Comments on: Gravity to the rescue http://blogs.discovermagazine.com/cosmicvariance/2005/11/14/gravity-to-the-rescue/ Random samplings from a universe of ideas. Mon, 09 Nov 2009 00:09:16 -0600 http://wordpress.org/?v=2.8.4 hourly 1 By: James http://blogs.discovermagazine.com/cosmicvariance/2005/11/14/gravity-to-the-rescue/comment-page-1/#comment-6824 James Mon, 21 Nov 2005 15:27:25 +0000 http://blogs.discovermagazine.com/cosmicvariance/2005/11/14/gravity-to-the-rescue/#comment-6824 Why not mate two rockets "nose to nose," and push on the asteroid with the exhaust plume from one of them? Should be fairly gentle, and broad enough to avoid cracking the thing. The other rocket keeps the package in place, of course. Why not mate two rockets “nose to nose,” and push on the asteroid with the exhaust plume from one of them? Should be fairly gentle, and broad enough to avoid cracking the thing. The other rocket keeps the package in place, of course.

]]> By: Matt McIrvin http://blogs.discovermagazine.com/cosmicvariance/2005/11/14/gravity-to-the-rescue/comment-page-1/#comment-6823 Matt McIrvin Sat, 19 Nov 2005 04:22:23 +0000 http://blogs.discovermagazine.com/cosmicvariance/2005/11/14/gravity-to-the-rescue/#comment-6823 PB got the right reason why the asteroid's mass matters. Mass won't matter in a one-body problem with a static background field, but this is a two-body problem (well, actually more if you count the sun and planets, but if you just think of it as delta-vee delivery it's two). However, the reason you might want to use gravity as a tether rather than simply pushing the asteroid is that asteroids rotate. Doing it this way means you don't have to waste time, fuel and effort spinning down the asteroid so it can be pushed safely. PB got the right reason why the asteroid’s mass matters. Mass won’t matter in a one-body problem with a static background field, but this is a two-body problem (well, actually more if you count the sun and planets, but if you just think of it as delta-vee delivery it’s two).

However, the reason you might want to use gravity as a tether rather than simply pushing the asteroid is that asteroids rotate. Doing it this way means you don’t have to waste time, fuel and effort spinning down the asteroid so it can be pushed safely.

]]> By: k1ng_keenan http://blogs.discovermagazine.com/cosmicvariance/2005/11/14/gravity-to-the-rescue/comment-page-1/#comment-6822 k1ng_keenan Thu, 17 Nov 2005 05:18:41 +0000 http://blogs.discovermagazine.com/cosmicvariance/2005/11/14/gravity-to-the-rescue/#comment-6822 this is interesting like MMH he is the coolest. but that would never work cause you dont have enough time to send the spaceship know what i mean, know what i mean?? JOKE TIME: what is a cheerios worst nightmare?? a serial killer hahaha get it? like a cereal killer or someone who smashes them cheerios dam you cheerio smaher!! i love you mom! this is interesting like MMH he is the coolest.

but that would never work cause you dont have enough time to send the spaceship know what i mean, know what i mean??

JOKE TIME:
what is a cheerios worst nightmare??

a serial killer

hahaha get it? like a cereal killer or someone who smashes them cheerios

dam you cheerio smaher!!

i love you mom!

]]> By: Alex R http://blogs.discovermagazine.com/cosmicvariance/2005/11/14/gravity-to-the-rescue/comment-page-1/#comment-6821 Alex R Thu, 17 Nov 2005 05:18:02 +0000 http://blogs.discovermagazine.com/cosmicvariance/2005/11/14/gravity-to-the-rescue/#comment-6821 The statement about it working for asteroids of a certain size is straightforward: "Parking" the ship near the asteroid requires thrust to keep the ship from falling into or orbiting the asteroid. The more massive the asteroid, the larger the thrust required... The statement about it working for asteroids of a certain size is straightforward: “Parking” the ship near the asteroid requires thrust to keep the ship from falling into or orbiting the asteroid. The more massive the asteroid, the larger the thrust required…

]]> By: bittergradstudent http://blogs.discovermagazine.com/cosmicvariance/2005/11/14/gravity-to-the-rescue/comment-page-1/#comment-6820 bittergradstudent Tue, 15 Nov 2005 15:13:52 +0000 http://blogs.discovermagazine.com/cosmicvariance/2005/11/14/gravity-to-the-rescue/#comment-6820 Yeah, PB, I was thinking about that, too... in essence, the problem is exactly the same as it would be if you tethered the asteroid to to the spaceship, and had the latter fire it's thrusters. It's just that here, you have the tether provided by gravity. Yeah, PB, I was thinking about that, too… in essence, the problem is exactly the same as it would be if you tethered the asteroid to to the spaceship, and had the latter fire it’s thrusters. It’s just that here, you have the tether provided by gravity.

]]> By: Elliot http://blogs.discovermagazine.com/cosmicvariance/2005/11/14/gravity-to-the-rescue/comment-page-1/#comment-6819 Elliot Tue, 15 Nov 2005 04:08:49 +0000 http://blogs.discovermagazine.com/cosmicvariance/2005/11/14/gravity-to-the-rescue/#comment-6819 I'm sure Pat Robertson wouldn't let an asteroid hit earth. Having Pat take care of it would be at least as effective as the inflation powered space vehicle. I’m sure Pat Robertson wouldn’t let an asteroid hit earth. Having Pat take care of it would be at least as effective as the inflation powered space vehicle.

]]> By: PB http://blogs.discovermagazine.com/cosmicvariance/2005/11/14/gravity-to-the-rescue/comment-page-1/#comment-6818 PB Tue, 15 Nov 2005 03:32:58 +0000 http://blogs.discovermagazine.com/cosmicvariance/2005/11/14/gravity-to-the-rescue/#comment-6818 If I may point something out: the spacecraft must exert a force on the asteroid, which will equal the force of the asteroid on the spacecraft. Unless the mass of the spacecraft is on the same order as the mass of the asteroid, then the spacecraft will simply be drawn into the asteroid without appreciably changing its path (unless it uses rocket fuel to keeps its distance). That being said, if the asteroid <em>is</em> roughly the same size as the spacecraft, then there's no point in using gavitational effects---it would be at least as effective just to push the asteroid out of the way. If I may point something out: the spacecraft must exert a force on the asteroid, which will equal the force of the asteroid on the spacecraft. Unless the mass of the spacecraft is on the same order as the mass of the asteroid, then the spacecraft will simply be drawn into the asteroid without appreciably changing its path (unless it uses rocket fuel to keeps its distance).

That being said, if the asteroid is roughly the same size as the spacecraft, then there’s no point in using gavitational effects—it would be at least as effective just to push the asteroid out of the way.

]]> By: Brad Holden http://blogs.discovermagazine.com/cosmicvariance/2005/11/14/gravity-to-the-rescue/comment-page-1/#comment-6817 Brad Holden Mon, 14 Nov 2005 22:49:08 +0000 http://blogs.discovermagazine.com/cosmicvariance/2005/11/14/gravity-to-the-rescue/#comment-6817 You can read about the gravity tractor in an article that appeared in Nature and on astro-ph/0509595. The gravitational acceleration that the authors calculate for a canonical space rock is tiny, and assumes a 20 ton spacecraft. The authors expect 20 or more years to move the rock any reasonable distance. My favorite solution so far has been to dump a bunch of silver paint on the rock and let the sun do the work. You can read about the gravity tractor in an article that appeared in Nature and on astro-ph/0509595. The gravitational acceleration that the authors calculate for a canonical space rock is tiny, and assumes a 20 ton spacecraft. The authors expect 20 or more years to move the rock any reasonable distance.

My favorite solution so far has been to dump a bunch of silver paint on the rock and let the sun do the work.

]]> By: plato http://blogs.discovermagazine.com/cosmicvariance/2005/11/14/gravity-to-the-rescue/comment-page-1/#comment-6816 plato Mon, 14 Nov 2005 22:27:39 +0000 http://blogs.discovermagazine.com/cosmicvariance/2005/11/14/gravity-to-the-rescue/#comment-6816 Elliot, <blockquote>Let me remind you: Alan Sokal from NYU became famous because he was able to submit a paper on "Hermeneutics of Quantum Gravity" to a renowned journal called "Social Text" and published by the postmodern social science experts at Duke University. The paper was a continuous flow of nonsense: for example it argued that the value of PI changes with the amount of political pressure and discrimination.</blockquote> http://motls.blogspot.com/2005/06/bogdanoff-papers.html I gave some light on this issue. But more importantly I have to agree with you, about what you are saying, even if Lubos thinks it was the right thing to do by Sokal. The travesty here was how new the era of quantum gravity is, and the decisive attempt to highlight how easily people can be fooled. If with good conscience you knew what you were doing to disrupt the publics views and encourage the failibilty of good science minds in the bunch, then the history, has been sourly infected. Why? Because good scientists were folded up into the bunch. The public mislead. This directed behaviors, around the issues of quantum gravity. Some would even quote Sokal article as to the reasons why "quantum gravity" was a failure? Da:) So now you know why honesty is important. Why "sokalitis," is not avery good thing? So I place it along side of the infamous remarks on stringevangelism. It filters, to the public. Some science tabloids take hold of it. See? Elliot,

Let me remind you: Alan Sokal from NYU became famous because he was able to submit a paper on “Hermeneutics of Quantum Gravity” to a renowned journal called “Social Text” and published by the postmodern social science experts at Duke University. The paper was a continuous flow of nonsense: for example it argued that the value of PI changes with the amount of political pressure and discrimination.

http://motls.blogspot.com/2005/06/bogdanoff-papers.html

I gave some light on this issue. But more importantly I have to agree with you, about what you are saying, even if Lubos thinks it was the right thing to do by Sokal.

The travesty here was how new the era of quantum gravity is, and the decisive attempt to highlight how easily people can be fooled.

If with good conscience you knew what you were doing to disrupt the publics views and encourage the failibilty of good science minds in the bunch, then the history, has been sourly infected.

Why? Because good scientists were folded up into the bunch. The public mislead. This directed behaviors, around the issues of quantum gravity. Some would even quote Sokal article as to the reasons why “quantum gravity” was a failure? Da:)

So now you know why honesty is important. Why “sokalitis,” is not avery good thing? So I place it along side of the infamous remarks on stringevangelism. It filters, to the public. Some science tabloids take hold of it. See?

]]> By: Count Iblis http://blogs.discovermagazine.com/cosmicvariance/2005/11/14/gravity-to-the-rescue/comment-page-1/#comment-6815 Count Iblis Mon, 14 Nov 2005 18:35:40 +0000 http://blogs.discovermagazine.com/cosmicvariance/2005/11/14/gravity-to-the-rescue/#comment-6815 Some time ago I read somewhere that one could neutralize threat posed by supervolcanoes by crashing a kilometer sized asteroid into it, thereby triggering the eruption of the supervolcano. By storing food to feed the world's population and evacuating people who live in the neighborhood you could neutralize the danger posed by the eruption. Some time ago I read somewhere that one could neutralize threat posed by supervolcanoes by crashing a kilometer sized asteroid into it, thereby triggering the eruption of the supervolcano. By storing food to feed the world’s population and evacuating people who live in the neighborhood you could neutralize the danger posed by the eruption.

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