Chapter 25
I finally made it! I’m at the MAV!
Well, right this second, I’m back in the rover. I did go into the MAV to do a systems check and boot-up. I had to keep my EVA suit on the whole time because there’s no life support in there just yet.
It’s going through a self-check right now, and I’m feeding it oxygen and nitrogen with hoses from the rover. This is all part of theMAV’s design. It doesn’t bring air along. Why would it? That’s a needless weight when you’ll have a Hab full of air right next door.
I’m guessing folks at NASA are popping champagne right now and sending me lots of messages. I’ll read them in a bit. First things first: Get the MAV some life support. Then I’ll be able to work inside comfortably.
And then I’ll have a boring conversation with NASA. Well, the content may be interesting, but the fourteen-minute transmission time between here and Earth will be a bit dull.
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[13:07] HOUSTON: Congratulations from all of us here at Mission Control! Well done! What’s your status?
[13:21] MAV: Thanks! No health or physical problems. The rover and trailer are getting pretty worn out, but still functional. Oxygenator and regulator both working fine. I didn’t bring the water reclaimer. Just brought the water. Plenty of potatoes left. I’m good to last till 549.
[13:36] HOUSTON: Glad to hear it. Hermes is still on track for a Sol 549 flyby. As you know, the MAV will need to lose some weight to makethe intercept. We’re going to get youthoseprocedures within the day. How muchwater do you have? What did you do with urine?
[13:50] MAV: I have 550 liters of remaining water. I’ve been dumping urine outside along the way.
[14:05] HOUSTON: Preserve all water. Don’t do any more urine dumps. Store it somewhere. Turn the rover’s radio on and leave it on. We can contact it through the MAV.
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Bruce trudged into Venkat’s office and unceremoniously plopped down in a chair. He dropped his briefcase and let his arms hang limp.
“Have a good flight?” Venkat asked.
“I only have a passing memory of what sleep is,” Bruce said.
“So is it ready?” Venkat asked.
“Yes, it’s ready. But you’re not going to like it.”
“Go on.”
Bruce steeled himself and stood, picking up his briefcase. He pulled a booklet from it. “Bear in mind, this is the end result of thousands of hours of work, testing, and lateral thinking by all the best guys at JPL.”
“I’m sure it was hard to trim down a ship that’s already designed to be as light as possible,” Venkat said.
Bruce slid the booklet across the desk to Venkat. “The problem is the intercept velocity. The MAV is designed to get to low Mars orbit, which only requires 4.1 kps. But the Hermes flyby will be at 5.8 kps.”
Venkat flipped through the pages. “Care to summarize?”
“First, we’re going to add fuel. The MAV makes its own fuel from the Martian atmosphere, but it’s limited by how much hydrogen it has. It brought enough to make 19,397 kilograms of fuel, as it was designed to do. If we can give it more hydrogen, it can make more.”
“How much more?”
“For every kilogram of hydrogen, it can make thirteen kilograms of fuel. Watney has five hundred and fifty liters of water. We’ll have him electrolyze it to get sixty kilograms of hydrogen.
” Bruce reached over the desk and flipped a few pages, pointing to a diagram.
“The fuel plant can make seven hundred and eighty kilograms of fuel from that.”
“If he electrolyzes his water, what’ll he drink?”
“He only needs fifty liters for the time he has left. And a human body only borrows water. We’ll have him electrolyze his urine, too. We need all the hydrogen we can get our hands on.”
“I see. And what does seven hundred and eighty kilograms of fuel buy us?” Venkat asked.
“It buys us 300 kilograms of payload. It’s all about fuel versus payload. The MAV’s launch weight is over 12,600 kilograms. Even with the bonus fuel, we’ll need to get that down to 7,300 kilograms. So the rest of this booklet is how to remove over 5,000 kilograms from the ship.”
Venkat leaned back. “Walk me through it.”
Bruce pulled another copy of the booklet from hisbriefcase.
“There were some gimmes right off the bat. The design presumes five hundred kilograms of Martian soil and rock samples. Obviously we won’t do that.
Also, there’s just one passenger instead of six.
That saves five hundred kilograms when you consider their weight plus their suits and gear.
And we can lose the other five 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, CO 2 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 be using them,” 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 okay, go on.”
“Since Watney won’t be flying the ship,” Bruce continued, “he won’t need the 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 three redundant thrusters.
We’ll get rid of those. Also, the secondary and tertiary comm systems cango. ”
“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. 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 Nineteen.”
Venkat blinked. “You’re taking the front of the ship off?”
“Sure,” Bruce said. “The nose airlock alone is four hundred kilograms. The windows are pretty damn heavy, too. And they’re connected by Hull Panel Nineteen, 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 pickup 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 four percent.”
“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 okay if everything works the way it’s supposed to.”
“Yeah. Great,” Venkat said.
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[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 carrying out 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 the 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 getting stuff in is going to be annoying.
Bring the stuff into the rover, attach the bedroom to the airlock from the inside, inflate it, bring the stuff into 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.