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How To Deflect an Asteroid With Today's Technology
Matt_dk writes "Apollo 9 astronaut Rusty Schweickart is among an international group of people championing the need for the human race to prepare for what will certainly happen one day: an asteroid threat to Earth. Schweickart said the technology is available today to send a mission to an asteroid in an attempt to move it, or change its orbit so that an asteroid that threatens to hit Earth will pass by harmlessly. But what would such a mission entail?"
Bruce Willis.
Obviously it depends on detection time. If we detect the asteroid years ahead of time, then even tiny changes in course will save us from impact. This could be done by simply crashing a small probe into it...something we've done successfully on more than one occasion. But, if we don't detect it until it's nearly on top of us then it may well be beyond our ability to do it. Therefore, the obvious solution is to increase detection technology.
Great warrior...hrmph! Wars not make one great.
What if we only have the ability to divert it a little bit, if and when that comes? Then we only control WHERE it hits, not WHETHER it hits. So how do we choose, I wonder?
The most beneficial thing we could do is build a system to detect such asteroids as early as possible. Once located, it's easy to deflect an asteroid that's far away. A small nudge or impact from a probe or the like would push it out of an intercept course while it's still far away. The closer it gets, the more force is required to push it off at an angle that will keep it out of our way. It may take a few newtons of force to deflect an astroid coming in from as far away as saturn, but much more to deflect an asteroid that's already close to mars.
I guess in simpler terms, if we had a really awesome early detection system, all we need is a small rocket launched from the ISS to impact it, wheras with a crappy system, we need Bruce Willis.
Bruce Willis died deflecting the last one. It'll have to be Ben Affleck next time... finally.
Set your phasers on "funky"!
None of them want to pay taxes again. Ever.
"Always forgive your enemies; nothing annoys them so much." - Oscar Wilde
Speaking of the apocalypse: Of course doomsday predictions are always for a future date. It would be much more interesting if someone figured out a doomsday prediction for a date 3 years past. That would mean someone has to make a time machine to go back and warn them that the world is about to end. Knowing the world didn't end we could be certain that we will succeed in the time-travel mission.
This of course means that when the world does end it isn't our fault- it's the fault of the people from the future failing to post-predict the apocalypse and make a time machine to stop it.
My webcomic
The "impact" method stands the chance of splitting the asteroid into man little pieces, and since that process of splitting absorbs energy less of it is available to deflect the body from its current course. To have enough mass going at a high enough velocity to contain enough energy to nudge it into a different trajectory you need heavy lift rockets with very fast final stage projectiles. The more velocity the more energy, but the more of that energy that will create debris that potentially causes even more problems. The best solution would be a very heavy object moving slowly, but the would be impossible to lift and deploy. Using nukes would allow a smaller projectile, but would very likely cause radioactive debris to renter earth's atmosphere. Not good. Its better to land on it and push it into the sun's gravity well.
The 'Gravity tractor' method requires just as much energy as pushing the asteroid, but you need LOTS of mass to make it work. Again you need heavy lift equipment to make this work, and I seriously doubt you can lift enough mass into space, and move it to where it needs to be, in time to effect the trajectory by much. You are still better off using that same fuel to get there quickly and push it lightly for a while into a new trajectory.
...we wouldn't.There is no possible threat to the Earth which humans could ever make even the smallest abount of diffence about. Instead there is a threat to civilisation. Pedantic, I know but the only threat to the earth is crashing into a star or another planet. Humanity compared is much more fragile, threatened by a mere mile wide rock or similar.
Reality is in fact, Virtual
I thought this was already solved?
You don't move the asteroid... you move the Earth! With lots of giant hydrogen powered rocket tubes at the South Pole!
http://www.youtube.com/watch?v=mf2lvRStVdg
Would you like to know more?
What, the movies have lied to me? Next you'll be telling me that you can't enhance a photo so many times that you get more information from a reflection in it then was originally taken.
You find out its orbital and mechanical properties as early as possible.
Then you send a gravity tug to change the orbit.
Cost of preventing impact >>> (cost of impact * probabilitiy of impact)
About once a century we get an impact that's equivalent to a few megatons, and there's a 75% chance of it hitting an ocean and about a 99% chance of not hitting a heavily populated area. Sucks if your farm happens to be ground zero, but there's no sane reason to spend billions of dollars a year trying to prevent it.
Nukes provide just a very short impulse; transferring it to the whole rubble pile might turn out to be problematic.
Gravity tractors (and few other methods) can work months, years; and force from them works uniformly (or in the case of some other methods - very gently)
One that hath name thou can not otter
The last 2 discovered asteroids that passed "close" (at least, closer than the moon, the last one was few days ago at 45k km) were found with very few days in advance. They weren't very big, but still could had done some big damage, and the early warning wasnt enough to even think on launching a ship, much less doing anything effective with it.
Early detection must be improved... that some of the asteroids that we know could take 15 years to get here and so give us enough time to prepare don't mean that some unknown or even known ones (if you want, because somehow changed its orbit) could be in its way here and detected when is already too late.
I think we are looking at this the wrong way. We should instead be trying to turn the moon into our own deathstar. That way we can change its orbital position to deflect or intercept the asteroid. That way we get multiple uses out of it and can also rule the solar system once our deathstar becomes fully operational. How hard would it be to put enough rockets on the moon to be able to drive it around... Seriously NASA WTF are you guys doing trying to land a little rocket on a asteroid when you could be asking for funding to drive the Moon.
Just because your target mass is large, doesn't mean you need a lot of mass to change its course. If you have a spaceship "heavy enough" to move a 1-ton rock, then it's also "heavy enough" to move a 100-ton rock because an object's deflection in a gravitational field is independent of that object's own mass.
This is an extension of an experiment you've probably seen in high school physics. Drop a tennis ball and a bowling ball, and they move just the same under gravity's influence.
But that's not to say that moving a larger mass is "free"; it does require more energy. As your tractor exerts 100x more force on the larger asteroid, it will also suffer 100x more force pulling it back toward the asteroid. Since your tractor isn't your impactor, it will have to spend energy fighting that force.
Now I have no idea what sort of propulsion you would use to maintain the tractor's position relative to the asteroid. If you used a chemical rocket then "more energy" requires "more mass", but that would seem to have a problem anyway in that you'd be throwing your exhaust right at the asteroid, pushing against your own gravitational pull.
In any case, remember that the Earth is a relatively small target, and the courses would have to intersect in 4 dimensions (don't foret time) to cause a collision. Given years of lead time, the "push" required wouldn't be as much as you may think.
He forgot to account for the Congressional hearings, where conservatives will deny the existence of "these so-called space rocks" (they aren't, after all, mentioned in the Bible), and just a ploy to rake in more moolah for Big Astronomy. Not to mention the flurry of state AG witchhunts into the astronomers' emails.
On the other hand, if one of the scientists said that there was a possibility that the asteroid had a diamond core, a private sector solution would no doubt be undertaken by DeBeers.
"I guess the moral of the story is, don't paint your airship with rocket fuel." -- Addison Bain
Ok, what we really need to do is create a simulator for a small craft to destroy the asteroid while said craft and means of deployment is being developed. Something using vector graphics should be quick and easy to come up with on the simulator side. The craft should be maneuverable and have a cannon capable of breaking the large asteroid into smaller and smaller chunks until these chunks can be destroyed by the cannon. Incidentally, the cannon should also be able to defend against alien craft in case of their interference. High scorers can be recruited to pilot the craft to save the earth.