5 ms·
Can we capture it?
by hd95489 4y ago
Can we capture it?
- esotericimpl 4y ago[dead]
- accrual 4y agoFrom a purely technical perspective: maybe. We'd need to know how similar the object's orbit is relative to Earth's. If the orbit is roughly coplanar and concentric with Earth, it will cost less change in velocity (delta-V) to reduce the differences and bring it into a stable orbit. The more different it is (e.g. if it swings all the up to Jupiter and back), the more it will cost. Once you know how much dV is required to capture, we'd next need to put that much dV at the object, which would be even more costly to launch. Lastly, depending on the object's composition it may not be possible to even apply much dV to it. If it's a essentially a coalesced pile of rubble, any force applied will just break it into pieces. If it's roughly solid, then maybe. Fun fact: Earth has had more than one "moon" in the past, they just tend to not last long before they're kicked out of orbit. [0] [0] https://en.wikipedia.org/wiki/2006_RH120 https://en.wikipedia.org/wiki/2006_RH120
- hd95489 4y agoEven if we break it up and capture a chunk it would be both a huge wealth of knowledge and if the chunks was big enough it could be extremely useful construct material
- eesmith 4y agoI don't think you have an idea of the delta-V issue. https://cneos.jpl.nasa.gov/sentry/details.html#?des=2023%20DW https://cneos.jpl.nasa.gov/sentry/details.html#?des=2023%20D... says its speed will be roughly 11 km/s (were Earth not present) and an impact velocity of 15km/s (were Earth in the way; Earth's gravity speeds things up). If we do that with rocket power, and not some complicated gravity-assist path, then we can look at New Horizons. That used an Atlas V rocket at around 570 tons to get the 478 kg payload up to 16 km/s. That's a 1:1000 mass ratio. Once you've caught up, you've got to turn things around and slow down. But you're talking about another 1:1000 or more mass ratio, leaving you with a few grams of material. This is all hand-waving to give a rough idea of the problem. We've had a few asteroid sample-return mission. Hayabusa2 returned a few grams of material from 162173 Ryugu. The hope is that OSIRIS-REx will return 60 grams from 101955 Bennu this fall. These used ion thrusters (more efficient than chemical rockets) and atmospheric braking to help slow down. Still, none of this is anywhere near being useful as construction material. It would be far cheaper to bring it up from Earth.
- hd95489 4y agoI was thinking gravity and atmospheric assists to get delta v required. You have to do something complex to pull this off. Or blow off a small piece to deflect the main bit and capture a small artifact
- eesmith 4y agoYes, that's what the current asteroid return missions already do, just to return tens of grams of material. That's not enough to use as building materials.
- seer 4y agoFunny, this feels like the plot from Don’t look up. On the less humorous side it would probably be pretty hard to impart enough delta-v to capture it.
- mabbo 4y agoThere's probably better candidates. For any two objects in orbits around a common body (like the sun) to match their orbits, they need to have their locations match and their velocity, at the same time. To collide, you only need your location to match. One way to do this is to get to a matching location and then do a hard change of velocity so that the asteroid is now in a stable orbit. But that's a lot of energy for a rock with a mess measured using scientific notation. There are better candidates out there where we could make a tiny change to their orbit and have them be captured naturally due to relative velocities being much closer to matching. Still a lot of energy, but a lot less.
- hd95489 4y agoI’m assuming it’s too risky to let them clip the atmosphere to provide the delta v?