Laser-zapping scientists will save the Earth from meteorite destruction

Re: Big Laser

Will the released gasses and debris scatter the laser rendering it ineffective for deflection?

Depends on the lasing duration. Vaporization of metallic, siliceous, and carbonaceous asteroid materials requires high temperatures where the resultant velocities of gaseous materials (and hopefully any colder material dislodged by the gases) may summarized as "frikkin' fast." Given the vacuum and micro-gravity environment, the material is unlikely to stay near the impact point.

Deep Impact (the probe, not the movie) used a big slug of copper to poke a comet. The mother probe spent 30 minutes around the moment of impact hiding behind its debris shield despite a "closest" approach of 500 kilometers, giving some idea how fast material is ejected from an energetic stimulation of cometary material.

Observations were slightly hindered by continued out-gassing from the Tempel-1's fresh crater, but that's addressable with a two-pulse pattern: zap the target, then use a differently focused pulse to disperse residual fumes. Rinse and repeat. (Rule #2 - always double tap - probably works for both asteroids and Zombieland.)

The situation would be more challenging if you tried a long-duration, continuous illumination of the target asteroid. Then you wouldn't have the opportunity for dispersion between pulses.

Re: Big Laser

"Instead the Lawrences plan to destroy meteorites"

Presumably for values of "plan" that primarily include threats that happen to be right on top of Russia or China at the time...

Re: Ah! Frickin' lasers!

What we really need now is a small spaceship that can rotate both clockwise and anti-clockwise, and accelerate forwards.

They could grind off the ablation layer if they thought that was a problem.

Re: Odds

Argh! I hate this logic! Why do people think like this?

The justification that something will soon be easy to do, does not mean the rational action is to wait for such a time. If we did that, we'd never do fucking anything! Come to that, we'd never have bothered chasing prey in the Serengeti (or whatever you want to call the prehistoric grasslands), safe in the knowledge that sooner or later the antelope would just wander toward us and we could kill it then.

Let's get on with it, otherwise we'll never reach those future promises.

Ugh......

Re: Odds

"I would argue that the odds of this happening is insignificant."

So there's a serial arsonist in your city, but since the odds he'll torch your house today are quite insignificant, you're quite happy to let the city wait until he's approaching your house with a gas can and lighter before they start building a fire department?

Re: Odds

This reasoning leads to extending period three. Potentially indefinitely. Making something trivial necessarily implies attempting to do it while it's not trivial.

Re: Odds

@mr.K

I suggest you go and Google Tunguska, or if that's not close enough in time to worry you, how about Chelyabinsk.

Both of those were near misses, that could have so easily been much, much worse. Maybe not extinction level, but seriously disruptive.

Perhaps you might then consider the justification here to be a little less thin?.

Re: Odds

More than that. I'd argue the period of time where NEO were a danger has passed. The local neighbourhood has cleared.

As an example of the risk, with galaxy collisions the predicted number of stellar collisions is around a dozen or two. That's very low for the amount of stars between two galaxies.

So while were not talking about planets hitting planets (unless we reclassify Pluto ;) ). We are talking about the odds while the system is currently in a rather stable state.

What are the simulations on collisions within a solar system with an age of ours? Unlike Galaxy collisions, we don't seem to have any local neighbours on a collision course. Most of our surrounding matter is orbiting in unison (around the Sun, or with our solar system around the Galaxy's core).

Re: Plans?

JeffyPoo, I don't quite get the finer points of the Plan Maturity Scale. Is it a scale of doability from the technical side, a scale of usefulness/sensibility, a scale of budgetability, or a combination?

Focussing purely on the technical side, FLW's Mile High Building is way past the 90-points-mark already.

Assuming statute mile (not nautical mile*), 1 mile = 1,609.3 metres.

Burj Khalifa (Dubai): 830 m

Currently under construction: Jeddah Tower, previously known as Kingdom Tower and Mile-High Tower. Jeddah Tower will be about 1,007 metres when finished. They changed the name because as Kingdom Tower it was initially planned to be 1.6 kilometres (1 mi) high, but the geology of the area proved unsuitable for a tower of that height.

Thing is, building tall is building expensive. While the structure itself scales pretty much linear, the cost doesn't. If vou venture into the Supertall/Megatall range, we are talking the sort of cash that would buy a nuclear carrier, including the planes (if they were availiable)

Anyway, back to the topic at hand: I notice that everyone from the original Star Wars gang is involved. So this is a also hedge to keep the funding coming, but at least it's for something useful and worthwhile this time.

^{* Basically the only acceptable non-metric unit. Because it's hard to be happy when you're not using the metric system.}

Re: Or an anti-matter beam!

You're thinking of Ghostbusters

Re: Or an anti-matter beam!

Why anti matter, when a laser beam would do the same? Or for that matter, drop a lot of white paint on one side to change its albedo and let solar radiation shove it to a different orbit that just misses Earth. If you've got time, that's probably the easiest option. Well it is, depending on how hard it is to cover a large asteroid with paint.

Re: Or an anti-matter beam!

Careful about the Sylkies!

Re: Or an anti-matter beam!

Positron beam is probably cheaper and much easier to generate.

"What happened to the plan to spray paint them?"

The main problem with painting asteroids, and with similar schemes involving covering them in foil or similar, is that it requires actually carrying stuff to the asteroid. And by far the biggest problem with space travel in general is that stuff is heavy and expensive to carry anywhere. A ground-based laser, or ever an orbital one, would likely be much cheaper - you can build a pretty decent laser for the hundred million or so it would cost for just a single launch with maybe a few tons of paint. Plus, a laser is reusable, and could be used for things like de-orbiting debris when not shooting asteroids.

The biggest problem is, as usual, likely to be political. Giant space lasers are always going to have people suspicious of them, while a big bucket of paint probably won't.

Re: This:

You'd be very surprised. Many of them are simply a bunch of rocks loosely held together by static and gravity - they can be a result of the really tough ones hitting each other really hard. We've only been looking at them closely (as opposed to going Wooh) for a short while and a lot of them seem to shed stuff as they come in and then go bang - this is where the shock wave in very thin atmosphere many miles up disassociates the loose pile of junk exposing all the lumps to the intense shock and heat.

They often do this where deceleration is a fraction of a G and the pressure is applied over a large surface. A more focussed push would break it up sooner.

Re: Momentum

You don't need momentum transfer from an external source. Laser ablation propulsion works by vaporising a small amount of surface material, with the vaporised material going one way and the object going the other. This is one of the most realistic proposals for clearing junk out of orbit, and has been proposed as a way of propelling spacecraft without needing them to actually carry a power source - you just have a lump of metal facing Earth that you can fire a laser at. The important part when it comes to asteroids is knowing what actually happens when you fire a laser at it.

https://en.wikipedia.org/wiki/Laser_propulsion#Ablative_laser_propulsion