Slipping the Surly Bonds of Earth (Vacuum balloon experiment)

[Falstaf]

The problem with space travel is weight. Did you know that the majority of the weight in any NASA shuttle launch is in rocket fuel? It happens to also be the primary money sink for the space program. It would cost you tens of thousands of dollars in rocket fuel to put a 2 liter bottle of cola in space.

 

What I am going to propose is a new idea that has old roots. The concept of a Vacuum Balloon is, in fact, extremely old (as far back as 1670C.E.). It could never be implemented because no material can be both light enough to float AND withstand the suction force of a vacuum without losing its displacement (size). Current Helium/Hydrogen balloons can go up to 30km, for relatively little expense (I believe there is even a DIY kit for around 300 USD). They can go no further because of several factors, primarily that the pressure outside the balloon is almost 1/100th what it is on sea level, causing the balloon to expand and burst. So what I propose is a launch system of a vacuum balloon that will be piggybacking off a helium balloon.

 

By inserting a small/medium sponge inside a balloon that has been vacuum sealed (presumably the balloon will have custom or commercial material composite fabric) and then attaching this balloon to a helium balloon, the prototype can reach an altitude of at least 30km, which contains 1/100th the external pressure at sea level. The prototype, while looking like a shirvelled grape/orange at sea level will undergoe a dramatic change. The sponge inside the prototype will expand due to lower external pressure, and push the area of the prototype out. As it expands, it will displace more and more volume, making it increasingly lighter and lighter. The result is (hopefully) an innovative and extremely cheap way to launch micro-satellites into geo-sync orbit by use of a 2 stage lighter-than-air method.

http://science.howstuffworks.com/scienc ... ion194.htm

http://www.scientificsales.com/SearchRe ... 2godvDshow

It would boil down to; Is the elastic force of the sponge stronger than 1/100th seal level pressure? If yes, the prototype need only be able to expand enough to displace the wieght of the sponge itself to float.

To test this theory one would need relatively cheap materials. A vacuum chamber (to simulate conditions at 30km up) and a prototype (a vacuum sealed balloon with elastics or a sponge inside) are all the materials necessary.

 

I would love comments/feedback/hypothesis

Edited May 29, 2011 by swansont

[swansont]

Balloons have lift because they displace air. Eventually there's no air left to displace.

[Falstaf]

Yes, eventually. I suppose it would stop pretty short of 100km (definition for space), but thats an incredible distance isn't it? Thats high enough to make a difference.

 

What I would like to see is a way to prove this mathematically. Can anyone flat out tell me "no, this won't work because of THIS law of physics..."?

[swansont]

It won't work because of Archimedes principle, but that's just a restatement of my prior objection. Let's say you get to 50 km. What then? You have a small payload at 50 km.

[John Cuthber]

"Yes, eventually. I suppose it would stop pretty short of 100km (definition for space), but thats an incredible distance isn't it? Thats high enough to make a difference."

 

Not really, no.

To lift something into space you are doing work against gravity. At the surface of the earth you are already something like 6400 Km above the centre of the centre of the earth. Moving another 30 Km up won't really help much in terms of the energy needed to get into real space. It's not usually enough to get to 100Km, you have to stay there for a while. If you get to 6400Km above the earth there's still a quarter of normal gravity pulling you back.

A balloon might help a bit, but you would still need a rocket anyway.

[insane_alien]

not to mention at 50km you need 1000m^3 per kilogram of mass (both of the balLoon and payload.).

 

I have a feeling that anything with such a low mass per volume would be quite fragile and be utterly unable to cope with surface pressures.