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Bad news for the Martian dinosaurs...
January 7, 2008 7:28 PM   Subscribe

There's a slight chance that an asteroid could impact Mars at the end of this month. Usually, collisions between heavenly bodies have vanishingly small odds (a million to one, say), but the chances on this one have been steadily improving, from 350-to-1 to 75-to-1 to 25-to-1 (link to Washington Post). Scientists say that this could be comprable to the famous Tunguska blast in Siberia a hundred years ago (not to be confused with this other Tunguska blast).

Sadly, this event would not be visible to the naked eye. However, Mars itself is just past opposition right now, which means it's rising in the east just as the sun sets, and shines brilliantly throughout the night. And who knows? Maybe if the asteroid hits the hidden Martian nuclear weapons base, we could get a really spectacular explosion!
posted by math (37 comments total) 2 users marked this as a favorite

 
"The chances of anything coming to Mars
Are a milion to one" he said. Ahhhhhhahhhh

posted by sourwookie at 7:35 PM on January 7, 2008 [2 favorites]


It's been neat to see the odds getting lower and lower; that's a good sign. Still long odds against an impact, though. I really do hope it hits. That would be amazingly neat.
posted by Steven C. Den Beste at 7:37 PM on January 7, 2008


I was afraid of this. Spirit and Opportunity know too much.

I remember when Shoemaker-Levy hit Jupiter a few years back. That had to have been one of the coolest events ever.
posted by bondcliff at 7:42 PM on January 7, 2008


"." * 60 * 1000 * 1000
posted by b1tr0t at 7:43 PM on January 7, 2008


What I can't figure out: the odds keep changing on this. How come the odds keep changing? Isn't this straightforward Newtonian physics? We don't have enough data on it? I think some equipment in space that could figure this stuff out might be a worthwhile investment rather than relying on Vegas-style odds.
posted by Camofrog at 7:43 PM on January 7, 2008


It might be Newtonian physics, but it is awfully hard to get enough data to gather an accurate inference based on this data (thus the best-guess probabilities) and it is impossible to model every single gravitational force, seen and unseen, that might cause a change in course.
posted by geoff. at 7:46 PM on January 7, 2008


Isn't this straightforward Newtonian physics?

Newtonian physics isn't simple.
posted by b1tr0t at 7:46 PM on January 7, 2008 [5 favorites]


What I can't figure out: the odds keep changing on this.

The longer you observe an object, and the closer the object gets, the more precise your measurement of its position and course.
posted by zippy at 7:46 PM on January 7, 2008 [1 favorite]


Well, my end-of-the-month holiday is certainly not going to include a stop-off on Mars, I'll tell you that.
posted by flapjax at midnite at 7:47 PM on January 7, 2008


Camofrog writes "What I can't figure out: the odds keep changing on this. How come the odds keep changing?"

NASA has been using the Mars rovers' onboard radio to hurl insults at the meteor. With each tirade, the meteor edges closer and closer.
posted by mullingitover at 7:48 PM on January 7, 2008 [4 favorites]


Odds recently lowered to 1-in-28, which is only about a 3.6% chance of impact. Hardly enough for Mars to start throwing little green Bruce Willises and Ben Afflecks at the problem. Still, how can you not root for the rock? C'mon, rock!
posted by steef at 7:54 PM on January 7, 2008 [7 favorites]


For some reason i can't quite wrap my head around the idea that a likelier collision is an 'improvement'. It just reads incredibly wrong to me.
posted by empath at 7:59 PM on January 7, 2008


One hopes the asteroid is made predominantly of water ice -- isn't that one of the old terraform-Mars standby ideas, to barrage it with water-ice-bearing asteroids? Give us a nice headstart (although I don't know how that would actually work, because I'd assume the ice would be vaporized during the descent).
posted by stavrosthewonderchicken at 8:07 PM on January 7, 2008


One hopes the asteroid is made predominantly of water ice

s/water ice/antimatter/

I like big booms and I cannot lie.
posted by ROU_Xenophobe at 8:28 PM on January 7, 2008 [4 favorites]


So extrapolating what happened with Jupiter and now Mars, I guess there's some fair odds that on November 2022 I'll need to grab a towel and go to the pub for some beer and cheese sandwiches.
posted by crapmatic at 8:33 PM on January 7, 2008 [2 favorites]


Turns out the odds have since decreased since the 4% chance to 3.6%.

When the odds drop, it usually means that it never hits, according to the article.
posted by Ironmouth at 8:35 PM on January 7, 2008


i can't quite wrap my head around the idea that a likelier collision is an 'improvement'.

A close-up view of the result of an asteroid hitting a planet? That would totally be a geologist's wet dream. A loud, noisy, explosive wet dream.
posted by mediareport at 8:36 PM on January 7, 2008


We don't have enough data on it?

No, we probably don't. We have a hard time finding some very large objects in the solar system. Asteroids are even harder to track, with few people actually tracking them. And they're tracked by sight, not radar.
posted by Cool Papa Bell at 8:47 PM on January 7, 2008 [1 favorite]


Isn't this straightforward Newtonian physics?

Nope. Frame dragging brings General Relativity into play, but really the problem is refining the orbits. When the starting position has +-500km errors, the end results after a few million miles of travel can be pretty dramatic.

In all of these, what you start with is a very large volume of space that the asteroid will pass though, that happens to have a planet it. As you get more accurate data, the volume of space that the object will pass through shrinks -- but as long as the planet is still in that volume of space, the chance goes up. Eventually, you get enough data that the volume of space is smaller than the planet and contains the planet -- a certain hit, or the volume of space no longer contains the planet -- a certain miss.

So, typically, the odd start low, increase, increase, increase -- then drop to zero. Rarely. they spike to one.

The usual datapoints that resolve this are "precovery" points -- where a newly discovered object is found to be on older images, but wasn't noticed when the images were originally captured. The long timebase between current observations and a precovery observation helps establish a more precise orbit.
posted by eriko at 8:54 PM on January 7, 2008 [5 favorites]


I can't even find my way to the bathroom at night.
posted by PareidoliaticBoy at 9:11 PM on January 7, 2008


eriko: In the morning I will read your response again and hopefully have enough neurons firing to process it, but I feel you have provided an answer ... thank you!
posted by Camofrog at 9:22 PM on January 7, 2008


steef writes "Odds recently lowered to 1-in-28, which is only about a 3.6% chance of impact. Hardly enough for Mars to start throwing little green Bruce Willises and Ben Afflecks at the problem."

Boy I hope if a 50m asteroid had even a 1% chance of hitting Earth someone would at least be having meetings or something.
posted by Mitheral at 10:05 PM on January 7, 2008


The problem is only data gathering, not that the models of the solar system aren't accurate enough -- they're accurate to predict the motion of the inner planets to within a meter over very long periods. However, when your only source of data is a small, dim spot of light, it's hard to make a very accurate reading on velocity (which isn't only "speed" but also "direction").
posted by lupus_yonderboy at 10:26 PM on January 7, 2008


I drew this to help me understand what eriko said. It is extremely oversimplified, and in 2d only, but I hope it can still help other visually inclined people.

The grid is space, the blue is where volume of space that the asteroid will pass through. Better data, less blue.
posted by Dr. Curare at 10:46 PM on January 7, 2008 [6 favorites]


If, by chance this thing did hit Mars, there would be so much science to be had.

...Which gives me an idea. Why not throw a meteroid at Mars on purpose? With all the worry about Earth bound rocks, it would be good sense to atleast have a try at stearing one. Solar sails, rocket boosters, ion engines... hit Mars and it would be like sending one of those rovers down there with a 50ft shovel attached.
posted by popcassady at 2:17 AM on January 8, 2008


Yeah, and if we can guide a rock to hit a pinpoint target on Mars, maybe....hmmm....

Mountainous_Area_In_Pakistan + Asteroid = Earth - Osama_Bin_Laden

Check my math please. ;)
posted by jamstigator at 3:44 AM on January 8, 2008 [1 favorite]


Dr Curare - Fantastic. Thanks for that!
posted by Jofus at 5:06 AM on January 8, 2008


Dr. Curare -- flagged your post to get the admins to remove the link -- lord knows I clicked on it.

Excellent rendering, thank you!
posted by eriko at 5:23 AM on January 8, 2008


I just hope this doesn't jeopardize the manned Mars mission President Bush promised. Mars, bitches!
posted by kirkaracha at 7:25 AM on January 8, 2008


Swapped the second link into the first comment, Dr. Curare. And yeah, that's pretty great.
posted by cortex at 8:23 AM on January 8, 2008


Big deal, they predicted a win for the Redskins last weekend too.
posted by poppo at 9:00 AM on January 8, 2008 [1 favorite]


The compulsive gambler in me feels compelled to put money on this.
posted by burnmp3s at 10:07 AM on January 8, 2008


Why not throw a meteroid at Mars on purpose? ... Solar sails, rocket boosters, ion engines...

There's more science to be had in merely solving the problems associated with the mere implementation of your suggestions (e.g. solar sails) than in exploring Mars this way.

This is like saying, "If only we could only invent the internal combustion engine, we could build a car to explore the other side of this town!"
posted by Cool Papa Bell at 1:24 PM on January 8, 2008


Tell me when the odds go to 1-in-20 so I can use my d20 to see if it will hit.
posted by Anything at 2:00 PM on January 8, 2008 [1 favorite]


The comments in this thread make me very sad about the state of science literacy in this country. Of course, it would have helped if the FPP linked to a better source explaining the science than the Washington Freakin' Post. The number dipped when they found some data points that were prior to the discovery date which helped them make a more accurate prediction. The asteroid was (at that time) not visible. It is again visible (giving the opportunity for more data points) and the odds are now dropping again.
The chances of an asteroid smacking into Mars this month are slipping away as astronomers continue to refine its course toward the red planet.

The space rock, an asteroid called 2007 WD5, is now expected to miss Mars by about 18,641 miles (30,000 km), according a Tuesday report by NASA's Near Earth-Object (NEO) program office.

Scientists now estimate the space rock's odds of walloping Mars on Jan. 30 at 2.5 percent, about a 1-in-40 chance, after a series of observations taken by astronomers using Spain's 11.5-foot (3.5-meter) Calar Alto Observatory. The new analysis lowered the asteroid's odds of a martian impact from a 3.6 percent chance released last week.

"If the estimated miss distance remains stable in future updates, the impact probability will continue to fall as continuing observations further constrain the uncertainties," said the report, which was compiled by researchers at NASA's Jet Propulsion Laboratory (JPL) in Pasadena, Calif.

Astronomers at the University of Arizona first glimpsed Asteroid 2007 WD5 last month while performing the Catalina Sky Survey. At the time, the space rock was hurtling through space at about 8 miles per second, which is about 28,800 miles per hour (46,349 kph) and 15 times faster than a rifle bullet, researchers said.

With an estimated diameter of about 164 feet (50 meters), the asteroid is similar in size to the object that slammed into northern Arizona about 50,000 years ago to create Meteor Crater, NASA scientists have said. Earlier analysis of the space rock's trajectory suggested that, if it did impact Mars, it could slam into the planet's surface at about 30,000 miles per hour (48,280 kph), release about 3 megatons of energy and leave a crater about a half-mile (0.8-km) wide, they added.

Such an impact could be observed by the multiple spacecraft currently orbiting Mars, such as NASA's Mars Reconnaissance Orbiter, and provide a wealth of information on the formation of craters and the red planet's interior, researchers have said.

"We estimate such impacts occur on Mars every thousand years or so," said JPL researcher Steve Chesley, who released the refined asteroid course with colleagues Paul Chodas and Don Yeomans, in a NASA announcement last week.
The comparison to Tunguska is also ignorant, considering Mars does not have a protective atmosphere anywhere near that of earth. Most scientists don't think the Tunguska asteroid/comet impacted earth, but exploded above ground, thanks to superheating in that atmosphere. (Some scientists think a lake in the area may be what remains of an impact crater, however.)

Considering that Comet Shoemaker-Levys drop through the clouds of Jupiter was visible from Earth, I'm not so certain that a Martian impact (with this orientation and Mars close to opposition) would not be visible from earth. Amatuers can see dust storms on the Martian surface and I'm betting that the impact would make quite a flash (as impacts on the Moon are said to do).
posted by spock at 1:07 PM on January 9, 2008


This is like saying, "If only we could only invent the internal combustion engine, we could build a car to explore the other side of this town!"

Exactly!
posted by popcassady at 1:11 PM on January 9, 2008


Spock, I think you missed the first link on my FPP, which points to this article from astronomy.com. Granted, astronomy.com is not an academic journal, but its science is usually pretty sound. I included the second link (to the Washington Post) because it had a more recent calculation (namely, 25-to-1) of the odds of impact.

Anyways, the astronomy.com article addresses many of your concerns:

"...Even Earth-based telescopes could potentially observe the impact because Mars is near opposition and, therefore, unusually close. Astronomers say asteroid 2007 WD5 is about 160 feet (50 meters) across. If it struck Mars, the energy would be similar to the 1908 Tunguska blast in Siberia, where a stony asteroid exploded above the taiga. The blast felled and scarred trees over 810 square miles (2,100 square km). One difference: Tunguska was an air burst and left no crater, whereas 2007 WD5 likely would reach Mars' surface intact."

Looking back at my FPP, though, I see that I didn't quite manage to spell "comparable" correctly. Ah well.
posted by math at 4:43 PM on January 9, 2008


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