I have some thoughts on the current mission over at PJMedia.
I’d read that they had a computer under-temperature prior to launch, possibly due to a long pad sit on top of second-stage LOX, but I haven’t seen an explanation of how the Dragon’s oxidizer would’ve frozen up around the valves. Could there perhaps have been some lubricant residue that gummed up at low temperatures?
Would a couple of heating blankets between the second stage and the Dragon’s trunk (powered by the pad) solve this issue?
The Dragon’s Draco thrusters burn a hypergolic mixture of Dinitrogen tetroxide and monomethylhydrazine.
Dinitrogen tetroxide has a freezing temperature of 12 degrees F (-11C).
Monomethylhydrazine has a freezing temperature of -62 degrees F (-52 C).
If something froze, it was probably the dinitrogen tetroxide. Some simple heaters on the propellant lines and valves can keep that from happening again.
Then I would recommend they do that, especially if the craft might undergo a cold soak on an extended space mission.
Yes, they should provide heat for the propellant lines. I was surprised to hear the lines aren’t currently heated. For the manned version, this problem is less likely to happen because the system must be pressurized before liftoff in case they need to use the launch escape system (Super Dracos).
It looks like my soda pop bet is still safe (although I’ve completely forgotten the terms and with whom.)
On the first successful Dragon flight, Elon Musk, the company’s founder and chief executive, noted that it made him a little nervous because it was almost too perfect, and provided nothing to learn from or room for improvement.
Really? when did he say that? Didn’t they have a bunch of sensor issues during final approach?
That was the second successful Dragon flight.
Ah! I keep forgetting about that one.
If this article is correct what caused the problem may be classified under federal law and so never released to the world.
SpaceX glitch may be deemed secret under US arms laws
16:22 05 March 2013 by Paul Marks
Odd that California lets a private company own a space munition but not a $10 piece of stamped metal with a coil spring designed in the 1900’s.
Being a government munition contractor provides some benefits it seems
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