The Unwise Idea of Wooden Satellites

[DaveE]

TL;DR Summary

Satellites made of wood?

I can't even count how many reasons this is a stupid idea. But then, what do I know?
https://gizmodo.com/japanese-resear...nkkDxSetcsgWyW8sJ81-JMHjl3_j65KKEh9kYry2-32Gs

 

[phinds]

]I can't even count how many reasons this is a stupid idea.

List three.

 

[Filip Larsen]

Ars Technica also ran an article detailing how most other media apparently misunderstood what kind of problem using wood in satellites aims to solve:
https://arstechnica.com/science/202...uing-idea-but-wont-solve-space-junk-problems/

 

[DaveE]

List three.

1) Difficult to produce consistently; difficult to have second sources; difficult to inspect.

2) Difficult to machine with precision (grain, inhomogeneity, etc.). Difficult to model mechanical strength accurately.

3) Low shear strength (for threaded fasteners, for example).

4) Poor thermal conductivity. You must conduct heat away from internal heat sources to radiate from the surface.

5) Not electrically conductive (which could be an advantage, but probably isn't). Poor electrical shielding from external radiation, EMP, or internal EMI.

6) New untested material. AFAIK, there's no Mil-Spec for S-level wood. No life test data in real deployments.

7) Outgassing, lots of outgassing.

8) Not cleanable, at least with conventional methods.

9) Structural stability from manufacture, storage, hard vacuum, and large temperature changes.

10) It's still space junk. You don't want your satellite hit by wooden junk or metal junk.

OK, your turn. List three advantages, I wasn't too impressed with the ones in the article.

 

[berkeman]

OK, your turn. List three advantages, I wasn't too impressed with the ones in the article.

1) They would be a lot prettier...

http://phinds.com/bowls/_master_index.htm

 

[f95toli]

I doubt the idea is to use this for "high value" satellites where the cost of failure would be catastrophic. More likely they are thinking of using wood in something similar to certain cubesat projects where you are launching tens or hundreds satellites that are only designed to operate for a relatively short period of time before they are designed to (hopefully) burn up.

Also, I doubt they are planning to use say oak. It is much more likely that they are either thinking of something like a high performance MDF or at the very least some laminated material (plywood) where the variations are much smaller. There are actually some pretty good standards for MDF based on physical properties.

Note also that some material that ARE frequently used in cryogenic/vacuum applications are not that dissimilar to laminated wood in their structure (say Tufnol). I have no idea of Tufnol has even been used to make parts for a satellite but it would not surprise me. You obviously only use it for part where you need low thermal and electrical conductivity, and presumably the same thing would be true for the wood they have in mind for the satellites.

edit: corrected some typos

 

[Vanadium 50]

I doubt the idea is to use this for "high value" satellites where the cost of failure would catastrophic. More likely theyare thinking of using wood in for something similar to certain cubesat projects where you are launching tens or hundreds satellites that are only designed to operate for a relatively short period of time before they are designed to (hopefully) burn up.

I agree that that's what they are thinking about. Where I fail to see the great step forward is that the innards are the majority of the mass, and the innards are made of what they have always been made of. Changing the skin material probably doesn't hurt much, but probably doesn't help much either.

 

[DaveE]

I doubt the idea is to use this for "high value" satellites where the cost of failure would be catastrophic. More likely they are thinking of using wood in something similar to certain cubesat projects where you are launching tens or hundreds satellites that are only designed to operate for a relatively short period of time before they are designed to (hopefully) burn up.

Also, I doubt they are planning to use say oak. It is much more likely that they are either thinking of something like a high performance MDF or at the very least some laminated material (plywood) where the variations are much smaller. There are actually some pretty good standards for MDF based on physical properties.

Note also that some material that ARE frequently used in cryogenic/vacuum applications are not that dissimilar to laminated wood in their structure (say Tufnol). I have no idea of Tufnol has even been used to make parts for a satellite but it would not surprise me. You obviously only use it for part where you need low thermal and electrical conductivity, and presumably the same thing would be true for the wood they have in mind for the satellites.

edit: corrected some typos

The thing is there are commonly used materials in satellites that are also cheap; aluminum, polyethylene, glass fiber composites, etc.

The reason wood is cheap in the lumber yard is that it doesn't have the screening and performance that you would want for even cheap satellites. As an example, why do people make circuit boards in the cheapest consumer products out of glass fiber composites instead of wood composites? Because it's cheaper to use manufactured materials than naturally produced materials when you care about performance.

Back in the day (several decades ago) I did a power supply design that really needed a common but sort of new IC that wasn't space qualified yet. We ended up paying something like $50K for 6 of them that you could buy commercially for about $15. Why? What did we get for the extra $49,985? Testing, traceability, QA, a dedicated production run following S-level procedures; basically $15K worth of paperwork and 6 ICs. That paper would be extremely difficult to produce if you start from a tree. That project built 3 satellites; one to deploy, one to test to death, and one spare in case something went wrong. For conventional satellites, this is an expensive game, with the cost spent on reliability in a harsh environment. Those customers won't tolerate "shooting from the hip", trying something new to save a few bucks isn't the point.

Yes, now days an overachieving high school science club can build a cube sat, perhaps out of wood. But they can't actually sell it to the DoD or a telecom company, those people need satellites that work. They also couldn't get it launched into space without some charity, basically piggybacking on real cube sat deployments.

edit: Oh oh, I just realized I said "satellite". Back around 1985 that was classified. please don't turn me into the FBI. The thing that I always thought was very DoD-esque was that back then I could have told you that it had to operate in a hard vacuum and survive something like 15g's of acceleration. But we couldn't say the two "S" words. WTF? How dumb did they think the Russians were?