posted December 20, 2007 08:44 PM               

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An asteroid similar to the one that flattened forests in Siberia in 1908 could plow into Mars next month, scientists said Thursday.

Researchers attached to NASA's Near-Earth Object Program, who sometimes jokingly call themselves the Solar System Defense Team, have been tracking the asteroid since its discovery in late November.

The scientists, based at the Jet Propulsion Laboratory in La Cañada Flintridge, put the chances that it will hit the Red Planet on Jan. 30 at about 1 in 75.

A 1-in-75 shot is "wildly unusual," said Steve Chesley, an astronomer with the Near-Earth Object office, which routinely tracks about 5,000 objects in Earth's neighborhood.

"We're used to dealing with odds like one-in-a-million," Chesley said. "Something with a one-in-a-hundred chance makes us sit up straight in our chairs."

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posted December 20, 2007 09:00 PM               

1:75 ain't good betting odds though.

posted December 21, 2007 09:33 AM               

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Originally posted by Lunar rock nut:
If this one hits Mars I will expect Tom, Joel and especially Scott S. with that big scope of his will provide us with unforgettable images.

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My gut feeling is that an explosion of that size wouldn’t be visible from Earth even with big 'scopes, but I'll need to do some math to figure it out.

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posted December 21, 2007 10:29 AM               

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My gut feeling is that an explosion of that size wouldn’t be visible from Earth even with big 'scopes, but I'll need to do some math to figure it out.

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posted December 21, 2007 11:42 AM               

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Originally posted by Lunar rock nut:
If the one mentioned in this thread hits Mars I will expect Tom, Joel and especially Scott S. with that big scope of his will provide us with unforgettable images.

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It's been about 2 months, 5+ inches of rain, some snow, and lots of wind since I last used the observatory. I guess this was just a little taunt from the weather demons I guess.

The joys of being a Seattle Astronomer!

posted December 21, 2007 11:48 AM               

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Originally posted by LCDR Scott Schneeweis:
...the Tunguska event was generated by an object much smaller then initially thought.

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posted December 21, 2007 02:34 PM               

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Originally posted by tegwilym:
I'd sure give it my best shot! It kind of cleared a bit last night and I tried some Mars imaging.

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posted December 21, 2007 02:48 PM               

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Astronomers Monitor Asteroid to Pass Near Mars

Astronomers funded by NASA are monitoring the trajectory of an asteroid estimated to be 164-feet wide that is expected to cross Mars' orbital path early next year. Observations provided by the astronomers and analyzed by NASA's Near-Earth Object Office at the Jet Propulsion Laboratory in Pasadena, Calif., indicate the object may pass within 30,000 miles of Mars at about 6 a.m. EST on Jan. 30, 2008.

"Right now asteroid 2007 WD5 is about half-way between the Earth and Mars and closing the distance at a speed of about 27,900 miles per hour," said Don Yeomans, manager of the Near Earth Object Office at JPL. "Over the next five weeks, we hope to gather more information from observatories so we can further refine the asteroid's trajectory."

NASA detects and tracks asteroids and comets passing close to Earth. The Near Earth Object Observation Program, commonly called "Spaceguard," plots the orbits of these objects to determine if any could be potentially hazardous to our planet.

Asteroid 2007 WD5 was first discovered on Nov. 20, 2007, by the NASA-funded Catalina Sky Survey and put on a "watch list" because its orbit passes near the Earth. Further observations from both the NASA-funded Spacewatch at Kitt Peak, Ariz., and the Magdalena Ridge Observatory in New Mexico gave scientists enough data to determine that the asteroid was not a danger to Earth, but could potentially impact Mars. This makes it a member of an interesting class of small objects that are both Near Earth Objects and “Mars crossers."

Because of current uncertainties about the asteroid's exact orbit, there is a 1-in-75 chance of 2007 WD5 impacting Mars. If this unlikely event were to occur, it would be somewhere within a broad swath across the planet north of where the Opportunity rover is.

"We estimate such impacts occur on Mars every thousand years or so," said Steve Chesley, a scientist at JPL. "If 2007 WD5 were to thump Mars on Jan. 30, we calculate it would hit at about 30,000 miles per hour and might create a crater more than half-a-mile wide." The Mars Rover Opportunity is currently exploring a crater approximately this size.

Such a collision could release about three megatons of energy. Scientists believe an event of comparable magnitude occurred here on Earth in 1908 in Tunguska, Siberia, but no crater was created. The object was disintegrated by Earth’s thicker atmosphere before it hit the ground, although the air blast devastated a large area of unpopulated forest.

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posted December 22, 2007 12:39 AM               

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Originally posted by Max Q:
What can I say, please god let it hit.

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Don't offend Mars (God of War), the asteroid might well swing by the planet and be redirected towards us!

posted December 22, 2007 07:43 AM               

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Originally posted by Robert Pearlman:
Regardless the size of the impactor, are there calculations that show that the Tunguska event would have been visible from Mars?

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If the impact area faces earth at the time, I would believe it will be seen given ideal observing conditions. Recently an impact was video recorded on the moon from the earth. It is an excellent video clip to watch considering it was a very small object. I don't remember details of the estimated size. The energy release was quite bright.

Terry

posted December 22, 2007 06:03 PM               

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Originally posted by Lunar rock nut:
From what I have read on Tunguska in the past it was more likely an impactor of cometary origin.

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posted December 22, 2007 06:34 PM               

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Originally posted by cspg:
Don't offend Mars (God of War), the asteroid might well swing by the planet and be redirected towards us!

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posted December 28, 2007 03:08 PM               

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Mars Impact Probability Increases to 4 Percent

The impact probability for a collision of asteroid 2007 WD5 with Mars on January 30 has increased from 1.3% to 3.9%.

Pre-discovery observations of asteroid 2007 WD5, taken on November 8, 2007 have allowed its orbit to be refined and the uncertainties for the late January Mars encounter have been improved. The impact probability resulting from the recent orbit refinement has increased to a surprising 3.9% (about 1 in 25 odds). The uncertainty region during the Mars encounter now extends over 400,000 km along a very narrow ellipsoid that is only 600 km wide. Since the uncertainty region intersects Mars itself, a Mars impact is still possible. However, the most likely scenario is that additional observations of the asteroid will allow the uncertainty region to shrink so that a Mars impact is ruled out. In the unlikely event of an impact, the time would be 2008 January 30 at 10:56 UT (2:56 a.m. PST) with an uncertainty of a few minutes.

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posted December 28, 2007 05:17 PM               

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Originally posted by Robert Pearlman:
In the unlikely event of an impact, the time would be 2008 January 30 at 10:56 UT (2:56 a.m. PST) with an uncertainty of a few minutes.

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posted January 03, 2008 09:45 AM               

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With new observations taken Dec. 29, Dec. 31 and Jan. 2 by the Magdalena Ridge Observatory in New Mexico, scientists at NASA's Near-Earth Object Program Office at the Jet Propulsion Laboratory in Pasadena, Calif., have updated their trajectory estimates for the asteroid. Based on this latest analysis, the odds for the asteroid impacting Mars on Jan. 30 are now about 1-in-28, or 3.6 percent. New Mexico Tech operates the Magdalena Ridge Observatory.

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posted January 03, 2008 11:26 AM               

I joined that email group and the posts are very interesting. Thanks for the link. I see some mention of "clones" in recent posts (as I understand it, "clones" are smaller close-by objects which may impact Mars even if the main object misses it). Are these known to exist with certainty for this asteroid - or is their existence a theoretical prediction? Can't wait until January 30th!

posted January 07, 2008 11:58 AM               

New H-alpha filter, and camera that has hardly been used. *sigh*

posted January 07, 2008 03:11 PM               

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Originally posted by tegwilym:
New H-alpha filter, and camera that has hardly been used.

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posted January 07, 2008 07:31 PM            

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Originally posted by LCDR Scott Schneeweis:
(close to 1 in 20)

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posted January 10, 2008 12:28 AM               

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2007 WD5 Mars Collision Effectively Ruled Out - Impact Odds now 1 in 10,000

Since our last update, we have received numerous tracking measurements of asteroid 2007 WD5 from four different observatories. These new data have led to a significant reduction in the position uncertainties during the asteroid's close approach to Mars on Jan. 30, 2008. As a result, the impact probability has dropped dramatically, to approximately 0.01% or 1 in 10,000 odds, effectively ruling out the possible collision with Mars.

Our best estimate now is that 2007 WD5 will pass about 26,000 km from the planet's center (about 7 Mars radii from the surface) at around 12:00 UTC (4:00 am PST) on Jan. 30th. With 99.7% confidence, the pass should be no closer than 4000 km from the surface.

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