[Newbies_Kid]

My link

This asteroid called apophis was discovered in 2004, predicted to be really closed to earth in 2036 (s*#t i'm just 46 at that time) but no harm was calculated by scientist. But, i want to talk for a worst thing that could be happen. As engineers or scientist, what the best solution you think to stop that asteroid from hitting earth.. shoot it or ask to Ultramen for help?

[forufes]

the usual.
we calculate the trajectories of the pieces, then we nuke it. KABOOM!!

[Newbies_Kid]

Is it possible if we attached hundreds or may be thousand of remote controlled parachutes on that asteroid? until it got into atmosphere we deploy the parachutes and guide it to suitable land spot.. The weight of that rock may be around 500 tonnes, so how much parachutes we needed?

[insane_alien]

or... a cooler idea... use the parachutes as solar sails so it never even gets close.

[Newbies_Kid]

Sorry, my english weren't good so i can't see your idea IA. what do u mean by solar sails?

[insane_alien]

a method of propulsion using radiation pressure.

[Newbies_Kid]

uh oh.. i just know what solar sail is ~. And that was really cool idea.

[DJBruce]

Newbies_Kid, on 1 August 2010 - 07:13 AM, said:

My link

This asteroid called apophis was discovered in 2004, predicted to be really closed to earth in 2036 (s*#t i'm just 46 at that time) but no harm was calculated by scientist. But, i want to talk for a worst thing that could be happen. As engineers or scientist, what the best solution you think to stop that asteroid from hitting earth.. shoot it or ask to Ultramen for help?

Worst case scenario the asteroid hits Earth landing in a city with high population density. Causing massive death instantly. The asteroid is estimated to not be nearly as big as the Chicxlub impact however it would still have a massive global impact and possibly cause an impact winter.

forufes, on 1 August 2010 - 07:26 AM, said:

the usual.
we calculate the trajectories of the pieces, then we nuke it. KABOOM!!

Actually this is a horrible horrible idea. All nuking an asteroid would do would be turn one asteroid into a bunch of slightly smaller asteroids coming at earth. Its analogous to being shot with a shotgun instead of a rifle. As both are going to do a lot of damage.

Solar sails are a cool idea. I also like the idea of focusing solar radiation at the asteroid so that it vaporizes small amount of the asteroid throwing it off its path. A mass driver approach would also be cool, however, I doubt very practical at the current time.

[Mr Skeptic]

Worst case scenario is that everyone got the trajectory wrong and it actually hits us while we weren't expecting it so we didn't even try to stop it. Close to that, we might realize on time to do something, with just about the only something we could do being a nuke. However, I think that then we'd have to develop a launch vehicle which could take too long. However, if we have plenty of warning (the pass by in 2036 will allow better measurements of its trajectory after that, and it will come close again and potentially hit us years later), if we have plenty of warning all we need to do is give it a little nudge. The tiniest nudge multiplied by the distance it is traveling will be enough to deflect it. There's several ways to do this, which roughly are crashing it, pulling it via our own propulsion, using its own mass as propellant.

[Newbies_Kid]

How about we change the nuke's warhead with something like a boxing gloves? Err.. i mean something that can "punch" it or at least propels it away with decent velocity. Assume the velocity of apophis at 0.0001 mph and with its mass about 2.7E10kg so we have its momentum about 1207008Kg.M/s then if we have 2000kg missile which could boost up at Mach 3 we have its momentum about 2040000Kg.M/s So the asteroid could flung away~~~ Is it cool?

This post has been edited by Newbies_Kid: 2 August 2010 - 11:12 AM

[Mr Skeptic]

Except its velocity might be more like 15,000 mph -- and yes, you can deflect that by crashing something into it. All it needs is a little tiny nudge in the right direction (if it is in fact going to hit earth), and it will be deflected.

[Ophiolite]

Newbies_Kid, on 1 August 2010 - 01:05 PM, said:

The weight of that rock may be around 500 tonnes, so how much parachutes we needed?

Where did you get the figure of 500 tonnes? Based upon a diameter of 270m and a chondritic composition (reasonable given its Sq spectral classification) then the mass of the object would be around 40,000,000 tonnes. You seem to be out by about five orders of magnitude.

Further, if we assume a minimal impact velocity of 15 kms per second then the total energy released would be around 4 x 10^18 joules. That's just under 1,000 megaton, or roughly 17,000 times the blast at Hiroshima.

[DJBruce]

Here are Apophis' statistics according to NASA:

Mass: 27,000,000,000 kg
Impact Velocity: 12.59 km/s
Impact Energy: 510 MT

Here's the most important one's, "Impact Probability: .0000076% and Torino Scale (max): 0". So although interesting to discuss I do not think anyone should lose any sleep over Apophis.

[Ophiolite]

OK. NASA are either using a slighty smaller diameter - 245m, rather than 270m, or a considerably lower density - 2.62 versus 3.5 g/cc. I can see no obvious justification for a value that is substantially below even that of carbonaceous chondrites, so I suspect they have used the smaller diameter.

I just checked the link you gave and NASA also quote the 270m diameter. I don't altogether buy their density number - I see they say they have used 2.6 rather than 2.62 - I'll put that down to significant figures quoted. It has an Sq spectrum so it ought to be an olivine or pyroxene rich rock, with densities in the 3.0 to 3.5 range.

However, on reflection, we should be looking at bulk density and asteroids are now thought to very porous. Moreover there are a handful of bulk density measurments of S type asteroids I've tracked down that are in the 2.6 range. So going with 2.6 g/cc and 270 m and an impact velocity of 12.59 kms/sec does indeed give us a mass of just under 27,000,000,000 kgs and an energy of 511 MT. You US taxpayers will be pleased to know NASA are not wasting your tax dollars with inaccurate calculations.

This post has been edited by Ophiolite: 2 August 2010 - 04:27 PM

[Newbies_Kid]

Ophiolite, on 2 August 2010 - 03:10 PM, said:

Where did you get the figure of 500 tonnes? Based upon a diameter of 270m and a chondritic composition (reasonable given its Sq spectral classification) then the mass of the object would be around 40,000,000 tonnes. You seem to be out by about five orders of magnitude.

Further, if we assume a minimal impact velocity of 15 kms per second then the total energy released would be around 4 x 10^18 joules. That's just under 1,000 megaton, or roughly 17,000 times the blast at Hiroshima.

I forgot to put a letter K after 500. But 500K Tonne is still too far from reported by NASA, that was actually my assumption, hope NASA scientist don't just assume that it won't hit us later.

[Newbies_Kid]

Mr Skeptic, on 2 August 2010 - 01:22 PM, said:

Except its velocity might be more like 15,000 mph -- and yes, you can deflect that by crashing something into it. All it needs is a little tiny nudge in the right direction (if it is in fact going to hit earth), and it will be deflected.

How you know that?? if it's true, the probability should more than what DJ Bruce said. that damn fast man. If that the case, we really need Ultraman help..

[J.C.MacSwell]

Worse case scenario is we calculate the trajectory to be on path to hit us, we come up with some wonderful plan to get it off course, execute it perfectly through a heroic international effort just in time, then realize it would have missed us... just prior to our compete and utter demise.

(dibs on any movie rights and royalties)

This post has been edited by J.C.MacSwell: 4 August 2010 - 03:57 PM