BIGGIE 1/51 1-20 .[15] The biggest threat will be about 100 minutes after closest approach.[15] Mars will pass about 27,000 km (17,000 mi) from the comets orbit at around 20:10 UT.[16]

• Astrophysics > Earth and Planetary Astrophysics

  An Early Look of Comet C/2013 A1 (Siding Spring): Breathtaker or Nightmare?

  Quan-Zhi Ye, Man-To Hui

  (Submitted on 27 Mar 2014)

  The dynamically new comet, C/2013 A1 (Siding Spring), is to make a close approach to Mars on 2014 October 19 at 18:30 UT at a distance of 40+/-1 Martian radius. Such extremely rare event offers a precious opportunity for the spacecrafts on Mars to closely study a dynamically new comet itself as well as the planet-comet interaction. Meanwhile, the high speed meteoroids released from C/Siding Spring also pose a threat to physically damage the spacecrafts. Here we present our observations and modeling results of C/Siding Spring to characterize the comet and assess the risk posed to the spacecrafts on Mars. We find that the optical tail of C/Siding Spring is dominated by larger particles at the time of the observation. Synchrone simulation suggests that the comet was already active in late 2012 when it was more than 7 AU from the Sun. By parameterizing the dust activity with a semi-analytic model, we find that the ejection speed of C/Siding Spring is comparable to comets such as the target of the Rosetta mission, 67P/Churyumov-Gerasimenko. Under nominal situation, the simulated dust cone will miss the planet by about 20 Martian radius. At the extreme ends of uncertainties, the simulated dust cone will engulf Mars, but the meteoric influx at Mars is still comparable to the nominal sporadic influx, seemly indicating that intense and enduring meteoroid bombardment due to C/Siding Spring is unlikely. Further simulation also suggests that gravitational disruption of the dust tail may be significant enough to be observable at Earth.

  Comments:	37 pages, 12 figures, ApJ in press
  Subjects:	Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)
  Cite as:	arXiv:1403.7128 [astro-ph.EP]
  	(or arXiv:1403.7128v1 [astro-ph.EP] for this version)

  Submission history

  From: Quanzhi Ye Mr [view email]
  [v1] Thu, 27 Mar 2014 16:41:35 GMT (1565kb)

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  Link back to: arXiv, form interface, contact.

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NASA Mars Spacecraft Ready for Rare Encounter With Comet

Oct 10, 2014, 10:24 AM ET

By ALYSSA NEWCOMB

ALYSSA NEWCOMBMore From Alyssa »

Digital Reporter

 via GOOD MORNING AMERICA

Artist's concept of Comet C/2013 A1, Siding Spring, heading toward Mars.

NASA

A comet will hurtle past Mars next weekend, nearly missing the Red Planet but providing a once-in-a-lifetime show that will be captured by NASA's fleet of spacecraft.

Comet Siding Spring will pass within 87,000 miles of Mars on Sunday, Oct. 19 -- that's about one-third the distance between the Earth and the moon.

The comet is expected to come closest to Mars at 2:27 p.m. ET that day, moving at about 34 miles per second.

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NASA moved its fleet of orbiting vehicles so they won't be impacted by dust particles from the comet. However, the fleet, including the newly arrived MAVEN, will be in a position to gather information about the size, rotation and gas composition of Siding Spring, agency officials said.

John Grunsfeld, astronaut and associate administrator for NASA's Science Mission Directorate, called next Sunday's event a "cosmic science gift that could potentially keep on giving."

"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," Grunsfeld said in a statement.

The comet is comprised of icy debris that researchers believe are remnants from the formation of the solar system. Its dramatic brush past the Red Planet is expected to yield new insights into the materials that existed during the formation of the solar system 4.6 billion years ago.