All Questions
Tagged with velocityorbital-mechanics
15 questions
18votes
2answers
3kviews
Every day, how much speed does Voyager lose due to the sun's gravity?
The Voyager spacecraft will never be pulled back into the sun because it achieved escape velocity. But it's moving away slower and slower all the time. Voyager is currently moving away from us at 31,...
3votes
1answer
833views
Calculate velocity vector of elliptical orbit given the position vector at that point, the instantaneous speed, the true anomaly, and the inclination?
Sorry if this is obvious, but I am an amateur at orbital mechanics and trigonometry was never my strong suit. I would like to calculate the velocity vector at a point in an orbit given: position ...
- 55
10votes
2answers
2kviews
What's the motion of two connected satellites orbiting the Earth after their separation?
Let's consider the following problem (it's a job interview question): two satellites are orbiting the Earth in a circular orbit; they are rigidly linked by a tether which is always pointing in the ...
- 433
10votes
4answers
4kviews
What is the velocity of the ISS relative to the Earth's surface?
This was asked once before, but I believe there was no clear answer given and accepted. The ISS has an orbital period of 92.9 minutes, or 5574 seconds. If it were in a completely equatorial orbit, ...
3votes
0answers
280views
Exact speed/distance of JWST (& others in L1/L2 halo) from Earth; is it measured any differently than for more distant deep-space missions?
How is the exact speed and distance from Earth of the JWST or any spacecraft in a Sun-Earth L1/L2 halo orbit determined? While deep space missions require ranging at hundreds of millions of kilometers ...
- 31
1vote
2answers
261views
How to correct my real orbit and turn it into predicted ideal orbit?
I want to launch my ship to the purple ellipse orbit. But because of non-ideal world I have non-ideal ship orientation and non-ideal thrust impulse. So, my initial speed is a bit bigger and it's ...
- 604
25votes
3answers
10kviews
If you release a tool outside the ISS in space will it remain at the "same" place forever?
If an astronaut doing a repair outside the International Space Station (ISS) gently lets go of a tool into space, will it keep "flying" (orbiting) at the same spot relative to the ISS where ...
- 369
1vote
0answers
151views
How to correctly change velocity in space?
The solver of the Lambert's problem gives me a hyperbolic velocity to move to some position on orbit. But the spacecraft is moving on orbit and changing the velocity takes some time. So, when I ...
- 604
3votes
1answer
1kviews
How to calculate the velocity vector in the case of a hyperbolic orbit?
The problem I'm trying to get a formula to calculate the state vectors $\vec{r}$ and $\vec{v} = \dot{\vec{r}}$ on an orbit, given a true anomaly $\nu$. I'm following the process described here : https:...
- 293
2votes
0answers
930views
Getting the Velocity Vector in an Elliptical Orbit
I have a 2-D two body set up. I am using the vis-viva equation to get the velocity scalar of my elliptical orbit. I have the Semi-Major Axis, the radius, the eccentricity vector. I am sure I can ...
5votes
0answers
2kviews
Solar system galactic velocity vector relative to ecliptic plane
The Solar system moves through the Milky Way galaxy with velocity of 230 km/s. The ecliptic plane is located ~60 degrees with relation to the galaxy plane, according to this source. The page also ...
- 6,450
2votes
3answers
1kviews
Point Ahead Angle and Doppler Shift Frequency Changes Calculation with the tangential/radial velocity component for Inter-Satellite Link
While calculating the Point Ahead Angle we work with Tangential Velocity vector component and to calculate the Doppler shift i.e changes in frequencies, we work with Radial Velocity Vector component. ...
- 83
13votes
3answers
558views
A spacecraft is travelling at X units per hour. But relative to what exactly? Does it depend on the orbit? How?
If I am walking, the ground is stationary, and I move $X \frac{\text{units}}{\text{hour}}$ relative to the ground. If I am in low-Earth orbit, then I am still moving $X \frac{\text{units}}{\text{hour}}...
- 1,006
4votes
1answer
1kviews
How do I calculate re-entry velocity when decaying from a circular orbit?
I am trying to find the velocity of an object during re-entry so that I can calculate the peak heat flux but I'm a bit stuck. I know how to find the velocity of the original, circular orbit (300km) ...
- 41
4votes
1answer
379views
At what point of travelling progressively faster around the Earth you are not going to fall back again?
My dad and I thought about a problem we had when discussing Earth's gravitational field. This wasn't the original question but I still would like to know the answer. So essentially my question is: Is ...
