I think space is awesome. I think going to Mars is awesome. I think it’s also important. I’m not going to make an argument why, but you can see one here.
A problem for human spaceflight is countering the negative impacts of moving in an environment where gravity is less than Earth’s. This is the predominant impetus for some space posts I’ll have as there is a ton here which can be applied to everyday people on Earth, and vice versa.
Sometimes I’ll hit on current treatments; sometimes I’ll hit on ways I think things could potentially be improved. Maybe this can be my small way to help the Mars movement.
I’ve tried to do my research here. I took a course on aerospace engineering and human spaceflight from MITx (some notes on that course here, here and here), I have one client who is a rocket scientist and have bounced some ideas off of, I do have an exercise science and mathematics background to begin with, (a lot of) etc. and I’ll try to stick to what I think I know best, but naturally I have to delve into other arenas some. If you have a background in this stuff and feel something could be more accurate, please let me know. If you would like to talk about these ideas some more (do I have any readers who work for NASA or in aerospace?), please let me know: firstname.lastname@example.org if you prefer email.
Finally, I want to stress, even if you’re not interested in space, I think this stuff can be valuable to learn about. Here is an index of what will be hit. Perhaps you’ll notice some areas you’re interested in for on Earth!
- Why is mass so critical?
- It costs how much to get to orbit? Taking an olive from every passenger saved an airline how much money?
- Our excessive bodyweight is part of what’s making the world warmer
- How big do astronauts need to be?
- Calculating how many calories you burn each day
- How many carbs make a pound? Protein? Fat? Where does that “3500 calories in a pound of fat” number come from?
- Manipulating our weight by not only how much we eat, but by what we eat (how to lose weight overnight)
- When what you eat affects performance, and when it doesn’t (do endurance athletes need carbs?)
- On the infinite machinations of bacon
- Why Beyonce is wrong and should stop yelling at me
- Some help from weed dealers
- Our unparalleled ability to pollute (wait, even space has too much garbage?)
- Exercise helps everything and everyone. Even astronauts.
- Machines vs free weights vs resistance bands- tension is tension. For the most part.
- The strongest guys in the world do a bunch of pulling on rubber bands?
- The shoulder joint likes to move; we should let it
- If you want to make or keep bone, you need to bang it around
- Cautionary tales for the elliptical, bike, and pool
- Nike knew this decades ago: Ounces matter
- Machines vs free weights vs resistance bands- tension is tension. For the most part.
- Tallying it up
- “One small step for a (wo)man; one giant leap for (hu)mankind”
Why is mass so critical?
I primarily signed up for the aerospace engineering and human spaceflight course for the human aspect. The first day of the class though, “uh, we’re doing rocket science.” With time to think about it though, I realize this is the way you want to learn it. Because so much stems from this equation, the rocket equation:
There are three variables we have to play with.
- Of the propellant and of everything else (the rocket and everything inside of it)
- Exhaust velocity
- throwing propellant out of the rocket
- Velocity of the rocket
- We can also think of this as how far are we traveling?
NASA tells us the exhaust velocity is dictated by the limits of chemistry, and we appear to have hit a limit already. Based on what the propellant gives, we get this:
This tells us if our rocket is a given mass, what portion of that mass must be propellant when we launch. Hydrogen-oxygen is the friendliest mass wise, as less of the vehicle needs to be propellant, 83%, compared to other chemistries. We can’t change this percentage. The mid 80s is as good as it gets. For comparison,
Notice how much mass the propellant takes up in a rocket versus other vehicles. These are ideal numbers. In reality, rocket mass often comes in around 97 percent being for fuel. Imagine if 97% of your car was gasoline! We can start getting the intuition of, “If the propellant is taking up so much mass, we have to be careful with how much mass everything else is.”
Next, the velocity of the rocket is dictated by where we want to go.
Again, we can’t change this. Given a certain distance from Earth requires a given amount of energy. Furthermore, we don’t have room to play around here. Bolding mine-
“Our target velocity at main engine cut off was 7824 m/s (25819 ft/s). If our engines shut down at 7806 m/s (25760 ft/s), only 18 m/s (59 ft/s) shy of the target value, we would make an orbit but not our designated target orbit. We would not be able to rendezvous with space station and would lose our mission objective. Like being two pennies short of a ten dollar purchase, this is only 0.2% less than the price of admission into space.“
So, if we’re say, going to Mars, the amount of energy we need is fixed, and so is the exhaust velocity. All that’s left is mass.
- m0 = mass of propellant and rocket together
- mass of the rocket on the ground, when ready for launch (propellant gets us in the air)
- m1 = mass of rocket once all propellant is gone
We only indirectly get to pick what we want the mass of the propellant to be. (We don’t get to pick what fraction of the overall mass needs to be propellant.) It has to be a certain number based on how heavy our rocket, and everything it contains, is. Meaning we have one variable we can adjust from here on out: The mass of everything else. The mass of the rocket’s structure, life support systems, heat shield, experiments, everything but the propellant.
Including the people in the rocket, what they eat, and what they use to exercise.
“So, just add more propellant then, who cares?”
Before pressing on, maybe you’re thinking, “screw how much everything weighs. Just add more propellant to keep the ratio the same.” It doesn’t work that way.
Fuel has a cost. Right now, for a SpaceX rocket, it’s only 0.3% of the cost.
-> Keep in mind, this is 0.3% of like 60 million dollars. The relative cost is low; the absolute is not. And 60 million is an inexpensive rocket.
As everything else gets cheaper though, the cost of the people, what they eat, how much space they take up, will matter more and more. We’ve already seen this with the airline industry.
In 1987, American Airlines saved $40,000 per year (in 1987 money), by eliminating one olive from each salad on each flight.
“As a consultant, I’ve sat in on airline fuel committee monthly meetings to discuss how we could reduce the weight on each aircraft in a fleet by a single pound,” said Andrew Kemmetmueller, the chief executive of Allegiant Systems”
“Using a pee density of 1000 kg/m3 I get an average urine mass of 0.3 kg. With an average of 80 passengers, this is total mass savings of 24 kilograms. Using the same model for the savings from the iPad, this would have a yearly fuel savings of 1.98 million dollars. It would have the added benefit of not having to get up in the middle of the flight to visit the restroom. So, it makes sense and saves money. This should be a law.”
By having every passenger weigh ~half a pound less, you may be able to save two million dollars on fuel that year.
Jet fuel prices seem to jump around a good amount for some reason, and I can’t find multiple sources to confirm, but let’s call it $3 per gallon.
- $2 million / $3 per gallon = 666,666 gallons of fuel from not even a half pound weight reduction per passenger
And the above are estimates for one airline.
-> I mentioned looking into this stuff has surprising applications to those of us on Earth. This is one of them. If you’re someone who wants to help preserve fossil fuels, help use less fossil fuels, decrease reliance on foreign oil, just save on energy all over, but you’re overweight or obese…the first place to start may be your own weight reduction.
A cargo jet has 60% to play around with. A rocket doesn’t even get half that, and rocket fuel is more expensive than jet fuel. Save an olive on a plane and you get such and such savings. Save an olive on a rocket and you get much more than such and such savings.
Overall, based on the aerospace engineering and human spaceflight class I took, it takes ten to twenty thousand dollars to put one kilogram into orbit. $10-$20,000 for 2.2 pounds. One professor stated reducing a satellite’s weight by one pound is worth between 10 and 50k.
So far, space has proven to be a very expensive endeavor. Every kilogram, pound, ounce, matters.
As of now, you won’t see an overweight astronaut. My assumption here actually isn’t that cost is accounted for with this, but rather health. You want astronauts who have the least possible chance of having adverse health issues. While being a little overweight is no big deal, it may even be healthy, you probably don’t want anyone with a propensity for overeating, or weight issues, going into space. That extra couple pounds is only, oh you know, maybe another $20,000, per flight, and you don’t want the other astronauts to wake up to an emptied food supply due to a late night hangry attack.
-> Per flight is critical. Ideally, the future of space involves flying at a much higher frequency, with the same vehicle. This is one of the major ways to reduce costs. It’s incredibly expensive to build something like a commercial jet liner. If that thing only flew once, imagine how much each ticket would be. The things run ideally for like 20 years. Similar to driving a car, the longer you have it, the further your money goes. The more often a plane can run, the longer it can run, the cheaper every ticket gets.
That said, it almost seems NASA has taken to a powerlifting / bodybuilding approach with their astronauts, in order to fight off muscle and bone wasting. (Although, the last couple years they seem to be moving to Cross-Fit (sigh; shoulder injuries people!).) Some of their astronauts are thick dudes. However, size is not needed as an astronaut.
“So, zero gravity, you’re not lifting heavy stuff, it’s all weightless I guess, so it’s not that you need to be particularly strong for the work, it’s so you can stay healthy?”
“Yes. I mean, some of these guys are lifting a pretty heavy load, but that’s mainly to counteract that stuff, it has nothing to do with spaceflight. The ability to deadlift 450lbs is not preparing them for something they’re doing in space, it’s actually conditioning the bones, for the bone loss and muscle mass loss.”
You certainly want to have some strength, endurance, be fit, but I don’t think we’re talking men who need to be above ~180 lbs. Well, we know they don’t. We’ve had plenty of female astronauts at this point, and I don’t believe there is anything they can’t do that they need a man for. (In space, there aren’t even spiders needing squashing.) While being stronger doesn’t hurt anything -but trying to get stronger, beyond a certain point, can increase the odds of injury and or increase the mass ($$$) of a person- endurance is probably more important.
Let’s do a basic calculation. Basal metabolic rate is how many calories are required to do nothing, and stay at the same weight. If you’re 200lbs, how many calories do you burn from being 200lbs?
I’ll use a random calculator, such as this one. It requires height, weight, age and gender. I’m going to use 5’10” (average male height), 200lbs (91kg), 48 (average astronaut age), and a male gender.
- Enter these in and we get a BMR of 1874 calories.
- Let’s say we’re 175lbs instead, keeping everything else the same. Then we get 1718.
Based on the same website, we should multiple these values by 1.725 to account for high activity levels.
- 200lbs = 1874 * 1.725 = 3232 kcal
- 175lbs = 1718 * 1.725 = 2963 kcal
- 3232 – 2963 = 269 kcal
To reiterate, by being 200lbs you are 11.3 kg (25lbs) * ~$15,000 = $170,455 more expensive than a 175lb person to get into orbit. This is for one astronaut, per flight. This is reason enough to be lighter.
-> I can’t emphasize cost enough here. It has so far been the biggest barrier to space travel. There are other technical challenges as to why cost is so high, but decreasing mass always helps decrease cost.
Next, once in orbit, such as on the International Space Station, you are ~300 calories a day more expensive. Calories are weight, and weight is money.
- 300 calories * 30 days per month = 9000 calories more expensive each month.
We’ll say this person who is 25lbs heavier is heavier due to an equal increased consumption in carbohydrates, protein and fat.
- 9000 calories / 3 = 3000 calories from each
- A gram of carbohydrate contains 4 calories
- A gram of protein contains 4 calories
- A gram of fat contains 9 calories
Then, knowing 453 grams = 1 pound,
- 1812 calories per pound of carbohydrates
- 453 * 4 = 1812
- 1812 calories per pound of protein
- 4077 calories per pound of fat
“Wait, I’ve heard a pound of fat is 3500 calories?” With body fat, you have to account for only ~87% being fat; the other 13% being water. 87% of 4077 = 3547 or ~3500.
Similarly, you may look at a pound of chicken, nearly pure protein, and see it’s only ~360 calories. Same idea. A lot of that one pound is water. So, to launch a pound of a macronutrient can require more than a pound of food. 453 grams worth of protein will require more than 453 grams of chicken.
This is important because we can see different macronutrients have different bangs for their buck. What we’re trying to do here is get as many calories for as little weight as we can.
-> This is where we can immediately question the space travel value of many vegetables. While vegetables have many things going for them, macronutrients (calories) are not one of them. Can we get the micronutrients we need in a pill that weighs less than multiple servings of vegetables each day? Can we avoid vegetables for a two year trip to Mars and be alright? Most Americans seem to view vegetables the way they view communists, and there doesn’t seem to be any major health ramification of that. At least not in the short-term.
If one macronutrient necessitates more mass to travel -if it takes two pounds of chicken to get one pound of protein, versus 1.5 pounds of pasta to get one pound of carbs, both of which have equal caloric values- then that matters. (Where the calories come from of course matters too. It’s not like we want a zero protein diet. I’ll get to that.)
I know NASA does a lot of work with dehydrating food, so I’m not sure what values to use here, and it’s probably variable as hell. But the fact we can rehydrate food once up in space, using water already on board (filtered urine and more), makes this difference, if there is any, less likely to matter. If we can get to where we have a 100% closed loop water system on a space station, then it may not matter at all. I’m going to assume NASA can get / has already gotten things to where water is pretty much only added after getting into space. We’ll say this is equal between the macronutrients. A pound of carbs requires the same mass as a pound of protein. In other words, to get a pound of any macronutrient always requires X amount of extra water, oxygen, whatever isn’t the macronutrient. (If these numbers are symmetrical but are off, then if anything these numbers are underestimates, as I’m not adding the extra mass from X.)
So, to feed this person each month,
- 3000 / 1812 = 1.66 pounds of carbs
- 3000 / 1812 = 1.66 pounds of protein
- 3000 / 4077 = 0.74 pounds of fat
- 1.66 + 1.66 + 0.74 = 4.1 pounds extra food from being 25lbs heavier 
We need 4.1 pounds of more food per month. We have to launch that food into orbit as well,
- 1.86kg (4.1 lbs) * ~$15,000 = $27,955
A typical Space Station trip is six months,
- $27,955 food cost per month * 6 months = $167,727
- $170,455 (from 25lbs lighter) + $167,727 (from less food) = $338,182 savings from the astronaut having less mass. No Werner Von Braun needed.
A trip to Mars will far exceed six months. A professor from UCSD, on NASA’s website, tell me 21 months is the bare minimum. 9 months to get there, 3 months while there, 9 months to come back. Iowa State tells me could be more than two years; could be less. I’m going to lean towards the 21 months here, but I’ll call it 24 months. If nothing else, we’ll say the extra three months are for extra supplies.
Next, the cost numbers I’ve used, $10 – $20k per kilogram, are to get things into orbit. I’m going to use the middle number, 15k. However, to get things onto Mars is probably more expensive per kg. I’m assuming you need a fancier ship. But, improvements in rocket technology may get this price lower. I’ll give more details on this at the end, but for now I’ll stick with 15k.
- 4.1 lbs more food per month * 24 months = 98.4 lbs
- 44.7kg (98.4 lbs) * $15,000 = $670,909
And the above is for one astronaut.
Getting fancier- not only how much you eat, but what you eat
Astronaut height restrictions seem to be 64 – 76 inches. Let’s say our average height is 70 inches, or 5’10”.
Because astronauts seem to have some muscle on them, we’ll say their average BMI is the high end of normal, at 25. This would put their weight at 175lbs.
From before, we calculated,
- 175lbs = 1718 kcal per day * 1.725 activity factor = 2963 kcal each day
A common recommendation, whether it’s the government, dietitians, whatever, is to eat 55% of your calories from carbohydrates. Astronauts actually eat this much as well.
- 2963 * 0.55 = 1629 calories per day from carbs
Why does this matter? What do we know comes with carbohydrates? If you’re someone who all of a sudden goes on a low carb diet, what do we know happens? You drop weight, sometimes a lot of weight -water weight- immediately.
For every gram of carbohydrate stored, we store three grams of water. There are four calories for every one gram of carbohydrates.
- 1629 calories / 4 = 407 grams of carbs each day
- 407 * 3 grams of water = 1222 grams of water stored
- 1222 grams of water = 2.7 pounds.
- 2.7 * 6 astronauts = 16.2 lbs from losing water weight
By moving to a zero carb diet, we can decrease the mass of each astronaut by 2.7 pounds.
- 1.23kg (2.7 pounds) * $15,000 = $18,409 per astronaut
Unlike fat and protein, carbohydrates are not an essential nutrient. We can do fine without them, through garnering energy from fat, and breaking down protein into glucose through a process called gluconeogenesis.
But physical performance is something to be mindful of here. Carbs can influence performance. Michael Scott provided a case study for this years ago.
The type of activity astronauts do most is low intensity, long duration work. This is the type of work we’d expect a lower carb diet to NOT impact. Something like a spacewalk can be 8 hours worth, but it’s not as if the person is sprinting. They’re doing low load work for a long period of time. Light, at times very light (minimal gravity!), construction work might be the best analogy.
On the other end, the astronauts are engaging in intense exercise in the gym. Something that low carbohydrate intake could impact, but if so, probably not much. Lifting heavy weights doesn’t usually need much glycogen, unless you’re going rapid fire like a circuit style, or a ton of volume. But that’s not really lifting heavy weights then. Shorter rest breaks = less weight you can lift.
There isn’t a ton of research on this, but I think there is enough to grasp the spectrum of where it matters. There is a footnote with a brief synopsis. 
If we had our astronauts doing serious middle distance type running, carbs would very likely be a concern. But for the activity they’re doing, I think they’re right in the sweet spot of not having to worry about it.
Not everyone does great on a zero carb diet though. Maybe not all astronauts do it. Although, the requirements for astronauts are insane enough as it is, I don’t think adding “does well on low – zero carb diets” would alter the selection process much.
This paper on astronaut nutrition makes the argument ketosis -what happens on a zero carb diet- could present an issue in needing the life support systems to remove ketones from the air. Based on the chunks of food the filters seem to need to be able to deal with, I feel this is unlikely a problem, but I don’t know enough about filtering to say one way or the other. Ketosis can also present issues with bad breath. We don’t want a crew who hates smelling one another. So these are things to be mindful of.
What we could then do is not longterm zero carbs, but only a few weeks before launch day. By getting the excess water out of the body right before launch, you get the launch benefit. Then, once in space, carbs can be ingested as needed. Something like a cyclical ketogenic / carb cycling diet.
Or we don’t do zero carbs, but instead of the ~400 per day, we bring things down to about 50-100 per day (still a 75% or more reduction), a number that can usually prevent ketosis.
-> By the way, this means bacon IS still on the table. Considering the seemingly infinite ways people use bacon nowadays, I’m not sure food boredom is something to worry about. 
Because keep in mind,
- 1812 calories per pound of carbohydrates
- 1812 calories per pound of protein
- 4077 calories per pound of fat
Say our astronaut is doing things the conventional way, something like,
- 2963 calories per day
- 55% carbs = 1629 calories from carbs
- 22% protein = 652 calories from protein
- 23% fat = 682 calories from fat
- 1629 calories from carbs / 1812 calories per pound = 0.90 lbs from carbs
- 652 / 1812 = 0.36 lbs
- 682 / 4077 = 0.17 lbs
=> 0.90 + 0.36 + 0.17 = 1.43 lbs of food per day
But let’s say we go to zero carbs.
- 2963 calories per day
- 0% carbs = 0 calories
- 40% protein = 1186 calories 
- 60% fat = 1778 calories
- 0 lbs
- 1186 / 1812 = 0.66 lbs
- 1778 / 4077 = 0.44 lbs
=> 0 + 0.66 + 0.44 = 1.1 lbs of food
1.43 lbs on average carb diet – 1.1 lbs on zero carb diet = 0.33 lbs per astronaut, per day.
Using Mars again,
2 years * 365 days = 730 days
730 days * 0.33 lbs = 241 lbs of food
241 lbs of food * 6 astronauts = 1445 lbs of food 
WHO RUN THE WORLD? Men.
But who run the universe?
Despite her yelling (over-singing) in every song, we all know Beyonce is delusional. Men rule the world. Maybe things will change moving forward, but human history is littered with men not only running the world, but ruining women in the process. 
The world means Earth. Women have a huge leg up when it comes to running the universe though. They tend to be smaller!
If instead of using 5’10” as our average astronaut height, we use 5’4″ (average woman height), then our average BMI of 25 would give an average weight of 145lbs. Using this calculator again, and an average age of 48, we get 1361 calories.
By the way, even if this were a male at this height, the daily metabolic cost would be 1455 calories- still higher. Women have higher body fat percentages, so they don’t burn as many calories each day.
-> I could see this being a nice advantage with longterm space travel too, should complications arise. Having extra body fat is good from a survival standpoint. Given women have more body fat at the same weight, perhaps they would do better should a food shortage occur.
Using our activity conversion from earlier:
- 1361 calories * 1.725 = 2348 calories
Compared to an average male astronaut,
- 2963 average male astronaut calories – 2348 average female astronaut calories = 615 calorie difference per day, per astronaut
- 615 calories (we’ll say zero carbs)
- 40% protein = 246 calories
- 60% fat = 369 calories
- 246 / 1812 protein calories per pound = 0.14 lbs
- 369 / 4077 fat calories per pound = 0.09 lbs
Totaling 0.23 lbs less food per day, per astronaut, just by switching to a female astronaut.
For Mars travel,
- 0.23 lbs * 6 = 1.38 lbs per day per crew
- 1.38 * 730 days = 1007 lbs of food
We also account for the fact women will weigh less to start.
- Average male astronaut weight = 175lbs
- All men at launch => 6 * 175lbs =1,050lbs
- Average female astronaut weight = 145lbs
- All female at launch => 6 * 145lbs = 870lbs
- 1050 – 870lbs = 180lbs
For food, for a two year round trip to Mars,
- 16.2 lbs of less water at launch (assuming average astronaut)
- We wouldn’t save as much water if we had all female crew.
- 2348kcal * 55% carbs = 1291kcal
- / 4 grams carbs per calorie = 322 carb grams
- * 3 water grams= 968 grams water = 2.134 lbs
- * 6 = 12.8 lbs of water
- We wouldn’t save as much water if we had all female crew.
- 1445 lbs of less food weight if going to zero carb diet for 6 astronauts
- This number would also be less if it were a female crew.
- 2348 calories moves from 1.13 lbs of food per day with carbs to 0.86 lbs with no carbs
- A difference of 0.27 lbs per day per astronaut equals 1182 lbs savings
- This number would also be less if it were a female crew.
- 1007 lbs of less food assuming switching to all female crew
- 180lbs less bodyweight assuming switching to all female crew
Adding the bolded numbers we get 2382lbs saved. 1082 kg (2382 lbs) * $15,000 = $16,239,546
Getting really fancy
When you have food, you need to have packaging to store it. I have to make some estimations here, but the point of this is there are further reductions in weight to be had.
From what I’ve seen, tightly sealed ziplock-esque bags are what astronauts primarily use. Something like this:
The good folks at GrassCity.com tell me a typical sandwich / snack “baggy” weighs about 1.5 grams. Ziploc.com tells me their snack size sandwich bags hold about 100 calories.
- 2963 average male astronaut calories – 2348 average female astronaut calories = 615 calorie difference per day, per astronaut
Let’s say our female astronaut needs six less baggies per day.
- 6 bags * 1.5 grams per bag = 9 grams
- 9 grams * 6 astronauts = 54 grams
- 54 grams * 730 day Mars trip = 39,420 grams => 86.5 pounds
39.3 kg (86.5 pounds) * ~$15,000 per kg = $589,500 
Other things I’m not going to calculate
Being smaller has further positives. Smaller people don’t defecate as much waste as bigger people. They don’t need as much toilet paper. (Although, a woman may need more than a man. Can you spare a square?) They don’t need as much oxygen, they don’t need as much water (to drink or clean themselves), they don’t need as large of a spacesuit, they don’t need as big of clothing. Some of these are things we think of as meaningless in the developed world, but they require resources to handle in space. Less use of resources means less strain on those resources.
What the mass ramifications are of this exactly I’m not going to try and figure out here.
Oh what the hell,
-Average male astronaut is 70 inches tall and 175lbs.
-Average female astronaut is 64 inches tall and 145lbs.
-Average female astronaut is 8.6% shorter and 17% less mass. We’ll call it in between, 12.6%. A female astronaut is ~12.6% smaller than a male.
-300lbs * 0.126 = 37.8 lbs
-37.8lbs * 6 astronauts = 227 lbs we could potentially save
Maybe a smaller crew can get by with a water reclaimer that has less mass. Or a water reclaimer that doesn’t need as many replacement parts. Or hell, just a water reclaimer less likely to fail because it doesn’t have to work as much.
Hopefully by now we can see even if the answer is, “It’d be a really small difference each day,” that matters over the longterm. Every iota counts.
Lastly, I assumed the above with a BMI of 25 for the astronauts. There is no reason this number needs to be 25 though. Reading and watching The Martian makes me think you might want to err on the side of staying a little heavier, in case a food shortage did occur. But from a health perspective, BMI could go all the way down to 18, which could bring our female astronauts down from 145lbs all the way to nearly 110lbs! Which would have a cascading effect on all the food numbers we’ve talked about. If anything, I think these numbers are low ball estimates.
But let’s move away from food. There’s another aspect of all this, and a huge item we haven’t hit yet.
One of the challenging aspects of space travel is microgravity. Without gravity to help pull and bang our bodies around, we start to literally decay. NASA has tried various remedies for this. They seem to have found one solid solution- intense exercise.
For this exercise they use a machine called Advanced Resistive Exercise Device. If you’re familiar with a gym, the thing is like a fancy Smith Machine.
The first thing you’ll notice about this device is…it’s enormous! NASA tells us,
“The ARED facility on-orbit mass not to exceed 700 lbs, and on-orbit spares mass not to exceed 150 lbs”
Looks like this thing is upwards of 850lbs on board the ISS. Because they say the “on-orbit” mass, I’m thinking that means to launch this thing requires even more mass. Possibly considerably more. (You have to break it apart, put it into bags, make sure they don’t move around.) But we’ll call it 850lbs for now.
“Currently planned maintenance of ARED includes periodic replacement of electrical cables at flex joints, brake cables and exercise cable, as well as an annual calibration and inspections. To the extent possible, maintenance activities will utilize existing standard ISS tools. Orbital replacement units (ORUs), access covers, caps, and structural parts that will be removed for on-orbit maintenance shall be designed with restraining and handling devices for temporary stowage by the crew in a microgravity environment.”
This thing sounds like a pain in the ass to maintain. Maybe not as far as space equipment goes, but certainly as far as gym equipment goes.
But resistive exercise IS necessary. We can’t not have the astronauts exercise. Even if we implement artificial gravity, exercise is something we are going to be wanting the astronauts to do.  And because we’re in microgravity, typical gym equipment doesn’t get the job done.
But what about these?
What about resistance bands? The tension of the bands doesn’t change in microgravity. I don’t pretend to be the first person toss the idea of bands around, but I’m not sure others were considering the mass ramifications. Plus, I think we can fine tune it based on what I’ve seen. For instance, I purposely used the EliteFts brand because of this:
These bands are effing strong! In fact, EliteFts makes the bands primarily as an outfitter for powerlifters. ARED can go up to 600lbs of resistance. Four of the “strong” bands, and we can get up to 550lbs. What do those bands weigh? A pound each?
-> I own a couple of the medium size, monster mini, bands. They are so light my scale doesn’t register them. I figured my scale needs a certain amount of weight on it before it registers anything. I stood on the scale, got my weight. Then stood on the scale with a 10 pound dumbbell, and my weight was 10 lbs heavier. When I stood on the scale with two medium sized bands in my hand, my weight was still the same. My scale goes to a tenth of a pound. Material capable of 91.5 pounds of tension didn’t register a tenth of a pound. The things are light.
So (maybe) four pounds to garner 550lbs resistance? Compared to 850lbs to garner 600lbs resistance? And 550 isn’t our minimum with the bands. ARED can’t go any higher though. 
These bands are not only sold for strong people, they were popularized by Westside Barbell, likely the strongest gym in the world.
These are not small people using these things. The body doesn’t know “oh this is barbell tension, we will grow differently than if we use band tension.” The body merely knows tension / resistance. If the tension is good enough for these guys, I’m sure it’ll be enough for astronauts. Especially female astronauts!
Let’s say on average, the bands weigh a pound each. Using EliteFts’ chart, they have 6 types of bands. We’ll say we bring a pair of each, and then a back up pair of each, totaling 24 bands, which equals 24 pounds. This is a far cry from 850lbs. I don’t know how long they last. Double the 24 bands for insurance, and we have 48 pounds on board, compared to 850lbs.
Sure, we’ll still need some other items, like a bench (I’m not sure if the 850lbs includes this or not), and things to anchor the person down -can’t be floating trying to exercise (although a band could potentially be used as an anchor!)- but we’re not going to come anywhere near 850lbs.
-> One thing we’d want to do is make sure we know how much the bands lessen in tension with use, so the astronauts don’t accidentally end up using less resistance over time. I’m sure we could study this fairly easily on Earth to get precise numbers.
I don’t see there being any difference exercise wise. You can do anything you want with these bands. Here is what seems to be a near, if not fully, exhaustive list of the exercises ARED users go through:
All this can be done with bands. You can strap the bands on the person’s shoulders, or have them slung around the hands with a person laying on their back (bench press). It can all be done. You could even still bring a barbell on board the ship and strap the bands to the barbell, anchor them below, and boom, you have all your barbell exercises.
Some may say the force curve is a problem with bands. The idea being when you use a band as resistance, as you get to the terminal part of a movement, the exercise is it’s hardest. Where with a barbell, it’s the opposite.
Think a bench press. As you get the bar further off your chest, it typically gets easier. With bands though, as the band gets further from your chest -as the band is stretched- it gets harder.
Again, the strongest people in the world use these, whether they use powerlifting gear or not.  In college my football teammates and I used bands a ton, and it’s not like people got weaker! Research tells us bands work just as well as weights too.
If you really were concerned about this, you could use different bands for different ranges of motion. Use a stronger band and only bench press halfway up. Then move to a lighter band, and do the second half of the range of motion. Boom, you’ve simulated an Earth bench press. Harder first half of movement; easier second half of movement.
Furthermore, this force curve doesn’t apply to everyone, or every exercise. For some, the top part of a bench press is their weak point. Or the top part of a chin up is their weak point. The halfway point of a bicep curl is the hardest part. And wouldn’t we rather make the easiest part of a movement harder? Why not make the latter portion of the bench press more challenging? So the triceps get some extra work.
With bands, there are positives the ARED can’t give. Anyone who trains people in a health conscious manner will often steer clear of the Smith Machine. The reason being the bar locks everyone into the same bar path. Where with free weights, your joints have greater freedom of motion. This is also why dumbbells tend to be friendlier to the body, especially the shoulders –the joint most injured in astronauts- compared to barbells.
-> The ARED does seem to have more wiggle room than your typical Smith Machine. But once you have a barbell, your joints are locked to some degree. The option of something dumbbell like -one band in each hand- is preferable for some. In a population with high upper extremity injury rates, like baseball pitchers, most who know what they’re doing will use predominantly dumbbells for this reason. (The range of motion of a pitcher’s throwing and non-throwing shoulders are quite different. They should be treated as such.) It’s why I always use dumbbells for someone having shoulder issues, before moving to a barbell, and mainly use dumbbells in those with a significant shoulder history.
Here is the treadmill used on board:
Notice those big straps, bungee like cords, holding the person down. This is to provide resistance in a microgravity environment. The resistance bands could double as the treadmill straps! We could save mass by not having to launch those things. NASA’s treadmill page doesn’t seem to state the mass of everything, but they look considerably heavier than resistance bands.
-> I asked the aerospace engineer I train about bands. He wasn’t sure, but his response was, “I assume they don’t use bands for fear of moving the ship around, vibrations, things like that.” This is a big concern on a spacecraft…but if we have the ability to get people running on board, I’m sure we can get to where they pull on some bands with no problem. You could use the treadmill station as a double for a deadlift station. You could also have the band anchored to something that’s nearly free floating. (Like how the cycle ergometer is.) Then, say as you pull the band with your arms, the object would float to you. But what you could do is use the lower body to prevent the object from coming towards you. Working the lower and upper body at the same time.
The treadmill NASA uses has an unpowered mode as well, where the resistance is from the person having to roll the treadmill themselves. You could add a band around the person’s torso, to increase the resistance. Similar to this, with feet on the treadmill:
But with some mechanical anchor, not a person (although, you could get creative (anchor both people down- lower body work for one person; upper body work for the other))-
-> Again, females / lighter people are beneficial here. They won’t wear down the treadmill as quickly. Which can save more mass on replacement parts.
The bands save mass in themselves, but can also save mass through concomitant uses.
While there are numerous things to look at here, what this comes down to is the mass savings are too enormous. Either NASA knows something I don’t, or they haven’t entertained this modality thoroughly enough. I have a feeing something like this might almost come across as too simple a fix. The ARED is quite a feat of engineering…but that’s part of the problem with it. Maintaining that thing is a bitch. It requires extra training for the astronauts, and takes time to set up and adjust. Enough they only get to train about two hours out of the 2.5 hours they exercise each day. The thing is gym equipment, yet has software in it! 
And then what do you do with that thing if you’re on Mars?
“Hey bro, I know we gotta hit up Schiaparelli today, but I gotta leave by 5pm. Gotta getta pump on.”
“Guessed you missed the memo, Lewis has that time booked already.”
“Ugh, why are all the machines always taken when I want to use them?”
Yes, we only have one machine for our entire crew!
Or what if you’re too far from from the homesite? Or want to do a couple day exploration? Or couple weeks? After two weeks muscular strength can decrease by ~10% in lesser gravity. You can bring bands anywhere, hook them to practically anything, and everyone can exercise at the same time. In the fitness world, they’re renown as great for frequent travelers. We can’t bring ARED in a rover. 
From this paper,
“Within all the challenges, a few aspects are unlikely to see much improvement. Crew exercise operational volume is primarily driven by the exercise movements and anthropometrics of the crews selected for flight. Even if novel movements and loading profiles are identified, the operational volume will still need to protect for the ranges of crew anthropometrics.”
The bands could save a lot of space, as would our female astronauts. In fact, they’d save space regardless of what equipment we use. We said a female is ~12% smaller than a male. Right away we could potentially have a 12% smaller workout space. We also don’t need as much resistance with women. How much difference would be tough to say, but women are virtually never as strong or stronger than men, given similar training.
This is where the nuances of bone come into play. When it comes to keeping / growing bone, it’s not whether bone is stressed -accepts force, it’s whether bone is strained -does it deform? Something like a ziploc bag can’t take a lot of stress before it deforms, but it can handle quite a bit of strain. We need bone to be stressed enough that it strains. Stress in itself is not enough.
On Earth, we know cyclists are more likely to suffer from bone density issues. Even compared to non-athletes! It doesn’t matter if you feel like you’re working your body a ton, you’re not straining your bones. You’re not deforming them. The fluid around and within them isn’t getting moved in and out. It’s not getting sloshed around.
You can appreciate this by filling a transparent water bottle half-way up. Move your arm in a constant circle. Or, place the bottle on a bike / elliptical and watch the fluid as the machine moves.
Nothing happens to the fluid. Things are very calm. There would be minimal, if any, fluid exchange going on. (More on why this is important.) Compare this to dropping the bottle a few inches onto the ground over and over, like walking.
We see a nice disruption.
Or in mountain biking, with all the shock absorption going on. Think of that water bottle sloshing all around. What do you find in mountain bikers? Higher bone mineral density than road cyclists.
Strain is what gets bone to form. Or in the case of astronauts, strain is what we want just to maintain bone density. On the treadmill or with weights, given sufficient resistance, things get compressed (strained) enough to throw the fluid out and around. On a bike, this doesn’t happen.
Because of this I not only recommend my clients go with walking for their cardio efforts, I actively encourage them to avoid the bicycle or elliptical (and the pool). Unless they’re getting a significant amount of impact training elsewhere. But when someone only has a few hours a week of activity, what you do really matters. Astronauts are busy people. The time spent on exercise may be able to be better utilized here.
Astronauts have a treadmill on board, and a cycle.
I can’t see bothering with the cycle. NASA would love to 1) Have their astronauts not have to engage in so much exercise everyday 2) Not have as much exercise equipment on board. By getting rid of the cycle you definitely help 2), and potentially help 1) by making your time spent exercising more efficient.
To emphasize this even more, even professional cyclists –up to 50% of Tour De France riders– have bone density issues. There is some evidence cyclists have less bone density than sedentary controls!
Sprint cyclists are indeed jacked, but they aren’t on their bikes as much as people like Tour de France cyclists are, and they do a ton of serious weightlifting. The idea here is by itself, cycling does not benefit bone. On Earth, in the context of a full workout program involving weightlifting and weight-bearing activity, then cycling (swimming, the elliptical) is nothing to worry about. In the context of every minute, every ounce, matters, then it’s relevant.
Sure, muscle deconditioning is also a concern, but that’s what the treadmill and resistance training are for. And the muscular concerns haven’t been as paramount as the bone. Keeping bone loss mitigated has been the tougher variable.
The only caveat I see here is if injury occurs. If something like a bum ankle happens, the cycle can make things easier to maintain conditioning in the meantime. It won’t do anything for bone, but it can help ameliorate the muscle wasting. We can hedge our bets here to some degree.
However, you could also do this with resistance training. Anchor the bands into a leg press so the person doesn’t have to stand on their legs. Make some days of the resistance training very fast and circuit based, to still get some work with the heart rate up. If you’re on Earth and this happens, sure mix the bike and pool in. When you’re in space and mass is so crucial, we can get more creative than that.
“The Ergometer portion of CEVIS is constructed of aluminum and weighs approximately 59 lbs.”
59lbs seems to be the minimum we would save here, but we’ll leave it at that.
One other small piece of equipment
After observing a lot of the astronauts running, I noticed a trend with their shoes. They’re fairly bulky. Notice the heel lift on these things:
I took a look at some thicker New Balance shoes, and these ones end up being 11.9 ounces.
A New Balance minimus shoe, something like this:
is about half the weight of the bulkier version. To be fair, Mike Hopkins, an astronaut, seems to already have made this transition:
So it’s not like we can say every astronaut is wearing the same / bulkier shoes.
-> Women have another advantage here. Smaller feet = less shoe mass.
But, do we even need shoes? An astronaut gets a minimum of two years to prepare for their flight. It’s not inconceivable one could get acclimated to training barefoot in that timeline. Or NASA could possibly make a couple pairs of the socks -you’re going to keep those for warmth- already on board have a little extra cushioning and rubber sole. Or you make the treadmill surface a little softer to run on. Or maybe you don’t. Remember, we want some impact on our body. Not having shoes may allow us to have a greater impact, which in this case is good. (Bangs the bones around some more.)
Each astronaut brings two pairs of shoes for a six month mission.
Let’s say each astronaut brings eight pairs of shoes on a 21 month / two year Mars trip. Two pairs of shoes for every six months.
- 6 astronauts * 8 pairs of shoes = 48 pairs of shoes
- 48 pairs * 0.74 lbs (11.9 ounces) average per shoe = 35.52 lbs
I’d say worst case we can halve that number by going to more minimal footwear, and best case, which I don’t think is too farfetched, we get rid of that number all together.
Rough tally of total savings
One vehicle likely to send us to Mars seems to be a version of the Falcon rocket, made by SpaceX. Here are some specs on their upcoming one, the Falcon Heavy:
SpaceX plans to have an even bigger rocket after this, but we’ll use it as a guideline.
Notice those specs again:
- Low Earth payload = 117,000 lbs
- Geostationary payload = 46,700 lbs
Payload is all the stuff we want to get into space, which isn’t contributing to the launch. The crew, experiments, life support, etc. Notice how drastic the payload capacity goes down, just by us going from low Earth to geostationary. LEO is about 1300 km from Earth where GTO is about 36,000 km. Remember our rocket equation earlier. The farther we go, the more the mass of the vehicle has to be for propulsion, not payload. The farther we go, the more the people and the resources they need, matter.
Mars, at best, ends up being about 56 million kilometers from Earth. The payload goes all the way down to about 29,000 pounds in that case.
NASA tells me multiple launches would be necessary to get everything we need to Mars. I’m going to focus on the human launch, assuming all 6 astronauts are on ship, and their most essential necessities are on that ship, like the exercise equipment and all their food. It probably wouldn’t happen that way e.g. they would rendezvous with some of the food later in the mission to spread the food supply out. Regardless though, all the mass I’m going through has to get there, one way or another.
Let’s say that 29,000 pounds contains an all male crew (every astronaut which made it to the moon was male), average height, average weight (maybe a little muscular), average diet, six of them, using the ARED and cycle machines, on a two year trip to Mars. From here, let’s see what types of saving everything we’ve gone through add up to:
- 180 lbs saved from female crew weighing less
- 12.8 lbs saved from minimizing water weight of female crew
- 1182 lbs saved from having no carbs as food weight (and more fat / protein instead)
- 1007 lbs saved from female crew eating less than male crew
- 86.5 pounds from less food packaging
- 227 lbs from smaller spacesuits
- 850lbs from no ARED
- 59lbs from no cycle ergometer
- 35.52 lbs lbs from no gym shoes
- Totaling 3,639.82 lbs
- Doesn’t include savings from less water use, less oxygen needed, less wear on treadmill, potentially no vegetables, etc.
- Totaling 3,639.82 lbs
But we’ll add:
- 48lbs from 48 resistance bands
- 150lbs from other miscellaneous exercise equipment (bench, anchors, etc.)
- 3,639.82 lbs minus 198 lbs = 3,441.82 lbs
What percentage of our payload is this?
- 3,441.82 / 29,000 lbs = 0.1187 or 11.87%
Or, you could say another ~3400 lbs of payload which gives some more room for error, allows another experiment on board, bigger heat shield, extra life support equipment, don’t need as big of a ship or as much fuel to support as big of a payload. Whatever is best.
SpaceX actually has the cost of things to orbit down to $4,654 per kilogram, but we’re not talking going to orbit, and this doesn’t include a ship which can do (wo)manned space flight. SpaceX is predicting their next ship to be $90 million, with a payload to Mars of 13,200 kg, bringing things to $6,818 per kilogram. While SpaceX doesn’t do every launch, using this number:
- 1564.46 kg (3,441.82 lbs) * $6,818 = $10,666,513
NASA and Russia actually have size restrictions for astronauts. From what I’ve seen, this is due to being able to properly fit in the vehicle. I haven’t come across anything with NASA outright saying bigger astronauts are too costly, so that’s why they aren’t allowed, but I don’t think it’s outlandish to have these restrictions because of cost. At least for now, until costs hopefully come down. Many of us are tired of low earth orbit and memories of a moon trip more than half the people currently alive weren’t alive for. We’re ready to go somewhere again. If part of what it takes is excluding bread and ice cream, considerable tugging on rubber bands, letting women lead the way, then so be it.
Throughout human history, women have had to deal with their physical stature being a detriment. Well, in the universe, at least for us to travel through it, women have some solid advantages over men. From a size perspective, you want your spacefarers being women. (Or the Napoleon dudes can finally calm down. There are uses for you besides horse jockey and police officer.)
And because anywhere we’d be traveling right now would have less gravity than Earth, the physical strength of men doesn’t matter as much. On Mars, everything is a third of what it is on Earth. Big rocks need to be enormous rocks for it to matter to a woman on Mars. Getting around a spacecraft involves minimal gravity as well. I’m sure if they need help opening the pickle jar, NASA can conjure up some simple way to help a girl out, without needing a guy nearby.
Women do have a greater propensity for bone issues on Earth, but not during spaceflight! Actually, male astronauts have been found to have a harder time.
Women are also healthier overall, they tend to live longer (and most males will attest they’re cleaner). This may be why they have less vision issues, which have become a top concern for NASA.
A paper from this year found women did better vision wise, and it was attributed to their cardiovascular health. The paper contains the following statement, which made me laugh, as any woman I know would agree with it (bolding mine),
“Overall, female astronauts demonstrated a significantly healthier cardiovascular status. Individually, the female astronauts had significantly healthier profiles on seven of twelve cardiovascular variables than the men (p values ranging from <0.0001 to <0.05). Male astronauts did not demonstrate significantly healthier values on any of the twelve cardiovascular variables measured”
Plus, how cool would it be if the first manned mission to Mars was fully womanned? How much progress would that show for humanity, considering what we’ve done to women in our history? How much would that affirm the idea of oh, hey, women can be valuable to society? 
-> Don’t worry, I’m thinking the same thing. Where are we going to put all the shoes? High heeled space boots, wedges space boots, open toe (tough to do that one), close toed, flats, “I’m feeling frisky,” colors men have never heard of. Sigh, even a Martian girl can’t have it all.
As a place like SpaceX can get the cost down more and more, as they can lessen the cost of putting the materials together, then the mass ($$$) of the people on board become a bigger and bigger fraction of the vehicle’s cost. The people become more important, not less!
Think of the airline industry. One plane may run for 20 years. My assumption is, once that thing is approved for flight, there are only so many ways for cost to then be further reduced. It’s been made, money has been spent, it’s time to make that money back. But if everyone weighed less, that would immediately lessen the cost of travel.
Reduce one olive from each salad when you only fly once every few months, and so what. Reduce one olive from each salad when you have thousands of flights every day? It matters. Should you be complaining about airline ticket costs if you have 50lbs to lose? How many extra olives is your own body?
I am ignoring increased water weight (the person is 25lbs heavier partially due to water), but I am also ignoring increased water consumption (a heavier person consumes more water, which has mass).
Carb intake doesn’t matter-
- Effects of a low carbohydrate weight loss diet on exercise capacity and tolerance in obese subjects.
- Exercise capacity and nitrogen loss during a high or low carbohydrate diet.
- Important to note exercise intensity was 60% VO2 max.
- Ketogenic diet does not affect strength performance in elite artistic gymnasts
- Included “hanging straight leg raise, ground push up, parallel bar dips, pull up, squat jump, countermovement jump, 30 sec continuous jumps”
- One reason I like this study perhaps the most, is it used non-obese subjects, which would be more applicable to astronauts. It also used movements more applicable to astronauts.
- The effect of weight loss by ketogenic diet on the body composition, performance-related physical fitness factors and cytokines of Taekwondo athletes
- This one actually found a slight benefit for the ketogenic (zero carb) diet
- The effect of an 8-week LCHF diet in national level Olympic weightlifters and powerlifters on body composition, strength and power performance.
- Another one we’d probably lean towards, as it studied the type of training many astronauts do on board the station i.e. serious lifting.
Carb intake does matter-
- Comparison of carbohydrate-containing and carbohydrate-restricted hypocaloric diets in the treatment of obesity. Endurance and metabolic fuel homeostasis during strenuous exercise.
- This study used VO2 max at 75%. A range we’d expect to matter.
- Blood ketones are directly related to fatigue and perceived effort during exercise in overweight adults adhering to low-carbohydrate diets for weight loss: a pilot study.
- This study was only two weeks, which might not be long enough to adapt to a no carb diet.
I think the space agencies have excessively worried about this, and the psychological aspect of food, to begin with. In my world, the fitness world, coming across people who have no problem eating the same thing everyday, for months and months, if not years, is common. Bodybuilders being exhibit A. Chicken, tilapia, rice, (beer, not milk, if you’re Ahnahld), maybe some tabasco, and that’s often about it. I’ve worked with and known quite a few people to say, “I eat for fuel, not for taste.” When I was playing football and obsessed with being as good as I could, I was one of those people. I didn’t have a beer until I was 22. I didn’t care about a comfort food, I cared about being good and winning. Comfort food was “help me kick your ass” food.
This whole Michelin star phase of food we’ve come across is very new to humans. The idea we need this endless rotation of new foods, innumerable iterations of each food, always have ketchup within arms reach, have a food nearby because you feel icky today, is a function of how good we got it right now. The notion we need this is false.
You want to take your body to a certain level? There will be sacrifices for that. What you eat being a huge one. If we’re talking lose some weight and be healthy, the sacrifice won’t be as much. If we’re talking elite performance, the sacrifice will be significantly greater. You want to go to Mars? Do something no human has ever done? Be supposedly the best of what the human species has to offer? But we’re concerned about an ice cream craving? Come on.
The same astronaut nutrition paper cautions against not only too little protein, but too much. I’ve been surprised to see the focus NASA has on too much protein, and where the protein is coming from. The primary impetus for this seems to be in very sedentary people, or bedrest studies, excessive protein, and all the acid that comes with it, can negatively impact bone. Bone density is crucial with astronauts, hence the concern.
But ideally astronauts are not too similar to bed rest studies. Ideally they are moving a ton, and exercising a ton. In these populations -those who move and exercise a lot- higher protein intake isn’t something to worry about. NASA seems on the fence about this, but I don’t think this is too complicated. We have populations on Earth, athletes and bodybuilders, who go crazy with protein intake and don’t have any negative bone ramifications. If anything, they’re doing great bone (and muscle) wise!
Finally, the number I’m using has protein at 40%. The paper says current recommendations are not to exceed 35% of calories from protein. We’re barely over the limit anyways.
There is a torture museum in San Diego. It details different ways humans used to mangle one another. The devices were overwhelmingly used against women and gays. In exhibit after exhibit, the information attached header reads something like, “This would be used when a woman spoke when not spoken to.” The devices make one wonder if the human imagination is a bad thing. It’s that horrific.
The caloric density of fat saves us a good amount of mass. The density has further positives with astronauts. Astronauts have had a hard time consuming their daily caloric needs. More dense food requires less chewing and time to eat. Think Big Mac versus vegetable medley. The less dense food requires more chewing. It can increase satiety perhaps before we want to, require extra food prep time, extra time to consume the food, and extra time to clean.
For the International Space Station, some throwaway items are tossed into the Earth’s atmosphere and burned up. They do this with their laundry right now, as it saves them from having the mass of extra water on board. But when doing something like a Mars trip, you can’t do this- there’s no atmosphere (while traveling there) to throw stuff into. With food packaging, the astronauts might release the garbage into space.
But maybe not. Space debris is becoming a bigger concern.
“We’re at what we call a ‘critical density’ — where there are enough large objects in space that they will collide with one another and create small debris faster than it can be removed,” he says. Something like a loose fleck of paint, moving at these speeds, can hit with the force of a grenade.”
Less food = less garbage to worry about.
Artificial gravity has its own issues. It’s made to be a panacea in sci-fi, but it may remain a sci-fi dream. To simulate Earth’s gravity would require us to build a ship with a radius of 224 meters. For context, a Falcon 9 (currently contracted by NASA) launch vehicle is 68 meters long. The International Space Station is 73 and 108 meters long and wide (and damn near one million pounds). Picture a standard 400 meter track. Stretch out more than half the track, or think the length of more than two football fields, and that’s just your radius of the ship. We are talking an utterly enormous ship, more than twice the size of anything we’ve ever built, which means god knows how much mass that thing will be, which means god knows how much money would need to be involved. (A bigger ship is also more susceptible to being hit by space junk.)
It will likely be that even in space, with the most advanced technology humans have to offer, we can’t avoid exercise [insert treadmill emoji].
600lbs may seem like a ton of weight, but in space, when doing something like a squat, we have to account for the person not lifting their bodyweight. On Earth, if you weigh 200 pounds, a 400 lb squat is more like a 600lb squat in space. I’m not sure any astronauts really need to worry about needing more than 600 pounds of resistance in space, but regardless, this limitation is not a concern with bands.
Powerlifting gear helps you at the bottom portion of movements, so the force curve is different to where the band actually works your weak point.
Another benefit of moving away from something like this- it requires less power. You don’t have to cool bands, you don’t have to turn a computer on to use them. For feedback with mission control and the health department, you can send updates through email, like a google doc. I train people all around the world doing things this way.
We also again gain the benefit of less space debris. If a band tears, or the tension wears out, we can send it home on the next flight. (If not glue it back together. NASA has some wildly strong adhesives.) We don’t need to throw it into space and have a 17,500 mile per hour rubber bullet orbiting us, nor do we need to waste the materials by throwing them off board .
Why don’t we really piss people off. Let’s make all six, or however many, make them all female astronauts. Make them all from a different race / ethnic background, a black, a jew, maybe make them all non-white for kicks. And be sure to include a couple lesbians. First thing they do on Mars? Plant a giant flag with a picture of a vagina, then get married. Maybe Martians can avoid the asininity of those debates from the get go.