Only nukes can stop planetsmash asteroids, say US boffins

Just for the record...

...lots of smaller objects would actually be preferred to one big one for one big reason: SURFACE AREA. Once a space object starts to interact with the atmosphere, air friction (or drag) kicks in, and as any person involved with aerodynamics will point out, surface area plays a pretty significant role in drag. Break the big rock up into many smaller ones, and you've suddenly got a lot more surface area, which means a lot more drag, a lot more heat buildup...a lot less rock actually making impact. Furthermore, these impacts will be scattered (more like a long-range blast from a shotgun) rather than concentrated (say a slug from a 13mm rifle), which reduces the damages both from the immediate impact and from after effects (Try this experiment out; take a handful of gravel and throw it out over water, then take one big rock about as big as the combined gravel and give that a heave.)

Torn from yesterday's headlines

WISE found it's first NEO the other day. This is the first of a long list.

Lots of other spacecraft and other automated surveys exist either dedicated to finding NEOs, or which will do so when one sails through it's field of view whilst it's staring at other targets. LINEAR is a good start if you're interested.

http://en.wikipedia.org/wiki/Lincoln_ Near-Earth_Asteroid_Research

I think you're going to need a bigger tin-foil hat. Made out of many thousands of tons of bedrock.

Re: Nuke?

It'd be little different from one made in atmosphere. The primary actions of a thermonuclear bomb work purely on a massive release of energy; this doesn't require any atmosphere to work (see the Sun; it's fusing like crazy even in a vacuum). Now, there won't be a secondary blast action due to no air to push, but that wouldn't be the action sought in an asteroid blast.

Nukes don't do a whole lot in a total vacuum

An atom bomb produces a lot of light and heat - which does wonders, when you have an atmosphere to react to it, and wreak havoc around the explosion - but in space, it's just so much light and heat. It might work well (if rather unpredictably) against an icy object, but you'd virtually have to attach the bomb to the surface of a dried up rock, in order to do any good. Most of these things will have seen far more radiation during their long life times, each time that passed near the Sun. One wonders how big a nuke you'd need to use, to cook through all those dried up layers of melted and frozen basalt (in which case, why not just attach something much more useful and controllable like a rocket engine - or even just an equivalent mass of chemical explosive, since it would probably be more effective?)

If vapourising rock was your means of deflecting the object, you'd be better off with some sort of 'geet big lasur in space', since you could maintain a steady burn on the target and control the redirection process more effectively and with much faster response times.

Really, we should stop looking at these things as a threat and maybe begin considering them as a potential resource. If you could steer one into a tame orbit, you could possibly think about landing things on it, mining it - even hollowing it out and using it as a long-haul, engine-less, means of getting to Mars and back.

Don't Tell Gordon Brown!

With an election coming he has plans to make sure that we keep him in power.

He has (according his own rhetoric) already saved the world from financial disaster.

In recent days he has put the alert level up to severe to make us think about something else other than the election.

So if those nasty terrorists don't make us quake in our boots all he needs now is to raise the prospect of "we are all doomed" and he might still scrape in on May 6th.

And where's the Gordon Brown icon anyway? It'd be nice to pick a failure when posting a message on El Reg!

is required.

Single Bullet vs Shotgun: The point being you are just as dead, whichever you get shot with.

Re: Vacuum

Fred Mbogo, since its lunchtime, I'll just chip in to observe that 'Project Orion' is a largely imaginary space ship of very dubious feasibility: the preservation of its memory serves to show that even smart people can be delusional. After all, most of the design principles behind these 'bomb-rockets' could be refuted using a basic application of 300 year-old physical laws, written by a man who devoted much of his own life to alchemy.

The existence of 'Project Orion's Wikipedia page (and the even more fanciful page on 'Nuclear pulse propulsion' in general) simply serves to reinforce the message that you shouldn't really believe everything you read in Wikipedia.

Either that, or we really COULD have gone to Mars and back, in under a month, in 1965, using a bill of materials to be found in Wallace and Grommet's tool shed... and JFK really DID conspire to prevent the USA from having a fleet of nuclear space battleships, because he thought that a futile and degrading war in Indochina would be a better way of projecting American military might. You take your pick, but on the whole, if deciding to believe in something, actually requires to to start not-believing, in a whole load of other things that most people take for granted, it's usually a good idea to check where your belief-system is heading you.

The risk we run by not possessing nuclear weapons to use against NEOs

is, I suspect, rather less than that accruing to having them around to use on each other. No nukes, please - humanity might then just have a chance to get through this century without its own little extinction event !...

Henri