[HN Gopher] Woodsat: A Space Agency Will Launch a Tiny, Wooden S...
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Woodsat: A Space Agency Will Launch a Tiny, Wooden Satellite
Author : pseudolus
Score : 96 points
Date : 2021-06-18 10:44 UTC (12 hours ago)
(HTM) web link (www.npr.org)
(TXT) w3m dump (www.npr.org)
| mauvehaus wrote:
| The article alludes to this, but one of the key challenges to
| using wood in space will likely be that wood changes shape as
| it's moisture content fluctuates. Here on earth, that's typically
| due to seasonal variations in humidity, and it's why your doors
| stuck in the summertime when it's more humid.
|
| In space, the equilibrium moisture content of wood is probably
| zero, or immeasurably close to it, whereas on earth, I don't
| think you can dry wood that far with typical drying equipment.
| Which is no doubt why they're using a thermal vacuum kiln, the
| vacuum bit being the key.
|
| The challenge then becomes maintaining that level of dryness
| between drying and space. Typical wood finishes slow, but don't
| stop moisture exchange. And if you coat the whole damn thing in
| something exotic to maintain a super dry material, you likely
| torpedo the whole "green" aspect.
|
| Plywood (and other manufactured wood products) moves much less
| than solid wood. I'm still curious if they're having to design
| around accommodating any movement in their mechanical design
| given the extremely uncommon atmospheric(?) conditions this will
| be subjected to upon launch. Moisture exchange will likely be the
| last of their concerns on reentry.
|
| I, for one would be delighted lto serve as a wood movement
| consultant on future wooden spacecraft. Though, really, all the
| principles of sound solid wood construction on earth have been
| known for millennia and there's no shortage of sources on doing
| it right.
| jedimastert wrote:
| > The challenge then becomes maintaining that level of dryness
| between drying and space.
|
| There's also stabilizing, in which you "fill in" all of the
| space the water left with a very thin resin. I'm sure you could
| find some all-natural stuff that would do the trick
| owenversteeg wrote:
| They apparently coated it with aluminum oxide, which is a
| super-hard finish used on wood flooring.
| croon wrote:
| Nice to see some Hearthian tech.
| wetmore wrote:
| That was my first thought as well!
| rjsw wrote:
| One script for Alien 3 had a wooden space station.
| webwielder2 wrote:
| Obligatory Onion: https://www.theonion.com/russian-scientists-
| announce-six-mon...
| idoh wrote:
| Wood has been in space before, see this link:
| https://space.stackexchange.com/questions/18856/puzzler-whic...
|
| Apparently, balsa wood makes a good heat shield.
| xoa wrote:
| While cute in a good way, can't help but feel this is a bit of a
| silly piece (though I think they're trying their best and it's
| nice to see more hopeful tech news vs the typical dreary
| disasters/panics). It's similar to coverage last year of the
| Kyoto University/Sumitomo Forestry satellite using wood which got
| a nod at the end. Ars Technica did a decent run down of that at
| the time [0], though reacting more to some of the "space junk"
| angles in mainstream media coverage vs cost. Wood, particularly
| when heavily treated, does have some interesting properties and
| it may stand on its own in that regard. But it won't be for cost,
| "green", "space junk", or any other such reasons it'll be purely
| about whether it serves a useful performance goal or not. As far
| as cost which this article mentions a bunch, even Starship's
| ultimate, genuinely paradigm shifting target costs to orbit are
| still something like $100/kg. Compared to $1000-10000+/kg it's
| easy to see why that's a huge deal, but the cost of any simple
| base component material going in would also still be
| comparatively near meaningless if it resulted in worse
| amortization. Stainless steel is single digit $/kg, even
| something like titanium is relatively speaking a minor
| contributor [1] vs the cost of production and complex parts that
| go into a sat or vehicle.
|
| For actually doing stuff _on_ other worlds, vs sats /ships, it
| could be quite different though. Growing something like bamboo on
| Mars or wherever might well have quite favorable production
| ratios for bootstrapping vs shipping stuff.
|
| ----
|
| 0: https://arstechnica.com/science/2020/12/wooden-satellites-
| an...
|
| 1: https://www.metalary.com/titanium-price/
| boo-ga-ga wrote:
| Reminds of Outer Wilds a bit:)
| jhgb wrote:
| Or, _The Wooden Spaceships_? Literally.
|
| https://en.wikipedia.org/wiki/Land_and_Overland#The_Wooden_S...
| beloch wrote:
| The elephant in the room is the cost of putting a payload in
| orbit.
|
| Even a large difference in materials price will be dwarfed by the
| cost of fuel and rockets if there's even a small weight increase.
|
| While wood is a material that will burn up in reentry, there are
| many others without wood's weight and reliability concerns, and
| people are starting to look into different construction methods
| to help satellites burn up on deorbiting reliably. e.g. Instead
| of joining pieces with bolts, use an epoxy that will fail at
| reentry temperature, ensuring the satellite breaks up into many
| small pieces and burns up.
|
| This is a fun stunt and good publicity for those involved, but
| wood probably isn't replacing materials engineered to be lighter
| and more predictable any time soon.
| Retric wrote:
| Cost to LEO has dropped a lot recently. At 951$/kg to LEO wood
| is probably good enough it's not an issue for most satellites.
|
| Overall strength is probably close enough to be irrelevant in
| many cases and construction costs could drop quite a bit. It's
| not the cost of the carbon fiber that's at issue it's how
| difficult the stuff is to work with.
| brandmeyer wrote:
| SpaceX is charging 1 megabuck for a 200 kg payload, (5
| kUSD/kg). That's still cheap enough that for bespoke
| spacecraft the launch is still much less expensive than the
| satellite.
|
| What is the basis for your < 1kUSD/kg estimate?
| Retric wrote:
| Costs go up for smaller payloads as your paying for more
| than just weight.
|
| As a sanity check a Falcon gets 22,800kg (expendable) and
| 16,800 (reusable) to LEO. At 5k/kg that would be 84M
| reusable, apparently they're charging ~85M for a reusable
| falcon Heavy launch and Falcon 9 is much cheaper.
|
| Actual prices aren't disclosed but the internal price are
| quoted at as ~40M new and under 15M refurbished, with 10
| total launches per rocket. Assuming the last launch isn't
| reusable by design that's (40M+ 9 * 15M ) ~= 175M to get
| (16,800 kg * 9 + 22,800kg) = 174,000kg to LEO. That's under
| 1k/kg, though I have seen 951$/kg quoted in terms of
| StarLink's costs.
|
| Clearly they charge customers more, but not 5k/kg more.
| brandmeyer wrote:
| Smallsat retail launch prices on Falcon 9 are published.
| Even if SpaceX is making money hand-over-fist at that
| price, they are still the cheapest ride in the business.
|
| https://www.spacex.com/rideshare/
|
| ~~disclaimer~~ ~~disclosure~~ excited bragging: my strtup
| is launching a payload on next week's transporter
| mission. We payed full retail and have no regrets.
| Retric wrote:
| Cool, though they also charge 5k/lb into polar orbits
| which have significantly lower capacity. Falcon 9 is
| 16,800kg to LEO but only 9,600kg to a polar orbit.
|
| Anyway, larger satellites are much cheaper in terms of
| cost to LEO, but it's still a useful datapoint.
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