[jacquesm]

Nobody is trying to do science here, that's one very cool dad and as far as his son is concerned it might as well be space.

Petty bickering over definitions doesn't matter much, after all no balloon could take you to the 100Km mark simply because they'd explode long before you got there (as did this one), but 30Km is three times as high as your typical passenger jet will fly and that's good enough for most people.

The article about the Karman line literally reads:

"Some people (including the FAI in some of their publications) also use the expression "edge of space" to refer to a region below the conventional 100 km boundary to space, which is often meant to include substantially lower regions as well. Thus, certain balloon or airplane flights might be described as "reaching the edge of space". In such statements, "reaching the edge of space" merely refers to going higher than average aeronautical vehicles commonly would.[5][6]"

http://en.wikipedia.org/wiki/K%C3%A1rm%C3%A1n_line

[bigiain]

There's a distinction (which admittedly might only be in my head) that a balloon _requires atmosphere_ to work, which means it can't get into _space_, since buoyancy in the surrounding air runs out by the time you get to "space" where there _is_ no "surrounding air".

'course that's no more a technical definition of "space" than "100km" or "the Karman line"...

Still, that's a cool project!

[jacquesm]

Well, that depends on what you mean by 'work', if with work you mean go up for ever then the answer is a clear 'no'.

However the 'envelope' for just about any balloon that is not built with extreme altitude in mind lies within rather than on top of the atmosphere.

A balloon will go up until the pull of gravity is balanced by the lift, and in most balloons that point will not be reached until the balloon bursts from a lack of counter-pressure by the atmosphere.

[dedward]

Why should they burst? Certainly a little rubber balloon will - but the difference between a good helium balloon and vacuum isn't much - a thin foil layer would contain it without bursting.

[cromulent]

The bursting is a fairly good automatic cut-down. If it doesn't burst, it will ceiling at some point, and then zoom around until something happens.

You might get some more height with a stronger balloon (or a larger balloon with less gas) but you want the flight to be over in a reasonable time if you ever want to get the payload back.

So then you have to use nichrome wire or something as a cutdown, just something else to worry about. 100k-ft is pretty good.

[sbierwagen]

Perhaps it is natural for an engineer to get irked when the press describes a thousand dollars worth of latex and helium, which only did 30km, and had no orbital velocity at all, as a "spacecraft".

It was a "spacecraft" in the same way a cameraphone is a "workstation", or BASIC is a production language.