Changing Planet

Powerful Jets From Mars-Bound Comet Spied by Hubble

These images by the Hubble Space Telescope show comet C/2013 A1 Siding Spring as observed on March 11, 2014. The original image on the left shows the solid icy nucleus is too small to be resolved, but it lies at the center of a dust cloud (coma) that is roughly 12,000 miles across. The image on the right shows when the glow of the coma is subtracted through image processing, and  resolves what appear to be two jets of dust coming off the nucleus in opposite directions. . Credit: NASA, ESA, and J.-Y. Li (Planetary Science Institute)
These Hubble Space Telescope images show comet C/2013 A1 (Siding Spring) on March 11, 2014. Left, the solid icy nucleus is too small to be resolved, but it lies at the center of a dust cloud (coma) that is roughly 12,000 miles (19,300 kilometers) across. Right, the glow of the coma is subtracted, resolving what appear to be two jets of dust coming off the nucleus in opposite directions. Credit: NASA, ESA, and J.-Y. Li (Planetary Science Institute)

After lurking in the outer reaches of the solar system for the past one million years, a comet is heading for a close encounter with Mars. The Hubble Space Telescope is keeping tabs on the icy interloper, seen in just-released images.

Comet C/2013 A1 (Siding Spring), which now lies some 353 million miles (568 million kilometers) from Earth, was discovered by Australia’s Robert McNaught, a prolific comet and asteroid hunter, more than a year ago. NASA’s Near-Earth Object Program Office at the Jet Propulsion Laboratory, in Pasadena, California, has been refining the comet’s exact trajectory ever since.

While researchers have ruled out a direct collision with Mars, the dusty coma of the comet (which is nearly as large as the entire Earth) will sweep directly across the red planet.  The comet core, or nucleus, is expected make its closest approach to the red planet on October 19 at 2:28 p.m. ET. It will pass within 85,600 miles (137,760 kilometers) of Mars—less than half the distance from the Earth to the moon.

Hubble snapped these views of Siding Spring in late January and again on March 11 (photo above), just as our planet crossed the orbital path of the comet. That allowed astronomers to precisely clock the speeds of the dust flying off the comet’s icy nucleus.

This chart shows the trajectory of Comet Siding Springs as it rounds the sun and passes by the planet Mars. Credit: JPL/NASA
This chart shows comet Siding Spring’s trajectory as it rounds the sun and passes by Mars. Credit: JPL/NASA

NASA Worries

With the comet particles blasting away from its surface at speeds of 125,000 miles per hour (56 kilometers per second), space agency officials are concerned about possible damage to spacecraft in orbit around the red planet.

“This is critical information that we need to determine whether, and to what degree, dust grains in the coma of the comet will impact Mars and spacecraft in the vicinity of Mars,” said Jian-Yang Li of the Planetary Science Institute in Tucson, Arizona.

At this moment in time, various mission teams are not sure exactly the level of risk they are dealing with, but they are preparing for all scenarios.

“Our plans for using spacecraft at Mars to observe comet Siding Spring will be coordinated with plans for how the orbiters will duck and cover, if we need to do that,” said Rich Zurek, Mars Exploration Program chief scientist at NASA’s Jet Propulsion Laboratory, in a statement in January.

How much threat Mars orbiters will face will really depend on how much dust is being thrown off by the comet, and in what direction the orbiters will be heading at the time of encounter.

Precautionary measures might include facing the orbiters away from the onslaught of the fast-moving particles, or making sure that the spacecraft are on the opposite side of Mars when they arrive—using the planet as a natural shield during the comet’s closest approach.

Meanwhile, the rovers on the surface are thought to be out of danger since the Martian atmosphere is thick enough to prevent the dust from doing any damage.

See for Yourself

By October 25 the comet will reach its closest approach to our planet, coming about 130 million miles (209 million kilometers) from the sun; however, it’s not expected to become visible to the naked eye.

It’s a safe bet that both backyard and professional stargazers will be training their telescopes on the red planet on October 19, hoping to get a good view of the cosmic near-miss.

This sky chart shows the view of Mars and Comet Siding Springs on October 19th. Sky-watchers need to face the southwest after dusk, looking for the teapot star pattern of Sagittarius constellation as a guidepost for finding orange-hued Mars low in the sky.  Credit: Starry Night Software / A.Fazekas
This sky chart shows Mars and comet Siding Spring as they will look on October 19. Sky-watchers need to face southwest after dusk and look for the teapot star pattern of the constellation Sagittarius as a guidepost for finding orange-hued Mars low in the sky. Credit: Starry Night Software / A. Fazekas

There is still hope that, starting around mid-September, Siding Spring may become visible in the evening skies through binoculars and backyard scopes for us Earthlings.

Quite a sky show might be seen from the surface of Mars through the electronic eyes of the Opportunity and Curiosity rovers looking up, as well.

Current brightness magnitudes indicate that the comet will be very bright to their digital eyes. Comet fans can hardly wait to see the picture postcards that will be beamed back from these intrepid robotic explorers. Stay tuned for more details!

Follow Andrew Fazekas, the Night Sky Guy, on Twitter, Facebook, and his website.

Andrew Fazekas, aka The Night Sky Guy, is a science writer, broadcaster, and lecturer who loves to share his passion for the wonders of the universe through all media. He is a regular contributor to National Geographic News and is the national cosmic correspondent for Canada’s Weather Network TV channel, space columnist for CBC Radio network, and a consultant for the Canadian Space Agency. As a member of the Royal Astronomical Society of Canada, Andrew has been observing the heavens from Montreal for over a quarter century and has never met a clear night sky he didn’t like.
  • Owen Iverson

    would have thought the comet tail in that illustration should be pointing directly away from the sun…

  • Owen Iverson

    would have thought the comet tail in that illustration should be pointing directly away from the sun…

  • Sunil Alexander

    Why don’t science help find the missing Malaysian plane? Why not not find cure for diabetes. Why are we so interested in mars and other planets. First fix the problems on earth..

  • Sunil Alexander

    Why don’t science help find the missing Malaysian plane? Why not not find cure for diabetes. Why are we so interested in mars and other planets. First fix the problems on earth..

  • Jake

    Imagine the awesome view of this on Mars as it passes by. Can we get one of the satellites/Rovers to snap some pics?

  • Jake

    Imagine the awesome view of this on Mars as it passes by. Can we get one of the satellites/Rovers to snap some pics?

  • Albert B. Turner, III

    Solar “wind” must be quite something, if it pushes matter from the comet to form its tail!

  • Albert B. Turner, III

    Solar “wind” must be quite something, if it pushes matter from the comet to form its tail!

  • Lizelle Pretorius

    Wow!!! I’d love to see this!! Mind blowing!!

  • Lizelle Pretorius

    Wow!!! I’d love to see this!! Mind blowing!!

  • Scott

    Too bad it won’t hit Mars. To imagine the changes, even if temporary. It would likely do wonders to getting humans to the planet sooner than later.

  • Scott

    Too bad it won’t hit Mars. To imagine the changes, even if temporary. It would likely do wonders to getting humans to the planet sooner than later.

  • Andrew Booth

    I bet there’ll be some impressive meteors and fireballs on Mars while the planet passes through the tail.

  • Andrew Booth

    I bet there’ll be some impressive meteors and fireballs on Mars while the planet passes through the tail.

  • Mihai Micoara

    Imagine the pictures that the Mars Rover will send in. Looking forward to seing them

  • Mihai Micoara

    Imagine the pictures that the Mars Rover will send in. Looking forward to seing them

  • Taeko Takahashi

    there will always be crisis on earth – hard to be excited about off planet endeavors with that fact however i think that there are people involved with space studies that want to help the planet and its inhabitants, living and yet to be

  • Taeko Takahashi

    there will always be crisis on earth – hard to be excited about off planet endeavors with that fact however i think that there are people involved with space studies that want to help the planet and its inhabitants, living and yet to be

  • Mark Pinnell

    How big is it?

  • assadZarif

    I would love to see some pictures

  • assadZarif

    I would love to see some pictures

  • Brian Cox

    Many of the tools used in space exploration are being used to search for the missing Airliner as well as millions of other uses on a daily basis.

    “Why don’t science help find the missing Malaysian plane? Why not not find cure for diabetes. Why are we so interested in mars and other planets. First fix the problems on earth..”

  • Brian Cox

    Many of the tools used in space exploration are being used to search for the missing Airliner as well as millions of other uses on a daily basis.

    “Why don’t science help find the missing Malaysian plane? Why not not find cure for diabetes. Why are we so interested in mars and other planets. First fix the problems on earth..”

  • Larry Wolf

    One thing not in the calculations of the orbit is the extent and the forces generated by the Comet’s tail which can change it’s mass and total forces of gravity on it and the forces from the plume itself. Then there are foreign objects possibly in it’s path (that we don’t know about yet) which could alter it’s path ever so slightly. So it’s forecast to be about 85,000 miles from Mars but it’s not out of the realm of probability that it won’t 100% sure not impact the planet.

    Of course if it did that will affect Earth in the near future and the collision would be visible in broad daylight from Earth. That’s because it’s traveling 125,000 mph near Mars and it’s 30 miles wide–bigger than anything to hit the Earth in the past 500 million years.

  • Larry Wolf

    One thing not in the calculations of the orbit is the extent and the forces generated by the Comet’s tail which can change it’s mass and total forces of gravity on it and the forces from the plume itself. Then there are foreign objects possibly in it’s path (that we don’t know about yet) which could alter it’s path ever so slightly. So it’s forecast to be about 85,000 miles from Mars but it’s not out of the realm of probability that it won’t 100% sure not impact the planet.

    Of course if it did that will affect Earth in the near future and the collision would be visible in broad daylight from Earth. That’s because it’s traveling 125,000 mph near Mars and it’s 30 miles wide–bigger than anything to hit the Earth in the past 500 million years.

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