Subject: Using a vacuum to lift things

Here's my question:
I'm writing a
science fiction story. In it, there's a device that uses
vacuum to lift
things. (In the story, it's used to rescue a marooned
astronaut.)

My idea is that it's spherical, sort of like a helium
balloon but with
rigid walls. It's dropped to the planet surface in a
colapsed state, then
inflated, as it inflates the walls become rigid, then the
air is pumped
out to create a vacuum.
My questions are:
1. Would this work? Can a vacuum be used to lift things?
2. How much does a cubic foot of earth air weigh?
3. How much air would have to be displaced to lift 100
pounds?

Re: Using a vacuum to lift things