Ok .. for all those asteroid hunters .. the way to avoid a collision with one is currently being debated … and perhaps, there's a role for a couple of solar sails in the ultimately successful strategy, as well..
Dr. Matloff's research indicates that an asteroid could be diverted by heating its surface to create a jet stream, which would alter its trajectory, causing it to veer off course. In 2007, with a team at the NASA Marshall Space Flight Center in Huntsville, Alabama, he investigated methods of deflecting NEOs. The team theorized that a solar collector (SC), which is a two-sail solar sail configured to perform as a concentrator of sunlight, could do the trick. Constructed of sheets of reflective metal less than one-tenth the thickness of a human hair, an SC traveling alongside an NEO for a year would concentrate the sun's rays on the asteroid, burn off part of the surface, and create the jet stream.
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To do that, it is necessary to know how deeply the light would need to penetrate the NEO's surface. "A beam that penetrates too deeply would simply heat an asteroid," explains Dr. Matloff, "but a beam that penetrates just the right amount -- perhaps about a tenth of a millimeter -- would create a steerable jet and achieve the purpose of deflecting the asteroid."
now here comes the politics ..
Quote:
At present," he adds, "a debate is underway between American and Russian space agencies regarding Apophis. The Russians believe that we should schedule a mission to this object probably before the first bypass because Earth-produced gravitational effects during that initial pass could conceivably alter the trajectory and properties of the object. On the other hand, Americans generally believe that while an Apophis impact is very unlikely on either pass, we should conduct experiments on an asteroid that runs no risk of ever threatening our home planet."
So, I'd like to ask .. what happens if the asteroid isn't made of material that results in a jet ? The success of this approach would seem to be completely dependent on the assumption that a jet could be generated from the surface material, which would be predicted only by a theory about the composition of asteroids and;
I’m not too sure I like the idea of ‘experimenting with Apophis !!
Leave that sucker alone, I say !
A little more seriously, surely if a giant solar reflector can create enough heat to deflect the trajectory, a sustained, well directed Fusion bomb campaign should be able to do the same, (if not better), and have the added benefit of reducing the technical risk/complexities.
Wiki list the main avoidance strategies as:
- Nuclear Weapons;
- Kinetic Impact;
- Asteroid gravitational tractor;
- Focused Solar Energy;
- Mass Driver (ejecting mass over time from the Asteroid);
- Conventional Rocket Motor;
- Wrapping the Asteroid in plastic
- Paint it black;
- Release a cloud of steam in front of it;
- Attaching a tether and ballast mass to alter the centre of gravity;
- Laser ablation;
- Magnetic Flux Compression;
- NEONet (I have no idea of what this is).
Take ya pick, folks !
(Perhaps this should be a survey question in the General Chat section ?)
Some of those suggestions are utterly ridiculous and most are beyond our present capabilities...not technically, but practically. In any case, the pollies won't spend the money to find them, let alone try to stop them.
The best bet to stop one would be to develop a powerful plasma or laser based weapon system, but where are they getting the multi-terawatt power generating capacity to power the weapon/s. Then you'd probably have the idiots turning the damn things onto one another.
I guess the first thing to do would be to work out the objects composition. And then come up with a solution from there. If the object was mostly ice, heat it up and turn it to liquid, breaking it up into smaller parts. If it is mostly iron or rock, possibly do the Bruce Willis thing and drill into it and set it with charges. I think trying to push it off course is ultimately the wrong thing to do, as it would possibly still have to be dealt with later on. I reckon break it up into as small as you could, and let the atmosphere do the rest. Im sure we'll get plenty of warning about any NEOs that will impact earth and Im sure the world powers will team up briefly to sort the problem out quickly. Never know, might be just what we need to truly start the road to peace.
Seems to me that neither party, Russian or American or who-ever-else, wants to take the blame if something goes wrong, yet they both want to be the hero's.
Also neither wants to spend there own money. To me seems both are sitting back and waiting for the other one to do the work. which could become a disaster.
I think most people forget that on the whole, NEO's have a rapid spin rate and none of them are 'the size of texas'. The biggest problem we have is successfully landing something on or just parking something near an NEO. Itokawa and Deep Impact just proved we could crash into one in an uncontrolled fashion. In order to park a bomb off the surface to blow off surface material enough to alter the trajectory in the right direction means pinpoint positioning and timing.
Targetting what with a missile? In order to nudge the target you need to 'push' it is a direction. You can't just hit it anywhere otherwise you will get unpredictable results. Park in the sense of place the missile in a predefined position off the surface of the asteroid and explode it. Physically impacting the asteroid itself may not produce the desired result. A single explosion is just going to blast material off the surface. In space there is no concusive effect so prolonged effects will come from irradiation of the surface.
Deep Impact was controlled in the sense that they could hit the target when they wanted to - not target the exact point that they wanted to hit.
My mysterious object - well I have put the results up for publishing. The 'old' camp says the results can be explained by YORP (just). The 'young' camp says YORP can't even come close so look for another mechansim. For me, I have no opinion on either - I'm struggling enough with math and working through the math required for Binary Asteroids. To give you an idea of how far behind I am, I have only just been able to derive;
DsDp = Sqrt(10^(0.4*dm)-1) from dm = 2.5 Log(F/F')
where DsDp = Size ratio, dm is delta magnitude of the eclipse events, F and F' are flux from the Uneclipsed and Eclipsed system.
Trying to get my head around angular momentum now......
Even breaking it into just a few pieces significantly reduces the chance of a cataclysmic explosion.Smaller pieces will lose most of their cosmic velocity as well as ablating a higher percentage of their mass. As long as the pieces hit at below 5km/sec they should not vaporize on impact creating a crater and sun blocking ejecta . If the explosion puts some stresses in to the asteroid, the stresses of atmospheric entry should make it more likely to fragment before impact. At least the moronic argument that multiple projectiles make it more likely to be struck has not been rearing its politically correct head lately.
Quick rough calculation of how many people would receive fatal blows from the meteorite fragments if blown up, assuming everyone is standing outside is a couple of hundred which reduces to only a couple of dozen if helmets are worn on the day as opposed to letting the whole block slam somewhere on the planet or ocean which averaged out for impact over the whole of land/ocean is about 250,000 . Ie, fragmenting reduces fatality risk by a factor of about a thousand and this is with the assumption of standing around outside with no protection.
I say blow it.
Ok .. for all those asteroid hunters .. the way to avoid a collision with one is currently being debated … and perhaps, there's a role for a couple of solar sails in the ultimately successful strategy, as well..
