4 ms·

Also importantly, you have to slow down at the other end.

dylan604 6y ago
If your ship can only handle 1G of acceleration, would that not also mean that it could only handle 1G deceleration as well? That means starting to slow down halfway to your destination.
- jandrese 6y ago
  I think it would be more like you time your arrival with the conjunction of some gas giants in the destination solar system and aerobrake multiple times to get your speed low enough so you can aerobrake on your destination planet. Bringing enough fuel to decelerate the same way you accelerated isn't usually practical, inflating your rocket by 15x its original size or more.
  - dylan604 6y ago
    One of my pet peeves about sci-fi is how ships jump out of FTL into a perfect orbit around a planet. The concept of temporal dampeners is laughable even after suspension of disbelief to allow for FTL.
    - rbanffy 6y ago
      Sci-fi-grade engines are always fun. If you want to jump straight into a stable orbit, just add the right velocity component to your exit point. Or select a synchronous orbit. Any sci-fi-grade navigation computer can do that.
      - jandrese 6y ago
        Even a Geo orbit is an orbit. I guess you could drop out at a Lagrange point. Of course depending on hour your Sci-Fi FTL engines work you could build up speed by stopping up high in the gravity well, let the planet accelerate you to orbital velocity, then jump sideways into an orbit once you're moving fast enough.
        rbanffy 6y ago
        Or you can just use the automatic preset that puts you in a stable orbit depending on the distance from the surface you chose. The default is synchronous (a.k.a. "standard orbit"). These functions are a hard requirement for passenger transportation anyway because you need to match orbit with the station you are docking with. Protocol is to jump to a random position a couple light seconds from the port, get authorization, then short jump to your assigned docking exit point.
        jandrese 6y ago
        I guess it comes down to the details of your fictional FTL drive. A lot of times normal space momentum is not maintained in FTL, and gaining normal space momentum requires conventional rockets where delta-V is hugely expensive in terms of mass and volume.
        rbanffy 6y ago
        I don't remember any sci-fi story with a jump drive mentioning this issue. There is one book, IIRC, Cassini Division, where a devastating attack is carried out by dragging one end of a wormhole at high speed to capture icy asteroids and launch them at a high velocity from the other end against a planetary target.

If your ship can only handle 1G of acceleration, would that not also mean that it could only handle 1G deceleration as well? That means starting to slow down halfway to your destination.

jandrese 6y ago
I think it would be more like you time your arrival with the conjunction of some gas giants in the destination solar system and aerobrake multiple times to get your speed low enough so you can aerobrake on your destination planet. Bringing enough fuel to decelerate the same way you accelerated isn't usually practical, inflating your rocket by 15x its original size or more.
- dylan604 6y ago
  One of my pet peeves about sci-fi is how ships jump out of FTL into a perfect orbit around a planet. The concept of temporal dampeners is laughable even after suspension of disbelief to allow for FTL.
  - rbanffy 6y ago
    Sci-fi-grade engines are always fun. If you want to jump straight into a stable orbit, just add the right velocity component to your exit point. Or select a synchronous orbit. Any sci-fi-grade navigation computer can do that.
    - jandrese 6y ago
      Even a Geo orbit is an orbit. I guess you could drop out at a Lagrange point. Of course depending on hour your Sci-Fi FTL engines work you could build up speed by stopping up high in the gravity well, let the planet accelerate you to orbital velocity, then jump sideways into an orbit once you're moving fast enough.
      - rbanffy 6y ago
        Or you can just use the automatic preset that puts you in a stable orbit depending on the distance from the surface you chose. The default is synchronous (a.k.a. "standard orbit"). These functions are a hard requirement for passenger transportation anyway because you need to match orbit with the station you are docking with. Protocol is to jump to a random position a couple light seconds from the port, get authorization, then short jump to your assigned docking exit point.
        jandrese 6y ago
        I guess it comes down to the details of your fictional FTL drive. A lot of times normal space momentum is not maintained in FTL, and gaining normal space momentum requires conventional rockets where delta-V is hugely expensive in terms of mass and volume.
        rbanffy 6y ago
        I don't remember any sci-fi story with a jump drive mentioning this issue. There is one book, IIRC, Cassini Division, where a devastating attack is carried out by dragging one end of a wormhole at high speed to capture icy asteroids and launch them at a high velocity from the other end against a planetary target.