Page 79 of The Martian

“If he electrolyzes his water what'll he drink?”

“He can electrolyze urine, so we only need to set a few liters aside for the last couple of days.”

“I see. And what does 780kg of fuel buy us?” Venkat asked.

“It buys us 300kg of payload. It's all about fuel versus payload. The MAV's launch weight is over 12,600kg. We need to get that down to 7,300kg. That's accounting for the bonus fuel. So the rest of this booklet is how to remove over five thousand kilograms from the ship.”

Venkat leaned back. “Walk me through it.”

Bruce pulled another copy of the booklet from his briefcase. “There were some gimmies right off the bat. The design presumes 500kg of Martian soil and rock samples. Obviously we won't do that. Also, there's just one passenger instead of six. That saves 500kg when you consider their weight plus their suits and gear. And we can lose the other 5 acceleration chairs. And of course, we'll remove all nonessential gear. The med kit, tool kit, internal harnessing, straps, and anything else that isn't nailed down. And some stuff that is.

“Next up,” he continued, “We're ditching all life support. The tanks, pumps, heaters, air lines, CO2 absorption system, even the insulation on the inner side of the hull. We don't need it. We'll have Watney wear his EVA suit for the whole trip.”

“Won't that make it awkward for him to use the controls?” Venkat asked.

“He won't use any controls,” Bruce said. “Major Martinez will pilot the MAV remotely from Hermes. It's already designed for remote piloting. It was remotely landed, after all.”

“What if something goes wrong?” Venkat asked.

“Martinez is the best trained pilot,” Bruce said. “If there is an emergency, he's the guy you want controlling the ship.”

“Hmm,” Venkat said cautiously. “We've never had a manned ship controlled remotely before. But ok. Go on.”

“Since Watney won't be flying the ship,” Bruce continued, “he won't need any of those controls. We'll ditch the control panels and all the power and data lines that lead to them.”

“Wow,” Venkat said. “We're really gutting this thing.”

“I'm just getting started,” Bruce said. “The power needs will be dramatically reduced now that life support is gone, so we'll dump three of the five batteries and the auxiliary power system. The Orbital Maneuvering System has 3 redundant thrusters. We'll get rid of those. Also, the secondary and tertiary comm systems can go.”

“Wait, what?” Venkat said, shocked. “You're going to have a remote controlled ascent with no backup comm systems?”

“No point,” Bruce said. “If the comm system goes out during ascent, the time it takes to reacquire will be too long to do any good. The backups don't help us.”

“This is getting really risky, Bruce.”

Bruce sighed. “I know, Venkat. There's just no other way. And I'm not even to the nasty stuff yet.”

Venkat rubbed his forehead. “By all means, tell me the nasty stuff.”

“We'll remove the nose airlock, the windows, and Hull Panel 19.”

Venkat blinked. “You're taking the front of the ship off?”

“Sure,” Bruce said. “The nose airlock alone is 400kg. The windows are pretty damn heavy, too. And they're connected by Hull Panel 19 so may as well take that, too.”

“So he's going to launch with a big hole in the front of the ship?”

“We'll have him cover it with Hab canvas.”

“Hab canvas? For a launch to orbit!?”

Bruce shrugged. “The hull's mostly there to keep the air in. Mars's atmosphere is so thin you don't need a lot of streamlining. By the time the ship's going fast enough for air resistance to matter, it'll be high enough that there's practically no air. We've run all the simulations. Should be good.”

“You're sending him to space under a tarp.”

“Pretty much, yeah.”

“Like a hastily loaded pick up truck.”

“Yeah. Can I go on?”

“Sure, can't wait.”

“We'll also have him remove the back panel of the pressure vessel. It's the only other panel he can remove with the tools on-hand. Also, we're getting rid of the auxiliary fuel pump. Sad to see it go, but it weighs too much for its usefulness. And we're nixing a Stage One engine.”

“An engine?”

“Yeah. The Stage One booster works fine if one engine goes out. It'll save us a huge amount of weight. Only during the Stage One ascent, but still. Pretty good fuel savings.”

Bruce fell silent.

“That it?” Venkat asked.

“Yeah.”

Venkat sighed. “You've removed most of the safety backups. What's this do to the estimated odds of failure?”

“It's about 4%.”

“Jesus Christ.” Venkat said. “Normally we'd never even consider something that risky.”

“It's all we've got, Venk,” Bruce said. “We've tested it all out and run simulations galore. We should be ok if everything works the way its supposed to.”

“Yeah. Great.” Venkat said.

[08:41]MAV: You fucking kidding me?

[09:55]HOUSTON: Admittedly, they are very invasive modifications, but they have to be done. The procedure doc we sent has instructions for each of these steps with tools you have on hand. Also, you'll need to start electrolyzing water to get the hydrogen for the fuel plant. We'll send you procedures for that shortly.

[09:09]MAV: You're sending me into space in a convertible.

[09:24]HOUSTON: There will be Hab canvas covering the holes. It will provide enough aerodynamics in Mars's atmosphere.

[09:38]MAV: So it's a ragtop. Much better.

LOG ENTRY: SOL 506

On the way here, in my copious free time, I designed a “workshop.” I figured I'd need space to work on stuff without having to wear an EVA suit. I devised a brilliant plan whereby the current bedroom would  become the new home of the Regulator and Oxygenator, and the now-empty trailer would become my workshop.

It's a stupid idea and I'm not doing it.

All I need is a pressurized area that I can work in. I somehow convinced myself that the bedroom wasn't an option because it's a hassle to get stuff into it. But it won't be that bad.

It attaches to the rover airlock, so the only way to get stuff in is annoying. Bring the stuff into the rover, attach the bedroom to the airlock from the inside, inflate it, bring the stuff in to the bedroom. I'll also have to empty the bedroom of all tools and equipment to fold it up any time I need to do an EVA.

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