowest and red being highest. You can see how Watney had to carefully make his way between craters to reach his destination, the Ares 4 landing site.

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