Most asteroid diversion schemes tend to involve some kind of impact – an explosion, a crash, a violent shove – but a French researcher has proposed an intriguing plan to alter the course of the asteroid Apophis before it swings into Earth's neighborhood in 2036: offer the asteroid some shade. A fleet of solar sail spacecraft could shift Aphophis's course by simply shielding it from solar radiation, the researcher says.
The idea is to eliminate the so-called Yarkovsky effect, a phenomenon that produces a tiny amount of thrust on the warm side of an asteroid (named for Russian engineer I.O. Yarkovsky). As the sun heats one side of the rock it emits more thermal radiation on its near side, which affects the asteroids orbit ever so slightly. Small asteroids emit too little radiation to matter and large asteroids are too big for the effect to move them, but Apophis is in that medium-sized goldilocks range that is just right.
A group of solar sailing spacecraft flying in formation could get between Apophis and the sun, blocking solar radiation and elimination the Yarkovsky effect, altering Apophis's orbit significantly over time.
Of course, it's not easy to predict Apophis's trajectory that far into the future with absolute certainty, and there's no guarantee nudging the asteroid might not make things worse. And, as critics have pointed out, if you're going to launch a mission all the way out to Apophis you might alter its orbit just as easily by – that's right – crashing a spacecraft directly into it.
Regardless, the strides being made in solar sail tech are promising, and the versatile way they are being employed – even in theory only – show a lot of potential for the nascent technology.
Wouldn't it get pushed towards Apophis by the sun, so I guess it would have to have it's own engine, which would fire directly at Apophis giving probably the same affect as the sun. Well i guess they could use multiple engines shooting at an angle, but wouldn't it be easier and lets costly just to ram it. I guess I'm just another critic.
Why wouldn't be much simpler to use a solar sail to tow the asteriod? Seems like an aweful lot needs to be accounted for to effectively shield it from the sun as kickbush states...why not work with the sun to pull it out of earth's path?
I agree with nibbler11. It seems easier just to shoot an anchor into it and use a solar sail to tow it into a different path.
Ramming an asteroid could increase the Yarkovsky effect if its rotation speed was increased by the collision. Of course, this could produce the desired result of altering the orbit.
I say tow it to the outer Lagrange point (I believe L2) where its close enough for us to reach it from earth on a regular basis and then we just mine it for all its worth.
@scrapiorn - the moon is awfully lonely, it could use a sibling. :)
I always wondered why I never see any suggestions about attaching a couple of rockets to an asteroid to push it to a slightly different orbit, everybody wants to crash or blow stuff up, which is pretty cool in itself don't get me wrong, I'd love to see that, but wouldn't a few rockets work just as well, and that's using fairly old, inexpensive technology, right? Of course I could be missing something important, lol, I'm definitely no rocket scientist.
It's a real good thing we definitely know that Apophis is gonna miss the Earth, because we'd be real idiots to not utilize the millions of unemployed people and massive available resources of our world in some kind of effort that would be sure to at least give us options we won't have otherwise. And then if Apophis were to miss, we'd be that much closer to a real human push into space. A national jobs program of any type seems like a good idea to me right now; but then again, I've been suggesting that for three years or so. I guess I should just have faith that SOMEONE has a better idea and that they'll pop it on us when there are enough of us out of work to implement it. Considering that we could build 25 more Cape Canaverals now, the plan must be even bigger and better than that.
Why not harvest the asteroid and utilize it for Earthly research and construction.
The iRobot advertisement keeps on interfering with posting comments today
Not a bad idea... The resources from the asteroid could prove to be useful, but wouldn't it be dangerous in doing so?
Apophis has a rotational period of ~30 hours so trying to tow it with a physical teather, or push it by landing a rock engine on it is impractical. Ramming it with a space craft would by much eaiser and would have a fairy predictable result.
Another option is called a "gravity tug". In thoery if a space craft wold hover very close to Apophis the space craft and Apophis would gravitationally attract eath other thus pulling the asteriod off course. The space craft wold need three or more ion drive engine that fire at an angle slightly away from the asteriod to keep the right distance. This wold require a lot of very complex math and very presice navigation.
@ xalar, Elmir1992, others...; I haven't checked the estimated mass and velocity recently of Apophis and I don't remember them from quite some time back, but I doubt we could get to it with something not created yet and then slow it to a stop by the time it gets to us, but so far the trajectory figures to give us a very close pass if in fact it doesn't hit, by all the published reports I've seen. While we may in fact be able to accomplish an interception, our best chance to live lies in an adjustment of it's trajectory to ensure the miss, at which time other options could be realistically entertained. It would be great if we could get someone actually in the know like Dave Huntsman or others who drop in here from time to time to get Nasa and Air Force options lists from their times in service.
@NOM ...if we use massive amounts of explosives, I doubt there'd be much rotation to worry about.
In the words of Jamie Hyneman, "Jamie want big boom."
Even more, we need newer technological means to protect our Earth from annihilation.
The effect was first measured in 1991-2003 on the asteroid 6489 Golevka. The asteroid drifted 15 km from its predicted position over twelve years (the orbit was established with great precision by a series of radar observations in 1991, 1995 and 1999).
In general, the effect is size dependent, and will affect the semi-major axis of smaller asteroids, while leaving large asteroids practically unaffected.
For purposes of "saving the earth" 15Km deflection is negligible.