Mars-bound Comet Prompts NASA To Assess Danger Posed to Red Planet Probes

by

WASHINGTON — NASA is soliciting ideas for assessing the threat posed to Mars-orbiting spacecraft by the cloud of debris the comet 2013 A1, also known as Siding Spring, will leave in its wake when it flies past the red planet in October 2014.

The solicitation, round seven in the Mars Critical Data Products Program, is for “characterization of the cometary environment around Comet 2013 A1 (Siding Spring) during its 2014 Mars encounter.” The competition is being managed by the Jet Propulsion Laboratory (JPL) in Pasadena, Calif., which plans to make an undetermined number of awards ranging in value from $25,000 to $50,000, according to an Aug. 5 request for proposals.

Responses are due Sept. 11, Jim Green, NASA’s director of planetary science, told members of the National Research Council Space Studies Board’s Committee on Astrobiology and Planetary Science Sept. 4.

Siding Spring, according to JPL estimates, will pass within 120,000 kilometers of the red planet. 

“In other words, right in front of Mars,” Green said Sept. 4. 

The close encounter, while posing a potential threat to hardware in Mars orbit, will also be a “fabulous opportunity” to get some pictures of the comet, both with the probes circling the planet and the Curiosity and Opportunity rovers trundling around on its surface, Green said.

“It should be pretty spectacular,” Michael Meyer, lead Mars scientist at NASA headquarters here, told SpaceNews during the meeting. “It may be so spectacular that we have to tell our orbital assets to look the other way to protect their optics.”

That is the crux of NASA’s damage mitigation strategy, such as it exists so far, Meyer said. Whether that will be necessary depends on what Siding Spring is made of, and how rapidly it will be shedding bits and pieces of its surface as it screams by Mars at about 56 kilometers a second. 

“If the debris has a high particle density, you’re going to turn your [spacecraft’s] heaviest surface toward that debris, because you don’t want to end up losing a mission,” Meyer said.

Meanwhile, added Meyer, there is an outside possibility that Siding Spring’s tour of Mars could disrupt the arrival of another visitor to that planetary system: NASA’s Mars Atmosphere and Volatile Evolution Mission (MAVEN) spacecraft.

Although chances are slim, it is possible that debris from Siding Spring might force MAVEN to delay the date on which it drops into Mars orbit. The $250 million Lockheed Martin-built spacecraft is currently scheduled to launch this November and arrive at Mars in September 2014 for a one-year mission to study the planet’s upper atmosphere.

“The idea is, there might be an escape route to not enter the near-Mars environment,” Meyer said. “It may be one of those things where you don’t end up coming back for a year.”

At the other extreme of possibilities, it could be that Siding Spring and its debris trail pose no threat at all to MAVEN, and that the spacecraft could be among the assets NASA harnesses to image the comet. 

MAVEN “has the kind of plasma experiments necessary to look at both the ionized and the neutral components [of Mars’ atmosphere] and their interaction … with the comet’s tail,” Green told members of the Space Studies Board.