Nasa chief Charles Bolden's advice on asteroid

[Jason]

Behind that advice, you can hear the NASA funding can a-rattlin'.

Which is why any theoretical asteroid impact will hit a major US city.

[Svartalf]

Whereas most asteroids that hit land actually end up in Siberia, the deserts of Northern China and Tibet, or in the Sahara.

[Tero]

So any suggestion on how we protect ourselves from vast speeding rocks?

Pray?

[Blind groper]

The key to intervention is early detection. A small nudge in an asteroid's orbit is sufficient to stop it hitting the Earth if that nudge is applied early enough. There are researchers working on systems for tracking asteroids and calculating their likely impact if it happens, while they are still out beyond Mars orbit.

If such an impact was calculated, the asteroid would need to be met by a space probe, and an engine installed to move it slightly, to make it miss.

I wonder if a few nukes might do it. Not to break it up, which would be disastrous, but to nudge it sideways?
Depends on the structure of the asteroid I suppose.

[Gawdzilla Sama]

The key to intervention is early detection. A small nudge in an asteroid's orbit is sufficient to stop it hitting the Earth if that nudge is applied early enough. There are researchers working on systems for tracking asteroids and calculating their likely impact if it happens, while they are still out beyond Mars orbit.

If such an impact was calculated, the asteroid would need to be met by a space probe, and an engine installed to move it slightly, to make it miss.

I wonder if a few nukes might do it. Not to break it up, which would be disastrous, but to nudge it sideways?
Depends on the structure of the asteroid I suppose.

Put up some mirrors a few years before it is due to arrive and focus the Sun on the rogue. Light pressure might be enough to move it to a different orbit.

[Blind groper]

Interesting idea, Gawdzilla, but do you have any idea how tiny, really really tiny, light pressure is? We are talking of a massive lump of rock, millions of tonnes, travelling at something over 10 kms per second. To divert it even a little bit is going to take an awful lot of thrust!

[Blind groper]

I had another idea, which is probably too costly to implement????

However, each asteroid that is going to come close to the Earth will be in a near Earth orbit, which means that it comes near our planet every time. Could we set up that many space probes to land on all the near Earth orbit asteroids when they come past next time? A space probe comes with its own engine - possibly an ion drive, that could use asteroid material for reaction mass.

It also can beep a signal for Earth receivers to monitor, and keep tract of position. If the asteroid, on a later close by pass, looks like it might hit the Earth, a radio signal could tell the probe to fire up its engine (for a period of months) to divert the asteroid that tiny bit needed. It might even be possible to automate the whole thing so that the probe computer monitors the asteroid position, and fires itself up to divert the asteroid without external instructions.

[Gawdzilla Sama]

Interesting idea, Gawdzilla, but do you have any idea how tiny, really really tiny, light pressure is? We are talking of a massive lump of rock, millions of tonnes, travelling at something over 10 kms per second. To divert it even a little bit is going to take an awful lot of thrust!

The boffin that proposed it said he had a design for a 46 square mile mirror that weighed a few hundred pounds for the mirror surface. He said a few years would be needed for some rock, a few decades for others. And the mirror, if focused carefully, would cause outgassing of rocky material, adding to the effect.

[Hermit]

Maybe they should be planning for " the end of civilisation ".

Not by trying to move an asteroid off course, but by protecting all the knowledge that has been gained so far, from any catastrophic impact.
I would put it all on a specially designed satellite, and have it updateable constantly.
Then, all you need to do is to provide the people who are left, with the means to access the satellite. So all the knowledge that we have will be safe for ever, so long as a few people survive.

They'd end up praying to it.

Most likely.

Still, I think it's a good idea, and not just for catastrophic asteroid impacts.

[FBM]

One of the possibilities offered up was to place a large mass next to the asteroid and let the gravity slowly pull it off course. The nuke possibility was rejected long ago, iirc. You'd just wind up with a lot of smaller pieces showering down on the earth.

[Tyrannical]

Interesting idea, Gawdzilla, but do you have any idea how tiny, really really tiny, light pressure is? We are talking of a massive lump of rock, millions of tonnes, travelling at something over 10 kms per second. To divert it even a little bit is going to take an awful lot of thrust!

The boffin that proposed it said he had a design for a 46 square mile mirror that weighed a few hundred pounds for the mirror surface. He said a few years would be needed for some rock, a few decades for others. And the mirror, if focused carefully, would cause outgassing of rocky material, adding to the effect.

They also theorized painting it black, and the increased force of light would move it. Of course that takes time.

[FBM]

I've heard of a "solar sail" before, but not sure if it was in this context.

[JimC]

I've heard of a "solar sail" before, but not sure if it was in this context.

Light possesses momentum, and when it reflects from a large area but light weight foil sail, it can produce effective changes in momentum of whatever it hits...

[FBM]

They've been proposed for providing thrust (?) to spacecraft, so given enough time I imagine they could alter the path of an asteroid. But I think it would take a long time. We'd need to know about the incoming rock well in advance.

[JimC]

They've been proposed for providing thrust (?) to spacecraft, so given enough time I imagine they could alter the path of an asteroid. But I think it would take a long time. We'd need to know about the incoming rock well in advance.

If an asteroid is a million times more massive than a spacecraft (which, for a dangerous one, will be a minimal figure), it will take a million times longer to alter its velocity, given the same area of light sail...

An ion engine, landed on the asteroid, and using the asteroids substance as reaction mass is a much more realistic solution...