Isn't the Bouncy Castle by Trump™ the new name for the Whitehouse? To be inauguarated by Silvio Berlusconi…
While waiting for TESS to get off the launchpad on Monday, chief exec Elon Musk joked on Twitter about how SpaceX might set about recovering the second stage of the booster. SpaceX will try to bring rocket upper stage back from orbital velocity using a giant party balloon — Elon Musk (@elonmusk) April 15, 2018 The idea is …
If it is any form of baloooooony tech it will most likely float just fine. So no need to do bouncy castles or other "on-land" attractions. Just do some splashing along the water a few times.
It is also a second stage so it can actually be made to deorbit nearly anywhere around the world. In fact, it may be better to make it deorbit somewhere away from civilization. Just in case.
To get rid of snarky comments from commentards at The Register about littering up outer space.
I'll happily deorbit the second stage anywhere around the world, so long as I can choose the targets randomly, in anger, about 30 seconds before I execute the deorbit command.
/wow -- apparently channelling a political entity today.
this is genius.
the best bit about it, is if you got the tension correct, the rocket could come to a complete stop (for some value of a small amount of time) next to a platform which could allow people to alight / derocket, and then go up to orbit themselves using nothing other than the tension in the ACME. rinse and repeat, with a few chemical kickers along the way to defeat that pesky friction stuff. you wouldn't want to hang about though i suspect when de-rocketing alighting.
It's not just big serious rocket companies using ballutes, Copenhagen Suborbitals are planning to use one to stabilise their capsule, in fact, they posted a video of the first test (ie, throwing it off a big building) just yesterday:
NASA used pure oxygen but at 21% atmospheric pressure so it was at the same partial pressure as in air, not at 107% atmospheric.
Still burns every thing at a higher rate and temperature as they found out when three astronauts were cooked in their capsule some time back. The very reason that the Russians chose to use just plain air at 1 Atm and take the weight/space penalty.
@SC- quite correct. On orbit, one maintains O2 at a cabin pressure equal to the partial pressure of O2 at sea level, about 5.1psi. I guess - but don't know - that having to design for a lower static pressure makes the spacecraft lighter? Wonder what they had to do with Apollo spacecraft to move to a mixed gas system after the Apollo 1 disaster (what an awful way to die)
Found an interesting systems description link:
Looks like internal pressure at launch was about atmospheric and the astonauts would be provided pure O2. Doesn't say whether the cabin was purged to eliminate the N2 but it's probably a reasonable assumption that it was. As the rocket lifts off the cabin is allowed to depressurize to 5.1psi or so, which happens around 20-40sec after launch. Atmosphere inside is definitely pure O2 at that point. On reenty the astronauts have to repressurize with external air during descent.
So the 'nauts are probably breathing pure O2 at full atmospheric pressure, at least while waiting for launch. Imagine that with countdown holds that might be quite a while. Wonder how close the men got to physiological limits...
@Chairman of the Bored "So the 'nauts are probably breathing pure O2 at full atmospheric pressure, at least while waiting for launch."
It seems that while waiting for launch, the astronauts were breathing a gas mix with a sensible partial pressure of oxygen, supplied by their suits. I've just read on Wikipedia that oxygen toxicity can turn up in minutes when breathing an oxygen partial pressure above 0.3 bar.
"The pilots are provided with redundant atmospheres by having a closed pressure suit circuit within the pressurized cabin."
as part of the pre-launch procedure:
"A ground supply of pure oxygen is connected to the pressure suit circuit purge fitting. Flow is Initiated with the face plates closed. The suit circuit gas is sampled periodically until an acceptable oxygen content is attained."
- the only gas mentioned as being supplied by spacecraft systems is oxygen, but then again nitrogen gas isn't consumed by human metabolism.
There is also this, which applies to spacecraft descent:
"The pressure in the suit and cabin remains constant at 5 psia (nominal) until an altitude of approximately 27,000 feet is reached.
As ambient pressure increases during descent, the cabin pressure relief valve admits ambient air into the cabin, preventing high differential pressures. The cabin pressure relief valve begins to open when the ambient pressure is 15.0 inches of water greater than cabin pressure and opens to maximum flow when the pressure differential is 20 inches of water.
At an altitude of 25,600 feet, or below, the pilots manually open the cabin inflow and outflow valves to circulate external air through the cabin and suit circuit.
Maximum negative pressure on the cabin should not exceed 2 psi as controlled by the cabin relief valve."
I found reading the page l linked to hurt my head a bit. Cabin pressure is specified in psia and tank pressures in psig; that's okay (a=absolute; g=gauge). Then you read the suits apparently maintain internal pressure between 2.5 to 3.5 inches of water below to 2 to 9 inches of water above cabin pressure. Cabin gas leakage is measured in "standard cubic centimetres". Oxygen supply quantities are specified in pounds and the gas supplied is sent through a 10-micron filter. A tracer chemical for urine analysis is specified in millilitres. I can see how it all made perfectly good sense at the time, but still my mind boggles.
@AC, thanks for that detailed post and great link. This really does boggle the mind. As a hardware engineer I tend to think I'm really hot stuff, but looking at what was accomplished in the early space program reminds me that (1) my ignorance is vastly larger than my knowledge, and (2) we truly do stand on the shoulders of giants. Thanks!
HIAD increases the size of the nose of the vehicle, and it's for a vehicle, not a stage.
But bringing a US back from orbit is (in energy terms per Kg) 20x harder than recovering a booster. Most TSTO rockets split the velocity each stage provides 50/50. F9 splits it more like 1/3:2/3.
Musks plan is putting a big ass inflatable at the back to keep the light end facing forward, rather than the engine end, which naturally wants to lead.
Does not sound that different, but is.
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