A comet headed for Mars | Hacker News Reader

A comet headed for Mars

economist.com

43 pointsbenjaminfox18 comments

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.

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.

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.

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.

I think we need an asteroid in orbit (or several). Then adjust their orbits as needed to absorb the impact.

The best bet, AFAIK, is to paint it: http://www.scientificamerican.com/podcast/episode.cfm?id=sho...

(No practical confirmation, of course, but the idea is supported by a lot of prominent physicists.)

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.

If it hits Mars, it could help to terraform the planet. The CO2 ice caps would melt and heat the atmosphere. It would melt a significant amount of frozen water in the soil and thicken the Martian air with water vapor too.

Wikipedia is predicting a 1 in 1250 chance of hitting Mars. Outgassing as the comet nears the sun could change its trajectory significantly also.

http://en.wikipedia.org/wiki/C/2013_A1

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

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.

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.

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

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.

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).

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.

> 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)

...

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

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.

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