5 ms·

Is there any simulation for projecting the path of the Roadster over its life? Kerbal Space Program? Is it going to orbit the Sun? I'm curious to know what hap

Is there any simulation for projecting the path of the Roadster over its life? Kerbal Space Program? Is it going to orbit the Sun? I'm curious to know what happens on its orbit over time. Could it collide somewhere down the line? Perhaps SpaceX just launched the first man made Planet? EDIT: Would love to hear the downvoter's reasons.

TeMPOraL 9y ago
> Is there any simulation for projecting the path of the Roadster over its life? Not public, no. > Is it going to orbit the Sun? Yes. > Could it collide somewhere down the line? Yes, but unlikely in the next couple million years. > Perhaps SpaceX just launched the first man made Planet? A planet has a definition involving size and shape, which the Roadster does not fit.
- manaskarekar 9y ago
  > Yes, but unlikely in the next couple million years. So, the reason I asked was because of not having a source. Did this come from SpaceX or someone authoritative who has done the math? > A planet has a definition involving size and shape, which the Roadster does not fit. That was a bit tongue-in-cheek, but I know, correctness > humor.
  - TeMPOraL 9y ago
    > So, the reason I asked was because of not having a source. Did this come from SpaceX or someone authoritative who has done the math? SpaceX said that wrt. their original projected trajectory of a Mars Transfer Orbit. Since right now we're talking about something more like Ceres Transfer Orbit, the projection can change (and, as per article, astronomers are asking Elon for details to calculate it), but keep in mind one thing: space is big and empty. The chance of it hitting anything on short timescales are close to 0.
    - manaskarekar 9y ago
      > SpaceX said that wrt. their original projected trajectory of a Mars Transfer Orbit. Since right now we're talking about something more like Ceres Transfer Orbit, the projection can change (and, as per article, astronomers are asking Elon for details to calculate it), but keep in mind one thing: space is big and empty. The chance of it hitting anything on short timescales are close to 0. But one of the reasons I asked was not because I was worried about whether it would hit something on a short timescale (even though there is a non-zero chance it could happen). I'm aware of the vastness of space. I was curious about what happens over 10, 10^3, 10^9, 10^12, 10^100 orbits later.
      - TeMPOraL 9y ago
        The answer is: over 10 orbits - no. Over 10^3 orbits - no. Over 10^9 and more - nobody really cares. By that time the Sun will be halfway to going cold.
        manaskarekar 9y ago
        Your answers seem to be about whether or not there will be a collision at those time points. My curiosity is about visualizing the orbit over time (which includes a non-zero possibility of collision). P.S. I doubt you would disagree that speculating about where the Roadster will be when the Sun will be getting colder is fun, and not 'nobody really cares.' Of course, such simulators are hard and expensive and mostly approximations, but doesn't hurt to ask about what options are out there.
        rtkwe 9y ago
        On time scales that large the exact orbit is unpredictable, see the Pioneer Anomaly [0] where the RTGs heat radiating away provides a tiny but non zero deceleration, over huge time spans even tiny forces add up. On top of that it's going to be slightly perturbed by Earth, Mars, and Jupiter in ways that can only really be modeled not solved explicitly.
        Thasc 9y ago
  - deleted 9y ago
    [deleted]
  - 282883392 9y ago
    The chance of anything colliding in space is very, very low. The Tesla will most likely be orbiting until the sun dies, or someone picks it up.
- jacquesm 9y ago
  It would be rather ironic if Elon's personal Mars lander got into a collision with his roadster. Hope he took out liability insurance on the roadster ;)
  - TeMPOraL 9y ago
    Haha :). Well, if the recent progress in the space sector continues, I'm confident that in the next few decades someone will make a mission to rendezvous with the Roadster, just for the kicks.
  - PeterisP 9y ago
    The liability insurance won't apply since it's breaking the speed limit - the launch video alone showed speed in excess of 10000 km/h.
    - jacquesm 9y ago
      The Australian police issued a speeding ticket!
alex_young 9y ago
Musk tweeted an orbital projection: https://twitter.com/elonmusk/status/961083704230674438?s=09 https://twitter.com/elonmusk/status/961083704230674438?s=09
- manaskarekar 9y ago
  I saw that, but that doesn't tell me what will happen 10^3 or 10^9 orbits later. Or does it? Not trying to be snarky, genuinely curious.
orbital-decay 9y ago
> Is there any simulation for projecting the path of the Roadster over its life? Kerbal Space Program? KSP has a very simplified model, and doesn't even offer full n-body simulation. You can try GMAT [1] as a general purpose orbital dynamics tool; it's fun to play with. There's also plenty of Python libraries for gravitational dynamics available, pykep being an example. Of course, you'll have to know the precise Roadster orbit parameters, and this is a problem. [1] https://sourceforge.net/projects/gmat/ https://sourceforge.net/projects/gmat/
- manaskarekar 9y ago
  Thank you for sharing this. I was hoping for info about stuff like this.
snowwrestler 9y ago
The only way to project the path of an object in the solar system is to computationally model the solar system and then run the simulation forward. Obviously space programs like NASA and ESA have such models; that's how they get space probes like New Horizons or Rosetta to their destinations. Interestingly, I've read that these simulations use Newtonian physics, not general relativity, to model the solar system. At interplanetary speeds, the error between the two is just too small to matter. So if you want to project the orbit for the "lifetime" of the Roadster, you'd have to just run the simulation forward until it finds a collision or the sun burns out. This would take a lot of energy and time... it would not be worth it. The main reason is that interplanetary space is very empty in general, so without running any simulation we can guesstimate that an accidental collision is very unlikely. Also, probably no one really cares if the Roadster hits an asteroid 513 million years from now. Finally, a physical model simulating that many objects is chaotic--even eensy weeny teeny tiny little errors will compound over time and produce a divergence from reality. I doubt anyone has characterized this drift beyond the horizon needed to plan missions--a few decades at most. So even if you ran the model forward for 513 million model years, there might be no way to constrain the accuracy of the final predicted location of the Roadster. Heck, maybe the difference between Newton and GR would matter at these time scales.
- rtkwe 9y ago
  There's also just forces that will be hard to characterize in a model, eg thermal recoil where the heat radiating off an object produces a tiny acceleration in the opposite direction. The roadster has black panels that will heat up more than the rest of the body work. Then there's other tiny forces like the solar wind. All tiny but over huge time spans their influence keeps widening the error bounds on the simulation.
  - orbital-decay 9y ago
    These uncertainties can be taken into account though, since there's an upper limit or an estimate for any of these forces. See also: https://en.wikipedia.org/wiki/Lyapunov_time https://en.wikipedia.org/wiki/Lyapunov_time

TeMPOraL 9y ago

> Is there any simulation for projecting the path of the Roadster over its life? Not public, no. > Is it going to orbit the Sun? Yes. > Could it collide somewhere down the line? Yes, but unlikely in the next couple million years. > Perhaps SpaceX just launched the first man made Planet? A planet has a definition involving size and shape, which the Roadster does not fit.

manaskarekar 9y ago
> Yes, but unlikely in the next couple million years. So, the reason I asked was because of not having a source. Did this come from SpaceX or someone authoritative who has done the math? > A planet has a definition involving size and shape, which the Roadster does not fit. That was a bit tongue-in-cheek, but I know, correctness > humor.
- TeMPOraL 9y ago
  > So, the reason I asked was because of not having a source. Did this come from SpaceX or someone authoritative who has done the math? SpaceX said that wrt. their original projected trajectory of a Mars Transfer Orbit. Since right now we're talking about something more like Ceres Transfer Orbit, the projection can change (and, as per article, astronomers are asking Elon for details to calculate it), but keep in mind one thing: space is big and empty. The chance of it hitting anything on short timescales are close to 0.
  - manaskarekar 9y ago
    > SpaceX said that wrt. their original projected trajectory of a Mars Transfer Orbit. Since right now we're talking about something more like Ceres Transfer Orbit, the projection can change (and, as per article, astronomers are asking Elon for details to calculate it), but keep in mind one thing: space is big and empty. The chance of it hitting anything on short timescales are close to 0. But one of the reasons I asked was not because I was worried about whether it would hit something on a short timescale (even though there is a non-zero chance it could happen). I'm aware of the vastness of space. I was curious about what happens over 10, 10^3, 10^9, 10^12, 10^100 orbits later.
    - TeMPOraL 9y ago
      The answer is: over 10 orbits - no. Over 10^3 orbits - no. Over 10^9 and more - nobody really cares. By that time the Sun will be halfway to going cold.
      - manaskarekar 9y ago
        Your answers seem to be about whether or not there will be a collision at those time points. My curiosity is about visualizing the orbit over time (which includes a non-zero possibility of collision). P.S. I doubt you would disagree that speculating about where the Roadster will be when the Sun will be getting colder is fun, and not 'nobody really cares.' Of course, such simulators are hard and expensive and mostly approximations, but doesn't hurt to ask about what options are out there.
        rtkwe 9y ago
        On time scales that large the exact orbit is unpredictable, see the Pioneer Anomaly [0] where the RTGs heat radiating away provides a tiny but non zero deceleration, over huge time spans even tiny forces add up. On top of that it's going to be slightly perturbed by Earth, Mars, and Jupiter in ways that can only really be modeled not solved explicitly.
      - Thasc 9y ago
- deleted 9y ago
  [deleted]
- 282883392 9y ago
  The chance of anything colliding in space is very, very low. The Tesla will most likely be orbiting until the sun dies, or someone picks it up.
jacquesm 9y ago
It would be rather ironic if Elon's personal Mars lander got into a collision with his roadster. Hope he took out liability insurance on the roadster ;)
- TeMPOraL 9y ago
  Haha :). Well, if the recent progress in the space sector continues, I'm confident that in the next few decades someone will make a mission to rendezvous with the Roadster, just for the kicks.
- PeterisP 9y ago
  The liability insurance won't apply since it's breaking the speed limit - the launch video alone showed speed in excess of 10000 km/h.
  - jacquesm 9y ago
    The Australian police issued a speeding ticket!

alex_young 9y ago

Musk tweeted an orbital projection: https://twitter.com/elonmusk/status/961083704230674438?s=09 https://twitter.com/elonmusk/status/961083704230674438?s=09

manaskarekar 9y ago
I saw that, but that doesn't tell me what will happen 10^3 or 10^9 orbits later. Or does it? Not trying to be snarky, genuinely curious.

orbital-decay 9y ago

> Is there any simulation for projecting the path of the Roadster over its life? Kerbal Space Program? KSP has a very simplified model, and doesn't even offer full n-body simulation. You can try GMAT [1] as a general purpose orbital dynamics tool; it's fun to play with. There's also plenty of Python libraries for gravitational dynamics available, pykep being an example. Of course, you'll have to know the precise Roadster orbit parameters, and this is a problem. [1] https://sourceforge.net/projects/gmat/ https://sourceforge.net/projects/gmat/

manaskarekar 9y ago
Thank you for sharing this. I was hoping for info about stuff like this.

snowwrestler 9y ago

The only way to project the path of an object in the solar system is to computationally model the solar system and then run the simulation forward. Obviously space programs like NASA and ESA have such models; that's how they get space probes like New Horizons or Rosetta to their destinations. Interestingly, I've read that these simulations use Newtonian physics, not general relativity, to model the solar system. At interplanetary speeds, the error between the two is just too small to matter. So if you want to project the orbit for the "lifetime" of the Roadster, you'd have to just run the simulation forward until it finds a collision or the sun burns out. This would take a lot of energy and time... it would not be worth it. The main reason is that interplanetary space is very empty in general, so without running any simulation we can guesstimate that an accidental collision is very unlikely. Also, probably no one really cares if the Roadster hits an asteroid 513 million years from now. Finally, a physical model simulating that many objects is chaotic--even eensy weeny teeny tiny little errors will compound over time and produce a divergence from reality. I doubt anyone has characterized this drift beyond the horizon needed to plan missions--a few decades at most. So even if you ran the model forward for 513 million model years, there might be no way to constrain the accuracy of the final predicted location of the Roadster. Heck, maybe the difference between Newton and GR would matter at these time scales.

rtkwe 9y ago
There's also just forces that will be hard to characterize in a model, eg thermal recoil where the heat radiating off an object produces a tiny acceleration in the opposite direction. The roadster has black panels that will heat up more than the rest of the body work. Then there's other tiny forces like the solar wind. All tiny but over huge time spans their influence keeps widening the error bounds on the simulation.
- orbital-decay 9y ago
  These uncertainties can be taken into account though, since there's an upper limit or an estimate for any of these forces. See also: https://en.wikipedia.org/wiki/Lyapunov_time https://en.wikipedia.org/wiki/Lyapunov_time