Balloon into orbit ?

[Jethro]

Anyone see the mildly amusing "James May Man Lab" last night ? I would have thought it would have had some attraction to a DIYer ...

Anyway, one segment was how to put a cremated pets ashes into space. Eventually they filled a balloon with the ashes (there were 2 simultaneous tries, one using helium and one hydrogen) and released it. They had equipped the balloon with cameras and GPS (to locate the cameras).

Eventually the balloons made it to 30Km, before bursting. Both cameras were successfully recovered.

This set me wondering ... would it be physically possible to use a balloon to get something into orbit ?

Obviously as the external air pressure decreases (to practically zero) then the pressure inside the balloon would cause it to expand. Could this be dealt with, in such a way as to allow ascent to continue ? Maybe a segmented balloon, that can expand in segments, until it escapes gravity.

Been years since I did serious physics, so I can't recall how high up you need to go to achieve a (presumably) low earth orbit.

[Chris J Dixon]

Seemed a jolly good wheeze.

The cameras they used seem to be the item of choice these days - any idea what they are. I reckon they took them well outside their stated performance envelope.

The fact that they were showing the video during the ascent was a big clue that it all ended happily.

They didn't say much about the technology - how were they getting the GPS data back? Was there also any danger of going beyond GPS range?

Chris

[John Williamson]

No.

One exception would be if the balloon was used to carry a rocket, which was then launched at maximum height.

You get to a pont where the density (Mass/ volume) of the gas inside the balloon matches the density of the outside air. This altitude can be increased by warming the gas inside the balloon, but will, nevertheless be reached sooner or later. 30km is good, the record for a balloon is 51km.

Normally, the lowest part of space is considered to be about 100 km up, but you need to be much higher to be in a permanent orbit, as even at that height, traces of atmosphere remain, and friction will slow down the orbiting body. The speed to maintain orbit at 124 miles would be

17,000 mph, roughly, but the object would drop out of orbit in days unless it had a motor running continuously. At 100km height, an item in "orbit" would probably not make a complete circuit.

[whisky-dave]

I saw it by acident/flicking

yes it did but I was suprised nothing was said about the dangers or at least don;t try this at home. I wouldn't really want that sort of thing falling on my roof or landing in front of meon the motorway or even walking.

Yep I'd like to know about that too

yes I thought that, some good pictures/video though.

There were many things they didn;t mention, if you do that sort of thing and if had come down on those eletric pylons or anything else who pays for the cost of any possible damage, and would/are farmers or anyone else be happy with people waliking across their property to recalim their cameras.

[Davey]

I saw it, and enjoyed it. I also wondered about the data and film recovery. Was the film recorded, or was it transmitted to them directly from the balloons? And did they have to clear it with the Air Traffic folks first? I would hate to have one of those get sucked into my engine while in flight. Maybe there's a Manlab website, but got to go shopping right now.

[Tim Streater]

No. Just getting it up there overlooks the "being in orbit" part.

There's no such thing as "escaping gravity". All objects in orbit around something are falling towards it. Satellites fall towards the earth, as does the moon. The earth falls towards the sun. Why don't all these things crash? Because of a clever trick called "being in orbit".

If the earth had no atmos at all, and was perfectly spherical, one inch would be plenty. As it is, with the earth being lumpy and not a sphere, prolly 30km or so would do it - with no atmosphere.

The ISS is at what 300km up? It needs regular altitude boosts due to atmospheric drag.

[Nightjar]

As they must have known that they would be dropping an object from a balloon, they would have needed permission from the Civil Aviation Authority who would, no doubt, mandate that they avoided airways. I suspect that it was probably done on a military live firing range, where there is plenty of dangerous stuff around anyway, so the odd falling camera wouldn't be a problem.

Colin Bignell

[Roger Chapman]

You need rotation as well as height. Even the moon would soon collide with the earth if the two weren't rotating around each other.

[Huge]

They're GoPro Heros. You see them *everywhere*, now.

[Jethro]

If JMs commentary was to be believed, the cameras came down 75Km from the launch site.

[Andrew May]

Google have done something similar here:

might have more details as to how they did it. I have not had an opportunity to watch it all the way through.

[Ian Jackson]

To get it to go even higher, why don't they have a pressure release valve which starts to let a little gas out when the balloon is in danger of bursting? Presumably it would reach a certain ceiling, and more or less drift on for ever?

[Onetap]

There were parachutes attached and the cat and budgie UFOs were soft toys.

[Nightjar]

It should be possible to predict where to release it to come down on, say, Salisbury Plain.

Colin Bignell

[Lobster]

Seems to be a reasonably common hobby these days - I remember reading about a similar launch here a while back, and there was one mentioned in The Times earlier this week - link to the Mail's version is here (Times is a pay-site):

This one was in the US, but in the Times article ISTR they mentioned getting permission after a risk assessment showed that there was a 1 in

400 chance of hitting a plane if it was launched in a built-up area, but they went 90 miles out into the sticks where the odds were more acceptable.

David

[Newshound]

Exactly; it's not the height you need, it's the 18,000 mph.

Suitably designed balloons can carry on circulating the globe in the jet-streams, no problem, just as long as they keep the gas in so that the buoyancy exceeds their weight

[Tim Lamb]

In message , harry writes

Never had a glider although we are only 15 miles from the club at Dunstable. The Luton Airport control zone and our 11kV overheads may be a bit off putting:-)

I did consent to a romantic helicopter pick up recently. Wonder if it worked out:-)

regards

[Alan]

In message , Jethro wrote

Joseph Kittinger did a free fall + parachute jump from a helium filled balloon at 31km.

There are Youtube videos of this.

[root]

After a time the Helium would start to diffuse through the fabric of the balloon (H2 would diffuse out quicker as the molecule is smaller) and it would lose bouyancy. There's also some advantage to having the balloon reach it's max. altitude and then start its "descent" as it makes the area of potential recovery smaller.

[Davey]

Wow, just DuckDuckGo'ed 'MANLAB 2011'. There's plenty of stuff out there, folks.