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Defending Earth From Asteroids With MADMEN
jolomo writes "A partner of Atlanta-based NASA Institute of Advanced Concepts is working on a concept they call MADMEN (Modular Asteroid Deflection Mission Ejector Nodes), which would launch a distributed attack against large Earth-bound objects. Thousands of MADMEN could be built by many nations and when launched, each would land on the object, drill into its surface and remove enough material to change its course."
I can't believe people would be as short sighted as to say 'the chances are so slim' blah blah blah.
If you had RTFA, they address those odds pretty well. The odds of getting another Tunguska sized impact are roughly 1 per 1000 years. That's an *average* people. To break it down, it could theoretically happen tomorrow. Further, if you had RTFA, you would note that an object of roughly the same size as the estimated Tunguska object (150 meters across) which was first discovered this year just passed within 3.8 million miles of our planet. That's roughly 16 times (two bytes) the distance from us to the moon....or pretty damn close.
These are ideas. If they sit around and come up with 1000 bad ideas for every good one, I still don't care. That one good idea might save my ass...or my family's collective ass.
There's always people who won't believe it can happen to them, though. Look at all the folks who insisted that, because of the SF quake in 1906, that they would be safe 'for their lifetime' since it couldn't happen again. Whoops. Tell that to the folks smashed in their cars when the elevated roadway collapsed. Or, 'Well, we know Mt. St. Helens is a Volcano, but it hasn't erupted since we've been keeping track...so it'll be safe as long as I'm alive.' Tell that to those folks who chose to stay and whose bodies will never be found underneath 100's of feet of mud.
Hell, the odds of being struck by lightning are VERY slim...but plenty of research goes into preventing that, and no one complains. The odds of being shot and killed are miniscule...but look how much money we spend on prevention. But as soon as you begin researching something that could, quite literally, kill millions of people in an instant, you're branded a 'waste of time and money'.
Tell you what. Give me back the taxes I spent that went to teaching your children, and I'll gladly redirect them to fund this type of research.
Actually, painting the entire rock a brighter or darker color significantly different from it's current color would work - if you have enough time, it's the best possible solution, as it's a passive one.
I'm not sure why people seem to think that you only need to paint half. I'm also not sure why other people think that because asteroids rotate this doesn't work - it is actually *because* the rock rotates that it does work.
This relies on a phenomenon called the Yarkovsky effect. It can be thought of this way: Imagine you're standing on the asteroid where it's "asteroid high noon". Light is being absorbed throughout the "asteroid day" and heats the surface, particularly if the asteroid is darkly colored (e.g. a carbonaceous asteroid). After a while, the asteroid rotates and the sun sets. The asteroid then reradiates this heat in the direction of "asteroid evening". As it rotates more, by the time "asteroid morning" rolls around, the area your standing on has cooled down enough to radiate much less. Ergo, there is a differential radiation pressure on either side of the asteroid, which results in a net force over time. If it rotates with the same spin orientation as its orbit, its orbit will get wider. If it rotates with the opposite spin as its orbit, its orbit will get smaller.
By painting the rock, you change this force - the brighter the paint, the more light is reflected, the less thrust, thereby changing the path.
One last comment - the effect is subtle, so it would need to be applied early. It also preferentially favors diversion for small asteroids, since the Yarkovsky effect is a surface phenomena. The larger the asteroid, the smaller the surface-area-to-volume ratio, and the less deflection this thrust will do.
That's physically impossible. In the absence of torque, a rotating object will rotate about precisely one axis. It is possible for objects to "tumble," i.e., continually change the direction of their angular momentum vector, but this only occurs if there is a similarly complex external torque. If the external torque is constant, the resulting effect is called "nutation" or "precession," but it is not tumbling.
For an example, consider the Saturnian moon Hyperion, which is irregularly shaped and thus tumbles chaotically under the influence of the gravity of Saturn and the nearby moon Titan. However, if we removed Hyperion from the vicinity of Saturn and put it out in space far from any external forces, it would rotate quite simply around one axis only.
Asteroids do not "tumble" unless they are A) very irregularly shaped and B) extremely close to a massive body, which can supply a tidal torque.