171: Velocity

It takes about two weeks for Captain Klees to find an algae pancake recipe that’s halfway tolerable, and by then the first hydroponic root vegetables are almost ready. By order of our dear captain, we ground crew are barred from eating the root vegetables beyond a sort of good faith first taste (just in case any particularly paranoid Hylarans are worried we’re trying to poison them or something), which we joke about as him wanting to get as much mileage out of his new recipe as possible, but we all understand the logic of it. The hydroponics aren’t extensive enough to feed everyone on the ground yet, especially when the novel crop is probably going to be very popular among a population that’s only ever had protein loaf. A lot of people aren’t going to get vegetables for a long time, and the simple truth is that we’ve had vegetables before and the Hylarans haven’t. So nobody protests when Captain Klees makes sure we’re at the bottom of the priority list.

Tinera stabs one-handed at a pile of green pancakes only marginally more palatable than the food blocks that Antarctica sends and frowns. “This spaceship mission is still fucking impossible.”

“We’ve only just started,” I point out, spearing a forkful of my own. The two of us are sharing a late breakfast, the rest of the crew already out and about. “It costs us nothing to try but time.”

“And the little fact that if we fail and have to set all the colonists down here anyway, the Hylarans might think they were betrayed and we failed on purpose.”

“How? They know more about the tech we need than we know. They’d understand the reasons for failure better than us. And even if we fail, we’ll work out a lot of social issues simply working together on this project. Besides. What if we succeed?”

She gives a little dismissive snort. I don’t respond. Tinera was one of the people most enthusiastic about this plan; if she’s getting all pessimistic, it means that a specific problem is bothering her. I just wait, and after a few seconds, she speaks.

“Have you heard Denish’s latest proposal?”

“I haven’t.”

“He thinks we should cap the speed of the ship at 20% of C.”

“Well, when it’s in systems looking for asteroids and soforth, it can hardly be expected to go faster than that without an acceleration rate too high to – ”

“Not just in systems. Altogether. Including between stars.”

“A maximum of twenty per cent? No! Not possible.”

She shrugs. “He insists it’s necessary.”

“Why? The Courageous did just fine getting here going much faster than that. Twenty per cent means you’re getting negligible advantage from time dilation, not to mention the actual increased time of the journey as the star systems experience time. These stars are twenty to thirty light years away. He’s talking about putting a full century between any chance at resource collection.”

She shrugs again. “He says that without it, resource collection is a no-go anyway. The Courageous was designed so that most parts were potentially disposable if the strain of high speed relative to the interstellar medium caused serious issues; it could drop whole rings, as you well know. On a journey like this, we absolutely cannot afford to rely on gimmicks like that; we can’t afford to expect to just drop bits off the spaceship to solve problems. They have no central AI, damaged engines, and have had to weld the spine for structural safety, so there’s no remotely realistic way of adding mass to the cylindrical shape of the ship as it stands; our choices are to be limited by the space we have, or build onto the outside, losing the streamlined shape. Furthermore, asteroid mining means creating mining craft, which frankly I think it an impossible ask but even if we do do that, our choices are to bolt them to the outside of the ship or put them in the pod launch rings for intersystem travel, and those pod launch doors are far too small for useful mining craft. If you want useful asteroid mining, we’re losing the shape of the ship, which means that the interstellar medium is a serious danger at high speed. And that’s not even getting into the electrostatic shielding. That shielding is the only thing stopping the outside of the ship from being torn apart as it gets near c. It also means that robotic repairs can’t be done on the hull. Which was a stupid risk to take on the way here and an even stupider one to take on this journey.”

I groan. She’s right. If only we had a fully functional, brand new javelin up there, all of this would be so simple – do basically the same thing that was planned to bring us here from Earth. Twenty or so years in space, give or take, depending on how far away the new expolanet is (we haven’t picked one yet). But everything wrong with the javelin that slows it down means more time and more stress on other things, more need for materials, more things to slow it down further. Until we’re at a maximum speed of twenty per cent of the speed of light.

“The reactor,” I point out, “is built to be safe for at least a hundred and fifty years. We have a bit more than a century left in it. We need to update that, or make sure that the ship has the means to repair it indefinitely. We need to check what the disposable parts are and if we can be certain the ship will have access to replacements. Moving to an older reactor is out of the question because they would require far too much fuel. But updating means the crew up there building new reactor parts from scratch for a system almost a century and a half more advanced than the tech we’re used to. We’d better hope that the current design is easy to repair and replace so they can just keep that indefinitely.”

“If it’s not, solar panels might be a better bet.”

“Solar panels don’t last forever either. How easy is it to recycle all parts of the Hylarans’ solar panels? They’re incredibly efficient, but are they infinitely recyclable? The glass and soforth, yes, sure, but we need one hundred per cent recyclability if we’re capping the ship speed that low. More importantly, how feasible is it to recycle them after a few dozen years of being immersed in potentially radioactive space dust? Without the electrostatic shielding, every foray outside, or bringing anything in, is a potential radioactivity hazard. Also, without the shielding, there’s mechanical wear from space dust to worry about. The panels would be torn apart at high speeds. We might be looking at ten, maybe even five per cent of c as a maximum speed, which more than doubles the journey time, which causes problems with wear in themselves… although if the ship is slow enough, it can probably save a lot of fuel by deploying solar sails instead.” I give Tinera a little grin to let her know I’m joking. If we’re reduced to solar sail speeds, we might as well give up now.

“They’re waking an astronomy expert to try to predict the resource availability out there,” Tinera continues, “and trying to see what they can get on the Kleiner array. But at that distance, getting an accurate read on something as small as asteroids…”

“Waste of time to try,” I agree. “Even I know that. The planets should allow some estimate of what any asteroids might have, though.”

“We can’t even be certain how much material we can expect to find in each star system. Every step of this is another uncertainty that we’ll be gambling lives on.”

“We don’t have to launch until we have enough information to be sure it’s worth it.”

“Some of that information is just impossible to get. There’s going to be some level of gamble no matter what we do.”

“I know.” I chew a mouthful of pancake. “You know what really kills me?”

“What?”

“If we do eventually get the Courageous out and about again… we’ll never know if they are successful. We’ll be dead long before it’s possible to even predict that.”

“Unless they blow up a year or so into the journey. They’ll still be in radio communication then. Maybe even visible with a really sophisticated telescope.”

“Ha. Yeah, let’s hope that doesn’t happen.”

The rest of the crew return from… whatever their errand was. “Ah, you guys are up,” Captain Klees says, while Tal heads straight for the computer.

“We’re talking about transportation and supply issues for the Courageous,” I say. “Twenty per cent of c? Really?”

“I know,” Captain Klees says. “But they’re right; this is going to be a whole lot harder if they have to put everything inside the existing hull and can’t use robotics or half of the optics in flight.”

“The time between supply stops – ”

“I don’t see the issue,” Tal says, booting up the computer. “Asteroids are huge. Just grab a big chunk of iron and ice and take it the whole thing between stars with you.”

“The fuel requirements to drag along chunks of iron tens or hundreds of kilometers in diameter are not insignificant. And fuel has to be irrevocably lost; you need to dump it out the back to push the ship forward, no matter what propellant you’re using. Because of physics.”

“Unless you move it with solar sails,” Tinera says very quietly with a little smile, and I’m struck with the absurd image of a huge asteroid covered in comparatively teeny tiny solar sails and a bunch of astronauts yelling at it to move.

Dandelion pulls a liquid meal out of our little refrigerator, stabs a straw into it and takes a pensive sip. “I don’t think it’s going to come up,” she says.

“Not for us, but I imagine it’s going to become pretty relevant for the ship pretty quickly!” I point out.

“Nah. We can build a ship that’ll stay together for a century or so. That’s all they really need.”

“A century?! It took us forty years just to get here! With the distances involved, and moving as slowly as Denish wants to, there’s no way they’ll get to a habitable exoplanet in that kind of time!”

Dandelion looks at me in some surprise. “Yeah, that’s impossible in these circumstances. But do you think most of the people up there actually care about reaching another exoplanet?”