6 ms·

what sort of delta V would a probe need to shadow it? Perhaps a Jupiter, solar transfer orbit could help...

deleted 8y ago
[deleted]
ahje 8y ago
From what I can tell from the animation in the article, it shouldn't be that far out. I'm not an astronomer or anything, but from my point of view, it would be quite interesting to find out more about that asteroid's composition etc.
- TeMPOraL 8y ago
  It's not about how far out they are, but how fast they are going relative to Earth. When you're trying to get to something in space, you need to roughly match both positions and velocities between you and your target.
  - Cthulhu_ 8y ago
    I did a quick googling, the earth's orbital speed is 29.78 km/second, so you'd need to cancel that out first, then speed up again to match the speed of the asteroid. For comparison, you need 9.4 km/s of delta-V to bring something in low earth object (7.8 km/s for orbit, plus 1.3-1.8 km/s for atmospheric and gravity drag). To put something in counter-rotating low earth orbit, you probably also need to add the rotation speed of the earth (at the location of launch), but, I don't know the figures there (not a three second googling away). So uh, yes. Needs a rocket with at least four times as much delta-V as what we currently use to put something in orbit. I'm reading the New Horizons project, which up until now was the fastest thing to leave Earth, was shooting away from us at 16.26 km/s - all from chemical thrust. The Voyager 1 is still going a bit faster thanks to gravity assists.
sathackr 8y ago
Probably a bunch. I'm not a rocket scientist, but Google tells me Jupiter's orbital velocity is about 13,000 m/s, with Earth's velocity being about 30,000 m/s. If my KSP-taught understanding of orbital mechanics is correct, you'd first have escape earth's gravity(~13,000m/s), then reverse your orbital velocity(about 60,000m/s, also matching the orbital plane of the asteroid in the process), and then do a standard hohmann transfer to the asteroid orbit(looks like about another 5,000m/s) just to get to the asteroid, but then you have to cancel the closing speed. I don't know enough to know how to calculate the approach velocity but looks like it might be a bunch. Chart showing d/v required to reach various objects in our solar system: https://i.imgur.com/WGOy3qT.png https://i.imgur.com/WGOy3qT.png
- pavel_lishin 8y ago
  I'd love to see Scott Manley do a video on what would be required. I guess I could do it myself, I'd just need to install the solar system mod...
  - sathackr 8y ago
    I bet he will. I have RSS installed, but not far enough into the tech tree for ions yet, which is about the only way I could imagine it being remotely possible. May be able to shave a few thousand DV off with some well-timed gravity assists.
    - pavel_lishin 8y ago
      Yeah, I'm nowhere near good enough at the game - I've never even landed on another planet. I absolutely don't know how to set up gravity assists.
Sir_Cmpwn 8y ago
It's orbiting the wrong way around, so you need to lose all of your orbital momentum and add it all back again. This is an extremely expensive maneuver to do in the inner solar system (i.e. from an Earth launch). The easiest way to do this is to achieve near escape velocity and adjust your orbit on the cheap at the edge of the solar system, but now you're talking about a mission which would span several decades.
- mrfusion 8y ago
  Nah. Just do a slingshot around Jupiter to turn Around.
  - Sir_Cmpwn 8y ago
    Not sure if your comment is sarcastic, but I'll humor it. Jupiter is orbiting the sun at 13 km/s (very fast). If you slingshot around it, you can definitely be moving away from it at a decent clip. However, you'll still be going around the sun at a pace near 13 km/s (very fast). You still have to lose all of that orbital velocity before you can even think about going in the other direction. And even if you reduce your orbital velocity to zero, now you're just going to fall into the sun. You need to add the bulk of what you just lost back into your orbital energy, but going the other direction. All of this has to be precicely manuvered to put you in an orbit to meet up with the probe. On top of all of that, you still have to climb out of Earth's gravity well and spend a lot of fuel getting to Jupiter. Also, once you start going the other direction, gravity assists become much more difficult to do with anything spinning normally. Inversely, if you don't turn around, you'll just wiz by the object when you meet up with it and have hardly any time for science.
- gene-h 8y ago
  Maybe we can take advantage of the fact it's orbiting the wrong way. Perhaps we can send an impactor and capture some of the ejecta. At the very least we can analyze the spectra of the impact flash to see what it's made of. Perhaps we can even fly through the ejecta plume and run it into a mass spectrometer to do isotopic analysis. If the time between the impactor and the probe is short enough, perhaps the ejecta will still be plasma which we can run straight through our mass spectrometer. It might even be possible to capture a small amount of ejecta if we use something like an aerogel particle collector like the Stardust mission used[0]. [0]https://www.nasa.gov/mission_pages/stardust/mission/index-aerogel-rd.html https://www.nasa.gov/mission_pages/stardust/mission/index-ae...

deleted 8y ago

[deleted]

ahje 8y ago

From what I can tell from the animation in the article, it shouldn't be that far out. I'm not an astronomer or anything, but from my point of view, it would be quite interesting to find out more about that asteroid's composition etc.

TeMPOraL 8y ago
It's not about how far out they are, but how fast they are going relative to Earth. When you're trying to get to something in space, you need to roughly match both positions and velocities between you and your target.
- Cthulhu_ 8y ago
  I did a quick googling, the earth's orbital speed is 29.78 km/second, so you'd need to cancel that out first, then speed up again to match the speed of the asteroid. For comparison, you need 9.4 km/s of delta-V to bring something in low earth object (7.8 km/s for orbit, plus 1.3-1.8 km/s for atmospheric and gravity drag). To put something in counter-rotating low earth orbit, you probably also need to add the rotation speed of the earth (at the location of launch), but, I don't know the figures there (not a three second googling away). So uh, yes. Needs a rocket with at least four times as much delta-V as what we currently use to put something in orbit. I'm reading the New Horizons project, which up until now was the fastest thing to leave Earth, was shooting away from us at 16.26 km/s - all from chemical thrust. The Voyager 1 is still going a bit faster thanks to gravity assists.

sathackr 8y ago

Probably a bunch. I'm not a rocket scientist, but Google tells me Jupiter's orbital velocity is about 13,000 m/s, with Earth's velocity being about 30,000 m/s. If my KSP-taught understanding of orbital mechanics is correct, you'd first have escape earth's gravity(~13,000m/s), then reverse your orbital velocity(about 60,000m/s, also matching the orbital plane of the asteroid in the process), and then do a standard hohmann transfer to the asteroid orbit(looks like about another 5,000m/s) just to get to the asteroid, but then you have to cancel the closing speed. I don't know enough to know how to calculate the approach velocity but looks like it might be a bunch. Chart showing d/v required to reach various objects in our solar system: https://i.imgur.com/WGOy3qT.png https://i.imgur.com/WGOy3qT.png

pavel_lishin 8y ago
I'd love to see Scott Manley do a video on what would be required. I guess I could do it myself, I'd just need to install the solar system mod...
- sathackr 8y ago
  I bet he will. I have RSS installed, but not far enough into the tech tree for ions yet, which is about the only way I could imagine it being remotely possible. May be able to shave a few thousand DV off with some well-timed gravity assists.
  - pavel_lishin 8y ago
    Yeah, I'm nowhere near good enough at the game - I've never even landed on another planet. I absolutely don't know how to set up gravity assists.

Sir_Cmpwn 8y ago

It's orbiting the wrong way around, so you need to lose all of your orbital momentum and add it all back again. This is an extremely expensive maneuver to do in the inner solar system (i.e. from an Earth launch). The easiest way to do this is to achieve near escape velocity and adjust your orbit on the cheap at the edge of the solar system, but now you're talking about a mission which would span several decades.

mrfusion 8y ago
Nah. Just do a slingshot around Jupiter to turn Around.
- Sir_Cmpwn 8y ago
  Not sure if your comment is sarcastic, but I'll humor it. Jupiter is orbiting the sun at 13 km/s (very fast). If you slingshot around it, you can definitely be moving away from it at a decent clip. However, you'll still be going around the sun at a pace near 13 km/s (very fast). You still have to lose all of that orbital velocity before you can even think about going in the other direction. And even if you reduce your orbital velocity to zero, now you're just going to fall into the sun. You need to add the bulk of what you just lost back into your orbital energy, but going the other direction. All of this has to be precicely manuvered to put you in an orbit to meet up with the probe. On top of all of that, you still have to climb out of Earth's gravity well and spend a lot of fuel getting to Jupiter. Also, once you start going the other direction, gravity assists become much more difficult to do with anything spinning normally. Inversely, if you don't turn around, you'll just wiz by the object when you meet up with it and have hardly any time for science.
gene-h 8y ago
Maybe we can take advantage of the fact it's orbiting the wrong way. Perhaps we can send an impactor and capture some of the ejecta. At the very least we can analyze the spectra of the impact flash to see what it's made of. Perhaps we can even fly through the ejecta plume and run it into a mass spectrometer to do isotopic analysis. If the time between the impactor and the probe is short enough, perhaps the ejecta will still be plasma which we can run straight through our mass spectrometer. It might even be possible to capture a small amount of ejecta if we use something like an aerogel particle collector like the Stardust mission used[0]. [0]https://www.nasa.gov/mission_pages/stardust/mission/index-aerogel-rd.html https://www.nasa.gov/mission_pages/stardust/mission/index-ae...