Can you describe an effective method to deflect a comet or asteroid headed for Earth?

[matt-browne-sfw]

Asteroid deflection strategies are methods by which near-Earth objects could be diverted, preventing potentially catastrophic impact events. See also

Asteroid deflection strategies - Wikipedia, the free encyclopedia

In particular

• 2 Popular strategies
  • 2.1 Nuclear weapons
  • 2.2 Kinetic Impact
  • 2.3 Asteroid gravitational tractor
  • 2.4 Use of focused solar energy
  • 2.5 Other proposals

 

[Nik]

Re: Can you describe an effective method to deflect a comet or asteroid headed for Ea

Um, divert it just enough to smack into Moon instead ??

 

[matt-browne-sfw]

Re: Can you describe an effective method to deflect a comet or asteroid headed for Ea

Um, divert it just enough to smack into Moon instead ??

But how can we really divert it?

 

[BladeOfFire]

Re: Can you describe an effective method to deflect a comet or asteroid headed for Ea

I think a way to divert it could be created but at the cost of using up opur nukes. If we use a concetrated beam of energy to hit the Asteroid sort of like a tractor beam and fling it out into the vast reaches of space.

 

[chrispenycate]

Re: Can you describe an effective method to deflect a comet or asteroid headed for Ea

The real answer depends on our technological level and the lead time we've got on the object. If we know twenty years in advance that the orbit of something is going to intercept that of the Earth at the same time the planet is at that point, and we've got interplanetary travel already, then it's not the same problem as if someone predicts a certain comet is going to produce a great show, then it outgasses enough to push it a couple of secondsof arc closer to Jupiter, which swings it off line a whole minute of arc, and suddenly in three months time that comet's got a one in thee chance of hitting the planet heat on, and we've got a couple of shuttles, a few soyuz boosters and whatever the Chinese are using – long march? Well, I suspect it's not even worth worrying about.
A bit more time, and our present technology level, an Orion interception craft and physical contact, a combination of kinetic and mounting a rocket on it to push it off line. I don't think we could get the ship back, nor do I think either remote control or robot craft are sufficiently flexible, so a manned ship with a sacrificial crew. The further away, the less energy required, so start early. Push it off line as a single lump, if possible (and no-one knows the tensile strength of a comet, so gently does it); if it breaks up, its centre of gravity will follow the intersection course, and any number of the fragments might hit Earth.
Slightly better warning, a "Star wars" (American military, not a galaxy far, far away) laser aimed at one side of the body (if it's not rotating too fast) boiling off matter from that side and pushing it off line. I would be easier if the thing were already in orbit, and easier still if there were a few dozen of them prepared to shoot down missiles, that could relay each other. Accurate aiming over that sort of distance would be problematic- what, a tenth of a second of arc, and you don't want to miss or hit head on…
Doing the same thing with a solar mirror array is an interesting alternative; what, four square kilometres of mirror (in independent bits, I think, rather than try and move that lot as one) focussed onto a combining mirror which is mobile enough to follow its target with the sort of precision we've just been looking at. And you'd better be darn sure the thing's decommissioned when the crisis is over – the temptation to vaporise Cleveland…
Kinetic strike or gravitational attrapment by an asteroid just pushes the problem one step further back, since you'd have to apply as much energy to the asteroid as to the dangerous object. It might be easier if you're already settled in the asteroids, otherwise, it just adds complexity.
How about a linear accelerator (mass driver) on the moon (installed to lift matter from the moon to Lagrange points, to build space stations) re-aimed to send a continuous stream of rocks (you can make them hydrogen bombs, if you like) at the intruder? Each individual rock would make practically no difference, but the cumulative effect would just slightly slow it down, so the Earth was already past.
Synthetic solar flare? Not for light pressure, but to encourage outgassing.

 

[Steve Jordan]

Re: Can you describe an effective method to deflect a comet or asteroid headed for Ea

I don't think we would need to sacrifice a crew to do the job. I am a firm believer in robotic tools with human monitoring and some direction/remote control, so I'd propose a module carrying a "swiss army knife" of possible tools, and a second ship to do a flyby with a manned crew to supervise the operation close-up, without landing, then return.

The tools I'd bring would be lasers of various frequencies (to burn part of the object away), fresh boosters, and explosives (to blast part of the object away), all intended to alter its arc (preferably, for the Sun). Also included would be survey equipment to determine the composition of the object (and help determine which tools or combinations would work best), and possibly some type of netting/scaffolding material to hold the object together during a change in trajectory (if it is deemed likely to fragment upon being disturbed).

The Swiss Army Module (SAM) would arrive first and begin its survey, to be complete upon arrival of the Human Support Module (HSM). As the HSM arrived, it would begin reversal of trajectory as engineers examined the survey data and made their decision on tools to use. SAM would be directed and remotely controlled to set up tools and activate them, and HSM would stay on-station to gauge success before going into Earth-return trajectory.

Something else to consider: As opposed to removing part of the object to alter its trajectory, the same could be accomplished by adding to its mass to alter its trajectory. So maybe a SAM just needs to deposit some appropriately dense waste material to do the job (we're already talking about ejecting trash into the Sun... this would be another way to get it there).

 

[Urien]

Re: Can you describe an effective method to deflect a comet or asteroid headed for Ea

I've always thought a gigantic tennis racket attached to the moon would do the job.

 

[Grimblade]

Re: Can you describe an effective method to deflect a comet or asteroid headed for Ea

Realistically speaking mankind isn't going to consider anything as advanced or efficient as some of the suggested means listed in this thread, especially considering the current "world leaders".

Let's face it - if the U.S. had it's way, which for some reason it no doubt would, they'd just nuke it regardless of the adverse effects it would have on our eco-system and morale as a species. Plus, based on their track record they'd probably miss, turn full circle and land a nice big 100 megaton warhead smack-dab in the middle of the Pacific.

Smoooooooth..

So whichever way you look at it the Earth is doomed. But that's what Sci-Fi is all about isn't it?

 

[Urien]

Re: Can you describe an effective method to deflect a comet or asteroid headed for Ea

This would be a blank post without this sentence.

 

[chrispenycate]

Re: Can you describe an effective method to deflect a comet or asteroid headed for Ea

I'm wondering about solar sail technology - if you had some of the foil available, say a hundred square kilometres you could focus the sun's energy and vaporise one side of a comet generating thrust, with only a few tons of mass to be transported.

 

[Pyan]

Re: Can you describe an effective method to deflect a comet or asteroid headed for Ea

If there's time...
Drill holes three-quarters of the way through it at right-angles to the direction of travel, fill with water- or CO²-ice. Then bathe it in heat, from a massive laser or solar reflector: the ice boils out of nozzles fitted to the holes, producing a change in the vector of approach, enough to divert it away from a direct hit.

 

[Grimblade]

Re: Can you describe an effective method to deflect a comet or asteroid headed for Ea

How about using the very same technology to develop a stable energy shield around the planet, thus protecting from any further cosmic caffuffles. How about we all.. WRITE ABOUT IT!? This is turning into a decent muse-thread.

 

[Nada]

Re: Can you describe an effective method to deflect a comet or asteroid headed for Ea

Actually, in the very question there is an important Dicotomy. A comet or an Asteroid?
The two cases are greatly different. We (humanity) would know of an asteroidal impact with a relevant margin, as a minimum a decade or so. For example Asteroid Aphophis MAY encounter Earth in 2036 if the encounter of 2029 plays badly. In that case it would be 7 years.
For such class of objects, you can try to give a small push so that the accumulated movement over multiple orbits displace the offending object at the "impact" moment. For volatile-rich objects the evaporation of part of the asteroid and the subsequent reaction push suffices. To obtain the evaporation either you use nuclear explosives or sun mirrors/sails or kinetic impactors. For Mass vs. Effectivity ratio a nuke is the most effective method but legal and political issue would probably impede the use of such a tool.

For volatile-poor bodies the gravitational tractor or the mass driver (look at Gregory Benford and David Brin's "HEart of A Comet") would work.
@steve: the removing or adding of MASS has no effect. You need to alter the MOMENTUM of the body. Apply a force in other words.
@pyan: do the calculation: if the material is there, this is exactly what you do; if there is no volatiles, the energy spent to bring water can better be used to build another solution (mass drivers is my favourite)

If instead it is a comet, the situation is dire, MUCH more dire. With the present and near future technological level, and given the present monitoring systems we would be able to see a long period comet when it is more or less at Jupiter orbit. This means 9 to 12 months before impact. All long-duration deviation methods do not work for lack of time.

In a study done in 2005 by the International Space University, named Cassandra, it has been proven that the main issue is not how to deliver the substantial push needed to move the comet, but the humongous amount of Delta-V needed to bring something to impact the comet. Even assuming an encounter with a delta V of several tens of km/s (no matching of velocity) and a very compact "impactor" spacecraft, the fuel needs are astronomical.
See below, there is a link to the report with all the numbers.

If a long period comet is posed to hit the Earth in the next 20-30 years, the only thing humanity could possibly do is try to survive the consequences.

In any case, one has to be very careful about fragmentation methods: if the body breaks up in rather big pieces, it would create a shotgun effect. Instead of a single big impact, there will be multiple slightly smaller impacts, which produce much more damage.

If you are interested, here is the link for the full report:
ISU - CASSANDRA: a strategy to protect our planet from nea-earth objects

In case you find errors in chapter 4 you can complain with the editor here

 

[Interference]

Re: Can you describe an effective method to deflect a comet or asteroid headed for Ea

DUCK!!!!!


(sorry. frivolous? Maybe)

 

[Nada]

Re: Can you describe an effective method to deflect a comet or asteroid headed for Ea

he he he. You would be surprised, but in discussions on the issue, I listened to people proposing to do that.
By MOVING Earth...

I'm surprised that I listened...

 

[Steve Jordan]

Re: Can you describe an effective method to deflect a comet or asteroid headed for Ea

he he he. You would be surprised, but in discussions on the issue, I listened to people proposing to do that.
By MOVING Earth...

I'm surprised that I listened...

Sure, I know that scientific team. Clark Kent... Hal Jordan... Diana Prince...

 

[TheEndIsNigh]

Re: Can you describe an effective method to deflect a comet or asteroid headed for Ea

I thought the current thinking was attach a small ion drive motor. These useually have very little power but a small shove in the right direction for long enough has astronomical effects. Thats the problem. If we have years it works however there are comets out there that will 'do for us' and its possible we only get months of warning (if at all). To get something to intercept it may take longer than the time we have.

However, look on the bright side. Given the little time we all have left, a few years here or there dosen't make a lot of difference.

 

[Drachir]

Re: Can you describe an effective method to deflect a comet or asteroid headed for Ea

I'm very disappointed. I thought by now that one of you would have figured out a foolproof way to save the Earth. I am going to be very angry if an asteroid falls on my head.

 

[Hilarious Joke]

Re: Can you describe an effective method to deflect a comet or asteroid headed for Ea

At least it would shut up your whinin'.

Just kidding, Drachir.

Kisses!

HJ.

 

[TheEndIsNigh]

Re: Can you describe an effective method to deflect a comet or asteroid headed for Ea

I'm very disappointed. I thought by now that one of you would have figured out a foolproof way to save the Earth. I am going to be very angry if an asteroid falls on my head.

now look 'ere.

It's not my fault you chose to encamp your measly humanity on a rock in the most unstable part of the galaxy.

Had it the sense to occupy one of the more stable and settled regions the threat wouldn't even have needed discussion.

Just a mere 20 light years away are some of the most desirable locations for establishing a foothold for new biosperes, being completely free of loose lumps of rock flirting about.

But no, you thought you could get away in some galactic backwater and now you come moaning about global catastrophies and the threat of imminent distruction.

I wouldn't mind but given the universe will end soon anyway, why bother worrying. All you have to do is ensure that you make the most of things in the short time we all have left.