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Today Space.com reported a new and exciting plan to save the Earth from a possible asteroid collision that doesn’t involve either Bruce Willis or Elijah Wood.
The idea, in a nutshell, it to build a 20 ton spacecraft that will approach the threatening asteroid, and use it’s weight to draw the asteroid toward it. The thrusters are situated so that the exhaust won’t disrupt the delicate gravitational bond, and the craft’s mass will slowly shift the asteroid’s course.
Sometimes the simplest ideas are the most elegant but I see one small flaw … launching 1 pound of material into space is $10,000, right?
1 tons = 2000 lbs
20 ton spacecraft = 40000 lbs
40000 lbs of ship = $400,000,000 launch.
“We’re sorry, we can’t afford to save the Earth today.”
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That dollar value only includes the 20 tons worth of spacecraft, not the weight of the rockets and their fuel. It would be about double that if they launched it in one go (assuming that’s possible, given this thing’s mass). Ouch.
As an alternative, perhaps we could create a smaller “space tug” to go snag a 20 ton rock in space, and steer it to where it needs to be.
Neat idea though.
There’s 2000 tons of man made space junk in orbit already. It may be fairly easy to collect the largest 1% of it and throw that towards an asteroid.
But then again $400M is under 2.5% of NASA’s 2005 budget of $16.043B
http://www.space.com/spacewatch/space_junk.html
http://en.wikipedia.org/wiki/NASA_Budget
In addition to the above comments, there would, presumably, be years, if not decades of warning leading up to such a collision, which would leave ample time to launch hundreds of affordable payloads to be assembled in orbit, most likely at a lagrange point to minimize gravitational interferance, and accellerated gradually, perhaps with an ion drive, up to the proper trajectory.(ya like my use of lots of big words?)
I was being facetious with the $ concern. I’ll bet that humanity would put aside financial concerns if looking down the throat of extinction.
One note though, an Ion drive is totally inappropriate for launch. Too shallow an acceleration curve. They’re great once in space, but that’s a whole different game.
What they could really use is a space elevator.
It seems to me that you don’t _want_ something that massive (unless it’s all fuel) because you only have to spend more energy getting it to where you want to use it. Plus, you’d also have to accelerate all that mass along with the debris you’re planning to shift. Lighter is better.
You are absolutely correct about the ion drive. It’s lousy if you are in a hurry, and useless for launch, but I meant that once the ship was built in orbit, an ion thruster could take it’s time getting up to the necessary velocity while carrying a fraction of the fuel a normal rocket would need.
Jason Bellows said: “I was being facetious with the $ concern. .”
I know :) I was just putting it in perspective.
I wonder perhaps if there’s enough space dust out there that a probe could use some kind of net to slowly collect enough of it on it’s way to an asteroid? I know that there have been experiments in the past that involved using sheets of some fancy schmancy material in orbit to collect space dust…
This “gravitational tractor beam” concept has me scratching my head. I can’t see what the advantage would be, unless it were a very fragile comet/asteroid, and there would be serious problems with fragmenting it. The point is to change the momentum of the object. Since momentum is mass * energy, it’d usually be more practical to put a big energy source up there and fling a small amount of mass very fast. I agree with Marius and Jason about the advantages/disadvantages of ion propulsion, but there’s a better way to put it to use. Plant a great big ion engine in the asteroid itself, and use the gentle but relentless thrust to change its course. See the article “The Asteroid Tugboat” in the November 2003 Scientific American. Of course, let’s hope your solar panels are pointed in the right direction, but there are ways around that…
But why go high-tech when brute force is cheap? Let’s use everybody’s favorite topic– nuclear power! A well-placed atomic bomb would vaporize asteroid-stuff, changing its course. Or a big atomic pile could run a mass driver that would excavate material from the asteroid with a big auger and fling it out the far end but fast.
Momentum equals mass*velocity, not energy.
Sounds like a great idea. Throw a 20 ton brick up in the air. The fuel on that breaks down and then we have two huge fucking things heading towards us.
I read the article on space.com What would be the problem with pulling it hard enough to break it up? If it broke up then it’d be in smaller pieces and wouldn’t cause damage… right? unless the pieces were too big to disintegrate in the atmosphere.
they could probably just ask bill gates for money if the earth was going to be destroyed. he would probably just say “yeah i should have atleast 600million on my floor somewhere”
I once had to do a project for about this in physics. I was about 12 at the time we had one of those over enthusiatic teachers. I suggested putting a big net up there and then my dad helped me do the math to work out cost and other factors.
THe only problem was that the net would be too big to build on earth although I’m sure there were many factors we didn’t consider.
Space.
Elevator.
Come on, guys, do research before yelling stuff out. They considered all of those ideas (ok – not the one with the net – how would that work?) Breaking it up is pointless, because
a) the results are unpredictable – who knows what’ll happen when you smack it with all your power.
b) most asteroids are rubble anyway
The point is that you’ve got a lot of mass hurtling towards you – you want to control it in the best way possible. Likewise once you’ve got that mass hooked you want to steer it – so getting together a lot of inert weight (space debris) to tow the asteroid is ridiculous. The proposed idea is to send up a massive engine, so that all your weight is power. If you’re collecting junk just to have gravity, you end up with even more weight but the same amount of power. The asteroid is heavy enough as it is, what you’d be doing is bringing more weight into the equation – but ending up with the same engine you dedicated to the task of towing.
So all in all, the weight taken up – the 20 tons – has to be entirely weight dedicated to strong propulsion systems.
Frankly there are a few official ideas out there I like better – like the solar sail. Finesse is the way to go
The US could just ‘borrow’ the money from itself.
Halley said: “I read the article on space.com What would be the problem with pulling it hard enough to break it up? If it broke up then it’d be in smaller pieces and wouldn’t cause damage… right? unless the pieces were too big to disintegrate in the atmosphere.”
Way late on this one, but nuking the asteroid would just mean many smaller objects heading towards us instead of the one large object. Many of the “smaller” pieces would still be big enough to survive entry into Earth’s atmosphere and would cause massive damage. Nudging the asteroid out of the way is a much preferable option.
Just send Bruce Willis and Elijah Wood already. Granted there’d be a last-minute hitch, alarm noises and a scary countdown, but they’d get the job done.
Has anyone thought to send a gang of strip miners to trim away all the mass and reuse it in say… my nintendo? Aside from that, we could just kiss it with some small nukes along its path to knock it gradually out of the way. Besides, what better way to reduce nuclear arsenals than to use them in space?
English reporter interviewing Von Braun during the Appolo program: “And you’re sure that there not going to land on London.”