How to deflect asteroids and save the Earth

April 16, 2009,

You may want to thank David French in advance. Because, in the event that a comet or asteroid comes hurtling toward Earth, he may be the guy responsible for saving the entire planet.

French, a doctoral candidate in aerospace engineering at North Carolina State University, has determined a way to effectively divert asteroids and other threatening objects from impacting by attaching a long tether and ballast to the incoming object. By attaching the ballast, French explains, "you change the object's center of mass, effectively changing the object's orbit and allowing it to pass by the Earth, rather than impacting it."

Sound far-fetched? NASA's Near Earth Object Program has identified more than 1,000 "potentially hazardous asteroids" and they are finding more all the time. "While none of these objects is currently projected to hit Earth in the near future, slight changes in the orbits of these bodies, which could be caused by the gravitational pull of other objects, push from the , or some other effect could cause an intersection," French explains.

So French, and NC State Associate Professor of Mechanical and Aerospace Engineering Andre Mazzoleni, studied whether an asteroid-tether-ballast system could effectively alter the motion of an asteroid to ensure it missed hitting Earth. The answer? Yes.

"It's hard to imagine the scale of both the problem and the potential solutions," French says. "The Earth has been hit by objects from space many times before, so we know how bad the effects could be. For example, about 65 million years ago, a very large asteroid is thought to have hit the Earth in the southern Gulf of Mexico, wiping out the dinosaurs, and, in 1907, a very small airburst of a comet over Siberia flattened a forest over an area equal in size to New York City. The scale of our solution is similarly hard to imagine.

"Using a tether somewhere between 1,000 kilometers (roughly the distance from Raleigh to Miami) to 100,000 kilometers (you could wrap this around the Earth two and a half times) to divert an asteroid sounds extreme. But compare it to other schemes," French says, "They are all pretty far out. Other schemes include: a call for painting the asteroids in order to alter how light may influence their ; a plan that would guide a second asteroid into the threatening one; and of course, there are nukes. Nuclear weapons are an intriguing possibility, but have considerable political and technical obstacles. Would the rest of the world trust us to nuke an asteroid? Would we trust anyone else? And would the asteroid break into multiple asteroids, giving us more problems to solve?"

The research was first presented last month at the NC State Graduate Student Research Symposium in Raleigh, N.C. The research, "Trajectory Diversion of an Earth-Threatening via Elastic, Massive Tether-Ballast System," has also been reviewed and accepted for presentation this September at the American Institute of Aeronautics and Astronautics SPACE 2009 Conference and Exposition in Pasadena, CA.

Source: North Carolina State University (news : web)

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3.8 / 5 (5) Apr 16, 2009
Using orbital mechanics in this way wins my vote over nearly all the other methods put forward so far
4 / 5 (4) Apr 16, 2009
How does one attach a tether to a pile of gravel?
5 / 5 (3) Apr 16, 2009
In order to accomplish this stunt, you'd have to: 1. Have a spaceship land on an crazily tumbling asteroid which is:

2. heading in the opposite direction at appx. 20 to 30 thousand miles an hour,

3. have that space ship haul a 1000 to 100,000 kilometer tether connected to

4. a huge ballast (iron ball?)

5. attached said Rube Goldbert mechanism to the asteroid after landing on it, and then,

6. wait and see what happens.....

7. Okay.....
2.3 / 5 (4) Apr 16, 2009
Dig a hole in the asteroid, maybe several holes, then sink nuclear rocket engines into the holes and turn them on. They can push the asteroid without causing break up. The VASIMIR rocket engine might work. Getting to the asteroid before time runs out will be major design challenge.
5 / 5 (2) Apr 16, 2009
a. If we have the technology to build and attach this tether, we will have already built the space elevator. So cost to orbit will be much more economical.

b. This tether won't be deflecting an asteroid on the final run of a collision course, but may work over several years.

Given a and b, why not land a mining machine, either powered by a massive solar array or by several tonnes of concentrated nuclear waste. Mine whatever the asteroid has in abundance (or even just cut it up into small enough pieces). Fling the mined stuff (or bits of asteroid) into space, with a rail gun, solar steam cannon, whatever, in the direction that will deflect the asteroid orbit wherever you want (maybe just aim at North Korea).
So the asteroid misses (or hits someone we don't like) and the mining machine can keep flinging mined stuff in useful directions.
The mining machine could also produce some sort of paint (eg soot, platinum dust) and fling this at less than escape velocity, eventually painting much of the surface. This would also help change the orbit.
5 / 5 (2) Apr 17, 2009
What about sending up a craft with very large mass and simply park it next to the asteroid in the direction you want the asteroid to drift? Gravity attraction would nudge the asteroid towards the craft, and craft would have fuel to keep nudging away from said asteroid. Of course, you'd need lots of advance warning for this. Not my idea, read about it somewhere last year. But strange no mention here.
5 / 5 (2) Apr 17, 2009
What's wrong with plain old nukes? Better take that chance than face human extinction!
3.7 / 5 (3) Apr 17, 2009
Nukes and rocket engines don't even pass freshman physics. Orbital mechanics and tethers reach the level of graduate physics but fail the ultimate test of multiplying improbabilities.

Chance of anchoring a tether to a pile of gravel or a snowball is slim to none.

Probability of building a long enough tether.

Probability of moving the counter-mass.

The probability of doing all this in time is the probability of humanity surviving long enough to control that much energy - slim to none.

Prepare to be assimilated by the BOG Obongo. Resistance to Obamination is futile. BOG Brother is watching - OBEY. It is hopeless. Invest in SOYLENT INDUSTRIES. Hank Reardon and John Gault were stillborn.
4 / 5 (4) Apr 17, 2009
While we're at it, why not just plan to open a hyperspace window infront of the inbound object? lol!!!
1 / 5 (1) Apr 17, 2009
this is so much more difficult than it needs to be.

Although they did use an appropriate (how many times around the world) analogy. This is what I require in order to understand the physical world around me. Having been around the world,... let's see ... zero times.

I propose that we send midgets on very small spaceships and with machine gun to blast the asteroids into oblivion.

Or get one of those giant, really long scissor type extensions with a boxing glove on the end and knock it out of orbit.

1 / 5 (1) Apr 17, 2009
How about just getting the tether transport system near the asteroid, then launch the empty end of rope into the surface with standard penetrating properties tailored to work with normal asteroid composition.
5 / 5 (2) Apr 17, 2009
All this bright ideas will come to naught unless we have a dependable rocket that have the range and speed and can be ready to launch [in the worst case]in less than a month in all weather conditions...which i can't see anywhere. Aerospace experts, please give me the short list!
5 / 5 (1) Apr 17, 2009
...And, by the way, here is a disturbing thought. Any country that have the technology to control an asteroid is also capable of dropping it anywhere on Earth...then it is not far from the next step of going out and collect a number of them, putting drives on them and putting them in other standby orbits to be used when needed...
1 / 5 (1) Apr 19, 2009
Many people seem to by trying to figure out how to land on and attach a tether... why make it hard? An ICBM missle with the nuclear warheads removed, a tip designed to dig into rock, like a bunker buster with barbs to hold it in it's hole, and a bit of a boost to the range, considering once it is up to speed and out of earth's gravity, it can coast at a pretty high velocity for quite some time, especially with the ballast's momentum helping it, fired straight at it with the ballast attached. A second stage rocket fires, and the ballast is released and pushed away from the missile several moments before the missile impacts like a large harpoon, the momentum of the ballast carries it past the asteroid and once the tether reaches it's maximum length, the asteroid is literally jerked off course.
1 / 5 (1) Apr 19, 2009
Now I couldn't give you the exact mechanics on how a system like this would work, how we'd launch with the ballast so it doesn't unbalance the rocket, etc. But with bunker busters capable of punching through reinforced concrete like wet paper towels, I am sure the engineers behind this idea could work out the bugs in this system and have something pretty effective, capable of launch in any weather, and most importantly, UNMANNED. This isn't hollywood, the last thing we want on an asteroid is people. You have to land safely, survive long enough to do the job, and then find a way to get off and back home. Why leave so much to chance?
5 / 5 (1) Apr 19, 2009
Many people seem to by trying to figure out how to land on and attach a tether... why make it hard? A second stage rocket fires, and the ballast is released and pushed away from the missile several moments before the missile impacts like a large harpoon, the momentum of the ballast carries it past the asteroid and once the tether reaches it's maximum length, the asteroid is literally jerked off course.


Um... making a tether that can run a space elevator - possible and even probable.

Making a tether that won't break when the counterweight reaches the end of the line...ain't gonna happen!

Honestly, the forces involved for having an object (counterweight on tether) instantly change direction from 12,000mph one way to 30,000mph the opposite way... well, lets just say you would have better luck trying to steer it off course by having a staring contest with it!

not rated yet Apr 19, 2009
Sigh.. and some day, we'll just hit asteroids with paintballs and watch the temperature fluctuations alter its trajectory.
not rated yet Apr 21, 2009
I don't see how it works. Wouldn't the tether go slack as both objects approach the sun? Their orbits are converging.
not rated yet Jun 10, 2009
.....This concept reminds me of Wiley Coyote and his Acme contracptions...If this asteroid shows up in 50 to 75 years, there might be a chance of coming up with some sort of plan....but....if it shows up next month, well, goodnight...

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