Tag Archives: rover

NASA Prepares its Science Fleet for Oct. 19 Mars Comet Encounter

NASA’s extensive fleet of science assets, particularly those orbiting and roving Mars, have front row seats to image and study a once-in-a-lifetime comet flyby on Sunday, Oct. 19.

Comet C/2013 A1, also known as comet Siding Spring, will pass within about 87,000 miles (139,500 kilometers) of the Red Planet — less than half the distance between Earth and our moon and less than one-tenth the distance of any known comet flyby of Earth.

Siding Spring’s nucleus will come closest to Mars around 2:27 p.m. EDT, hurtling at about 126,000 mph (56 kilometers per second). This proximity will provide an unprecedented opportunity for researchers to gather data on both the comet and its effect on the Martian atmosphere.

“This is a cosmic science gift that could potentially keep on giving, and the agency’s diverse science missions will be in full receive mode,” said John Grunsfeld, astronaut and associate administrator for NASA’s Science Mission Directorate in Washington. “This particular comet has never before entered the inner solar system, so it will provide a fresh source of clues to our solar system’s earliest days.”

Siding Spring came from the Oort Cloud, a spherical region of space surrounding our sun and occupying space at a distance between 5,000 and 100,000 astronomical units.  It is a giant swarm of icy objects believed to be material left over from the formation of the solar system.

Siding Spring will be the first comet from the Oort Cloud to be studied up close by spacecraft, giving scientists an invaluable opportunity to learn more about the materials, including water and carbon compounds, that existed during the formation of the solar system 4.6 billion years ago.

Some of the best and most revealing images and science data will come from assets orbiting and roving the surface of Mars. In preparation for the comet flyby, NASA maneuvered its Mars Odyssey orbiter, Mars Reconnaissance Orbiter (MRO), and the newest member of the Mars fleet, Mars Atmosphere and Volatile EvolutioN (MAVEN), in order to reduce the risk of impact with high-velocity dust particles coming off the comet.

The period of greatest risk to orbiting spacecraft will start about 90 minutes after the closest approach of the comet’s nucleus and will last about 20 minutes, when Mars will come closest to the center of the widening trail of dust flying from the comet’s nucleus.

“The hazard is not an impact of the comet nucleus itself, but the trail of debris coming from it. Using constraints provided by Earth-based observations, the modeling results indicate that the hazard is not as great as first anticipated. Mars will be right at the edge of the debris cloud, so it might encounter some of the particles — or it might not,” said Rich Zurek, chief scientist for the Mars Exploration Program at NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, California.

The atmosphere of Mars, though much thinner that Earth’s, will shield NASA Mars rovers Opportunity and Curiosity from comet dust, if any reaches the planet. Both rovers are scheduled to make observations of the comet.

NASA’s Mars orbiters will gather information before, during and after the flyby about the size, rotation and activity of the comet’s nucleus, the variability and gas composition of the coma around the nucleus, and the size and distribution of dust particles in the comet’s tail.

Observations of the Martian atmosphere are designed to check for possible meteor trails, changes in distribution of neutral and charged particles, and effects of the comet on air temperature and clouds. MAVEN will have a particularly good opportunity to study the comet, and how its tenuous atmosphere, or coma, interacts with Mars’ upper atmosphere.

Earth-based and space telescopes, including NASA’s iconic Hubble Space Telescope, also will be in position to observe the unique celestial object. The agency’s astrophysics space observatories — Kepler, Swift, Spitzer, Chandra — and the ground-based Infrared Telescope Facility on Mauna Kea, Hawaii — also will be tracking the event.

NASA’s asteroid hunter, the Near-Earth Object Wide-field Infrared Survey Explorer (NEOWISE), has been imaging, and will continue to image, the comet as part of its operations. And the agency’s two Heliophysics spacecraft, Solar TErrestrial RElations Observatory (STEREO) and Solar and Heliophysics Observatory (SOHO), also will image the comet. The agency’s Balloon Observation Platform for Planetary Science (BOPPS), a sub-orbital balloon-carried telescope, already has provided observations of the comet in the lead-up to the close encounter with Mars.

Images and updates will be posted online before and after the comet flyby. Several pre-flyby images of Siding Spring, as well as information about the comet and NASA’s planned observations of the event, are available online at:

http://mars.nasa.gov/comets/sidingspring

Source: NASA

Rover landing site candidates. Credit : ESA

Four possible landing sites are being considered for the ExoMars mission in 2018 :ESA

Four possible landing sites are being considered for the ExoMars mission in 2018. Its rover will search for evidence of martian life, past or present.

ExoMars is a joint two-mission endeavour between ESA and Russia’s Roscosmos space agency. The Trace Gas Orbiter and an entry, descent and landing demonstrator module, Schiaparelli, will be launched in January 2016, arriving at Mars nine months later. The Rover and Surface Platform will depart in May 2018, with touchdown on Mars in January 2019.

Rover landing site candidates. Credit : ESA
Rover landing site candidates. Credit : ESA

The search for a suitable landing site for the second mission began in December 2013, when the science community was asked to propose candidates.

The eight proposals were considered during a workshop held by the Landing Site Selection Working Group in April. By the end of the workshop, there were four clear front-runners.

Following additional review by an ESA-appointed panel, the four sites have now been formally recommended for further detailed analysis.

 

The sites – Mawrth Vallis, Oxia Planum, Hypanis Vallis and Aram Dorsum – are all located relatively close to the equator.

“The present-day surface of Mars is a hostile place for living organisms, but primitive life may have gained a foothold when the climate was warmer and wetter, between 3.5 billion and 4 billion years ago,” says Jorge Vago, ESA’s ExoMars project scientist.

“Therefore, our landing site should be in an area with ancient rocks where liquid water was once abundant. Our initial assessment clearly identified four landing sites that are best suited to the mission’s scientific goals.”

The area around Mawrth Vallis and nearby Oxia Planum contains one of the largest exposures of rocks on Mars that are older than 3.8 billion years and clay-rich, indicating that water once played a role here. Mawrth Vallis lies on the boundary between the highlands and lowlands and is one of the oldest outflow channels on Mars.

The exposed rocks at both Mawrth Vallis and Oxia Planum have varied compositions, indicating a variety of deposition and wetting environments. In addition, the material of interest has been exposed by erosion only within the last few hundred million years, meaning the rocks are still well preserved against damage from the planet’s harsh radiation and oxidation environment.

By contrast, Hypanis Vallis lies on an exhumed fluvial fan, thought to be the remnant of an ancient river delta at the end of a major valley network. Distinct layers of fine-grained sedimentary rocks provide access to material deposited about 3.45 billion years ago.

Finally, the Aram Dorsum site receives its name from the eponymous channel, curving from northeast to west across the location. The sedimentary rocks around the channel are thought to be alluvial sediments deposited much like those around Earth’s River Nile.

This region experienced both sustained water activity followed by burial, providing protection from radiation and oxidation for most of Mars’ geological history, also making this a site with strong potential for finding preserved biosignatures.

“While all four sites are clearly interesting scientifically, they must also allow for the operational and engineering requirements for safe landing and roving on the surface,” adds Jorge.

“Technical constraints are satisfied to different degrees in each of these locations and, although our preliminary evaluation indicates that Oxia Planum has fewer problems compared to the other sites, verification is still on going.”

The next stage of analysis will include simulations to predict the probability of landing success based on the entry profile, atmospheric and terrain properties at each of the candidate sites.

The aim is to complete the certification of at least one site by the second half of 2016, with a final decision on the landing site for the ExoMars 2018 rover to be taken sometime in 2017.


Download the full report: Recommendation for the narrowing of ExoMars 2018 landing sites

More ExoMars images, including digital terrain models of the candidate landing sites, are availablehere.

Source: ESA