{"id":9305,"date":"2005-11-14T11:19:32","date_gmt":"2005-11-14T16:19:32","guid":{"rendered":"http:\/\/blogs.discovermagazine.com\/cosmicvariance\/2005\/11\/14\/gravity-to-the-rescue\/"},"modified":"2005-11-14T11:19:32","modified_gmt":"2005-11-14T16:19:32","slug":"gravity-to-the-rescue","status":"publish","type":"post","link":"https:\/\/preposterousuniverse.com\/blog\/2005\/11\/14\/gravity-to-the-rescue\/","title":{"rendered":"Gravity to the rescue"},"content":{"rendered":"

Apparently nuclear bombs and Bruce Willis are two things that are just too hard to control. So if a massive asteroid appears to be on a collision course with Earth, a couple of astronauts have invented a new way to save us from this cosmic menace: a gravity tractor<\/a>.<\/p>\n

gravity tractor<\/a> It’s a simple enough idea: instead of blowing up the asteroid, just use gravity to gently deflect it from its path. If you have plenty of warning, you can send up a spaceship that is as heavy as you can manage, and simply park it next to the asteroid. The gravitational pull of the ship will gradually tug the asteroid off course; a tiny force, indeed, but if you let it accumulate for a few years you might be able to do the job.<\/p>\n

I confess to a certain amount of skepticism. The gravitational field of such a ship will be incredibly tiny, and even if you plug in the numbers and it seems to work, I would worry that other trace effects (e.g. outgassing or radiation from the ship) won’t be equally important and work in the opposite direction. And when I heard a report about the idea on NPR, there was a curious statement from one of the idea’s supporters, that it would work well for asteroids of such-and-such a mass. Where I was taught about gravity, the acceleration is independent of the mass, so that was a little confusing. It may be that the size<\/em> of the thing is important — if the asteroid center of mass is too far away from the tractor, you’re in trouble, since gravity falls of as 1\/r<\/em>2<\/sup>.<\/p>\n

But it’s certainly a more sensible idea than the one mentioned by John in an earlier comment<\/a>, and again at the bottom of the gravity-tractor article: a space vehicle propelled by the pressure of the inflationary vacuum state<\/a>, recently granted U.S. patent 6,960,975. That’s just completely crazy.<\/p>\n","protected":false},"excerpt":{"rendered":"

Apparently nuclear bombs and Bruce Willis are two things that are just too hard to control. So if a massive asteroid appears to be on a collision course with Earth, a couple of astronauts have invented a new way to save us from this cosmic menace: a gravity tractor. It’s a simple enough idea: instead […]<\/p>\n","protected":false},"author":4,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[28],"tags":[],"class_list":["post-9305","post","type-post","status-publish","format-standard","hentry","category-science"],"jetpack_featured_media_url":"","_links":{"self":[{"href":"https:\/\/preposterousuniverse.com\/blog\/wp-json\/wp\/v2\/posts\/9305","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/preposterousuniverse.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/preposterousuniverse.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/preposterousuniverse.com\/blog\/wp-json\/wp\/v2\/users\/4"}],"replies":[{"embeddable":true,"href":"https:\/\/preposterousuniverse.com\/blog\/wp-json\/wp\/v2\/comments?post=9305"}],"version-history":[{"count":0,"href":"https:\/\/preposterousuniverse.com\/blog\/wp-json\/wp\/v2\/posts\/9305\/revisions"}],"wp:attachment":[{"href":"https:\/\/preposterousuniverse.com\/blog\/wp-json\/wp\/v2\/media?parent=9305"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/preposterousuniverse.com\/blog\/wp-json\/wp\/v2\/categories?post=9305"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/preposterousuniverse.com\/blog\/wp-json\/wp\/v2\/tags?post=9305"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}