Five hundred thousand calories.
I need five hundred thousand calories or I am going to die.
Maybe less, I’m doing back-of-the-envelope, easy numbers head math, but that’s a good estimate.
Scientists like precise numbers, NASA is full of scientists who love really precise numbers. I’m an engineer. I like easy numbers that I can crunch quickly in my head and if they are accurate enough to be within the tolerance that I need, good enough.
I’m sure at least one scientist back home has calculated down to the third fucking decimal point exactly how many calories I need but I don’t have a spare fuck to give for that level of precision at the moment.
Alright, let’s go over the situation.
I’m an astronaut aboard the Iris. We were on the final leg of our mission to Mars. Actually, we had been to Mars and were returning home when docking with the shuttle went badly.
Badly is a bit of an understatement. We fucking collided.
The Iris is in constant transit between Earth and Mars. It never stops, it doesn’t enter orbit around either body. It just goes back and forth between the two planets.
This is the most energy-efficient way to conduct multiple Mars missions. A shuttle takes a crew from Earth and docks with the Iris as the Iris approaches Earth. The new crew boards the Iris and transfers all the supplies they need with them. The old crew enters the shuttle with the samples they collected from Mars, undocks, and returns to Earth. Once the Iris reaches Mars, the process repeats. The crew that was just on Mars takes a shuttle up to Iris with their samples, and the crew that boarded from Earth nine months before takes the shuttle down to Mars with the rest of their supplies.
This whole process is about conserving energy in order to conserve fuel. Because Iris never enters orbit, it is on a pseudo-free return trajectory from Earth to Mars and back again.
All rocket engines work the same way, all based on Newton’s third law of motion. A rocket pushes something out the back in one direction. That pushes the body of the rocket in the other direction. The force the rocket engine pushes the body of the rocket with, we call thrust. Most people are familiar with chemical rocket engines. Fuel and oxygen are mixed in a chamber and ignited. Hot gas shoots out the back of the rocket engine pushing the rocket.
That works very well for short durations. Lots of fuel is consumed to generate lots of thrust very quickly. That’s not so good for long-duration space travel.
For that, a ship like the Iris is powered by ion engines. Ion engines use electricity to propel ionized gas at extremely high velocity. Remember that force is mass times acceleration. Chemical rockets use huge amounts of mass and accelerate it to supersonic speed. The Saturn V main engines had an exhaust gas velocity of approximately 2,400 meters per second or Mach 7.
Ion engines use very little exhaust mass but propel it at 50 kilometers per second, or more than 20 times the exhaust velocity of a chemical rocket.
This allows a spaceship to generate thrust with very little fuel consumption. We don’t count electricity because the Iris is powered by a nuclear reactor like a submarine. We only concern ourselves with the amount of xenon gas we have to have.
The downside to ion engines is that the way they produce thrust means that they produce low amounts of thrust for long periods of time. Chemical engines, conversely, produce high amounts of thrust for short periods of time. It’s the difference between total impulse and specific impulse and gets into all sorts of rocket efficiency technical bullshit that gives aerospace and propulsion engineering a hard-on that really doesn’t matter right now.
Suffice it to say, when the Iris has a problem, we can’t just flip the ship around and fire up the engines and go home.
I am along for the ride. At best, I can fire up the engines and accelerate towards Mars, slingshot around it as fast as possible without launching myself out toward Jupiter, then decelerate hard as I approach Earth and cut some of my travel time, but there is no way of making a U-turn and going straight home.
So…
The shuttle collided with us as we approached Earth.
Our replacement crew was killed.
The entire docking assembly was ripped open and the rest of my crew was killed.
I was busy in the engine compartment preparing to transfer ship’s maintenance to the next engineer, which is why I survived when the forward compartment decompressed.
The automated ship systems did what they were designed to do and put us back on course.
That was the problem. trans
During the collision, our communication system was damaged. NASA sent a signal to Iris to go into emergency park mode and enter orbit around Earth. Iris never read the signal and so continued on her merry way back to Mars.
Why didn’t I do anything to try and fly the ship?
One, I’m not a pilot.
Two, we don’t actually fly the fucking ship from up here.
Remember everything I said about how ion engines work? It’s not like we have a joystick and can pilot the ship like a jet. Some big supercomputer back on Earth calucaltes the most fuel-efficient trajectory it can and transmits that to Iris so it can adjust its trajectory over days and weeks of trust at a Newton at a time.
That’s why the ship’s internal computer is programmed with “in case of emergency, resume pre-planned trajectory.”
So now I’m headed back to Mars.
Seven months out, Seven months back. Give or take a little bit.
Hence my need for five hundred and forty thousand calories or I am going to die.
It should be a lot more than that. NASA plans on us having between 2,100 and 2,800 calories per day, but I don’t have that.
As an adult human male, I can survive at about 1,200 calories per day. It will suck. It will suck a lot, but it’s doable. Below 1,000 calories per day, I’ll die.
Fourteen months at 1,200 calories per day, that’s five hundred and four thousand calories. Call it five hundred thousand because I don’t have any spare fucks for that last four thousand to carry over in my math.
NASA sends us up with prepared meals, each one containing 1,250 calories. We were a crew of six. One day’s worth of meals for the entire crew is 22,500 calories.
I’m set right?
Wrong.
The number one concern of any and every space flight is weight. We’re always worried about weight.
Force is mass times acceleration. Thrust is force. Trust comes from fuel. The more mass you have to accelerate to launch velocity the more fuel it takes.
Weight, weight, weight, weight, fucking weight.
These missions are highly planned. Everyone has their food rationed out over the course of the mission. Ideally, we don’t want to have any more weight than we need so we don’t carry more food than we need for the mission. We have a little bit of wiggle room so in stores we have one week of extra rations. There were two days left in the mission for our transfer window. So I have nine days worth of food for a crew of six.
That is a total of 162 food packs or 202,500 calories. God dammit, I’m going to have to get precise with my math. Fuck!
Stretch that out on 1,200 calories per day, or just under one food pack per day, and let’s say that’s 170 days’ worth of food.
Great.
That brings me most of the way to Mars.
Why am I focused on food? Why not air or water? That’s the first thing you learn in survival training. Three minutes without air, three days without water, or three weeks without food is what it takes to kill you.
I have air and water. I have it in abundance. I have enough air for a crew of six and it is on a closed-loop replenishment system. Even after the forward compartment decompressed, refilling it with air from the reserves, I have plenty. Water is also a closed-loop, and I have enough for a crew of six.
Food is the one resource that isn’t on a closed-loop.
I’m not even going to entertain the idea of trying to make it one.
I have under half as much food as I need.
What about the crew currently on Mars?
Fuck ’em. I know that sounds mean but without the resupply, I don’t have food for their return trip either. They aren’t bringing any food up from Mars with them. And with the docking assembly gone, they can’t get aboard anyway. NASA is going to have to figure out how to help them without the Iris.
I need to focus on myself. What are my options?
Die. I can always die. But I don’t really want to do that.
I need to make up a difference of 300,000 calories and I’m not growing fucking potatoes on a spaceship.
What do I have?
I have 162 prepared meal packets, a bunch of rocks and shit from Mars, a mostly intact spaceship, and… fuck…
Decompression in a spaceship is not like what you see in the movies. The ship doesn’t explode and blow everything out into space. The air vents but most of what is in the ship stays in the ship.
Lean pork is roughly 1,100 calories per pound. Give or take, roughly 60% of a live harvested animal becomes food.
A 180 lbs pig is roughly 120,000 calories after processing.
Long pig is what some tribes in the Pacific Islands called it.
I have five crew members.
No, I have five long pig vacuum frozen in the forward compartment.
At 120 to 180 lbs each, I have almost half a million calories of unprocessed lean long pork aboard.
It wouldn’t be difficult to recover with an EVA one at a time as needed. Out the EVA airlock, around to the docking assembly, manually open the docking door, …, and return.
I have a microwave oven. I have tools.
I have fourteen months to fix the communications system and work out a plan with NASA on how to get me off this interplanetary meat locker.
I have enough calories.
I will survive.
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