3 ms·
The slingshots used to deorbit were around Venus, so it slightly gained velocity while the Parker probe lost it to get closer to the sun without expending as mu
by BlarfMcFlarf 3y ago
The slingshots used to deorbit were around Venus, so it slightly gained velocity while the Parker probe lost it to get closer to the sun without expending as much fuel.
As for its velocity around the sun, it’s intuitively like pendulum. When far away, it’s like the raised pendulum, and when near the sun, it’s like the pendulum at the bottom of its swing. Its a strained metaphor, but if you look at the orbit, it’s a very deep swing and a very large object it’s swinging towards, so it ends up quite fast at the bottom.
- pfdietz 3y agoWhat the Venus flybys did was not add energy so much as remove angular momentum. The hard part about getting close to the Sun is that conservation of angular momentum prevents it. Related to this: a minimum energy transfer between two circular orbits is normally the two-burn Hohmann transfer: an elliptical orbit that is tangent to each circular orbit. But if the radii of the two circular orbits have a sufficiently large ratio, it takes less delta-V to use three burns: go into an elliptical orbit that goes out to very large distance, do a small burn to lower (or raise) the periapsis to be at the other orbit, then circularize with a third burn. This is because doing a burn at large distance adds or removes a very large amount of angular momentum.