Gas to float things in to space?

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mvandiermen

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Would helium balloons or any other gas or maybe vacuumed air float above our atmosphere, to carry things in to our orbit (with a bit of propulsion at the end to carry them out)?
 
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drwayne

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Re: Gas to float things in to our atmosphere?

Yes, balloon launched ideas have been "floated" from time to time. I know of a number of
amateur groups who use the technique.

Two things to keep in mind when thinking about this sort of "lift and launch" approach

(1) To lift a large payload require a really large balloon, which poses some very significant challenges
of material for the balloon.

(2) There is a tendency to think of the problem of getting into orbit as just getting to the right altitude,
and giving it a little nudge to get it going. This is incorrect. To maintain orbit requires the object be going
at speeds ~ 17,500 miles per hour, which is quite snappy.

The savings from a balloon assisted lauch are mainly that you avoid the drag of the atmosphere, which
cuts down on both drag and structural stress.

Welcome to the forum!
 
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drwayne

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Re: Gas to float things in to our atmosphere?

Out of curiosity, what would "vacuumed air" be?
 
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MeteorWayne

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Re: Gas to float things in to our atmosphere?

mvandiermen":e6619axd said:
Would helium balloons or any other gas or maybe vacuumed air float above our atmosphere, to carry things in to our orbit (with a bit of propulsion at the end to carry them out)?

No, balloons can only float within the atmosphere, because they are lighter than the atmosphere that they displace. Anying is heavier than the vacuum of space, so noting can "float" there in the balloon sense.
 
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drwayne

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Re: Gas to float things in to our atmosphere?

Yes, I should have put the qualifier that the balloon can only lift something high in the atmosphere,
not above it, i.e. into space.
 
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mvandiermen

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Re: Gas to float things in to our atmosphere?

drwayne":1cgf3p5q said:
Out of curiosity, what would "vacuumed air" be?
I don’t know what I was thinking when I said that, for a second I thought it may be possible to have a container with no atmosphere/gas in it.

MeteorWayne":1cgf3p5q said:
No, balloons can only float within the atmosphere, because they are lighter than the atmosphere that they displace. Anying is heavier than the vacuum of space, so noting can "float" there in the balloon sense.
I wonder if the atmosphere reaches the edge of the earths gravitational pull?


_______________________________________

Seems to me like a cheap way to get things into space. I was thinking it was a good idea to maybe offer payload charges to get things into space this way; maybe a future endeavor.
 
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drwayne

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"I wonder if the atmosphere reaches the edge of the earths gravitational pull?"

There is no "edge" of the Earths gravitational pull.

You can get a rough idea of the reduction in gravitational pull at an altitude of X by the following factor

(6400/(6400 + x))^2

where X is sthe altitude in kilometers. One rough criteria for the transition from endo to exoatmospheric
regimes is 100 km in altitude - plugging those number shows that you still have roughly 97% of surface
gravity at 100 km

This might confuse some who equate the idea of weighlessness in orbit to gravity not acting.
That is not true, the weighlessness is the result of the fact that the spacecraft and everything in it
are all falling together.
 
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csmyth3025

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Re: Gas to float things in to our atmosphere?

MeteorWayne":12el93rl said:
mvandiermen":12el93rl said:
Would helium balloons or any other gas or maybe vacuumed air float above our atmosphere, to carry things in to our orbit (with a bit of propulsion at the end to carry them out)?

No, balloons can only float within the atmosphere, because they are lighter than the atmosphere that they displace. Anying is heavier than the vacuum of space, so noting can "float" there in the balloon sense.

Wikipedia has an interesting article on high altitude records, a portion of which follows,

"In 2002 Japan achieved a new record: an ultra-thin-film balloon named BU60-1 made of polyethylene film 3.4 µm thick with a volume of 60,000 m³ was launched from Sanriku Balloon Center at 6:35 on May 23, 2002. The balloon kept ascending slowly at a speed of 260 m per minute and successfully reached the altitude of 53.0 km (174,000 ft), establishing a new world record for the first time in 30 years...."

It seems our friends at Scaled Composites (the folks who brought us Spaceship One) believe that air launched vessels for transporting crews to orbit (eventually) is the way to go. Although air-breathing airplanes are not able to achieve altitudes like that of the record-setting Japanese balloon, such heights may not be needed. It seems that the 50,000 ft altitude at which Spaceship One was launched is sufficient.

In terms of reusable launch craft, airplanes such as White Knight One (the mother ship for Spaceship One) compare favorably to the traditional rocket launch approach. They are less complicated, can use "off the shelf parts", can return to the launch site intact, and can be returned to use with comparatively minimal servicing. These same features make aircraft based launch platforms preferable over balloon launch platforms.

The question, of course, is whether such an air launch platform can be scaled up to carry a fully orbital crew transfer vehicle (~6 passengers plus the operating crew) and sufficient fuel to complete the trip and make the necessary orbital maneuvers. Here, again, Scaled Composites seems to be moving in that direction (along with their partner Virgin Galactic).

For comparison, the venerable B-52 has a service ceiling of 50,000 ft and can carry a bomb load of about 70,000 pounds. It was used to air launch the X-15, which weighed about 34,000 pounds fully fueled. Spaceship One weighed a mere 8,000 pounds at launch. In terms of aerodynamics, the 58 year old B-52 seems to have what it takes to provide a platform for an air launched crew transfer vehicle. If a Russian Soyuz spacecraft is used (capacity=three persons), it would consist of three modules - the orbital module, the re-entry module, and the service module. The orbital and service modules are jettisoned and burn up on re-entry. The total weight of this spacecraft (all three modules) is about 16,000 pounds. I have no idea how heavy the fueled booster rocket for this craft would be (if air launched), but it seems that 54,000 pounds (70,000 - 16,000) would be in the ball park (I might be wrong about this). [EDIT: Checking wikipedia, the mass of one solid rocket booster used for the space shuttle is 1,300,000 pounds. I guess 54,000 pounds isn't in the ball park after all]

I don't think it's a stretch of the imagination to envision that a purpose-built air launch mother ship using modern composite materials could accommodate an orbital crew transfer vehicle. It's my understanding the the good old US government is thinking of throwing $6 billion (that's with a "B") at the problem of developing a crew transfer vehicle and launch system over the next few years. I'm not a spokesman for Scaled Composites, but I suspect that if you handed them $6 billion they could probably come up with something that works and still walk away with a tidy profit.

Chris
 
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TimO_10101

Guest
The problem is that even stratospheric balloons that are the size of skycrapers really DONT have much weight carrying capability. The rockets that have been launched from them are not all that big.

You couldn't put something the size or weight of a Shuttle up; it's just not practical....

(If it was this easy, NASA and the Air Force would have been doing it decades ago.)
 
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drwayne

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EarthlingX":1amvyeky said:
drwayne":1amvyeky said:
"I wonder if the atmosphere reaches the edge of the earths gravitational pull?"

There is no "edge" of the Earths gravitational pull.
There is an 'edge' to the sphere of influence, but that is 'a bit' more out ...
Sphere of influence (astrodynamics)

And of course, in the old days of Apollo, there was the transition that the craft went through when it
was far enough out that the moon's graviation dominated over the Earth's, and you were "going
downhill"

Wayne
 
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kg

Guest
Re: Gas to float things in to our atmosphere?

mvandiermen":gkwtpxdf said:
I don’t know what I was thinking when I said that, for a second I thought it may be possible to have a container with no atmosphere/gas in it.

I posted a similar sort of question last week and didn't get a response. I was reading about a particular type of Aerogel that is evacuated. I think this means that there is a vaccume instead of a gas trapped in it's pores. According to this wiki article its density is .2 mg/cm3 less than air! I was wondering if anyone knows anything about this material and if it actually floats like a balloon?
http://en.wikipedia.org/wiki/Aerogel#Silica
...The world's lowest-density solid is a silica nanofoam at 1 mg/cm3,[6] which is the evacuated version of the record-aerogel of 1.9 mg/cm3.[7] The density of air is 1.2 mg/cm3....
 
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EarthlingX

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Re: Gas to float things in to our atmosphere?

kg":38ovs4ih said:
mvandiermen":38ovs4ih said:
I don’t know what I was thinking when I said that, for a second I thought it may be possible to have a container with no atmosphere/gas in it.

I posted a similar sort of question last week and didn't get a response. I was reading about a particular type of Aerogel that is evacuated. I think this means that there is a vaccume instead of a gas trapped in it's pores. According to this wiki article its density is .2 mg/cm3 less than air! I was wondering if anyone knows anything about this material and if it actually floats like a balloon?
http://en.wikipedia.org/wiki/Aerogel#Silica
...The world's lowest-density solid is a silica nanofoam at 1 mg/cm3,[6] which is the evacuated version of the record-aerogel of 1.9 mg/cm3.[7] The density of air is 1.2 mg/cm3....

I have this idea about a 20-30km high floating platform, on balloon cubes.
Each such cube would be able to carry a couple of tons, and they all together form a platform.
If you launch a rocket from that height, you are above the main atmosphere pressure changes due to elevation, which force non perfect design of your rocket engines, specifically, nozzle. Calculating that balloon and structure was a bit big bone for me ..

The difference in the hot air density and cold air density, which allows hot-air balloons to float, is also not very big.
Hot air balloon
 
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CalliArcale

Guest
TimO_10101":78ypq8v8 said:
The problem is that even stratospheric balloons that are the size of skycrapers really DONT have much weight carrying capability. The rockets that have been launched from them are not all that big.

You couldn't put something the size or weight of a Shuttle up; it's just not practical....

(If it was this easy, NASA and the Air Force would have been doing it decades ago.)

Yeah, but they do have a way-cool name: rockoons!!!

kg":78ypq8v8 said:
I posted a similar sort of question last week and didn't get a response. I was reading about a particular type of Aerogel that is evacuated. I think this means that there is a vaccume instead of a gas trapped in it's pores. According to this wiki article its density is .2 mg/cm3 less than air! I was wondering if anyone knows anything about this material and if it actually floats like a balloon?

Aerogel doesn't even float at sea level, where the air is much thicker. It is an incredibly awesome substance, so far mostly used by NASA for exotic applications, but recently it has come down in price. We may soon see houses insulated with it, and it has an R-value comparable to nothing currently on the home insulation market. An inch of it will outperform a foot of fiberglass insulation. But although it is very light indeed, it doesn't float in air.

You can make a vessel that has no air at all inside of it, but this is not useful as a balloon because to date, all structures capable of maintaining such a vacuum are heavy. Pull all of the air out of a normal balloon and the balloon collapses, crushed by atmospheric pressure.
 
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mvandiermen

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Re: Gas to float things in to our atmosphere?

I thought I was subscribed to this post but I was not, so I just read allot of the responses now.

Re: government space programs and army

I don’t see why some people fly modified jets in and out of space but some government space programs use rockets and do not control a horizontal reentry that would not require heat protection (for light loads). I have not looked into it so I don’t know anything about it, ...just an off-topic thing I think about allot.
 
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csmyth3025

Guest
Re: Gas to float things in to our atmosphere?

mvandiermen":18wi2xw0 said:
I thought I was subscribed to this post but I was not, so I just read allot of the responses now.

Re: government space programs and army

I don’t see why some people fly modified jets in and out of space but some government space programs use rockets and do not control a horizontal reentry that would not require heat protection (for light loads). I have not looked into it so I don’t know anything about it, ...just an off-topic thing I think about allot.

So far, nobody is flying "modified jets in and out of space". Scaled Composites and Virgin Galactic are working on doing something like this (as well as the Skylon group, separately, in England), but they still use rockets for the final leg of the journey. They're spending a lot of money (by private sector standards) to produce working working vehicles.

Government agencies tend to stick with a "project" until the money runs out or the politicians make them do something different.

Chris
 
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