1
$\begingroup$

I once read an article about proposed project to move a NEO (near earth object) using a small satellite that would land on its surface and drill out small pieces of the object, slinging it out into space. This force would "eventually" alter its orbit (trajectory). Is there any possibility that this could happen to Earth, as we continue to launch rockets out into space?

$\endgroup$
  • 3
    $\begingroup$ Possible duplicate of How would we move Venus or Mars into Earth's orbital zone? $\endgroup$ – kim holder Nov 29 '15 at 22:56
  • 2
    $\begingroup$ There are a number of questions on the site that deal with misconceptions due to not having a sense of the scale involved. The one that I think comes closest to your question is here. I believe there are a couple more but I haven't found them. Rockets are teeny weeny bitty things compared to the Earth. Also, the ones that are launched in the direction of the Earth's orbit counterbalance the one's launched opposite the direction its going, if you want more comfort. $\endgroup$ – kim holder Nov 29 '15 at 23:11
  • 1
    $\begingroup$ For an answer that is more precisely what is asked here, look at Is Earth's orbit altered by recoil from take-off/launch/recovery of aero/space vehicles?. $\endgroup$ – kim holder Nov 29 '15 at 23:57
  • $\begingroup$ Never mind between 40,000 tons gained with space dust and 90,000 tons lost to escaping hydrogen and helium per year, the couple hundred tons from rockets hardly play any role (and with Baikonur and Cape Canaveral being on opposite sides of the globe that pretty much balances out anyway ;) $\endgroup$ – SF. Nov 30 '15 at 6:54
3
$\begingroup$

In principle, yes, but practically, no. For one thing, a NEO is much smaller than Earth, so the amount of effort required to slingshot the necessary mass is within reason (whereas the relative amount of mass of rockets being launched from Earth is infinitesimal).

This is also assuming that rockets are "slung" into space, but they aren't. The majority of a rocket's thrust is due to the exchange of momentum between the rocket and the exhaust -- not reactions between the rocket and the Earth (although you could say there is some due to atmospheric effects).

Finally, even if you were slinging mass from the Earth (or if the reaction forces from conventional rockets were significant enough), you would have to make sure each launch is timed correctly so that momentum is exchanged in the same direction -- otherwise the launches will generally cancel out.

$\endgroup$
  • 4
    $\begingroup$ Most of the mass of launch vehicles also ends up either back on Earth or in orbit, so with that little mass we managed to fling out of Earth's gravitational grip, we're not really thrusting the planet anywhere. We're merely rearranging a minute portion of its mass to be a bit more feng shui. :) $\endgroup$ – TildalWave Nov 29 '15 at 23:26
  • $\begingroup$ Yes, good point, with gravity acting like an elastic band. $\endgroup$ – Brian Lynch Nov 29 '15 at 23:27

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.