Stephen Baxter - Moonseed

“Which is why I say,” Jays said to Geena, “we’re further away from the Moon than we were in 1961…”

Geena leaned forward. “Okay. I heard how cruel life is. I heard how hard it is to achieve this. Now tell me how we do it.”

Frank looked up at her. “Five weeks?”

“Five weeks.”

His eyes, hooded by his thick spectacles, narrowed.

“The logic of how you get to the Moon hasn’t changed since 1969,” said Frank Turtle.

Frank started sketching on the back of a napkin: schematic mission profiles with the Earth shown as a flat floor, the Moon as a ceiling above it, and little rockets and landers clambering between the two, like medieval angels flying between Heaven and a flat Earth.

“You need some way to get to Earth orbit, or beyond. Then you need some kind of transfer vehicle, to drive you to the Moon. You need a habitat to sustain you on the journey. And you need some kind of lunar lander, like Apollo’s, to drop you to the surface and bring you back up again. For an extended stay you probably need to double all that, to drop a shelter or surface-stay resources in place.

“Now, Earth’s gravity well is deep. If you want to send a ton to the Moon, you need to throw seven tons from Earth’s surface, most of it lox propellant. Which is why we needed a Saturn V for Apollo.

“But today we don’t have a Saturn V, a heavy-lift capability. The Shuttle’s payload capability is a fraction of Saturn’s. You’d need four Shuttle launches for every lunar mission, or some similar number with low-payload expendables. Like our Titan IV, the Russians” Proton, the Europeans” Ariane—”

Jays said, “If we’d built the National Launch System, we’d have heavy-lift now. But they canned that in “92.”

Geena said, “Maybe the Russians” Energia — ninety tons to LEO—”

“Junk,” Jays said bluntly. “The Energia was a piece of shit, even before they closed down the production lines. Believe me, I went out there for an Apollo-Soyuz anniversary event, and I saw what’s left of it. Energia is not an option.”

“Okay,” Frank said. “Well, alternatively we have those old studies of Shuttle-derived vehicles…”

Geena knew about some of that. There might have been the Shuttle-C, an unmanned throwaway variant of the Shuttle, capable of orbiting seventy or eighty tons. But the cost advantage would have been minimal compared to existing systems like the Titan IV, so that too got canned in 1990.

“But,” said Frank, “there was another baby I worked on called Shuttle-Z. Looked like the Shuttle on steroids: your regular solid rocket boosters and external tank, but then a cargo element that was fatter than the external tank, with four Shuttle main engines. Could have sent a hundred and thirty tons to LEO. One hell of a bird. But that would have meant a lot of changes to the processing and launch facilities, so it wasn’t economical either.”

Jays said, “If we got to sit around and wait for Shuttle II — VentureStar, or whatever the hell they call it now—”

“Yeah. We’ll never get anywhere. But what about reviving the Saturn V production lines? Have you seen those studies?…”

“Enough.” Geena held up her hands. “Let’s get real, guys. In a few weeks we aren’t talking about a new heavy-lift vehicle, or rebuilding the Saturns, or Shuttle-derived vehicles, or any of that. And we ain’t going to get an OTV. We have to think in terms of what we’ve got. We have to develop an architecture based on Shuttle and the available low-lift expendables.”

“Off the shelf and to the Moon.” Frank grinned.

“And what,” Jays said quietly, “about cost?”

Geena took a deep breath. What she was about to say went against years of ingrained NASA cultural orientation.

“Forget about the cost.”

Frank spluttered. “ What?”

“I know. It’s hard. But cost isn’t going to be a factor here. Timescale is all. It’s a mind game, guys. The rules are, assume you can spend what you like, but all you can do is requisition existing components.”

“Umm.” Frank pulled at his lip. “Your mission, should you choose to accept it…” He pulled over another napkin, and sketched Earth and Moon, this time as two spheres. He drew tight circular orbits around each of Earth and Moon, then a figure-of eight around the two worlds.

“Let’s be specific about what we have to achieve here. If we are restricted to the current fleet of medium-lift vehicles, we have to consider Earth orbit rendezvous. Several launches, by the Shuttle and other vehicles, carrying up the components of the mission, to be assembled there. Probably using Station as a refuelling shack.

“First of all we need propellant for the TLI burn.” He drew a little arrow, at the Earth end of the figure-8. “Trans-lunar injection. We coast for three days to the Moon. We need our habitat vehicle to keep us alive. Then LOI: lunar orbit insertion, another burn, which we have to carry fuel for, to place us in orbit around the Moon. Next, into the lander. A deorbit burn, descent, soft-land standing on your rockets. More fuel, of course. Ascent back to orbit, maybe using the same engines — maybe not, like Apollo. Rendezvous in lunar orbit. Then the trans-Earth injection, coast back to Earth, probably aerobrake to orbit and have Shuttle come pick you up.”

“Pretty much like Apollo,” Jays said.

“Well, the rules of celestial mechanics haven’t changed. Almost certainly this architecture is going to provide us with the minimum-weight configuration. You could consider direct-ascent, for instance, where you take your whole ship, transfer habitat and all, down to the surface… But we ran some studies a few years ago along these lines, about how light, how cheap you could get. It wasn’t encouraging.”

“Stick to what you have,” Geena said.

“Let’s start with the lander. Everything else is going to scale to that. Now, the old Apollo Lunar Module was around sixteen tons, full up weight. But that included a surface shelter for six man-days on the Moon, effectively. And there were a lot of structural costs in the mass estimates, because of the split between ascent and descent stages, and the nature of the design. We did some studies that showed you could cut that to maybe a quarter.”

Jays snorted. “Bull hockey. Believe me, that old LM was just a bubble of aluminum. Those Grumman guys shaved it thin.”

Frank grinned. “Old man, that bird will look like a Chevy compared to what I’ll show you now.” He quickly sketched an Apollo LM, the familiar spidery descent stage, the bulbous ascent stage. “The whole thing stood maybe twenty-three feet tall. Now look at this.” Alongside he sketched something that looked like a scale model of the Apollo descent stage. There,” he said. “Six feet tall. Nothing but fuel tanks, legs and a rocket engine. The structural integrity is actually expressed through the tanks themselves.”

Jays looked closely. “No ascent stage?”

“You use the same engine for ascent as for descent. You refuel on the surface, from an unmanned tanker.”

Geena, looking at the blurred little sketch, said uneasily, “Where’s the cabin?”

That wolf grin again. “What cabin?” And Frank sketched on two stick figures with space helmets, side by side, standing on the platform, holding onto some kind of rail. “We call it the open cockpit design.”

“Jesus,” Jays breathed.

“Well, we had to keep the weight down,” Frank said. “It was a strong, closed design.” He sighed. “But we never got to build it, of course. And we couldn’t do it now in a couple of weeks. So I guess we can’t use any of this.” He made to crumple the napkin, but Geena covered his hand to stop him.