
A comet headed for Mars - benjaminfox
http://www.economist.com/blogs/babbage/2013/02/comet-headed-mars
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redact207
I'm thoroughly impressed with the calculations involved in all of this. The
fact that we're on one wobbly, fast-moving planet looking at another fast-
moving, wobbly planet predicting the trajectory of a sputtering fast-moving
comet and re-calibrating the orbits of mars-orbiting telescopes so their out
of danger but looking at the comet while it goes past is just astounding.

I won't be impressed, however, if said comet takes out curiosity. Would give a
good first-person shot of what planetary extinction looks like though.

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jacquesc
This idea got me wikipedia'ing around. Really interesting article here:
<http://en.wikipedia.org/wiki/Asteroid_impact_avoidance>

Seems like if a comet were headed to earth, the best bet would be to get as
much mass into space, and shoot it as fast as you can in order to knock it off
course.

Much less fun than a Bruce Willis shlock disaster movie, but seems pretty
practical.

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adastra
Depends on how much time you have and how big we're talking about. If you have
years, or lets say a decade, you'd probably try a bunch of things in parallel.
Some strategies could be crazier than others, but you wouldn't waste too much
time on things that have huge technological risk. Landing a automated mining
robot + mass driver seems far-fetched. As does painting it (for something
kilometers in diameter, how would that work exactly?)

So you're probably talking about one or more kinetic impactor missions to try
and deflect it billiard ball-style. Before those actually launch, the laser-
ablation strategy seems like a pretty attractive option to do in parallel.
You'd build an array of lasers that ablate the surface of the asteroid,
ejecting material that works as reaction mass. Northrop has 100kw solid-state
lasers working right now: <http://optics.org/news/1/7/13>

Seems plausible that you could get something up and running quickly to see if
it would work. Before either scaling it up or dropping back on the riskier
impactor missions.

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InclinedPlane
Ablation is the best bet if you need to move something as much as possible as
fast as possible. And for that you want a device which outputs a lot of EM
radiation at tremendous power levels and ideally is as compact as possible in
order to transport it near enough to the object. Nuclear weapons meet all
those criteria and so are likely to be the best tools for pushing around big
rocks quickly on short notice. You simply explode them at an appropriate
stand-off distance and the energy release of mostly soft x-rays causes the
surface near the explosion to ablate, generating thrust.

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lambdasquirrel
So we could in theory deflect an object away from a collision towards Earth.
How hard is it to make this comet hit Mars for sure?

Just a thought.

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eru
Making the comet hit should be much harder than deflecting one. Becaues
planets are such small targets in the grand scheme of things.

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spectre256
The trajectory of this comet makes things especially difficult. It is moving
fast, travelling in the opposite direction of all the planets and is coming in
at a large angle relative to the plane of the solar system. From Phil Plait's
post it will be moving at over 55km/s relative to Mars during the
flyby/impact. Simply intercepting this comet is basically impossible today.

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hakaaaaak
I hope it misses. It will mess up our equipment on Mars if dust is flying
everywhere.

But if it does get hit, I hope that the people of our planet can start
focusing more on technology development for energy, propulsion, protection,
insulation, and terraforming. As for everything else (other than praying),
those can be extracurriculars. The main obstacle to this would be the lack of
immediate incentive. The asteroid mining companies try to provide future
incentive by saying there are resources to be mined. However, to completely
change our culture, education, and occupations to gear towards space
colonization, we'll need a lot more than that.

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JoeAltmaier
Imagine having eyes on the ground for such a stupendous event! It would be a
once-in-a-civilization opportunity. Fingers crossed.

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aashaykumar92
Relatively speaking, there is very little data to go off of as of now. The
comet hasn't been tracked long enough for them to truly see if it will even be
close to Mars.

I do think, however, that if it does look well on its way to hitting Mars,
it'd be worth while to send a large chunk of mass and try to push it in
another direction. It could prove to be a trial for a future, Earth-
threatening instance. So far the ability to deflect a comet/asteroid is only a
theory--putting it to practice is a great way to test it.

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enraged_camel
I've actually heard it said that the benefits of allowing it to hit Mars would
be greater, since we would learn a lot from the event and use that knowledge
to explain what happened to our own planet 65 million years ago. In addition,
some scientists mentioned the possibility that an impact of such magnitude
might help terraform Mars (although admittedly I've only heard the soundbites
and haven't looked into the actual science of it).

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aashaykumar92
Hmm I guess that makes sense but there are two options I see:

1) The comet hits Mars, has negative effects on the planet but we end up
learning a lot about what happened to Earth.

2) We deflect the comet, learn how to protect ourselves from such things in
the future, and we can still visit Mars in the future and hope for life on
there.

Now obviously I demonstrated a bias above, but I definitely think it's more
worth our time to look into the future than what happenED--especially in this
situation. Right now, there are more discussions/plans of humans visiting Mars
than there ever has been. A comet hitting the planet would most likely cancel
or severely postpone many of those plans.

Learning how to protect ourselves should be prioritized, then discovery should
be close after. Both of these may become delayed processes if we just allow a
comet to hit Mars. Let me know your thoughts.

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kalms
> If it really is that big, and if the comet were to hit the side of Mars
> facing Earth (it seems that it might do, but it might also hit the far side)

...

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sixQuarks
uhmmm... has anyone calculated the risk of this comet hurtling towards earth
after being projected by a near miss of Mars?

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lutusp
Very, very improbable -- the risk to Earth from this comet is much less than
the risk from any number of similar objects in unrelated orbits. And the
latter risk is very low.

The fact that this comet is going to approach Mars doesn't mean it presents
any plausible risk to Earth.

