Join 3,421 readers in helping fund MetaFilter (Hide)


Bright lights, big galaxy.
March 6, 2012 6:52 PM   Subscribe

Phil Plait (previously) writes about asteroid 2011 AG5.
posted by curious nu (24 comments total) 12 users marked this as a favorite

 
I didn't see it mentioned in the article: what sort of damage does an object of that size do when it hits us? I guess it'd also depend ocean/land, and inhabited/uninhabited.
posted by codacorolla at 7:46 PM on March 6, 2012


I have to agree with Schweikart and Plait, there is no reason why NASA shouldn't begin planning a mission now.
posted by IvoShandor at 7:50 PM on March 6, 2012


He estimates 100 megatons in the article, roughly twice the size of the Tsar bomb, the biggest ever exploded.
posted by Devils Rancher at 8:20 PM on March 6, 2012


I threw numbers at an impact calculator, but rereading the article, there aren't enough knowns yet. The composition isn't known; the exact size isn't known; and it's impossible to guesstimate the vector and velocity if it does hit us. I'd guess it would leave a pretty decent sized crater for starters.

Edit: on preview, 100 megatons has a regional effect.
posted by ZeusHumms at 8:22 PM on March 6, 2012


Is an impact deflection the best way to go? Wouldn't landing a nuclear powered engine right on the thing work better? It would have until 2040 to gently push it into a different orbit.
posted by Bonzai at 8:29 PM on March 6, 2012


There is some strange reasoning in that piece:
The best time to deflect an asteroid is before it enters the keyhole. The keyhole is 360 kilometers across, so only a relatively small change in the asteroid’s path is needed to miss it. But once AG5 passes through the keyhole (if it does), then it has to miss the entire Earth! Instead of it missing a target 360 km across, it has to miss a planet 13,000 km across. That usually requires a much larger change in velocity. Either way, hitting it earlier is better.
Hitting it earlier is certainly better, but hitting it just after it passed through the keyhole is only a little worse than hitting it just before. It would miss the Earth (the entire Earth!) because in either case it would have around 17 years for a small deflection to magnify itself into a large one as the orbit proceeds. The change in velocity required to make it miss the keyhole, starting say six months before perigee, would be only a little less than the change in velocity starting soon after perigee that would make it miss the Earth.

Put another way, that "keyhole"
But if AG5 passes us at just the right distance, the orbit will change just the right amount to put it on a collision course with Earth. This region of space is called a “keyhole”, and in this case, should AG5 slip through it, it will hit us 17 years later, in 2040.
can be calculated for any point in its orbit once we have enough observations of the orbit, and there is no reason I can see that the keyhole should expand suddenly to some unmanageably huge extent after the asteroid makes it closest approach in 2023.
posted by jamjam at 8:32 PM on March 6, 2012 [1 favorite]


We should try to crash this into mars. The red planet could use the mass.
posted by humanfont at 8:51 PM on March 6, 2012


can be calculated for any point in its orbit once we have enough observations of the orbit, and there is no reason I can see that the keyhole should expand suddenly to some unmanageably huge extent after the asteroid makes it closest approach in 2023.

If it passes through that keyhole it will be during the 2023 approach. I think Phil is simply saying it would be easier to make the asteroid miss that keyhole then than to make it miss Earth in 2040, if it passes through the keyhole in 2023. If it passes through that area, it is going to hit Earth. The chances of this are slim but not zero.
posted by IvoShandor at 8:52 PM on March 6, 2012


I wonder why the author seems to feel the need to point it out when someone is a former astronaut. Does visiting space make you an astrophysicist?
posted by moonbiter at 8:52 PM on March 6, 2012 [2 favorites]


can be calculated for any point in its orbit once we have enough observations of the orbit, and there is no reason I can see that the keyhole should expand suddenly to some unmanageably huge extent after the asteroid makes it closest approach in 2023.
Jimjam. It's not a question of it needing to be "in" the keyhole to hit us. Rather, if it passes 'through' the keyhole, it's orbit will change, and hit us the next time around.

The "Keyhole" is apparently only 240 miles across. Much smaller then the whole earth. So in 2040 we'd need to adjust it's path by the entire size of the earth, whereas in 2023 we'd need to only adjust it by 240 miles.

Or we could just blow it up, which doesn't seem like it would be that difficult, given it's size.
posted by delmoi at 9:00 PM on March 6, 2012


I was wondering about the whole keyhole thing. Can we predict it that accurately? - If we can't predict it very precisely, then there's a chance that it could be missing the keyhole, and anything we do to it could actually re-direct to the keyhole instead. 240 miles is a pretty small keyhole in space.
posted by carter at 9:10 PM on March 6, 2012


Or we could just blow it up, which doesn't seem like it would be that difficult, given it's size.

Figure out the total potential energy of the object, based on its mass.

That's the amount of energy it takes to "blow it up" -- that is, be able to disperse the mass so much that every bit of it hits escape velocity for that mass.

Boggle at the very large number this is for any object that is a true threat for impacting the Earth and causing dramatic damage.

Move to plan B.
posted by eriko at 9:42 PM on March 6, 2012 [3 favorites]


IvoShandor: "I have to agree with Schweikart and Plait, there is no reason why NASA shouldn't begin planning a mission now."

I kind of agree. Plait seems to be right that this is a minimal risk, and something that we should plan for anyway.

Fully planning this kind of mission would be an awfully handy thing for humanity to add to its resume for the next time, when the odds are greater than 1 in 625. We should use this excuse to draw up a full (ie. not purely hypothetical) mission plan for deflecting an asteroid. This stikes me as money being incredibly well-spent, even if such a contingency is (hopefully) never necessary.
posted by schmod at 9:43 PM on March 6, 2012


I have to agree with Schweikart and Plait, there is no reason why NASA shouldn't begin planning a mission now.

Unfortunately, I can think of almost 700 billion reasons.
posted by chimaera at 9:43 PM on March 6, 2012 [2 favorites]


Does visiting space make you an astrophysicist?

If it makes you feel better, Schweickart obtained a BS and later an MS in aeronautics/astronautics from a little school called MIT. I don't know exactly how high he ranks on the educational background of pre-Shuttle astros, but that's got to be up there. They weren't just fighter jocks. Among his later jobs at NASA was developing some of the tech used to save Skylab. Still not technical enough for you? Try the rest of the B612 Foundation team.

The point about a contingency mission is that we know asteroids are a realistic threat Earth faces, and an impact is potentially civilization-ending -- although all kinds of alternative scenarios are pretty devastating themselves, such as a Pacific-wide tsunami. We also know that the earlier we can act, the less we need to do, e.g. the various deflection strategies. Blowing it up is actually not a really good option unless we have no others available. One doesn't really need to have a degree to understand these concepts; some persons who have been elected to Congress might even be capable.
posted by dhartung at 11:48 PM on March 6, 2012 [2 favorites]


I don't know exactly how high he ranks on the educational background of pre-Shuttle astros, but that's got to be up there.

He was part of the third astronaut group, chosen in 1963. It was the first group to not require test pilot experience, as NASA was looking for more scholarly candidates.

Deke Slayton, who hired Rusty, noted that he was very sharp.
posted by Brandon Blatcher at 12:38 AM on March 7, 2012


I don't know exactly how high he ranks on the educational background of pre-Shuttle astros, but that's got to be up there.

The educational background of post-Shuttle astros had to be higher. Consider Story Musgrave:

He received a BS degree in mathematics and statistics from Syracuse University in 1958, an MBA degree in operations analysis and computer programming from the University of California, Los Angeles in 1959, a BA degree in chemistry from Marietta College in 1960, an M.D. degree from Columbia University College of Physicians and Surgeons in 1964, an MS in physiology and biophysics from the University of Kentucky in 1966 and a MA in literature from the University of Houston–Clear Lake in 1987.

I mean, you're already a fucking astronaut. You've done enough. Do you really need that MA in literature?
posted by twoleftfeet at 2:20 AM on March 7, 2012 [6 favorites]


What's likely to happen is that there will be a near earth object which collides with a population center or other strategic center within the next few decades. These collisions happen all the time. There's a reverse power law which describes the relationship between the frequency of collision and the size of the impact. Briefly put, extremely large objects collide infrequently, but smaller objects collide frequently. This has always been the case. What has changed is that the effect of a small collision can have more dramatic effects on a noosphere - a well-connected economy - than it ever had on the atmosphere. Look for a political reality that acknowledges "space terrorism" as a real threat. It doesn't have a good guy vs. bad guy narrative - it's just rocks slamming into the planet - but we really should care about that.
posted by twoleftfeet at 2:44 AM on March 7, 2012


I mean, you're already a fucking astronaut. You've done enough. Do you really need that MA in literature?

It helps with the poetry writing
posted by Brandon Blatcher at 4:04 AM on March 7, 2012


Does visiting space make you an astrophysicist?

If you are a physicist? Yes.
posted by ceribus peribus at 5:24 AM on March 7, 2012 [2 favorites]


I have to agree with Schweikart and Plait, there is no reason why NASA shouldn't begin planning a mission now.

How about NASA develops some type of rocket that they can actually use on a budget to get something greater than shoebox-sized objects outside of LEO? Because they certainly don't have one now.

We're literally 30 fucking years from putting a useful probe, let alone anything approaching a useful sized engine anywhere near the asteroid belt. Mars? Sure, I can drop a shoebox-sized probe on Mars, and it can be so well-engineered that it outlives it's expected lifespan by a couple of years but shit, Mars is a planet. And I might miss because I can't translate the metric system properly. And That probe wasn't moving that planet measurably.

I for one would love to see a 2012 Saturn V heavy lifter type, but it just isn't gonna happen. Space seems to be done. Nobody has set foot on the moon for thirty eight years. Nobody. Let that sink in for a moment.

Plan in one hand and shit in the other, I'll bet you on which one is more full. And that 2^??? tons of asteroid is gonna trump your plan. NASA or no.
posted by Sphinx at 11:23 AM on March 7, 2012


How about NASA develops some type of rocket that they can actually use on a budget to get something greater than shoebox-sized objects outside of LEO?

Curiosity is the size of MiniCooper and headed towards Mars.

Nobody has set foot on the moon for thirty eight years. Nobody.

There's a reason we never went back to the moon!
posted by Brandon Blatcher at 12:04 PM on March 7, 2012 [1 favorite]


How about NASA develops some type of rocket that they can actually use on a budget to get something greater than shoebox-sized objects outside of LEO? Because they certainly don't have one now.

This isn't right.

Cassini's mass is 2500 kg+. New Horizons is 478 kg. Not really shoeboxes, unless you change the meaning of the word shoebox. Yeah, no one has gone to the moon, but NASA has launched dozens upon dozens of probes far larger than shoeboxes since the last moon landing. The temporary end to manned space travel hasn't meant the end of space, or whatever it is you think it has meant.

The tech for this mission exists now. Something in here is full of shit, but it isn't either one of NASA's hands.
posted by IvoShandor at 6:18 PM on March 7, 2012


That's the amount of energy it takes to "blow it up" -- that is, be able to disperse the mass so much that every bit of it hits escape velocity for that mass.

It only needs to reach escape velocity relative to the mass of the object itself, which is going to be very, very small.
posted by delmoi at 3:28 AM on March 8, 2012


« Older ... it was notable for the nation’s top law enforc...  |  The YouTube channel of user zj... Newer »


This thread has been archived and is closed to new comments