Calculate trajectory

[Coahoma]

Hello all

I wish to buy Universe sandbox 2 but i have some questions about this simulation.

I know it is possible to create complex solar systems simulation  but i don't know if it is possible to simulate trajectory  for a space probe .
I suppose all datas are reals 

[Coahoma]

No one knows if it is possible to simulate body trajectories (probe or anything else)

[tntristan12]

By "simulate" do you mean "predict"? What I mean is this: for a given set of initial conditions, are you asking if it is possible to determine the general trajectory of a particle under the influence of multiple forces? If so, then the answer is no. Not exactly.

Let me elaborate. In order to determine the trajectory of a particle, you must first determine the kinematics (free motion) of the particle and its kinetics  (the forces acting on it). For two massive bodies acting under mutual gravitational attraction, it is possible to analytically determine the shape of the trajectory. However, for any more than that you must absolutely integrate the conditions if all gravitating bodies over time. This allows you to view the simulation progressing over time, which gets less and less accurate the faster you go. That is why US2 limits your time warp rate based on acciracy, otherwise you get weird phenomena like planets being ejected from the solar system. However, you cannot analytically determine the shape of the trajectory in these circumstances. The closest you could do would be to... well, run another simulation. And there is really no good reason to do that.

[Greenleaf]

By "simulate" do you mean "predict"? What I mean is this: for a given set of initial conditions, are you asking if it is possible to determine the general trajectory of a particle under the influence of multiple forces? If so, then the answer is no. Not exactly.

Let me elaborate. In order to determine the trajectory of a particle, you must first determine the kinematics (free motion) of the particle and its kinetics  (the forces acting on it). For two massive bodies acting under mutual gravitational attraction, it is possible to analytically determine the shape of the trajectory. However, for any more than that you must absolutely integrate the conditions if all gravitating bodies over time. This allows you to view the simulation progressing over time, which gets less and less accurate the faster you go. That is why US2 limits your time warp rate based on acciracy, otherwise you get weird phenomena like planets being ejected from the solar system. However, you cannot analytically determine the shape of the trajectory in these circumstances. The closest you could do would be to... well, run another simulation. And there is really no good reason to do that.

While everything, you say, is true, I think the answer of "no" is incorrect in relation to the question.
Yes, you can simulate a trajectory of a space probe in US². It is done exactly like the motion of the planets, which is also simulated, through numerical integration, and is not through an analytical solution or using ephemerids (tables of approximate positions over a time period).


A numerical integration consists of starting at known initial positions and velocities and then move forward in tiny steps by observing all the forces affecting the bodies. As "tristan" explained, this can be done more or less accurately, and absolute accuracy can never be reached. That s not special for US², though. That is a fact of simulating complex systems like a solar system with many planets... so... simulate a probe, if you want, and if you increase the accuracy setting, and consider a not too long time interval, you will be able to see it move as it would in real life.

[Coahoma]

By "simulate" i mean calculate to create trajectories to send probe for a grand tour (frome earth to anywhere or visiting each planets) using gravity assist.

[Greenleaf]

You can do that, but you would need to calculate the corrective thrust, needed at various points of the journey, yourself. If you (correctly) calculate the required velocity vector of the probe as it leaves Earth, you can send it on its way, and it will move according to newtonian gravity from there.


Currently only newtonian gravity is taken into account. Relativistic effects, solar wind, atmospheric drag and forces like the Yarkovsky effect is also not considered... and it is hard to add a rocket thrust force at a very specific point in time, to generate corrective delta v. Apart from that... yes, you can.

[DiamondMiner10]

By "simulate" i mean calculate to create trajectories to send probe for a grand tour (frome earth to anywhere or visiting each planets) using gravity assist.

You will also have to calculate where all the planets will be by the time the probe gets there, how fast the planets move, their gravity, and so on. It might be really really hard but yes I do think it is possible to do that

[tntristan12]

You will also have to calculate where all the planets will be by the time the probe gets there, how fast the planets move, their gravity, and so on. It might be really really hard but yes I do think it is possible to do that

Indeed. There's a reason NASA gets paid big bucks to do these sorts of calculations all the time!

[Greenleaf]

You will also have to calculate where all the planets will be by the time the probe gets there, how fast the planets move, their gravity, and so on. It might be really really hard but yes I do think it is possible to do that

No, that is what US² does after all... calculate where the planets are, how they move and how they attract ;-)