54 Humans in One 8-meter Gravitics Module | Hacker News Reader

54 Humans in One 8-meter Gravitics Module

gravitics.com

39 pointsgeox43 comments

From the photo, "stand roughly within the cut-away mockup, and smile at the camera" is that all they're doing. (On Earth. It's supposedly a mockup of a proposed space station module.)

If I recall, the record for stuffing adults into a standard-sized phone booth is about 1/4 that number.

I think it's just meant to be a more easy-to-grok illustration of how big this thing is. Nobody's truly planning on cramming 54 people into one of these in orbit, barring an extreme Seven Eves-style emergency.

Big-picture...yes, likely. Though it also has a strong "of course we'll use it for our group photo backdrop" vibe.

Small-picture...I don't think whoever did the article is really aware of the big picture.

On the other hand, the situation kind of reminds me of the Boeing/Airbus promotional materials for new planes where they nearly always show it in the "hyperrich Saudi prince" configuration - piano, lounge, bar, maybe a dozen people in a 787-sized cabin.

So, pessimistically, one of these is gonna end up crammed with 200 people not 54.

I think if space travel were as common as air travel, sure - but right now, nobody with a net worth of under a million is going into orbit except as part of a national space agency.

https://en.wikipedia.org/wiki/Inspiration4

On the plus side, with 200 people if you just rotate people around regularly you can significantly reduce the radiation exposure of those on the inside of the cluster and their total exposure while in space. Their body and water mass surely make for a decent shield.

Or again, realistically with humanity being humanity, whatever disadvantaged group emerges in space will end up as the shield layer.

I agree, but I still found myself agonizing at the idea of spending a few months with 54 people in such a configuration.

Better would be to embrace the absurdity of filling a space capsule with only one type of thing. Show me an image of how many bananas it can hold.

how many swimming pools?

They don't state the volume directly, instead claiming it's roughly half that of the ISS. According to Wikipedia the ISS is 1,005 m^3 and an Olympic-size swimming pool holds 2500 m^3. That would place this module at about 500 m^3 or 20% of a swimming pool.

https://en.wikipedia.org/wiki/International_Space_Station

https://en.wikipedia.org/wiki/Olympic-size_swimming_pool

Edit: This random Reddit thread says bananas are 156.1 cm^2 and pack with 65% efficiency. That means the module would hold about 2 million bananas.

https://www.reddit.com/r/theydidthemath/comments/rdiyis/requ...

Interesting that they chose an 8 meter diameter, probably assuming a launch on the 9-meter Starship as Blue Origin's New Glenn is only 7m diameter. It would be interesting to see a weight projection for a completed module to see how well it fits within Starship's planned capacity of between 100 to 200 tons to orbit.

A 50cm (max) gap between the module's outer edge and Starship's inner edge does not seem like much room for support or deployment infrastructure in the launch vehicle, and would also require bay doors that fully open - and maybe a robot arm to safely deploy.

I haven't seen any reference to explicit collaboration between Gravitics and SpaceX. Maybe it's still too early, but I would hope the two have open lines of communication to avoid expensive redesigns later on.

The starship users guide[1] indicates that an 8 meter diameter payload is the maximum that can be accommodated.

[1] https://www.spacex.com/media/starship_users_guide_v1.pdf

Yeah, that makes sense and they are likely communicating. The dimension is often used approximately to know what class of launch vehicle it is fitting in. For the standard existing rockets we will say things like "this spacecraft fits in a 5m fairing", but the actual static payload envelope is 4.82m or something. So don't take it as a precise measurement.

China is developing a 10m diameter rocket that looks heavily inspired by Starship; methalox engines, stainless steel construction, possibly partly/fully reusable

But yeah I can't imagine this going on any other rocket. At some point in the future there will be a market for habitable volume. Right now habitable volume is built like an RV, a mostly self-contained singular unit, but in the future modular construction might look like big rigid bubbles of air with windows, and every couple of units you have a "mechanical" area for hvac, power, water etc, similar to how high-rise buildings are designed.

They are working on 4m and 6M versions as well and yeah, the 8m is for Starship.

https://www.gravitics.com/news/nasa-saa-verification

I'm not sure what the point of cramming 54 people into the cross-sectional area is as a demonstration. After all, if you give each person one square meter, you could fit the entire population of the earth into the state of Connecticut. (with some room left over)

54 people in the module volume even seems like it would be quite cramped and unpleasant for anything more than a short trip.

Also, is enclosed volume really the thing that needs to be optimized? Presumably the ISS has so much less enclosed volume for its size because its mission demands more external surface area and/or other things like modularity that are at odds with maximizing enclosed volume.

I think the driving force for the shape of the ISS is actually the available launch vehicles. Skylab was a lot closer to the size of this thing than the ISS is because it went up on the last Saturn V.

I walked through the Skylab replica at Space Center Houston just last week and was blown away by the scale.

https://www.youtube.com/watch?v=d1sr6aVzW9M

Sure; they say it's "roughly half" the "usable volume" of the ISS.

The latter being 388 or 900 or 1005 m^3 because habitable != pressurised, and for the latter NASA publishes two values[0][1], so that's about 194/450/502 m^3 total or 54 people 3.5/8.3/18.6 m^3 per person.

For comparison, the Apollo CSM and lander were 6.2 m^3 and 6.7 m^3 total for 3/2 crew, so even at that (I agree unpleasant) density, it's a plausible size for the pressurised volume of an emergency-return-to-earth lifeboat.

[0] "Habitable Volume: 13,696 cubic feet (388 cubic meters) not including visiting vehicles"

"Pressurized Volume: 35,491 cubic feet (1,005 cubic meters)"

- https://www.nasa.gov/international-space-station/space-stati... cubic meters

[1] https://www.nasa.gov/reference/international-space-station/#...

Given the name I was under the impression that this would be a rotating module to create artificial gravity, but it seems instead it is just a large capsule.

I was wondering that too, and if there actually were any projects working towards rotating space habitats.

> However, there are no current practical outer space applications of artificial gravity for humans due to concerns about the size and cost of a spacecraft necessary to produce a useful centripetal force ... Scientists are concerned about the effect of such a system on the inner ear of the occupants.

https://en.wikipedia.org/wiki/Artificial_gravity

Looks like visitors to space will have to keep dealing with zero-gee for the foreseeable future.

IMHO the concerns that people won't be able to handle the rotation are under tested. While I'm sure there are people who won't be able to handle it just like there are people who can't put on VR goggles without barfing, I suspect the average human could tolerate it just fine.

I would love to see a pair of Starships hooked together with a sturdy cable a couple of dozen meters long and then spun around each other to simulate gravity.

A pair of Starships isn't even necessary. You could do it with a counterweight. Honestly the counterweight approach seems like a pretty easy experiment to try, I don't know why it hasn't been done yet.

Where are you going to find a counterweight in space? Launching two Starships is much easier than trying to capture an asteroid or something.

Bring it with you and deploy it. It doesn't need to have the same mass as a Starship, just a significant fraction would do.

When it comes to singular revolving modules, they need to be above a certain size, otherwise the Coriolis effects will just disorient everyone inside.

An extreme example to illustrate would be a small module with a radius that equals the height of a stationary standing occupant. Their feet would feel normal, but their head would still be "weightless" and getting very dizzy. Actually moving is even worse: Not only would the weights of objects vary depending on their "height", but "falling" objects would seem to have curved paths, so your sometimes-heavy feet would keep "missing" the place you intended to put them down.

If you split the module into two with a tether or girder in-between (or replace one half with a dumb counterweight) that reduces the Coriolis effect... but now you've got something that alternately sweeps through space in a kinda-dangerous way, and it becomes harder to safely enter or exit.

TLDR: Spinning becomes useful on scales we aren't ready to do yet.

How's the air quality on the ISS? I think I remember seeing something about it smelling pretty bad, and I know I've seen terrible reports about the waste containment systems that were used on the shuttle.

Stuff like that isn't quite as sexy as a big volume, but I would think it is at least as important to solve, if not quite a lot more important.

I don’t know this should demonstrate. You can stuff them in their but only for a short time before the all start to go crazy.

Would I step into if my life depends on it, yes but for anything else this is just worthless.

The person for scale +53 more is obviously tongue in cheek.

I expect most of the team working on the module is in the picture.

I thought the Gravitics site was pretty cool.

Question from someone with no knowledge of this industry. How are aerospace startups like Gravitics generally funded? Is it a billionaire or two funding in the short term until it delivers products? Funding from other big aerospace companies like Lockheed Martin as a sort of "skunkworks" project company? VCs? Government DARPA-like funding?

I'm just curious how these big, super expensive hardware efforts get funded for years before they deliver any functional products.

A lot of the time the path looks like this:

1. Initial VC funding for your cool idea to carry you to something (analysis, initial demo) you can feasibly sell to get to a more formal demonstration

2. Science and Technology government org funding for a demonstration (DARPA, SBIRS, SpaceWerx, NASA ventures, FFRDC lab, etc.)

3. Large government funding (NASA, Space Force, etc.) for full product delivery or buying enough data to keep funding further build-out

You can see some of that path on their website

2022: Announced $20m in VC funding, April 2024: SpaceWERX contract for $1.7M, June 2024: Starting to work agreements with NASA

So they are currently on step 2

Unless they're going to build 8m diameter module in orbit, the various inflatable projects make much more sense from a launch standpoint.

Probably depends greatly on the expanded configuration and what equipment is inside.

Starship’s cargo bay is 9m in diameter.

I’m not understanding the bragging about packing 50 people in a box like sardines

It's simply a demonstration of scale. The number of people helps those amongst us that find it challenging to visualize the size of these things.

Is it just me, or is that just a wood mock-up? That was kinda disappointing to realize.

I look at the image of all those people and wonder: will they have additional "floors" in the real thing? Because all I see is the possibility of someone getting stranded in the middle in zero G, unable to reach a surface to push off of...

If you're wearing clothes, you can remove them and throw them to produce some delta v.

Always keep a tungsten cube in your pocket!

https://thume.ca/2019/03/03/my-tungsten-cube/

Filming what happens next has often been proposed as a great revenue driver.

You can "swim" in space by pushing against the air. Not very well, but you won't get stuck.

Please enjoy these very confused birds flying around in a vomit comet:

https://www.youtube.com/watch?v=w4sZ3qe6PiI

I was imagining a standard 3D lattice of struts that could be configured however you want - as equipment mounts, wall studs, etc. They don't need to take too much load so the lattice itself could even be modular in my mind.

Bet you could fit even more in if you blend them first

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