Landing site selected for UK's ExoMars rover in 2021

A group of scientists and engineers in Leicester has recommended Oxia Planum as the best landing site for the British-built Mars rover. Due to land in 2021, the ExoMars rover will be the first of its kind to travel across the Martian surface and drill down to determine if evidence of life is buried underground. Dr. Graham Turnock, Chief Executive of the UK Space Agency said: "After the Earth, Mars is the most habitable planet in the solar system, so it's a perfect destination to explore the possibility of life on other planets, as well as the history of our own." Both of the potential landing sites - Oxia Planum and Mawrth Vallis - preserve a rich record of geological history from the planet's wetter past, approximately four billion years ago, however the potential for science return had to be balanced with the prospect of landing safely. Professor John Bridges, from the Space Research Centre, University of Leicester, a member of the Landing Site Selection Working Group, explains why Oxia Planum has been recommended: "After over 4 years of careful study of HiRISE and more recently CaSSIS images Oxia Planum was chosen because scientists were convinced that its fine grained sediments, deposited during the ancient Noachian epoch, were ideally suited for the exobiology rover. "With an enormous catchment area the sediments will have captured organics from a wide variety of environments over a long period of time, including areas where life may have existed. The fine sediments should also be ideal for the ExoMars drill - it aims to get to 2 metres depth.

"Remote identification with the Mars Express and Mars Reconnaissance Orbiter Infrared spectrometers shows the presence of clays and other minerals giving clues to its aqueous history. A large group of scientists have been working on proposing, characterising and down selecting the sites, all of which had fascinating aspects, but Oxia Planum is the clear winner on both science and engineering constraints."

The UK Space Agency is the second largest European contributor to the ExoMars mission, having invested euro 287 million in the mission and Pounds 14 million on the instruments. This, in addition to successful negotiations with the European Space Agency (ESA), secured key mission contracts for the UK space sector.

Sue Horne, Head of Space Exploration at the UK Space Agency said: "I have been working on ExoMars for over 10 years and am amazed at the ingenuity and dedication of UK engineers and scientists in building the rover and instruments that will work in the extreme environment of Mars. Our end goal is in sight and it is getting very exciting."

The government's modern Industrial Strategy is backing businesses to succeed by increasing investment in science, because countries that invest in ideas create more opportunities for business. The ambition is for the UK be the world's most innovative economy - and the development of the ExoMars rover in the UK is a part of this ambition.

Airbus Defence and Space in Stevenage is leading the build of the rover while the UCL Mullard Space Science Laboratory is leading on a key instrument known as the PanCam, a high-resolution 3D camera which will be used to look at the terrain and rocks to try to detect signs of life. The University of Leicester and Teledyne e2v are working on the Raman Spectrometer with STFC RAL Space providing some of the electronics, including the data processing board.

The recommendation was made following a two-day meeting held at the National Space Centre in Leicester, UK, which saw experts from the Mars science community, industry, and ExoMars project present and discuss the scientific merits of the sites alongside the engineering and technical constraints. The Leicester recommendation will be reviewed internally by ESA and Roscosmos with an official confirmation expected mid-2019.

Opportunity Emerges in a Dusty Picture

NASA still hasn't heard from the Opportunity rover, but at least we can see it again. A new image produced by HiRISE, a high-resolution camera aboard NASA's Mars Reconnaissance Orbiter (MRO), shows a small object on the slopes of the Red Planet's Perseverance Valley. That object is Opportunity, which was descending into the Martian valley when a dust storm swept over the region a little more than 100 days ago. The storm was one of several that stirred up enough dust to enshroud most of the Red Planet and block sunlight from reaching the surface. The lack of sunlight caused the solar-powered Opportunity to go into hibernation. The rover's team at NASA's Jet Propulsion Laboratory in Pasadena, California, hasn't heard from it since. On Sept. 11, JPL began increasing the frequency of commands it beams to the 14-year-old rover. The tau -- a measurement of how much sunlight reaches the surface -- over Opportunity was estimated to be a little higher than 10 during some points during the dust storm. The tau has steadily fallen in the last several months. On Thursday, Sept. 20, when this image was taken, tau was estimated to be about 1.3 by MRO's Mars Color Imager camera. This image was produced from about 166 miles (267 kilometers) above the Martian surface. The white box marks a 154-foot-wide (47-meter-wide) area centered on the rover.

The University of Arizona in Tucson operates HiRISE, which was built by Ball Aerospace & Technologies Corp., in Boulder, Colorado. NASA's Jet Propulsion Laboratory, a division of Caltech in Pasadena, California, manages the Mars Reconnaissance Orbiter Project for NASA's Science Mission Directorate in Washington.

Mars Reconnaissance Orbiter preparing for years ahead

NASA's Mars Reconnaissance Orbiter (MRO) has begun extra stargazing to help the space agency accomplish advances in Mars exploration over the next decade. The spacecraft already has worked more than double its planned mission life since launch in 2005. NASA plans to keep using it past the mid-2020s. Increased reliance on a star tracker, and less on aging gyroscopes, is one way the mission is adapting to extend its longevity. Another step is wringing more useful life from batteries. The mission's extended service provides data relay from assets on Mars' surface and observations with its science instruments, despite some degradation in capabilities. "We know we're a critical element for the Mars Program to support other missions for the long haul, so we're finding ways to extend the spacecraft's life," said MRO Project Manager Dan Johnston of NASA's Jet Propulsion Laboratory, Pasadena, California. "In flight operations, our emphasis is on minimizing risk to the spacecraft while carrying out an ambitious scientific and programmatic plan." JPL partners with Lockheed Martin Space, Denver, in operating the spacecraft. In early February, MRO completed its final full-swapover test using only stellar navigation to sense and maintain the spacecraft's orientation, without gyroscopes or accelerometers. The project is evaluating the recent test and planning to shift indefinitely to this "all-stellar" mode in March.

From MRO's 2005 launch until the "all-stellar" capability was uploaded as a software patch last year, the spacecraft always used an inertial measurement unit - containing gyros and accelerometers - for attitude control. At Mars, the orbiter's attitude changes almost continuously, with relation to the Sun and other stars, as it rotates once per orbit to keep its science instruments pointed downward at Mars.

The spacecraft carries a spare inertial measurement unit. The mission switched from the primary unit to the spare after about 58,000 hours of use, when the primary began showing signs of limited life several years ago. The spare shows normal life progression after 52,000 hours, but now needs to be conserved for when it will be most needed, while the star tracker handles attitude determination for routine operations.

The star tracker, which also has a backup on board, uses a camera to image the sky and pattern-recognition software to discern which bright stars are in the field of view. This allows the system to identify the spacecraft's orientation at that moment. Repeating the observations up to several times per second very accurately provides the rate and direction of attitude change.

"In all-stellar mode, we can do normal science and normal relay," Johnston said.

"The inertial measurement unit powers back on only when it's needed, such as during safe mode, orbital trim maneuvers, or communications coverage during critical events around a Mars landing." Safe mode is a precautionary status the spacecraft enters when it senses unexpected conditions. Precise attitude control is then essential for maintaining communications with Earth and keeping the solar array facing the Sun for power.

To prolong battery life, the project is conditioning the two batteries to hold more charge, reducing demand on the batteries, and is planning to reduce the time the orbiter spends in Mars' shadow, when sunlight can't reach the solar arrays. The spacecraft uses its batteries only when it is in shadow, currently for about 40 minutes of every two-hour orbit.

The batteries are recharged by the orbiter's two large solar arrays. The mission now charges the batteries higher than before, to increase their capacity and lifespan. It has reduced the draw on them, in part by adjusting heater temperatures before the spacecraft enters shadow. The adjustment preheats vital parts while solar power is available so the heaters' drain on the batteries, while in shadow, can be reduced.

The near-circle of MRO's orbit stays at nearly the same angle to the Sun, as Mars orbits the Sun and rotates beneath the spacecraft. By design, as the orbiter passes over the sunlit side of the planet during each orbit, the ground beneath it is about halfway between noon and sunset. By shifting the orbit to later in the afternoon, mission managers could reduce the amount of time the spacecraft spends in Mars' shadow each orbit. NASA's Mars Odyssey spacecraft, older than MRO, successfully did this a few years ago. This option to extend battery life would not be used until after MRO has supported new Mars mission landings in 2018 and 2021 by receiving transmissions during the landers' critical arrival events.

"We are counting on Mars Reconnaissance Orbiter remaining in service for many more years," said Michael Meyer, lead scientist of NASA's Mars Exploration Program at the agency's Washington headquarters.

"It's not just the communications relay that MRO provides, as important as that is. It's also the science-instrument observations. Those help us understand potential landing sites before they are visited, and interpret how the findings on the surface relate to the planet as a whole."

MRO continues to investigate Mars with all six of the orbiter's science instruments, a decade after what was initially planned as a two-year science mission to be followed by a two-year relay mission. More than 1,200 scientific publications have been based on MRO observations. Teams operating the two instruments named most often in research papers - the High Resolution Imaging Science Experiment (HiRISE) camera and the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) mineral-mapper - are dealing with challenges but are ready to continue providing valuable observations.

For example, some HiRISE images taken in 2017 and early 2018 show slight blurring not seen earlier in the mission. The cause is under investigation. The percentage of full-resolution images with blurring peaked at 70 percent last October, at about the time when Mars was at the point in its orbit farthest from the Sun. The percentage has since declined to less than 20 percent. Even before the first blurred images were seen, observations with HiRISE commonly used a technique that covers more ground area at half the resolution. This still provides higher resolution than any other camera orbiting Mars - about 2 feet (60 centimeters) per pixel - and little blurring has appeared in the resulting images.

Using two spectrometers, CRISM can detect a wide range of minerals on Mars. The longer-wavelength spectrometer requires cooling to detect signatures of many minerals, including some associated with water, such as carbonates. To do this during the two-year prime science mission, CRISM used three cryocoolers, one at a time, to keep detectors at minus 235 Fahrenheit (minus 148 Celsius) or colder. A decade later, two of the cryocoolers no longer work. The last has become unreliable, but is still under evaluation after 34,000 hours of operation. Without a cryocooler, CRISM can still observe some near-infrared light at wavelengths valuable for detecting iron oxide and sulfate minerals that indicate past wet environments on Mars.

The Context Camera (CTX) continues as it has throughout the mission, adding to near-global coverage and searching for changes on the surface. The Shallow Radar (SHARAD) continues to probe the subsurface of Mars, looking for layering and ice. Two instruments for studying the atmosphere - the Mars Color Imager (MARCI) and Mars Climate Sounder (MCS) - continue to build on nearly six Mars years (about 12 Earth years) of recording weather and climate.

Steep Slopes on Mars Reveal Structure of Buried Ice

Researchers using NASA's Mars Reconnaissance Orbiter (MRO) have found eight sites where thick deposits of ice beneath Mars' surface are exposed in faces of eroding slopes.These eight scarps, with slopes as steep as 55 degrees, reveal new information about the internal layered structure of previously detected underground ice sheets in Mars' middle latitudes.The ice was likely deposited as snow long ago. The deposits are exposed in cross section as relatively pure water ice, capped by a layer one to two yards (or meters) thick of ice-cemented rock and dust. They hold clues about Mars' climate history. They also may make frozen water more accessible than previously thought to future robotic or human exploration missions. Researchers who located and studied the scarp sites with the High Resolution Imaging Science Experiment (HiRISE) camera on MRO reported the findings today in the journal Science. The sites are in both northern and southern hemispheres of Mars, at latitudes from about 55 to 58 degrees, equivalent on Earth to Scotland or the tip of South America.

"There is shallow ground ice under roughly a third of the Martian surface, which records the recent history of Mars," said the study's lead author, Colin Dundas of the U.S. Geological Survey's Astrogeology Science Center in Flagstaff, Arizona. "What we've seen here are cross-sections through the ice that give us a 3-D view with more detail than ever before."

Windows into underground ice
The scarps directly expose bright glimpses into vast underground ice previously detected with spectrometers on NASA's Mars Odyssey (MRO) orbiter, with ground-penetrating radar instruments on MRO and on the European Space Agency's Mars Express orbiter, and with observations of fresh impact craters that uncover subsurface ice.

NASA sent the Phoenix lander to Mars in response to the Odyssey findings; in 2008, the Phoenix mission confirmed and analyzed the buried water ice at 68 degrees north latitude, about one-third of the way to the pole from the northernmost of the eight scarp sites.

The discovery reported today gives us surprising windows where we can see right into these thick underground sheets of ice," said Shane Byrne of the University of Arizona Lunar and Planetary Laboratory, Tucson, a co-author on today's report. "It's like having one of those ant farms where you can see through the glass on the side to learn about what's usually hidden beneath the ground."

Scientists have not determined how these particular scarps initially form. However, once the buried ice becomes exposed to Mars' atmosphere, a scarp likely grows wider and taller as it "retreats," due to sublimation of the ice directly from solid form into water vapor.

At some of them, the exposed deposit of water ice is more than 100 yards, or meter, thick. Examination of some of the scarps with MRO's Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) confirmed that the bright material is frozen water. A check of the surface temperature using Odyssey's Thermal Emission Imaging System (THEMIS) camera helped researchers determine they're not seeing just thin frost covering the ground.

Researchers previously used MRO's Shallow Radar (SHARAD) to map extensive underground water-ice sheets in middle latitudes of Mars and estimate that the top of the ice is less than about 10 yards beneath the ground surface. How much less? The radar method did not have sufficient resolution to say. The new ice-scarp studies confirm indications from fresh-crater and neutron-spectrometer observations that a layer rich in water ice begins within just one or two yards of the surface in some areas.


Astronauts' access to Martian water

The new study not only suggests that underground water ice lies under a thin covering over wide areas, it also identifies eight sites where ice is directly accessible, at latitudes with less hostile conditions than at Mars' polar ice caps. "Astronauts could essentially just go there with a bucket and a shovel and get all the water they need," Byrne said.

The exposed ice has scientific value apart from its potential resource value because it preserves evidence about long-term patterns in Mars' climate. The tilt of Mars' axis of rotation varies much more than Earth's, over rhythms of millions of years.

Today the two planets' tilts are about the same. When Mars tilts more, climate conditions may favor buildup of middle-latitude ice. Dundas and co-authors say that banding and color variations apparent in some of the scarps suggest layers "possibly deposited with changes in the proportion of ice and dust under varying climate conditions."

This research benefited from coordinated use of multiple instruments on Mars orbiters, plus the longevities at Mars now exceeding 11 years for MRO and 16 years for Odyssey. Orbital observations will continue, but future missions to the surface could seek additional information.

"If you had a mission at one of these sites, sampling the layers going down the scarp, you could get a detailed climate history of Mars," suggested MRO Deputy Project Scientist Leslie Tamppari of NASA's Jet Propulsion Laboratory, Pasadena, California. "It's part of the whole story of what happens to water on Mars over time: Where does it go? When does ice accumulate? When does it recede?"