Using Gravity To Tow Asteroids 508
cryptocom writes "Space.com is reporting that two scientists at NASA are proposing using a 20-ton spacecraft to pull asteroids off a possible collision course with Earth, using the spacecraft's own gravity as an attractor. This idea would not only be cheaper, but have a much higher chance of success, due to not having to actually land on the asteroid's surface."
The mother of all asteroid deflection devices (Score:5, Insightful)
2000 lbs in a ton
20 ton spacecraft
$10,000/pound to get to geosynchronous transfer orbit
$400,000,000 just to launch this thing into a geosynchronous transfer orbit (not counting construction costs). I assume the fuel to move it isn't included in the 20 ton estimate either (since it will burn off on the way) so that would need to be lifted as well. I wonder if a huge nuke would be cheaper and easier to construct and launch? Then again, with the current U.S. national debt at over 8 trillion (with which we could pay for the launch costs of 20,000 of these things) maybe the launch costs aren't unreasonable.
Re:The mother of all asteroid deflection devices (Score:5, Funny)
Re:The mother of all asteroid deflection devices (Score:2, Insightful)
Re:The mother of all asteroid deflection devices (Score:3, Funny)
You've obviously never taken a modern finance course - everything has a price!
Re:The mother of all asteroid deflection devices (Score:2, Insightful)
Re:The mother of all asteroid deflection devices (Score:5, Insightful)
That's silly.. The goal is "saving civilization". There are many ways to accomplish this goal, a perfectly valid input into the decision process is "how much does this method cost".
Re:The mother of all asteroid deflection devices (Score:5, Funny)
I.e. I don't think that world leaders would look at the figures and go "Hrmmmmm...when you say extinct...how extinct?"
Re:The mother of all asteroid deflection devices (Score:5, Funny)
You've obviously never been in a scheduling meeting with management.
Re:The mother of all asteroid deflection devices (Score:2)
Better yet, they could have several of these things circling up there, just in case.
PS: yeah, I know it's not Tuesday, but I couldn't resist :7
Up out of the well? (Score:2)
Of course, that's going to require some infrastructure. Which reminds me, why was the ISS built in LEO again?
Re:The mother of all asteroid deflection devices (Score:2, Interesting)
Re:The mother of all asteroid deflection devices (Score:5, Insightful)
Nonsense. In fact, there's a whole work force [soa.org] employed to do exactly that.
-Adam
Re:The mother of all asteroid deflection devices (Score:2, Insightful)
Another way to figure the price of human life - what does a gun, and a single bullet cost? Or, if you're desperate, a nice, sturdy piece of string?
Another way to compute it: what's the price of a woman spending nine months and giving birth to a new "life".
True, some individuals are worth "more". But the
Re:The mother of all asteroid deflection devices (Score:2, Interesting)
The spacecraft design with the angled rockets is wasteful, but if you are getting the fuel from the asteroid, the fuel i
Re:The mother of all asteroid deflection devices (Score:5, Funny)
Re:The mother of all asteroid deflection devices (Score:2)
Re:The mother of all asteroid deflection devices (Score:2)
Re:The mother of all asteroid deflection devices (Score:2)
Re:The mother of all asteroid deflection devices (Score:2)
Most likley, but you might end up making the world's largest shotgun out of a asteriod made of iron.
Re:The mother of all asteroid deflection devices (Score:2)
Re:The mother of all asteroid deflection devices (Score:2, Insightful)
Re:The mother of all asteroid deflection devices (Score:5, Insightful)
Does the cost of operating your car double when you add a passenger?
Not unprecidented (Score:4, Insightful)
For recent comparison, the shuttle orbiter is over 100 tons and capable of carrying about 30 tons of payload to LEO Cassini was about 6 tons, and we sent it all the way to Saturn.
If we could afford to launch all these things, then we can afford to launch something to prevent a cataclysmic astroid strike.
Re:The mother of all asteroid deflection devices (Score:2)
Re:that's what i was thinking (Score:2, Insightful)
Re:that's what i was thinking (Score:3, Funny)
Re:that's what i was thinking (Score:3)
Re:that's what i was thinking (Score:3, Interesting)
Lunar and Martian industrialization is not a twenty year job. It's a several hundred year job. I can get more into this if you care. It's questionable whether the moon could ever support a mostly self sufficient industrial base because it is so deficient of many critical elements (nitroge
Re:that's what i was thinking (Score:3, Informative)
F=G*m1*m2/d^2
Cutting the distance in half quadruples the force of gravity; distance is far more relevant than mass. You can pick how much gravitational attraction there is between your craft and the asteroid (within limits, but those limits aren't closed to being reached)
Lets say that your craft has the new HiPEP engine under testing (JIMO's engine). I believe that's a 0.5 newton engine (very strong for an ion engine). It takes the entire 20 tonnes of craft mass to run. Lets assume
Re:that's what i was thinking (Score:5, Insightful)
No humans, no coming home. Also, they mention 20 years prep time - i.e., they're not planning to build it until a threat is discovered, and the couple billion dollar cost would be amortized over that time to perhaps 100 mil per year, split around the world's space agencies. I'm sure that's more than enough time and low enough cost. Also, a 200 meter asteroid is hardly a worldwide cataclysmic event if it hits; it's like a single large nuclear weapon hitting a random place on the planet, if you can trust the impact calculator [arizona.edu].
Humans perhaps.... (Score:2, Funny)
Question, I assume there will only be one of these made at the time, so what happens if it BREAKS?
1.No humans = no fixing it,
2.No fixing it = End of civilization
3. E.O.C. = ????
4. Profit!!!
Re:Humans perhaps.... (Score:5, Insightful)
Adding humans will around 20x your cost. So, take your pick: 20 completely different designs, or one manned mission with a significant chance of failure, for the same price. It's a pretty simple call; there's a reason why almost all probes that we launch are unmanned. The manned space program gets funding. The unmanned space program does the research.
Re:Humans perhaps.... (Score:5, Insightful)
about an unmanned mission if the fate of the world hangs in the balance?
From a political point of view I can't see anyone supporting a robot probe
mission to save the earth.
Re:Humans perhaps.... (Score:4, Insightful)
Re:Humans perhaps.... (Score:3, Funny)
Put Bruce Willis on the probe. The minor detail of whether or not to include an air supply can be left to the engineers.
Re:that's what i was thinking (Score:3, Insightful)
Yeah, they're up to, what ... 2 now? Yeah, WAY ahead of us, they're sitting at about 1958 at the moment as far as space race progress goes. I'd say something pithy about their remarkable survival rating so far, but given the closed speech society that exists over there, I'm not willing to claim that they've had no fatalities. They could have had dozens at this point, we'd never know.
Re:that's what i was thinking (Score:5, Insightful)
Why would you launch it from earth??? It's just weight for weight's sake, so build it from stuff already in space, or at the very least, on the moon. Only the engines, control module, etc would need to be lifted from earth. My personal opinion would be to find a nearby asteroid or similar of the appropriate size, shape it as needed, and slap some thrusters on/in it.
The crew. The time the crew would be away from earth would be how long? 10 years? 20 years? Managing and provisioning crews for such a long amount of time is probably among the major challenges facing the extension of our space travel abilities.
What crew? Why on earth would you crew it? Remote operation should be just fine.
Coming home. What happens when a ship this large is re-entering Earth's atmosphere? That sucker will have a lot of force coming down.
OK, now you're just being stupid. What possible reason would there be for landing this contraption on earth?
Re:that's what i was thinking (Score:2)
Re:that's what i was thinking (Score:2)
Crew? Why would this need a crew? a computer could do this job easily and you could provide basic commands remotely abit with a large time delay.
No reason to reenter earths atmosphere, this wouldn't be damaged in anyway by pulling an astroid. You simply need to being it back in orbit if you need to do regular mantainence and this baby would be ready at minimal cost to defend against futu
Salvage one had the right idea (Score:2)
You could borrow an idea from salvage one [geocities.com] and use the space left over from the spent fuel as the hold.
Re:that's what i was thinking (Score:5, Informative)
20 ton spaceship. That's actually smaller than the Space Shuttle.
I can't remember the source now, but the Shuttle can lift about a 30ton payload. The boosters themselves can lift far more but of course have to carry the Shuttle too (which is something like 120tons).
The Saturn V rocket [wikipedia.org] was capable of lifting 118 tonnes (with the 3 stage versions).
The Shuttle Derived Launch Vehicle [wikipedia.org] will have a capacity of 125 tonnes.
All seem plenty to lift a 20ton spaceship if it's the only thing being launched. Even with a Shuttle it should be doable, or we can have another up there waiting to deploy it or use the ISS team.
Since we're able to use existing launchers to get the spaceship into orbit, it shouldn't cost any more to launch than any existing mission. All your left with is the pricetag for building it and giving it enough fuel to reach the asteroid.
The crew. The time the crew would be away from earth would be how long? 10 years? 20 years? Managing and provisioning crews for such a long amount of time is probably among the major challenges facing the extension of our space travel abilities.
Coming home. What happens when a ship this large is re-entering Earth's atmosphere? That sucker will have a lot of force coming down.
Due to the distance it would have to travel a robotic mission remote controlled from Earth would make the most sense. Just in case anything breaks which isn't workaroundable/fixable it would probably make sense to send more than one.
In this case it'd be best to leave it out there - without enough fuel to return it'd be cheaper and without a crew to bring home there's no real reason to.
Shelf life. So we make a ginormous space tractor. Maybe we don't face an asteroid threat for 15,000 years. That's a lot of upkeep.
The launchers are already around, and it wouldn't take long to build a ship which is essentially a remote controlled engine with a lot of metal attached.
Assuming that we'd know of the threat in enough time to send this to the asteroid, as long as we still have the launchers to get it into space in the first place it shouldn't be unreasonable that we can build them as we need them.
If we don't have that kind of timescale then we're probably in trouble even if we could send it straight away. Since the launchers seem capable of lifting more than 20 tonnes though, we could just build a 40 tonne version and half the time we'd need (disclaimer: not linear, i think it'd be more like 3/4?).
Re:that's what i was thinking (Score:3, Interesting)
Why does it need a crew if it's just going to use gravity to nudge an asteroid?
Re:The mother of all asteroid deflection devices (Score:2)
Mine twenty tons of what?
Are you going to use the raw material, or are you going to smelt it into something other than ore? How much would it cost to send a complete mining, smelting, power generation factory to the Moon?
It is probably cheaper to send the truck into space from Earth.
Re:The mother of all asteroid deflection devices (Score:2, Funny)
Re:The mother of all asteroid deflection devices (Score:2)
Re:The mother of all asteroid deflection devices (Score:2)
20 Ton Tractor (Score:3, Interesting)
That would place it safely in the realm of 'Cube Truck' capacity.
Hell, they wouldn't even have to stop at the scales in some states.
How exciting, sort of (Score:5, Funny)
Neat... although, if this works, it will totally kill the Hollywood "asteroid catastrophe" genre. The concept of sitting a giant hunk of metal next to an asteroid for 20 years to gradually shift its path doesn't exactly make for fast-paced, high-tension action movie fare.
Re:How exciting, sort of (Score:2)
Re:How exciting, sort of (Score:2)
'If this glacier moves faster than one inch a year we're all gonna die!!'
Until the 20 ton hunk of metal pulls a "Skylab" (Score:2)
Advanced warning (Score:5, Insightful)
Re:How exciting, sort of (Score:2, Funny)
They only have one small problem to solve (Score:2, Funny)
Interesting, but slow (Score:5, Interesting)
If they're concerned about the amount of impulse delivered by a direct nuclear weapon impact, why not a series of projectile impacts (or at-a-distance, low impulse nuclear detonations)? While you'd have to launch more payload into space, the prep time would certainly seem to be far lower.
I'd say so! (Score:2)
... and blow it up!
It's been awhile since I've taken physics... (Score:5, Interesting)
So comes the hard part of determining how far out the spacecraft would have to meet the asteriod and glide along beside it so as to veer the asteroid to a safe range of R kilometers from Earth. Any ideas?
Re:It's been awhile since I've taken physics... (Score:2, Interesting)
On the other hand, the same gravitational force would be acting on the spacecraft, and F=ma gives us 5509 m/s^2 there...
Am I calculating this wrong? Because it seems it would take a hell of a lot of fuel to keep that spacecraft from just crashing into the asteroid... And they plan to keep this spacecraft sitting next to the roid for years?
Nuke it.
Re:It's been awhile since I've taken physics... (Score:5, Informative)
Re:It's been awhile since I've taken physics... (Score:5, Insightful)
F = GmM/r^2
For a 20000kg object, and a 9e19kg object (Hygiea), with a distance of 205km between them (1 km away from the asteroid, but the distance between is the centre of masses is much greater, Hygiea has a radius of 204km), the force is 2870N. In comparison, the force of gravity from the Earth will be that much 3.53e12 km away (471 times the distance of Pluto from the Sun at it's farthest point in orbit). It's just more than the gravitational force of four 70kg people standing on the ground.
In other words, if a big asteroid comes at us, we are royally boned.
Re:It's been awhile since I've taken physics... (Score:3, Informative)
Interesting Concept (Score:2)
Re:Interesting Concept (Score:4, Funny)
20-ton spacecraft collisions (Score:3, Funny)
mir (Score:3, Informative)
I for one welcome... (Score:2, Interesting)
So, by the same means they can put an asteroid in a direct collision course.
astronomical engineering (Score:2)
Astronomical Engineering: A Strategy For Modifying (Score:2)
Tow cable? (Score:2)
i've been away for a few days.... (Score:3, Funny)
Not good enough (Score:2, Funny)
This just in:
Response from FEMA: "Not good enough. We need more time."
I tried this... (Score:4, Funny)
Re:I tried this... (Score:3, Funny)
From Jack Handy... (Score:3, Funny)
Why not launch a ship to bowl at it? (Score:2)
Simple...
NeoThermic
Terraforming? (Score:4, Interesting)
Isn't the problem here... (Score:5, Interesting)
Isn't the problem here the 20 ton spacecraft?
Which
a) is difficult to move all by itself.
b) doesn't do much to a 6800 ton asteroid travelling at 1600 miles per hour.
Should this be addressed first? (Score:2)
Of course, dragging the object by gravity would avoid the issue of having to despin the object or coming up with a thruster or multiple thrusters placed on the
Save Money (Score:2, Funny)
"That's no moon!" (Score:3, Interesting)
If it employed some sort of lightwight truss-style, perhaps geodesic framework with cable "netting", it could form a lightwieght, but voluminous enclosure that could be used to capture orbiting space junk before heading off for its mission.
Overall, the idea of gravity-towing sounds pretty neat to me.
Armageddon 2 (Score:2)
Sounds like the makings of a sequel. Armageddon 2: Nerds Save the World
Why can't we simply use an Ion engine. (Score:5, Interesting)
Re:Why can't we simply use an Ion engine. (Score:5, Interesting)
I thought of this exact idea, but then realized there is bit of a wrinkle: the ion stream will be pushing the asteriod away from the craft (and vice versa) but at the same time, gravity will be pulling them towards each other. So, you will be working against gravity.
And then the problem becomes that ion thrusters don't tend to have a very high amount of thrust. Their strength is that they can produce thrust without wasting very much matter because of the high velocity with which the ions move away from craft. So, I wonder if the ion drive will even produce as much force as the gravitational attraction between the asteroid and the craft. It might not. Even if it does, you still are fighting against gravity.
This should make...... (Score:3, Funny)
If you have an engine that can push... (Score:2, Interesting)
Fuel? (Score:3, Interesting)
Correct me if I'm wrong, but wouldn't pulling it with gravity use even MORE fuel, since you're basically expending the same amount of fuel to move the target, plus additional fuel to move the 20-ton gravity "tug"?
Re:Fuel? (Score:5, Insightful)
Re:How about simply attaching stuff on the asteroi (Score:3, Informative)
Nope. All gravitational force exerted on an asteroid is directly proportional to its mass. Since Force=Mass*acceleration, the mass cancels out of the equation - the acceleration (and hence the trajectory) is independent of its mass. This is the exact same reason why objects of different weights fall at the same rate - both
Provided we have decades of advanced warning? (Score:3, Insightful)
Absurd (Score:3, Interesting)
Sorry, but this won't work. (Score:3, Informative)
Assuming a spherical iron asteroid with a 100m radius (the article mentions two football fields across) and a 20 ton ship you can provide a maximum gravitational force of about 1 pound. This is find and dandy and could provide a deflection of nearly the diameter of the earth over a decade period.
But...
The problem is how to produce that required force on your ship without impacting the asteroid. Conventional rockets or ion thrusters would necessarily be directed in the direction of the asteroid which would nullify any net force on the system (ship+asteroid). If you get enough distance between the asteroid and the ship so yout thrust can miss the asteroid and provide a net force, the force you can provide on the asteroid due to gravity drops as the square of the distance and becomes unusably low. You'd need litterally centuries or millenia of advance warning!
If anyone has ideas how to avoid this problem, I'm all ears. :)
Re:Sorry, but this won't work. (Score:4, Interesting)
And there is another way to do it. If you put two thrusters at the end of a boom that is that is the same length as the asteroid's diameter (assuming it is spherical), you could aim them so that they are nearly tangential to the asteroid's surface, resulting in more efficient use of fuel. The downsides are 1) extra mass for the boom & dual thrusters, and 2) balancing the thrust so that the "tug" doesn't spin.
But this entire approach strikes me as overly complex. Given that the whole setup is only going to exert less than 1lb of force on the asteroid, I'd have thought it was easier to mount a gymballed 5lb thruster on the surface and fire it in synchrony with the asteroid's rotation. You'd need to spread the force across a wide surface area, and take steps to minimize vibration stresses, but that's just engineering ... not "rocket science" :-)
News for Nerds? (Score:3, Funny)
I'm disappointed in you, Slashdot nerds. For shame!
NASA patent... (Score:3, Funny)
God loses his appeal based on prior art, ends civilization in retaliation.
FIRST POST OF NEW IDEA - NOT FOUND BY GOOGLE (Score:3, Interesting)
Basically one of the big problems of moving an asteroid is its rotation. Trying to move a big spinning object, is really hard. There is a tremendous amount of energy contained in the spin so fighting it will be very expensive.
So don't fight it, USE it. Lower a long rope to the surface of the asteroid letting the spin of the asteroid keep it taught. (same idea as a space elevator). Now ferry rocks way beyond the "Geosync" point, if the rotation is anything substantial it shouldn't be too far from the surface (a few tens of kilometers, no need for carbon nanotubes). Release the rocks into space, timing the release so that they shoot off in the same general direction.
What you're doing is converting the enormous rotational energy of the asteroid into kinetic energy of the rocks. Depending on how long your rope is (and thus how fast your rocks are released) you are going to get a substantial thrust in the opposite direction. (for every action there is a reaction). You are also making the asteroid smaller. As for the released rocks, while they may someday in the distant future hit the earth they'll be small and won't make it past the upper atmosphere.
Of course in addition to the long time frame (given) that this will take; this assumes that the asteroid is rotating (probably won't have to be too fast) and that you can attach the cable to some point on the asteroid. I believe most asteroids we've discovered have a substantial rotation, this is probably due to the violent manner in which they were formed and subsequently battered. As for the cable attachment, some nets and cables stretching around the asteroid should handle this just fine.
So there you have it. Instead of launching a huge expensive power hungry spacecraft that'll provide an absolutely tiny acceleration, you could send a relatively tiny spacecraft consisting of a few solar powered low mass robots (to move the rocks to the cable) and some sort of conveyor mechanism. While this'll take some engineering, it certainly is less than trying to have a 20 ton spacecraft do precision (because gravity is inverse squared you need to be close) station keeping off a tumbling (maybe chaotically!) asteroid for decades. If the rotation rate is high enough, you could even use the asteroid to generate energy (microwave beaming?).
wisebabo
Re:Redundant question (Score:2)
Re:They are wrong (Score:2)
So that would be 2000 x 21 x 10,000-- or $420,000,000.
Let' sell some more IOUs to the Japanese and Chinese.
Re:They are wrong (Score:2)
Re:Relative position of spacecraft to asteroid (Score:4, Informative)
Why not move the earth? (Score:5, Funny)