# Aerospace Spaceblimp elevator

1. Feb 18, 2011

### FtlIsAwesome

Could supersized blimps, filled with helium, hydrogen, or a mix of those two or a vacuum support an elevator cable at high altitudes for easier spacelaunch? I'm thinking around an altitude of 80-120 km, but they could possibly float at other heights.
Would such a structure require carbon nanotubes?

There is a much older (now defunct) thread about multiple types of elevators/fountains, and this was one of the things mentioned briefly.

2. Feb 18, 2011

### Staff: Mentor

Well if you have a balloon you don't need an elevator - balloons go up. But the altitude you can get isn't enough to make a big difference: maybe 40km. And it doesn't help you any with the orbital velocity.

3. Feb 18, 2011

### FtlIsAwesome

The absence of atmosphere could aid in launches.
I'm thinking of huge blimps, like over 2 km diameter.

4. Feb 19, 2011

### JaredJames

Blimps and airships need an atmosphere to work in.

No atmosphere means they cannot achieve lift. Regardless of size.

5. Mar 10, 2011

### FtlIsAwesome

At an altitude of 350 km, the ISS experiences atmospheric drag, so it requires regular boosts to keep it in orbit. A satellite will need to orbit much higher to not need boosts.

The blimps float at the altitude where the air density matches their average density. Thus vacuum blimps would be preferable for highest altitude.
Bigger blimps can "contain" larger vacuums, therefore having a lower average density.
The blimps would probably need to be assembled in orbit, because they wouldn't be able to withstand the air pressure at the ground.

The altitude record for an unmanned ballon is 51.82 km.

I've tried looking at atmosphere models to find the air density at those altitudes (which determines the average density of blimps that float at those altitudes), but I haven't been able to get what I need.

Once constructed, a blimp drops down a cable. The cable is then attached to the ground. Spacecraft can climb up the cable, and once at the top they can use rockets to go into orbit or an escape trajectory.

6. Mar 10, 2011

### JaredJames

The moment a force is applied to the cable the blimp would need to counteract that force using the buoyancy.

The moment pressure is applied to the blimp, if it isn't constructed strong enough it will collapse - the problem is that making something to 'contain' a vacuum whilst under external pressure gives a larger average density than a standard hydrogen blimp - making it useless.

If you are going to use something like this it would have to be in geosynchronous orbit, in which case if you have the materials for such a cable you'd be better off building a space elevator and using that.

7. Mar 11, 2011

### mugaliens

So with your blimp you're just 1/7th of the way there, energy-wise.