Comet 2013 A1 (Siding Spring) close approach to Mars in October 2014

[Rick]

...and closest approach should be in ten minutes or so, give or take...

[MarkS]

But too low in the sky for a decent image

[Rick]

I hope there'll be some interesting images from some of the spacecraft operating there...

[Rick]

Comet Siding Spring skims past Mars

A recently discovered comet has whizzed past Mars, giving scientists a unique chance to study an object from the farthest reaches of the Solar System.

The comet, known as Siding Spring, raced past Mars at 126,000mph (203,000 km/h), missing it by 139,500 km.

Rovers on the Martian surface and satellites were primed to catch the event on their cameras and instruments.

Siding Spring comes from the Oort Cloud - a spherical region of space far beyond the planets.

Researchers believe the comet is very little altered from the time of its formation more than 4.5 billion years ago.

"Siding Spring probably got knocked into the inner Solar System by the passage of a star near the Oort Cloud," says Carey Lisse, from the Johns Hopkins University Applied Physics Laboratory, US.

More: http://www.bbc.co.uk/news/science-environment-29665247

[Rick]

Mars Reconnaissance Orbiter Studies Comet Flyby

The orbiter continues operating in good health after sheltering behind Mars during the half hour when high-velocity dust particles from comet C/2013 A1 Siding Spring had the most chance of reaching the paths of Mars orbiters. It maintained radio communications with Earth throughout the comet's closest approach, at 11:27 a.m. PDT (2:27 p.m. EDT), and the peak dust-risk period centered about 100 minutes later.

More: http://www.jpl.nasa.gov/news/news.php?feature=4344

MAVEN Studies Passing Comet and Its Effects

NASA's newest orbiter at Mars, MAVEN, took precautions to avoid harm from a dust-spewing comet that flew near Mars today and is studying the flyby's effects on the Red Planet's atmosphere.

The MAVEN spacecraft -- full name Mars Atmosphere and Volatile Evolution -- reported back to Earth in good health after about three hours of precautions against a possible collision with high-velocity dust particles released by comet C/2013 A1 Siding Spring.

More: http://www.jpl.nasa.gov/news/news.php?feature=4345

Mars Odyssey Orbiter Watches Comet Fly Near

The longest-lived robot ever sent to Mars came through its latest challenge in good health, reporting home on schedule after sheltering behind Mars from possible comet dust.

NASA's Mars Odyssey was out of communications with Earth, as planned, while conducting observations of comet C/2013 A1 Siding Spring on Sunday, Oct. 19, as the comet flew near Mars. The comet sped within about 88,000 miles (139,500 kilometers) of Mars, equivalent to about one-third of the distance between Earth and Earth's moon. Odyssey had performed a maneuver on Aug. 5 to adjust the timing of its orbit so that it would be shielded by Mars itself during the minutes, around 1 p.m. PDT (4 p.m. EDT) today, when computer modeling projected a slight risk from high-velocity dust particles in the comet's tail.

More: http://www.jpl.nasa.gov/news/news.php?feature=4346

[Rick]

Opportunity Views Comet Near Mars

NASA's Mars Exploration Rover Opportunity captured images of a comet passing much closer to Mars than any previous known comet flyby of Earth or Mars. The images of comet Siding Spring were taken against a backdrop of the pre-dawn Martian sky on Sunday (Oct. 19).

mages of comet A1 Siding Spring from the rover's panoramic camera (Pancam) are online at:

http://www.jpl.nasa.gov/spaceimages/details.php?id=PIA18591

http://www.jpl.nasa.gov/spaceimages/details.php?id=PIA18592

http://www.jpl.nasa.gov/spaceimages/details.php?id=PIA18617

Researchers used Opportunity's Pancam to image at a range of exposure times about two-and-one-half hours before the closest approach of the nucleus of comet Siding Spring to Mars. By the time of closest approach at about 87,000 miles (139,500 kilometers), dawn had lit the sky above Opportunity.

More: http://www.jpl.nasa.gov/news/news.php?feature=4348

Mars Orbiter Image Shows Comet Nucleus is Small

The High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter captured views of comet C/2013 A1 Siding Spring while that visitor sped past Mars on Sunday (Oct. 19), yielding information about its nucleus.

The images are the highest-resolution views ever acquired of a comet coming from the Oort Cloud at the fringes of the solar system. Other spacecraft have approached and studied comets with shorter orbits. This comet's flyby of Mars provided spacecraft at the Red Planet an opportunity to investigate from close range.

Images of comet Siding Spring from HiRISE are online at:

http://www.jpl.nasa.gov/spaceimages/details.php?id=PIA18618

More: http://www.jpl.nasa.gov/news/news.php?feature=4349

[Rick]

MAVEN Ultraviolet Image of Comet Siding Spring's Hydrogen Coma

NASA's Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft obtained this ultraviolet image of hydrogen surrounding comet C/2013 A1 Siding Spring on Oct. 17, 2014, two days before the comet's closest approach to Mars. The Imaging Ultraviolet Spectrograph (IUVS) instrument imaged the comet at a distance of 5.3 million miles (8.5 million kilometers).

The image shows sunlight that has been scattered by atomic hydrogen, shown as blue in this false-color representation. Comets are surrounded by a huge cloud of atomic hydrogen because water (H2O) vaporizes from the icy nucleus, and solar ultraviolet light breaks it apart into hydrogen and oxygen. Hydrogen atoms scatter solar ultraviolet light, and it was this light that was imaged by the IUVS. Two observations were combined to create this image, after removing the foreground signal that results from sunlight being scattered from hydrogen surrounding Mars.

More: http://www.jpl.nasa.gov/news/news.php?feature=4352

[Rick]

Mars Orbiter's Spectrometer Shows Oort Comet's Coma

The Compact Imaging Spectrometer for Mars (CRISM) observed comet C/2013 A1 Siding Spring as the comet sped close to Mars on Oct. 19. CRISM recorded imaging data in 107 different wavelengths, showing the inner part of the cloud of dust, called the coma, surrounding the comet's nucleus.

Two images from CRISM presenting three of the recorded wavelengths are online at:

http://www.jpl.nasa.gov/spaceimages/details.php?id=PIA15291

Comet Siding Spring -- an Oort Cloud comet that may contain material from the formation of the solar system some 4.6 billion years ago -- was making its first voyage through the inner solar system. CRISM and many other instruments and spacecraft combined forces to provide an unprecedented data set for an Oort Cloud comet.

More: http://www.jpl.nasa.gov/news/news.php?feature=4353

[Rick]

Mars Spacecraft Reveal Comet Flyby Effects on Martian Atmosphere

Two NASA and one European spacecraft that obtained the first up-close observations of a comet flyby of Mars on Oct. 19, have gathered new information about the basic properties of the comet's nucleus and directly detected the effects on the Martian atmosphere.

Data from observations carried out by NASA's Mars Atmosphere and Volatile Evolution (MAVEN) mission, NASA's Mars Reconnaissance Orbiter (MRO), and a radar instrument on the European Space Agency's (ESA's) Mars Express spacecraft have revealed that debris from the comet added a temporary and very strong layer of ions to the ionosphere, the electrically charged layer high above Mars. In these observations, scientists were able to make a direct connection from the input of debris from a specific meteor shower to the formation of this kind of transient layer in response; that is a first on any planet, including Earth.

Comet C/2013 A1 Siding Spring traveled from the most distant region of our solar system, called the Oort Cloud, and made a close approach around 2:27 p.m. EDT within about 87,000 miles (139,500 kilometers) of the Red Planet. This is less than half the distance between Earth and our moon and less than one-tenth the distance of any known comet flyby of Earth.

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