Need 1.2 billion to build and launch hundreds of drone satellites that go to asteroids to mine and refine ore. Then shuttle the ore via ion thrusters to space 3D printers at Earth's Lagrange Point 4, which then use solar heaters to build space habitat components

So like, Kickstarter or something?

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FYI For anyone starting their own space program (he mentions casually) there's a thing called ITAR registration, which is pretty much mandatory for anything space or rocket related

"International Traffic in Arms Regulations" is basically a set of rules in the U.S. saying you can't do business with anyone on the govt naughty list

But you have to register for this, which costs $2250 ($2750 renewal) every year, which is currently reduced to $500 because of COVID until 2021

Skipping = Jail+fine

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Texas Instruments makes a nice D-type 16-bit flip flop with 3 states:
74LVTH16374

Put 4 of these together with a few capacitors and other helper components and you've got a 64 bit register appropriate for RISC-V CPU built from scratch

Also the 16374 has an operating temp range of -40C - 85C. Storage, -65C - 150C. Quite manageable with active controls

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What you lose in space and power consumption, you gain with parts availability and development cost

It's not exactly radiation hardened, but a computer built with coarse electronics, even CMOS, is less susceptible in low Earth orbit

Besides RADHARD components tend to be much slower than contemporary consumer chips anyway. Might as well go bigger to make things easier and cheaper to build

Launch costs will tumble even more

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Looking at the precautions for potting compound made me realize how incredibly toxic some of this stuff is. Especially the chemicals used in aerospace for high/low temperature tolerance

Some of this stuff will make your eyebrows fall out with one whiff

All of them need a respirator, long sleeves, and thick gloves to handle safety

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The Curiosity rover has 2 radiation hardened computers (primary + backup) clocked at a maximum 200MHz. The CPU alone costs $200K, without the mainboard and other support hardware

Plan is to make my own radiation "tolerant" CPU with similar specs, but in RISC-V RV64, in my living room for the same price as a PizzaHut dinner for 2

Piece of cake

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Found my starting point. The registers can be built with a bunch of these D-type 3 state flip flops:
74ALVCH16821

PDF Datasheet assets.nexperia.com/documents/

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According to my rough calculations, I need an O'Neil Cylinder built in Earth's Larange point 5, with a diameter no less than 1.14km and length no less than 7.61km, to support a renewable forest for firewood for a single a wood stove in a single orbit

Seasons like winter can be simulated with solar shading and moisture pumped through a central line of needle spray nozzles. The Coriolis effect on falling snow and rain would be remarkable

Maintaining this wouldn't require much processing power

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Finding bucket seats good enough (and cheap enough) to withstand a launch into orbit and reentry is a challenge

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This can probably be built in a weekend with a bit of spare stainless steel, some pipes, and maybe a gasket or two

How hard can it be

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TIL This is the "noise" captured by Voyager 1 in the interstellar medium. I can't be entirely sure there are no space whales

Wonder how practical it would be to build something approaching the Voyager probes' durability in my living room

www-pw.physics.uiowa.edu/voyag

· · Tootle for Mastodon · 1 · 2 · 8

There's technically no rule against using bamboo inside a spacecraft, aside from weight considerations (and possible sensitivity to temperature fluctuations)

The only hazard is possibly flammability, but that has countermeasures

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A DIY space program needs lots of antennas

It's possible to build a fairly adequate parabolic dish (beam waveguide type so the base is stationary) with EMT electrical conduit. The dish just needs to support itself and EMT conduit is fairly easy to bend to the correct shape and is robust enough to survive outdoors even under heavy snow

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There's a lot of "X has more processing power than the Apollo lander" and similar phrasing and that's usually not a good comparison

Spacecraft hardware is highly specialized and extremely capable in the narrow field in which they're used

From a biological perspective, it would be like comparing brain size and neuron count. Behavior is a lot more accurate indicator of intelligence and capability

I can't even guess how smart an octopus is, but we don't typically use their size to compare

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And speaking of space hardware, being resilient is often more important than just capability and speed

In fact, most space-rated hardware is going to be slower than their consumer counterparts, but that's OK because the software is highly optimized to run on it

The trick to getting the DIY space program operational on that front is making sure the hardware is resilient and the programming optimized and actually fits the purpose more than increasing raw speed

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This is by far one of the better animations of a rocker bogie that I've seen in a good while. It moves the middle suspension bar to the rear, which frees up the middle for actual storage, power etc...

Via:
youtube.com/watch?v=49AJeDyDjm

See also:
en.wikipedia.org/wiki/Rocker-b

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This is by far the simplest practical breakdown of the rocker bogie mechanism that's easy to understand. It's one thing to read papers with angle calculations, pressure delta etc... but another to actually see just the moving components

I think this platform would work quite nicely for the simplest practical rover

wpirover.wordpress.com/2011/11

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Personal hygiene is important under the DIY space program. Of course, a spinning habitat would make things a lot simpler, but in the meantime, we'll probably go with the no-rinse shampoo too

reddit.com/r/Damnthatsinterest

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I was looking at the engine detail of the Redstone rocket engine, the heart of the PGM-11 missile. It occurs to me that this particular geometry lends itself quite well to the expander cycle

This particular engine had a turbopump powered by decomposed high-test peroxide

In theory, H2O2 is a pretty neat way to power a turbopump (also used by Copenhagen Suborbitals is using it for their engines) and as a monopropellant for RCS thrusters, but it's kind of a pain to handle and store safely

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Fiber optic cables don't seem to fare well without special shielding and different methods of construction in a high radiation environment. While they're resistant to transient EM spikes, they do tend to break down and attenuate more of the laser light over longer distances

This is a bit of a dilemma. Either go with copper lines for signaling and sensors and risk spikes and have them acting as antennas in a EM field, or go with fiber. Alternatively, I may have to make my own

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Also, I may have accidentally landed myself on some kind of list by searching for "radiation sources" too many times

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I'm both heartened and terrified that some of you are genuinely interested in this backwater space program

Please be patient about the first several (dozen?) explosions

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Speaking of explosions...

The number of accidents in rocketry is too damn high!

Some of that is the inherent danger of the fuel + oxidizer and the complicated plumbing involved. I have neither the intelligence or patience to grasp all of that mess so if I build a rocket, it will probably use the expander cycle

The plumbing is *far* less complex with fewer moving parts. Which means fewer places for things to go wrong and fewer areas of concern to monitor (less work for the computer)

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I know the new hotness is Methane right now, but I'd go with Dimethyl Ether as the fuel instead. It's very cheap and can be made from biofuel (possibly on Mars via a different process as well)

As the oxidizer, I'd use Nitrous Oxide. Laughing gas, basically. It's also very cheap and made by the millions of tons. Best of all, it can be decomposed into a very hot gas at 577 C

Dimethyl Ether auto ignites at only 350 C so there's the startup process solved. No need for pyros, sparks, etc...

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No nonsense that can fail explosively. Just a tiny electric pump to get the N2O going over the catalyst, which is more than hot enough to ignite the mixture

Also, the expander cycle limits the maximum size of an engine, which means you have to build more smaller ones anyway. While that's extra work, you get spares if one or two shutdown mid-flight

And expanders don't have complicated turbopumps which need high temp/high speed moving parts and seals so they're cheaper to build

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Hmm...

An expander cycle rocket engine with a radiation resistant computer and sensors will probably cost more than the $2.41 I found in my couch this morning

I'm gonna need to engineer this to within an inch of its life

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@cypnk for a moment I thought this was a test fusion reactor design

@Ted I can probably build one of those with the left over bits of a microwave

@cypnk
Reasonably priced, easy to bend and work with, strong as metal yet lightweight. Great stuff. Many sources of jigs, bending apparatuses(I like apparati!), and ideas out there on the interwebs. One of my favorite materials for building #3Dprinter frames.

@Tay0 Yes indeed! It's kinda amazing how good it is for building basic tent structures and greenhouses too

@cypnk "IF IN DOUBT, ASK" should be printed on everything

@phooky
Aside with the infamous: DONT ASK TO ASK, JUST ASK.
@cypnk

@dredmorbius And detect shapes with relative accuracy. Meanwhile, self driving cars...

@cypnk
At $25 apiece, the RPI compute module would be great. You could have them running in pairs, each pair doing a very specific task. The small size, low weight and interoperability would make them ideal with a few spares onboard in case of failure. In places where you need the GPIO, the standard RPI would work equally well.

@Tay0 For something in LEO, I can imagine it being a perfect fit for E.G. a cubesat. Very little power and the new RPI 4 Model B has good imaging capability as well

But it wouldn't be "DIY" if I don't solder the registers and build a CPU myself ;)

@mdhughes Well, that was thoroughly fun

Also, thanks to this clip I finally know where the audio sample came for this track that I heard back in the mid 90s (MTV AMP)

youtube.com/watch?v=xuWgR4I_HS

@mdhughes @cypnk space clothes are amazing. I love the way the miniskirts are removable.. NASA really did amazing work their. And the purple wigs protect against cosmic rays, but not for men, so they don't need to wear them

@cypnk
A friend of mine built rockets with, essentially, tyre rubber and liquid oxygen.

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@cypnk everything is okay as long as you don't have to dick around with hydrazine

@cypnk you've probably read it, but "Ignition!" by John Clark was a suitably nerdy and hilarious read for me last year.

@loppear My favorite was the description of what high test peroxide does to things (and people). Also, indirectly, the reason I'm avoiding it even though a lot of other amateur rocketry folks do use it

@cypnk
They really don't deal with squirrels well at all when run on overhead poles either.

@Tay0 Yup. Any kind of stress, even on "outdoor armored" cables is a problem. Another reason we would dig trenches for ours even if it's a huge pain (and in New York, you can't move a stick without a permit of some kind)

@cypnk
We run a cable called OPGW as static or ground lines on our transmission lines. It's a stranded, weather proof ground line with fiber in its core. I hear it's tough stuff. The stuff they run on regular distribution electric poles needs some kind of treatment like this.

@penguin42 At ambient pressure, this shouldn't be an issue, but baked bamboo doesn't really outgass any more than other types of plastic sent up there

@cypnk @penguin42 not only will it burn up in the atmosphere upon violent re-entry…it’s also biodegradable!

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