Rocket-based travel must minimize the amount of mass that is carried. At the extreme end, this would include eliminating mostly non-functional systems such as clothing

Not all clothing is without function, however: In particular, individuals with large breasts would benefit from some sort of 'underwear' to support said breasts

What would be the ideal design to minimize the mass of this underwear? The garment should have about as much support as a regular modern bra, and shouldn't be much more uncomfortable. The tech level of materials can be considered to be modern day. The wearers are regular humans under a 1g gravitational effect

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    $\begingroup$ Is there a reason that you think a regular modern sports bra has unnecessary mass? Also, if a rocket is able to make such long burns at 1G that women will a) need to get up and walk around; b) would find it uncomfortable not to have a bra on for that length of time; and c) have a large enough habitable area that walking around is a thing; then the rocket is so advanced that it seems unlikely that every gram counts. You should also have a look at this question from our sister site: space.stackexchange.com/questions/24206/… $\endgroup$ Commented Jul 11, 2023 at 23:10
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    $\begingroup$ @IchthysKing the point is that building a rocket that can sustain 1G for days and is big enough to walk around in is so far in advance of current tech that we cannot really imagine it. However, if we do imagine it then we can shave a tiny amount of mass off the huge living area's structural elements (shrinking it by a few mm in each dimension) to allow for clothing. (Not to mention other options, such as selecting crew carefully - maybe we only allow astronauts <50 kg who take 30 kg of clothing instead of allowing nude 80 kg astronauts.) $\endgroup$ Commented Jul 11, 2023 at 23:27
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    $\begingroup$ @KerrAvon2055 But removing clothing on top of that will reduce the mass even more $\endgroup$ Commented Jul 11, 2023 at 23:32
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    $\begingroup$ @IchthysKing Even in the decidedly not super-powerful rockets launched to the ISS, there's enough mass budget for the astronauts to wear ordinary street clothes. If your space program cannot spare even a handful of kilograms for the comfort and convenience of its astronauts, then I question their priorities. $\endgroup$
    – Cadence
    Commented Jul 12, 2023 at 2:19
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    $\begingroup$ The goal, as stated, is "The tech level of materials can be considered to be modern day. The wearers are regular humans under a 1g gravitational effect." These are analogous to "what's the best women's underwear for daily use on Earth." The only difference is mass, and the implementations for earth-wear are extremely varied with negligible difference in mass. $\endgroup$ Commented Jul 13, 2023 at 16:22

6 Answers 6


If they are worried about the mass added by the bra, they must as well worry about the mass of the breasts that that bra is supposed to support, considering that in most relevant cases the supported object adds more mass than the support object: based on the data available on-line, an A-cup breasts seems to weight around 200 grams while an H-cup breasts ranges around 2800 gram, while on the other hand a normal bra, not decorated with diamonds or other fancy stuff, doesn't reach that weight.

As a consequence, the selection committee will put as one of the physical requirements that the candidate's cup size shall not exceed a given value, let's say A, which will make a dedicated bra right out superfluous.

At the end, there are a lot of physical requirements in term of height, sight, hearing and whatsoever that a candidate astronaut must satisfy. Adding one about the chest size is not so strange.

Yes, you won't have Lara Croft or C.J. in the crew, but that's a consequence of your choice of worrying about the garment mass.


So, the premise of the question is Big Titty Rocket Girlfriends...


Jokes aside - I'm struggling to find any meaningful advantage in terms of weight/performance over a regular Bra vs No Bra vs super-advanced material bra.

Unless we are transporting thousands upon thousands of Ladies who are all packing Page 3-esque Chest Artillery, then the weight saving at a crew level is so negligible as to be irrelevant.

I mean, if for your story, you want a Nudist space Colony - I'm all for it. I'm just questioning the justification of 'every gram counts' when it comes to Bras.

At most you could maybe save a few grams on a Bra for a BTRG, then assume that they have 2 Bras (to alternate - Space/weight is a luxury) and that only ladies above a B Cup require Bras (which is your average size FYI) - assuming a crew size of 100 (for easy maths) with 50:50 Gender split - all of whom are fit and healthy, you are going to have maybe 12 or so ladies who require 2 bras, so that's 14 x (say) 20 grams. a whopping 280 Grams saved.

If weight is that expensive, then you'd pick short people and put them on a reduced calorie diet to get them down to their minimum healthy weight.

That all said - BTRG in Space Lingerie sounds awesome and that's a hill I'm willing to die on.

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    $\begingroup$ Can I upvote this 10000 times? $\endgroup$
    – elemtilas
    Commented Jul 12, 2023 at 2:23
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    $\begingroup$ Honestly, if every gram counts, one might think that chest and booty measurements (for women and men, btw) would be the limiting factor, not clothing. Let's face it, the weight of the clothing << the weight of the body being covered <<<< the weight of the engine. $\endgroup$
    – JBH
    Commented Jul 12, 2023 at 2:51
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    $\begingroup$ @JBH - You are technically correct as usual, but I'd be throwing out the life support before we get to thiccness restrictions. $\endgroup$ Commented Jul 12, 2023 at 3:54
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    $\begingroup$ If you have your astronauts lose weight before sending them into space, then you also mostly solve the bra problem. Breasts are mostly fat tissue. When you force all your astronauts to get slim, they will also lose a couple cup sizes. $\endgroup$
    – Philipp
    Commented Jul 12, 2023 at 7:51
  • $\begingroup$ as far as i know there's breast reducing procedure as well, if they really need to thin down the grams, probably they would propose the astronaut to do these , if it is really that troubling $\endgroup$ Commented Jul 12, 2023 at 9:59

Off-topic, maybe, but I remember a healthy, young double-amputee arguing that they should have been a good candidate for working on the early ISS. They had suitable skills and something like 20% less mass and energy requirements for the same upper-body strength and dexterity.

If every gram counts, you may wonder why we are taking people at all.


Frame challenge:

Modern rockets that have the ability to carry passengers like the SpaceX Starship weigh about 5,000 tonnes. So whilst reducing take off weight obviously has cost implications, a few hundred grams here and there doesn't even make up a rounding error against the rocket and its fuel.

A much more practical weight reduction to the order of kilograms would be to copy what Peter F Hamilton did in "A night without stars" and have a restriction on the maximum height an astronaut can be.

  • $\begingroup$ As the human weight will got to orbit, it would be fairer to compare this to the payload to LEO (23 tons). It is still insignificant. Most women are lighter than men anyway. Why send men into space? $\endgroup$ Commented Jul 12, 2023 at 11:50
  • $\begingroup$ @RichardKirk that's the payload of the Falcon 9. Starship is expected to get more like 150 t of payload. Further, humans take a lot of empty space, making them a low-density cargo, and a Starship carrying people will be volume-limited, not mass-limited. (Similarly, a fully loaded Crew Dragon doesn't come close to maxing out the payload mass of Falcon 9.) $\endgroup$ Commented Jul 12, 2023 at 12:15
  • $\begingroup$ Yeah, but we all know SpaceX is not real. So there. $\endgroup$
    – Daron
    Commented Jul 12, 2023 at 19:02

Chop off a Boob

enter image description here

Much like the mythological Amazons, your lady astronauts are required to have their breasts surgically removed to save those precious extra few grams.

Men don't have it quite so bad. They are only required to be short and weedy, remove their fingers and toenails and eyelashes, and be completely hairless. You know. Like one of those cats.

enter image description here

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    $\begingroup$ Modern problems require modern solutions. $\endgroup$
    – BMF
    Commented Jul 12, 2023 at 11:44

Dress for extreme temperatures

Your end goal should not be to reduce weight, but to reduce mission costs, and a lack of clothing actually increases your mission costs despite reducing weight.

Depending on where you are, space is generally going to be 1 of 2 things, it is either really hot or really cold. In the deep of space, your ship needs an Active Thermal Control System which could require several kilowatts of continuous power per crew member just to keep your living area in a habitable temperature range. While clothing tends to be light weight, power and environmental systems are very heavy. So keeping your crew area comfortable for naked people is actually more expensive than clothing them and keeping your cabin a bit hotter or colder.

If you are in a hot area of space, you can put on a hot suit which assists with your natural perspiration to help your "sweat better" keeping you cooler than if you were naked. Or if you are in cold space, a cold suit can insulate you making you warmer. With well thought out clothing designs, a few hundred grams of synthetic fiber can allow you to keep the cabin at a good +5 to -20°C outside of comfortable ranges for a naked crew which could easily save you several kg and thousands of dollars worth of solar/reactor/HVAC equipment per crewman.

So, if you want to cut costs by cutting a couple of kg from your mission weight, it is better to cut back a bit on your Power and ATC systems knowing that this might cause the occasional brown out, and give your crews the clothing they need so that when someone runs the coffee maker and the microwave at the same time, it doesn't lead to everyone freezing their ###s off.

Legal Repercussions

There is also the liability issue of sending a mostly naked crew into space. While you might save a few hundred dollars per naked crew member, if a sexual crime of any nature takes place during the mission, you risk a lawsuit for creating a working environment that may have encouraged that crime to happen. So, your mission command organization could realistically get sued for millions of dollars for creating an unsafe workspace. Even if you can't prove that there is a single practical advantage to clothing in space, your legal department would never allow such a minor cost cutting practice.

These factors together mean that the ideal space attire is actually going to look a lot more like a Star Trek Federation uniform than a space bimbo bikini.


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