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.
> 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
I had vinyl flooring installed that had a top layer of Aluminum Oxide. Really durable, most people couldn’t tell that it wasn’t wood floor. And about 1/4 the price of laminated flooring.
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 $/kg, even something like titanium is relatively speaking a minor contributor [1] vs the cost of production and complex parts that go into a sat or vehicle.
For actually doing stuff on other worlds, vs sats/ships, it could be quite different though. Growing something like bamboo on Mars or wherever might well have quite favorable production ratios for bootstrapping vs shipping stuff.
The elephant in the room is the cost of putting a payload in orbit.
Even a large difference in materials price will be dwarfed by the cost of fuel and rockets if there's even a small weight increase.
While wood is a material that will burn up in reentry, there are many others without wood's weight and reliability concerns, and people are starting to look into different construction methods to help satellites burn up on deorbiting reliably. e.g. Instead of joining pieces with bolts, use an epoxy that will fail at reentry temperature, ensuring the satellite breaks up into many small pieces and burns up.
This is a fun stunt and good publicity for those involved, but wood probably isn't replacing materials engineered to be lighter and more predictable any time soon.
Cost to LEO has dropped a lot recently. At 951$/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.
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.
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.
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.
~~disclaimer~~ ~~disclosure~~ excited bragging: my strtup is launching a payload on next week's transporter mission. We payed full retail and have no regrets.
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, clearly larger satellites are much cheaper in terms of cost to LEO, but it’s still a useful datapoint.
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.