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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