Space & Innovation

Landing Spot Selected for ExoMars Mission

The chosen site, Oxia Planum, is laced with tantalizing chemical fingerprints of clays and other minerals.

Scientists with the European Space Agency's ExoMars mission have picked Oxia Planum as their top site to land a rover that will look for past or present day life on Mars.

Data collected by orbiting spacecraft show Oxia Planum, located near Mars' equatorial region, is laced with tantalizing chemical fingerprints of clays and other minerals that form when rock interacts with water. Scientists estimate the region is about 3.9 billion years old, a time when Mars was believed to be warmer and much wetter than it appears today.

Life, if it ever existed, is expected to be challenging to find on Mars because the planet's thin atmosphere offers little protection from cosmic and solar ultraviolet radiation. Also, the same processes that form rock, tend to destroy organic molecules.

Photos: Watching the Sunsets of Mars Through Robot Eyes

Mars also is covered with potentially toxic salts, know as perchlorates, which complicates not only the search for life, but the techniques used to look for organics.

Oxia Planum, however, shows signs of past volcanic activity, so scientists are hopeful some deposits containing organic material may have been covered in lava and preserved. Relatively recent erosion then may have made some of those deposits accessible.

The ExoMars rover is scheduled to launch in 2018, though a recently discovered technical issue may delay the flight to 2020. The rover will be outfitted with a drill that can extract samples from about 6.5 feet, or 2 meters, beneath the surface. Onboard instruments will then search samples for molecular biosignatures.

Video: Meteorite Reveals Secrets of Mars' Past

Scientists made detailed evaluations of three other sites - Aram Doraum, Hypanis Vallis, and Mawrth Vallis - but decided to focus on Oxia Planum after weighing a host of engineering and science factors.

For example, ExoMars needs to land on a relatively low-lying site so it can fly through as much of the Martian atmosphere as possible to slow itself for a parachute touchdown. Scientists also took into account forecasts of horizontal and vertical wind speeds during the descent, as the rover will land at the end of the 2019 global dust season.

The landing site evaluation team also had to avoid potential hazardous slopes and boulders.

So Liquid Water Flows on Mars -- Now What?

"Our preliminary analysis shows that Oxia Planum appears to satisfy the strict engineering constraints while also offering some very interesting opportunities to study, in situ, places where biosignatures might best be preserved," ESA project scientist Jorge Vago said in a statement.

ESA and Roscosmos, the Russian Space Agency, which is a partner in the project, will make a final call on the ExoMars landing site six months before launch.

Artist's impression of the European ExoMars rover exploring the Martian surface.

Watching a sunset on Earth can be a dazzling and beautiful natural wonder. But what about sunsets on other worlds? Situated over 50 percent further away from the sun than Earth, there's one planet that we've also had the fortune to see the sun drop below the horizon while standing on the surface -- Mars. However, we have yet to experience this Martian perspective with our

own

eyes; instead we depend on images beamed to Earth after being witnessed by robotic lenses and CCDs from NASA's landers and rovers.

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Our first robotic views of a Martian sunset came from NASA's Viking Program, which set two landers down on the Martian surface in 1976. Viking 1 operated until 1980, whereas Viking 2 survived until 1982. In this observation by Viking 1 across the mission's landing site of Chryse Planitia, one of the lander's many sunsets was imaged 30 Martian days (sols) after touch down. The banding in the sky "is an artifact produced by the incremental brightness levels of the camera,"

according to NASA

.

On July 4, 1997, NASA returned to the Martian surface with the Mars Pathfinder mission that consisted of a lander and the first successful Mars rover called "Sojourner." With improved optics, better views of the Martian atmosphere and landscape were possible. Captured on sol 21 of the mission, this view of a sunset behind two prominent hills nicknamed "Twin Peaks" is as striking as it is scientifically important. Pathfinder's lander used its optical instrumentation to measure the dusty particles the setting sunlight was passing through, boosting our understanding of the Martian atmosphere.

ANALYSIS: The First (Ever) Rover Tracks on Mars

Where there's a sunset, there's also a sunrise. The Pathfinder mission captured this series of photographs just as dawn was breaking over Chryse Planitia on sol 25 of the mission. While the sun was low on the horizon, Pathfinder was also able to image high-altitude clouds of ice glinting in the sunlight.

PHOTO: A Blue Sunset On Mars

NASA's Mars rover Spirit captured probably one of the most famous scenes to ever come from Mars. With a bluish inverted triangle of light emanating from a setting sun, giving way to a brownish sky, this view across Gusev Crater captivated the world.

The image was captured on the 489th sol

after landing on the Red Planet in January 2004. Spirit, along with sister rover Opportunity, had a prime mission of only 3 months. When Spirit photographed this dreamy scene it was already operating a year longer than intended. The rover would continue to explore Gusev Crater until it became stuck in a sand trap in 2009. NASA lost contact with the stranded robot and officially ended its epic adventure in 2010.

PHOTOS: Ode to Mars Rover Spirit

The Phoenix Mars Lander was an arctic explorer. Landing in the northern hemisphere's late spring, the solar-powered robot enjoyed 3 months of continuous sunlight at its high latitude location. But as the mission continued, the sun slowly dipped toward the horizon, reducing the intensity of sunlight until it was finally lost. In

this series of observations

recorded on Sept. 5, 2008, the sun can be seen skirting along the silhouetted horizon, emerging from a lazy sunset into sunrise.

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NASA's Mars rover Opportunity is no stranger to Mars sunsets. Landing on Mars within weeks of its rover twin Spirit, Opportunity continues to doggedly explore Mars to this day. 11 years of continuous operations

has taken its toll

, but having recently completed

the first ever marathon on an alien world

, Opportunity is the reigning champion of Mars roving. And with all that roving has come thousands of Mars sunsets and sunrises.

This particular view was captured on Nov 5, 2010

, when the rover was traversing the plains of Meridiani Planum, heading to its current area of study, Endeavour crater.

PHOTOS: 10 Years On Mars: Opportunity's First Sols

Mars rover Curiosity is the newest addition to NASA's ground campaign on the Red Planet. Landing on Aug. 6, 2012, the rover has already provided compelling evidence that the barren planet was once a lot wetter than it is now, also uncovering traces of organic compounds. These historic discoveries provide a tantalizing glimpse into Mars' geological history when it may have been habitable for microorganisms. Although Curiosity is a robotic geologist and chemist, it's also rather good at astronomy.

It has also admired the Gale Crater sunsets

, not only producing some stunning views with its high-resolution optics, but adding to our scientific understanding of atmospheric composition.

ANALYSIS: Mars Rover Watches the Sun Set and Moon Rise

This sequence of photos show Curiosity's view of the sun setting over Gale Crater. The strange bright bands across the sun is caused by the over-saturation of Curiosity's Mastcam CCD pixels, creating a bleeding effect across pixel rows.

PHOTOS: Curiosity's First Week on Mars

With every sunset, there's a robot's shadow. This view of Opportunity was captured in March 2014 when the sun was about to set.

ANALYSIS: Bathing in the Sunset of an 'Earth-Like' Alien World

There's also no lack of photographs of Curiosity's shadow on Mars. In this stunning image, shortly after landing on the Red Planet, the nuclear-powered rover shoots its own shadow as the sun sets behind it. In the distance, Mount Sharp is illuminated in the evening sun.

MORE: Compare these Mars sunsets with the ones we have on Earth -- which do you prefer?