# Returning from Geo-stationery Orbit

1. Jun 27, 2017

### Chatterton

I know when a Soyuz capsule returns from the ISS it has to orbit Earth a few times before re-entry due to all the momentum it borrowed from ISS.

What would happen if your ship was in the Clarke zone? Assuming we have the radiation shielding covered already. Would it be conceivable that a ship parked like that could just drop capsules in a fairly straight down manner? Assuming we have all the heat-shielding worked out.

2. Jun 27, 2017

### Staff: Mentor

It's more because they don't want to carry the fuel required to de-orbit in less than a single orbit. Instead, they can break a little bit, fall towards Earth, and then use the air friction to slow them down further and further over successive orbits until the density of the air is high enough that they finally fall back to Earth instead of making another orbit.

No, because the ships would still be moving tangentially "around" the Earth. Firing a capsule straight towards the Earth would just result in an elliptical orbit since the capsule would retain all of the tangential velocity and gain an additional radial component.

3. Jun 27, 2017

### Chatterton

So, to do it right, my team of commandos will have to de-orbit the old fashioned way, spinning around the globe a few times before hopefully landing in relatively the same area, which would make even clumsier and more random than WWII paratrooper action and oh my God I think that cold be wicked cool. And it would take a while too, right? I think I remember something from Chris Hadfield's book about sleeping on the way down.

4. Jun 27, 2017

### Staff: Mentor

Not necessarily. They could have control systems designed to keep them in close proximity prior to and during reentry.
I'm not sure how long it would take. Geostationary orbit is about 22,000 miles above sea level, so I assume it would take a while, with the exact time depending on the velocity the capsules were launched at, the exact orbit, and a few other details.

5. Jul 5, 2017

### stefan r

Consider a reverse escape from lunar gravity. Then your paratroopers can hang out in a bunker complex in lava tubes. You can also magnetic launch artillery. No need for explosives in the shells. Just crack the heat shield at the altitude you want. Between 2500 and 2600 m/s for Δv. If you give them 3,000 m/s they can launch at multiple angles and all arrive at once.

Dropping from Earth-Moon Lagrange point 1 is easier than dropping to earth from geosynchronous. That can be done with 750 m/s. Geo requires around 1500 m/s before you can aerobrake. Launchers and fuel tanks sitting in geo are huge targets.