They were trapped, but now there is an escape. All but Kendall gather in the wardroom to discuss their options, squeezing about a single table but, unlike at meal-times, confidently, keenly, meeting each other’s gazes. It occurs to Peterson that he has lived with these men for two years but he barely knows them. He sees seven men he knows chiefly by their reputations and the psychological profiles in their records. Their faces are as familiar to him as his own, but they might as well be the gold visors of spacesuit helmets for all their expressions tell him what each is thinking. Not once since they became isolated on the Moon have they worked together. He trained extensively with Curtis for the trip here, but once they had landed each had their separate duties… and since they lost the Earth, he has barely exchanged a dozen words with the man. And now… Now, the Curtis he knew is not the fevered-looking man on the other side of the table with arms folded across a stack of ring-binders.
The Moon has changed them all; despair has made strangers of them.
But now, with salvation a very real possibility, they are no longer uncomfortable in each other’s company. Hope has made amiable strangers of them.
Hope: half a dozen modules in Low Earth Orbit. An elusive hope: they need to find a way to reach the space station. They have one ALM ascent stage left—and Peterson gives thanks it still remains, not launched out of desperation by one of them during the past two years.
A thought occurs to him: how to get from lunar orbit to Earth?
We need another engine for TEI, Peterson says.
We can rip a DPS out of one of the descent stages, says Bartlett. They’re throttleable.
What about fuel? demands Fulton. How you going to fuel the burn? You think maybe we can just brew up some Aerozine 50 out of Moon rocks?
Both the Descent Propulsion System and Ascent Propulsion System are powered by Aerozine 50 and dinitrogen tetroxide. The latter they can perhaps manufacture through the catalytic oxidation of ammonia, but Aerozine 50 is beyond their capabilities. For it, they need sodium hypochlorite as well as ammonia. The third ingredient of Aerozine 50, unsymmetrical dimethylhydrazine, requires a chemical plant.
Bartlett gestures dismissively. All those descent stages on the mare, he says, each one has a minute, maybe half a minute, of Aerozine 50 left in the tanks.
So where we put the DPS? asks Neubeck. There ain’t no room in the LM.
There is a defeatist whine in the man’s voice, and it is a moment before Peterson calms himself enough to reply:
We bolt it to the goddamn back, he snaps.
Bartlett shakes his head. We’re going to have to put it on the top, he says, or we throw off the centre of gravity. We don’t need the drogue assembly in the docking tunnel, so we rip it out and we build us a frame to put in there for the DPS.
Fulton is not convinced: You reckon we can get 20,000 lb fuel from all the descent stages?
Why not, says Bartlett. Say you burn about ninety percent of that on the way down. That’s got to leave between 150 and 200 lb per LM.
There’s gonna be some losses decanting it, Fulton replies.
Peterson watches the two argue back and forth. The others are content to let them thrash it out. Fulton has always played the sceptic—but for that, he might have been commander of Falcon Base. Bartlett is a smart guy; perhaps, after Alden, the smartest guy on the Moon—
It won’t work, says Alden in his slow, careful way.
Bartlett turns on him. Sure it will work, he insists.
Alden shakes his head. How much does the ascent stage weigh?
10,024 lb, says Curtis from memory.
You add a DPS onto that, plus 20,000 lb of fuel, continues Alden, and the APS is not going to reach lunar escape velocity.
APS thrust is 3,500 lbf, says Curtis. You can get maybe 12,000 lbs into lunar orbit with that.
We don’t need 20,000 lb of fuel, Bartlett points out. We only need enough for the TEI burn.
Again, Curtis quotes figures from memory: The CSM is 66,871 lb fully loaded, the SPS has 20,500 lbf thrust. You need a 203 second burn for TEI.