‌“This is Earth gravity, question?” Rocky asks. His ball rests on the control-room floor next to the pilot seat.‌

I check the Centrifuge control screen. We are up to full rotational velocity and spool extension. The crew compartment has done the 180-degree turn correctly. The diagram shows the two halves of the ship at full separation. We are spinning smoothly in the void. The “Lab Gravity” value reads “1.00 g.”

“Yes. This is Earth gravity.”

He steps side to side, rolling his geodesic dome one face back and forth. “Not much gravity. What is value, question?”

“Nine point eight meters per second per second.” “Not much gravity,” he repeats. “Erid gravity is 20.48.”

“That’s a lot of gravity,” I say. But that’s to be expected. He’d told me all

about Erid before, including its mass and diameter. I knew their surface gravity had to be roughly double Earth’s. Nice to have my calculations verified, though.

And side note: wow. Rocky’s mass is 168 kilograms. That means on his homeworld he tips the scales at almost 800 pounds. And that’s his native environment, so I assume he can move around just fine.

Eight hundred pounds and can skitter around effortlessly. Mental note: Do not get in an arm-wrestling match with an Eridian.

“So,” I say, leaning back in the pilot’s seat. “What’s the plan? Fly into the Petrova line and get some Astrophage?”

“Yes! But first I make xenonite room for me.” He points down the hatchway toward the rest of the crew compartment. “Mostly in sleep room. But tunnels in lab and small area in control room. Is okay, question?”

Well, he can’t just stay in a ball forever. “Yes, that’s fine. Where is the xenonite?”

“Xenonite parts in bags in dormitory. Liquids. Mix. Become xenonite.” Like epoxy. But really, really strong epoxy.

“Interesting! Someday I want to know all about xenonite.” “I not understand science. I just use. Apology.”

“That’s okay. I can’t explain how to make a thinking machine. I just use

it.”

“Good. You understand.”

“How long will your xenonite construction take?”

“Four days. Could be five days. Why you ask, question?” “I want to work fast.”

“Why so fast, question? Slower is safer. Less mistakes.”

I shift in my chair. “Earth is in a bad state. It’s getting worse all the time. I have to hurry.”

“Not understand,” says Rocky. “Why Earth so bad so fast, question? Erid go bad slower. Have at least seventy-two years before big problems.”

Seventy-two years? Man, I wish Earth had that kind of time. But seventy- two years from now Earth will be a frozen wasteland and 99 percent of the human population will be dead.

Why isn’t Erid as badly affected? I furrow my brow. I only have to think for a moment before I have my answer: It’s all about thermal energy storage.

“Erid is much hotter than Earth,” I say. “And Erid is much larger with a much thicker atmosphere. So Erid has a whole lot more heat stored in its air. Earth is getting cold fast. Very fast. In fourteen more years, most humans will be dead.”

His voice becomes monotone. It’s a very serious intonation. “Understand.

Stress. Concern.” “Yes.”

He clicks two claws together. “Then we work. We work now! Learn how to kill Astrophage. You return to Earth. You explain. Save Earth!”

I sigh. I’m going to have to explain this eventually. May as well be now. “I’m not going back. I’m going to die here.”

His carapace shudders. “Why, question?”

“My ship only had enough fuel for the trip here. I don’t have enough to go home. I have tiny little probes that will return to Earth with my findings. But I will stay here.”

“Why is mission like this, question?”

“This was all the fuel my planet could make in time.” “You knew this when you left Earth, question?”

“Yes.”

“You are good human.”

“Thanks.” I try not to think about my impending doom. “So, let’s collect Astrophage. I have ideas for how we can get some samples. My equipment is very good at detecting trace amounts—”

“Wait.” He holds up a claw. “How much Astrophage you ship need for return to Earth, question?”

“Uh…just over two million kilograms,” I say. “I can give,” he says.

I sit up in my chair. “What?!”

“I can give. I have extra. Can give that much and still have plenty for my return to Erid. You can have.”

My heart skips a beat. “Seriously?! It’s a lot of fuel! Let me repeat it: two million kilograms. Two times ten to the sixth power!”

“Yes. I have much Astrophage. My ship was more efficient than planned on trip here. You can have two million kilograms.”

I fall back into my seat. I pant. I almost hyperventilate. My eyes well up. “Oh my God…”

“No understand.” I wipe away tears.

“You are okay, question?”

“Yes!” I sob. “Yes, I’m okay. Thank you! Thank you thank you!” “I am happy. You no die. Let’s save planets!”

I break down, crying tears of joy. I’m going to live!

—

Half the Chinese crew stood on the flight deck. Some were actually doing their jobs, but most were there to catch a look at humanity’s saviors. The whole science team was there as well. The same set of usual suspects we had at our weekly status meetings. Stratt, me, Dimitri, Lokken, and our latest science addition, Dr. Lamai. Oh, and no science team would be complete without a gambling-addicted swindler, so Bob Redell was there too.

To be fair, Bob had done his job well. He had managed the Sahara Astrophage Farm magnificently. It’s rare to find a scientist who is also a good administrator. It was no easy task, but the farm was generating Astrophage at the levels he’d promised.

The helicopter came in low and slow, then landed perfectly on the helipad. A ground crew rushed up to secure it. The rotors remained spinning and the cargo door opened.

Three people walked out, each dressed in blue jumpsuits, each bearing their country’s flag on the shoulder. A Chinese man, a Russian woman, and an American man.

The ground crew ushered them to a safe distance, and the chopper took off again. Moments later, a second helicopter landed. Just like the first, this helicopter carried three astronauts. In this case, a Russian man, a Russian woman, and an American woman.

These six would be the prime and backup crews for the Hail Mary. Either of the helicopters could easily have carried all six astronauts, but Stratt had a very strict rule: Under no circumstances could any crewmember and their backup share a plane, helicopter, or car. Each position was specialized and would require years of specific training. We wouldn’t want one car crash to ruin humanity’s chances of survival.

The candidate pool wasn’t deep. There just weren’t many coma-resistant people out there who had “the right stuff” and were willing to go on a suicide mission.

Still, even with the reduced pool, the winnowing and selection process had been long, brutal, and filled with endless politicking by every government involved. Stratt stayed firm and insisted on only the best candidates, but some concessions had to be made.

“Women,” I said. “Yes,” Stratt grumbled.

“Despite your guidelines.” “Yes.”

“Good.”

“No, it isn’t.” She frowned. “I got overruled by the Americans and Russians on it.”

I folded my arms. “I never would have thought a woman would be so sexist against women.”

“It’s not sexism. It’s realism.” She righted a strand of hair that had blown into her face. “My guidelines were that all candidates must be heterosexual men.”

“Why not all heterosexual women?”

“The vast majority of scientists and trained astronaut candidates are men. It’s the world we live in. Don’t like it? Encourage your female students to get into STEM. I’m not here to enact social equality. I’m here to do whatever’s necessary to save humanity.”

“Still seems sexist.”

“Call it what you like. There’s no room on this mission for sexual tension. What happens if there’s some kind of romantic entanglement? Or dispute? People kill for less.”

I looked across the deck to the candidates. Captain Yang welcomed them aboard. He took special interest in his countryman—the two were all smiles and handshakes.

“You didn’t want a Chinese guy either. You thought their space program was still too young. But I hear you picked him to be the prime crew commander.”

“He’s the most qualified. So he’s the commander.”

“Maybe the Russians and Americans over there are qualified too. Maybe the people literally saving the world will keep it professional. Maybe cutting off literally half of the talent pool because you’re afraid astronauts can’t keep it in their pants isn’t a good idea.”

“We’ll have to hope so. The Russian woman—Ilyukhina—is on the prime crew as well. She’s a materials expert and by far the best candidate for the task. The science expert is Martin DuBois—the American man. Two men and one woman. Recipe for disaster.”

I put my hand to my chest in mock surprise. “Goodness me! DuBois appears to be black! I’m surprised you allowed it! Aren’t you afraid he’ll ruin the mission with talk of rap music and basketball?”

“Oh, shut up,” she said.

We watched the astronauts get surrounded by deck crew. They were absolutely starstruck—especially with Yáo.

“DuBois has three doctorates—physics, chemistry, and biology.” Stratt pointed to the American woman. “Over there is Annie Shapiro. She invented a new kind of DNA splicing that’s now called the Shapiro method.”

“Seriously?” I said. “The Annie Shapiro? She invented three entire enzymes from scratch to splice DNA using—”

“Yes, yes. Very smart lady.”

“She did it for her PhD thesis. Her thesis. Do you know how many people are on track for a Nobel Prize from research they did in grad school? Not many, I can tell you that much. And she’s your second choice for the science expert?”

“She’s the most talented DNA splicing specialist alive. But DuBois has strength in a huge variety of fields, and that’s more important. We don’t know what they’re going to encounter out there. We need someone with a broad knowledge base.”

“Amazing people,” I said. “Best of the best.”

“I’m glad you’re impressed. Because you’ll be training DuBois and Shapiro.”

“Me?” I asked. “I don’t know how to train astronauts!”

“NASA and Roscosmos will teach them the astronaut stuff,” she said. “You’re going to teach them science stuff.”

“Are you kidding? They’re way smarter than me. What would I teach them?”

“Don’t sell yourself short,” said Stratt. “You’re the world’s leading expert on Astrophage biology. You’re going to impart every single thing you know about it to both of them. Here comes the prime crew.”

Yáo, Ilyukhina, and DuBois walked over to Stratt.

Yáo bowed. He spoke with a very slight accent, but otherwise perfect English. “Ms. Stratt. It is an honor to finally meet you. Please accept my deepest gratitude for selecting me as the commander for this critical mission.”

“Nice to meet you too,” she said. “You were the most qualified. No thanks required.”

“Hello!” Ilyukhina lunged forward and hugged Stratt. “I’m here to die for Earth! Pretty awesome, yes?!”

I leaned to Dimitri. “Are all Russians crazy?”

“Yes,” he said with a smile. “It is the only way to be Russian and happy at the same time.”

“That’s…dark.” “That’s Russian!”

DuBois shook Stratt’s hand and spoke so softly as to be almost inaudible.

“Ms. Stratt. Thank you for this opportunity. I won’t let you down.”

I and the other science leads all shook hands with the three astronauts. It was a disorganized affair, more like a cocktail mixer than a formal meeting.

In the middle of it all, DuBois turned to me. “I believe you’re Ryland Grace?”

“Yeah,” I said. “It’s an honor to meet you. What you’re doing is just…I can’t even comprehend the sacrifice you’re making. Or should I not talk about it? I don’t know. Maybe we don’t talk about it?”

He smiled. “It’s on my mind quite often. We don’t have to avoid the subject. Besides, you and I are birds of a feather, it would seem.”

I shrugged. “I guess so. I mean, you’re way more advanced than I am, but I do love cellular biology.”

“Well, yes, that too,” he said. “But I was talking about coma resistance. I hear you have the coma-resistance markers, just like me and the rest of the crew.”

“I do?”

He raised his eyebrow. “They didn’t tell you?”

“No!” I shot a look over to Stratt. She was busy talking to Embezzler Bob and Commander Yáo. “First I’m hearing of it.”

“That’s odd,” he said.

“Why wouldn’t she tell me?”

“You’re asking the wrong person, Dr. Grace. But my guess is they only told Stratt and she only told people who needed to know.”

“It’s my DNA,” I grumbled. “Someone should have told me.”

DuBois deftly changed the subject. “In any event: I am looking forward to learning all about the Astrophage life-cycle. Dr. Shapiro—my counterpart on the backup crew—is also very excited. We shall be a classroom of two, I suppose. Do you have any experience teaching?”

“Actually, yes,” I said. “A lot.” “Excellent.”

—

I’m all smiles. It’s been three days since I found out I won’t die and I’m still all smiles.

Well, actually, I could still easily die. The trip home is long and dangerous. Just because I survived my coma on the way here, that doesn’t mean I’ll survive it on the way home. Maybe I can stay awake and just eat the feeding- tube slurry when my normal food runs out? I can do four years all alone, right? We were in comas to keep from killing one another. But solitary confinement is a whole different set of psychological damage. I should read up on it.

But not now. Right now I have to save Earth. My own survival is a problem for later. But it’s a problem, not a hopeless guarantee of death.

The light on the Centrifuge screen blinks green.

“Gravity at full,” I say with a smile.

We were back in zero g for a short time, but now I have the centrifuge going again. I had to “spin down” because I needed to use the engines. We can’t have centrifugal gravity and propulsion at the same time. Just imagine firing up the spin drives while the ship is in two pieces connected by a hundred meters of cable. It’s not a pleasant thought.

During the decades (gasp!) that Rocky’s been here, he surveyed the system very well. He gave me all the information he’d accumulated. He cataloged six planets, noted their size, mass, positions, orbital characteristics, and general atmospheric makeup. He didn’t have to travel around to do it. He just did astronomical observations from the Blip-A. Turns out Eridians are as curious about things as humans are.

And it’s a good thing too. This isn’t Star Trek. I can’t just flip on a scanner and get all that information about a star system. It took Rocky months of observations to get things at this level of detail.

And more important, Rocky knows all about the local Petrova line. As expected, it goes to one specific planet—probably the one that has the most carbon dioxide. In this case, it’s the third planet from the star, “Tau Ceti e.” At least, that’s what Earth calls it.

So that’ll be our first stop.

Sure, we could fly the Hail Mary through any part of the Petrova line and get some Astrophage that way. But we’d only intersect the line for a few seconds. A solar system is not a static thing. We have to keep moving at least fast enough to maintain orbit around the star.

But Tau Ceti e is a nice, big planet in the widest part of the Petrova line. We can park the Hail Mary in orbit and be immersed in local Astrophage for half of every orbit. And we can stay there as long as we want, getting as much data as we need to about the Astrophage here and the dynamics of the Petrova line itself.

So we’re on our way to the mysterious planet.

I can’t just ask Mr. Sulu to plot a course. I spent two days doing math, checking my work, and rechecking my work before I figured out the exact angle and thrust to apply.

Sure, I have 20,000 kilograms of Astrophage left. And yes, that’s quite a lot of fuel considering I can get 1.5 g’s by spending 6 grams per second. And yes, Rocky’s ship apparently has scads of Astrophage (I still don’t understand how he has so much extra fuel). But I’m conserving fuel anyway.

I got us going a good head of steam and we’re on course for Tau Ceti e. I’ll do the orbital-insertion burn in about eleven days. While we wait, we may as well have gravity. So we’re back to centrifuge mode.

Eleven days. Truly astonishing. The total distance we’ll be traveling to get there is over 150 million kilometers. That’s about the same as the distance from Earth to the sun. And we’re doing it in eleven days. How? By having an absurd velocity.

I did three hours of thrust to get us going, and I’ll do another three when we get to Tau Ceti e to slow down. Right now, we’re cruising along at 162 kilometers per second. It’s just ridiculous. If you left Earth at that speed, you’d get to the moon in forty minutes.

This entire maneuver, including the burn I’ll have to do to slow down at the end, will consume 130 kilograms of fuel.

Astrophage. Crazy stuff.

Rocky stands in a bulb of clear xenonite in the floor of the control room. “Boring name,” Rocky says.

“What? What name is boring?” I ask.

He’d spent days building up the Eridian Zone throughout the ship. He even installed his own new tunnels from deck to deck. It’s like having giant hamster Habitrails running everywhere.

He shifts his weight from one handhold to another. “Tau Ceti e. Boring name.”

“Then give it a name.”

“Me name? No. You name.”

“You were here first.” I unclip my seatbelts and stretch out. “You identified it. You plotted its orbit and location. You name it.”

“This is you ship. You name.”

I shake my head. “Earth-culture rule. If you’re at a place first, you get to name everything you discover there.”

He thinks it over.

Xenonite is truly amazing. Just a centimeter of transparent material separates my one-fifth atmosphere of oxygen pressure from Rocky’s 29 atmospheres of ammonia. Not to mention my 20 degrees Celsius from Rocky’s 210 degrees Celsius.

He’s taken over more of some rooms than others. The dormitory is almost entirely his domain now. I insisted he move all his crap into his compartment, so we agreed he could have most of the space in there.

He also put a large airlock in the dormitory. He based it on the size of the Hail Mary’s airlock on the assumption that anything important in the ship would likely be small enough to fit through that. I can’t ever go into his zone. My EVA suit would never stand up to his environment. I’d get squished like a grape. The airlock is really so we can pass items back and forth.

The lab is mostly mine. He has a tunnel leading up the side and another teeing off to run along the ceiling and ultimately through the ceiling into the control room. He can observe any of the scientific stuff I do. But in the end, Earth equipment wouldn’t work in his environment, so it has to be in mine.

As for the control room…it’s tight. Rocky put the xenonite bulb in the floor next to the hatchway. He really did try to keep the intrusion to a minimum. He assures me the holes he added to my bulkheads won’t affect the ship’s structural integrity.

“Okay,” he finally says. “Name is ♫♩♪♫.”

I don’t need the frequency analyzer anymore. That was an A-below- middle-C major fifth, followed by an E-flat octave, and then a G-minor seventh. I enter it into my spreadsheet. Though I don’t know why. I haven’t had to look at that thing in days. “What does it mean?”

“It is name of my mate.”

I widen my eyes. That little devil! He never told me he had a mate! I guess Eridians don’t kiss and tell.

We’d covered some biological basics during our travels. I explained how humans make more humans, and he told me where baby Eridians come from. They’re hermaphrodites and they reproduce by laying eggs next to each other. Stuff happens between the eggs and one of them absorbs the other, leaving one viable egg that will hatch in one Eridian year—forty-two Earth days.

Laying eggs together is, basically, the Eridian equivalent of sex. And they mate for life. But this is the first I’ve heard of Rocky doing it.

“You have a mate?”

“Unknown,” Rocky says. “Mate possibly has new mate. I gone a long time.” “Sad,” I say.

“Yes, sad. But necessary. Must save Erid. You pick human word for ♫♩♪♫.” Proper nouns are a headache. If you’re learning German from a guy named

Hans, you just call him Hans. But I literally can’t make the noises Rocky

makes and vice versa. So when one of us tells the other about a name, the other one has to pick or invent a word to represent that name in their own language. Rocky’s actual name is a sequence of notes—he told it to me once but it has no meaning in his language, so I stuck with “Rocky.”

But my name is actually an English word. So Rocky just calls me the Eridian word for “grace.”

Anyway, now I have to come up with an English word that means “Rocky’s spouse.”

“Adrian,” I say. Why not? “Human word is ‘Adrian.’ ” “Understand,” he says. He heads down his tunnel into the lab.

I put my hands on my hips and crane my neck to watch him leave. “Where

are you going?” “Eat.”

“Eat?! Wait!”

I’ve never seen him eat. I’ve never even seen an orifice other than the radiator vents on top of his carapace. How does he get food in? For that matter, how does he lay eggs? He’s been pretty cagey about it. He ate in his ship when we were connected. And I think he snuck a few meals here and there while I slept.

I scamper down the ladder into the lab. He’s already halfway down his vertical tunnel, climbing the many handholds. I keep up, climbing my own ladder. “Hey, I want to watch!”

Rocky reaches the lab’s floor and pauses. “Is private. I sleep after eat. You watch me sleep, question?”

“I want to watch you eat!”

“Why, question?” “Science,” I say.

Rocky shifts his carapace left and right a few times. Eridian body language for mild annoyance. “Is biological. Is gross.”

“Science.”

He wiggles his carapace again. “Okay. You watch.” He continues downward.

“Yes!” I follow him down.

I squeeze into my little area of the dormitory. All I have these days is my bed, the toilet, and the robot arms.

To be fair, he doesn’t have much room either. He has most of the volume, but it’s laden with all his junk. Plus, he made an ad-hoc workshop in there and a life-support system out of parts from his ship.

He opens one of his many soft-sided bags and pulls out a sealed package. He tears it open with his claws and there are various shapes I can’t identify. Mostly rocky material like his carapace. He sets about tearing them apart into smaller and smaller pieces with his claws.

“That’s your food?” I ask.

“Social discomfort,” he says. “No talk.” “Sorry.”

I guess eating for them is something gross that is to be done in private.

He tears the rocky chunks off the food and exposes meat underneath. It’s definitely meat—it looks just like Earth meat. Considering we are almost certainly descended from the same basic building blocks of life, I bet we use the same proteins and have the same general solutions to various evolutionary challenges.

Once again I’m struck by melancholy. I want to spend the rest of my life studying Eridian biology! But I have to save humanity first. Stupid humanity. Getting in the way of my hobbies.

He pulls all of the rocky chunks off the meat and sets that aside. Then he tears the meat up into small chunks. At all times, he keeps the food on the packaging it came in. It never touches the floor. I wouldn’t want my food touching the floor either.

After a while, he has shredded the edible parts of his meal down as far as his hands can do it. Far more than any human would with their food.

Then he steps over to the other side of his compartment, leaving his food where it was. He pulls a flat, cylindrical container from a sealed box and places it under his thorax.

Then things…get gross. He did warn me. I can’t complain.

The rocky armor on his abdomen splits and I see something fleshy rip open underneath. A few drops of shiny silver liquid dribbles out. Blood?

Then a gray blob plops out of his body into the pan. It lands with a damp- sounding splat.

He seals the pan and puts it back in the box it came from.

He returns to the food and flips over onto his back. The gaping abdominal hole is still open. I can see inside. There’s soft-looking flesh in there.

He reaches over with a few of his hands and grabs some choice morsels of food. He brings them to his opening and drops them in. He repeats this process, slowly and methodically, until all the food is in his…mouth? Stomach?

There is no chewing. There are no teeth. As far as I can tell, there are no moving parts inside.

He finishes the last of his meal, then lets his arms fall limp. He lies spread- eagle on the floor, immobile.

I resist the urge to ask if he’s okay. I mean, he looks dead. But this is probably just how Eridians eat. And poop. Yeah. I’m guessing that blob that came out earlier was what’s left of his previous meal. He’s a monostome— that is, the waste comes out the same opening that food goes into.

The opening in his abdomen closes slowly. A scab-like material forms where the break in the skin was. But I don’t see it for long. The rocky abdominal covering folds back into place shortly thereafter.

“I…sleep…” he slurred. “You…watch…question?”

A food coma for Rocky is no small thing. This doesn’t look voluntary at all. This is a biologically enforced post-meal siesta.

“Yes, I watch. Sleep.”

“Sle…ee…p…” he mumbles. Then he conks out, still belly-up on the floor.

His breathing speeds up. It always does when he first falls asleep. His body has to dump all the heat in the hot circulatory system.

After a few minutes, he stops panting. Now I know he’s well and truly asleep. Once he gets past the panting phase, I’ve never seen him wake back up in less than two hours. I can sneak off to do my own thing. In this case, I’ll write down everything I just saw about his digestive cycle.

Step 1: Subject defecates from mouth.

“Yup,” I say to myself. “That was pretty freaking gross