Moving Asteroids

[bobvanx]

Analyzing a rock's rotational velocity versus its mass and diameter can bound whether it's a single body or a pile of rubble. If it's a single body, it can rotate faster than a loose conglomeration.<br /><br />The nice thing about spinning up a solid body is that you are storing all that energy as angular momentum so you can release it precipitously. Though I don't really know how we'd spin up a big rock.<br /><br />Using in-situ materials, we could build a mass driver, or maybe mine iron and make a sort of iron-ion plasma drive, or maybe even... Oh, I know!<br /><br />...build a helio-gyro out of the asteroid! Angle the solar reflectors so they increase the spin until you get to a meaningful rate.

 

[Leovinus]

Spin it up by attaching little rockets to each end facing in opposite directions. Or if you have plenty of time, try to do something with solar wind and solar sails. <div class="Discussion_UserSignature"> </div>

 

[Leovinus]

Another way to spin up the asteroid would be to take the stuff you dig from the middle and hurl it off in opposite directions on each side of the asteroid with some big pitcher device. <div class="Discussion_UserSignature"> </div>

 

[bobvanx]

A solar or nuclear powered digger/pitcher! Sort of like a lathe in space.<br /><br />This could be very easy.

 

[Saiph]

If you have enough rockets/energy to spin up the asteroid to the point where these spin and split plans would work, you may as well just do a standard burn (i.e. just move it) as it'll take the same amount of energy. <div class="Discussion_UserSignature"> <p align="center"><font color="#c0c0c0"><br /></font></p><p align="center"><font color="#999999"><em><font size="1">--------</font></em></font><font color="#999999"><em><font size="1">--------</font></em></font><font color="#999999"><em><font size="1">----</font></em></font><font color="#666699">SaiphMOD@gmail.com </font><font color="#999999"><em><font size="1">-------------------</font></em></font></p><p><font color="#999999"><em><font size="1">"This is my Timey Wimey Detector.  Goes "bing" when there's stuff.  It also fries eggs at 30 paces, wether you want it to or not actually.  I've learned to stay away from hens: It's not pretty when they blow" -- </font></em></font><font size="1" color="#999999">The Tenth Doctor, "Blink"</font></p> </div>

 

[Leovinus]

Are you sure that inducing a spin is just as easy as sideways movement? To me, spinning a rock would be easier than pushing it. <div class="Discussion_UserSignature"> </div>

 

[bobvanx]

Leo,<br /><br />I suspect you are suffering from a gravity-centric view on that.<br /><br />If we spin something up here, there is the whole Earth to push against. I can get a playground merry-go-round spinning so fast children fly off it, for example, but I could never throw them as far myself. Spinning up a free-floating rock to some arbitrary speed would eat up gobs of reaction mass, and it might be true that it would be just as effective to us that propulsion to change the orbit.<br /><br />Spiral orbits like SMART-1 are not well characterized, you are certain to know. Short burns applied at specific points in an orbit are better understood.<br /><br />By spinning a rock and then splitting it, you can store the energy so it gets released a the most advantageous moment of the orbit. I don't know if that has any merit, but it might.

 

[Leovinus]

It was just a thought. I didn't know if anyone had thought of it before, so I threw it out there to kick around. <div class="Discussion_UserSignature"> </div>

 

[bobvanx]

>>mine the thing<br /><br />That's my favorite choice! If the human race succeeds in becoming a space-fairing civilization, those big hunks of metal are going to be super valuable someday.

 

[nexium]

My guess is moving the 1 kilometer asteroid or comet a few years before impact takes less energy than spinning it up to 1 rpm.<br /> If impact is next month, there may not be enough time to get it to 1 rpm or drill a one meter hole to the center to insert a high yield nuke. Neil

 

[Saiph]

careful there, you've changed the parameters. You gave yourself a few years to shift the asteroid, so why did you only give yourself a month to spin it up? <div class="Discussion_UserSignature"> <p align="center"><font color="#c0c0c0"><br /></font></p><p align="center"><font color="#999999"><em><font size="1">--------</font></em></font><font color="#999999"><em><font size="1">--------</font></em></font><font color="#999999"><em><font size="1">----</font></em></font><font color="#666699">SaiphMOD@gmail.com </font><font color="#999999"><em><font size="1">-------------------</font></em></font></p><p><font color="#999999"><em><font size="1">"This is my Timey Wimey Detector.  Goes "bing" when there's stuff.  It also fries eggs at 30 paces, wether you want it to or not actually.  I've learned to stay away from hens: It's not pretty when they blow" -- </font></em></font><font size="1" color="#999999">The Tenth Doctor, "Blink"</font></p> </div>

 

[nexium]

Hi Saiph: You are correct. I was thinking, we can't move a 1 kilometer asteroid enough in a month or two to change a probable hit to a probable miss, so spining up and blasting is a last minute fix that will be better than nothing more than 1/2 th the time, even if we can only get it up to 1/2 rpm. With bad luck, most of the peices will hit Japan killing 50 million people. Had we done nothing, the impact would have destroyed Outer Mongolia and half of Siberia killing one million people. We can have the same bad luck if we move it, but not enough.<br /> I suggest we put fewer than ten humans per colony in asteroids which cross Earth's orbit. The colonists will have extreme motivation to make sure their asteroid doesn't hit anything including Earth. We could get volunteers from persons serving life sentences in prision, jilted lovers etc. Free fall would be a blessing for badly crippled persons unlikely to recover. Fart propulsion for the handicapped. Neil

 

[bobvanx]

>>I suggest we put fewer than ten humans per colony in asteroids which cross Earth's orbit. <br /><br />What a wonderful, market economy solution!!! Assuming of course, that these colonists have sufficient will to live, and never decide to "punish" Mother Earth...<br /><br />Dude, you just came up with an excellent sci-fi story.