The Parker Solar Probe’s new top speed could get you from NYC to LA in just 20 seconds. It’s not done yet.

  • PetDinosaurs@lemmy.world
    link
    fedilink
    English
    arrow-up
    36
    arrow-down
    2
    ·
    edit-2
    1 year ago

    So, it doesn’t work the way you think.

    It’s only going that fast because it’s near the sun. The same way a satellite close to Earth needs to move faster than one farther away. You can’t really use that velocity to go elsewhere. It had to lose a lot of energy to get as close to the sun as it is. It would need to gain that back to get to earth.

    I’m really blanking on a way to explain this concisely and I can’t explain orbital mechanics in a Lemmy post.

    If you play Kerbal space program, you can definitely use that to get a very intuitive understanding of this concept.

    • Mossy Feathers (She/They)@pawb.social
      link
      fedilink
      English
      arrow-up
      5
      ·
      1 year ago

      Thanks! I didn’t think about the fact that it’d lose velocity to gravity as it gets further away.

      I wonder if you could slingshot a probe by firing it to fly by the sun and then shedding mass at its perihelion. The idea being that the craft would be mostly dead weight, increasing the force exerted on the craft by the sun’s gravitational pull. Once you reach the perihelion, you eject the mass behind the craft so that there’s less force acting on the craft as it moves away from the sun.

      • PetDinosaurs@lemmy.world
        link
        fedilink
        English
        arrow-up
        7
        ·
        edit-2
        1 year ago

        👍. I like science.

        You wouldn’t just drop mass along side you in space. It would just continue to float along beside you.

        You definitely have to throw it behind you, like you said, but that’s what rockets do. They throw mass behind them to make them move forward. That’s a rocket.

        When you throw mass behind you at one point in your orbit, you raise the height of your orbit on the opposite side of the orbited object (this is simplified).

        So you’re basically right, it’s partially about the mass of the object, but it’s mostly the firing of the rocket.

        You’ve got some pretty good intuition though. That’s basic orbital mechanics.

      • Rivalarrival@lemmy.today
        link
        fedilink
        English
        arrow-up
        3
        ·
        1 year ago

        Just “shedding mass” won’t do it. Uncouple a payload from the mass of the ship at perihelion, and they will just float along together, side by side in their original orbit.

        But, if that “mass” is “rocket fuel”, and you “shed” it by burning it behind you, you’ve got the right idea. As the other commenter said, the Oberth effect means the closer you are to the sun, the faster you are moving, and the greater the effect that burning will have.

      • LinuxSBC@lemm.ee
        link
        fedilink
        English
        arrow-up
        2
        ·
        1 year ago

        Yes, the Oberth effect means that firing a rocket at the periapsis changes your orbit more than at any other point in the orbit.