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Old June 3 2012, 08:28 PM   #137
Re: SpaceX is a go for April 30th: 1st commercial launch to space stat

Kerosene isn't a hypergolic--thats fuels like UDMH, MMH, "Aerozine," pentaborane, zip propellants. Anything that will combust upon touching an oxidant--like nitrogen tetroxide--that too is a hypergolic.

Now kerosene and HTP (pure H2O2 that blew the nose off the Kursk from a torpedo) are non cryogenic and storable at room temps like hypergolics are, but you still need the spark plug, if you will.

So while they are storable propellants, they are not hypergolic. Also there is a movement away from hypergolics due to toxicity.

Some of you might remember the recent satellite shoot-down where folks were worried about the threat of that one small craft's hypergolic fuel. Now, maybe that was just a fancy excuse for a test of the Standard Missile 3, and maybe it wasn't. At any rate, hypergolic depots are simply not on the table.

Hyperspace05 wrote: View Post
Anyone expressing "doubts about depots" is heavily invested in creating huge launch vehicles we cannot afford to operate. I would express huge doubts about their objectivity.
Actually it was the individual work worked for ULA and did work on the DTAL lander concept:

An approach using propellant transfer appears to be more expensive than building some variety of heavy lift vehicle

In fact, it doesn't need to be either or

"Michael Gazarik, NASA’s space technology program director, says that CPST and the Space Launch System (SLS) heavy-lift rocket currently under development are complementary technologies. 'To explore deep space we need a heavy-lift vehicle — SLS — and we need this technology.'"

Still, the position of folks in the know is that depots are what we cannot afford now, in that "concerns about fuel boil-off in orbit remain. A paper presented by Patrick R. Chai and Alan W. Wilhite of the Georgia Institute of Technology at this year’s International Astronautical Congress estimates that depot tanks would lose about $12 million worth of propellant a month in low Earth orbit if protected only with passive insulation. But the state of the art in cryocoolers that would be needed to prevent boil-off falls short by 'an order of magnitude' and would require “significant research” to meet likely requirements."


The challenge for fuel depots is simply that the marginal specific cost of payload to orbit is generally lower for larger launch vehicles.

Lots of rancor remain:

The SLS and the Multi-Purpose Crew Vehicle (MPCV) are needed today. Fuel depots will be needed tomorrow, when a robust space operations infrastructure has been established and operations beyond LEO are common.

So, spaceflight is harder than popular culture has led on.

Last edited by publiusr; June 3 2012 at 09:05 PM.
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