sciencetech-blog

comments

Nasa is preparing its fleet of martian scacecraft and rovers for a unique front row seat as a comet passes close by.

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

Researchers say it will provide an unprecedented opportunity to gather data on both the comet and its effect on the Martian atmosphere. 

Scroll down for video 

An artist's concept of Comet Siding Spring (2013 A1) and Mars. Closest approach to Mars is on October 19, 2014. Spacecraft will collect in a 'duck and cover' move to avoid dust from the comet

Siding Spring's nucleus will come closest to Mars around 11:27 a.m. PDT (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.'

Nasa's Mars orbiters lining up behind Mars for their 'duck and cover' maneuver to shield them from comet dust that may result from the close flyby of Comet Siding Spring (C/2013 A1) on Oct. 19, 2014.

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.

This graphic depicts the orbit of comet C/2013 A1 Siding Spring as it swings around the sun in 2014.

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, 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 nucleus.

COMET SLIDING SPRING

Comet Siding Spring comes from the Oort Cloud, material left over from the formation of the solar system. 

'This comet is coming into the solar system straight from the Oort Cloud. It's likely this is its first time this close to the sun,' said space scientist David Humm, of the Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Maryland.

Oort Cloud material, including comets, is scattered through a vast region that begins outside the orbits of Neptune and Pluto and extends a substantial fraction of the distance to Proxima Centauri, the closest neighboring star. 

Oort Cloud comets can tell scientists about the materials - including water and carbon compounds - that existed during the formation of the solar system some 4.6 billion years ago.

The images above show -- before and after filtering -- comet C/2013 A1, also known as Siding Spring, as captured by Wide Field Camera 3 on NASA's Hubble Space Telescope.

Studying this close encounter will be the largest fleet of orbiting scientific observatories ever flown to another world, orbiting around (and rolling on the ground of) Mars. 

These instruments will, for the first time ever, have the chance to make close-up observations of a comet new to the inner solar system. And though it will not be the easiest task, the teams operating these instruments and spacecraft have developed plans to take advantage of this rare opportunity.

Siding Spring is small (the nucleus is less than a mile in diameter) and fast (it will pass Mars at about 34 miles per second). CRISM, HiRISE, and CTX were built to study a slowly-moving planet, so they will use MRO's ability to rotate in order to capture images as the comet speeds by Mars.

The instruments will observe the comet repeatedly for two and a half days as it gets closer and closer to Mars before it makes its closest approach.

 The peak density of comet dust at Mars is expected 98 minutes after closest approach of the nucleus, and the MRO spacecraft will position itself behind the planet at that time.

How graphic shows the science observations that may be captured by NASA Mars spacecraft during the close encounter with Comet Siding Spring (C/2013 A1).

'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 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.

On Oct. 19, the comet will have a very close pass at Mars, just 82,000 miles (132,000 kilometers) from the planet.

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.