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
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
Found my starting point. The registers can be built with a bunch of these D-type 3 state flip flops:
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
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
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
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
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
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
And then there's this guy who built an entire rocker bogie car for his kid
There's a lot of reading involved when it comes to starting your own space program
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
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
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
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)
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...
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
Going with Dimethyl Ether and Nitrous Oxide as fuel and oxidizer also because they can be kept liquid at similar temps
-141 C To −24 C for Dimethyl Ether and −90.86 C to −88.48 C for Nitrous Oxide. Which means, they can share a bulkhead in the tanks
This significantly cuts complexity and reduces weight
Also, both have enough expansion at warmer temperatures that I can use "Autogenous pressurization". Same as SpaceX's Starship (though mine will probably be made of glue and aluminum foil)
Apparently a turbocharger from a V8 isn't actually designed to funnel liquid propellant at -89 C at turbopump tolerance. Or survive reentry down from orbital speeds (because reusable rockets or GTFO)
My plan to use a rice cooker to make homemade high-temp composites is probably gonna have issues too
I hope lockdowns lift a bit so I can go trash diving. I'm sure someone's thrown out an orbital grade turbopump somewhere
Although there are significant drawbacks with a multi-nozzle rocket engine design, I think for small scale development, the benefits outweigh them. Biggest benefit being combustion stability, which is greater in smaller combustion chambers (see Apollo's F1 issues). The biggest drawback is the additional manufacturer of nozzles and chambers, but once you get the design finalized, they're relatively straightforward to do repeatedly
Today in gloriously-impractical-yet-want, here's an actual core memory unit including the Gerber files for the circuit board and schematic
Spacecraft don't use these anymore since there are better options, but part of me feels like there's still some value in here
I also wonder if it's feasible to have core memory backed SRAM
So the system reads/writes to SRAM in normal use, as a fast buffer, while it slowly updates the core memory
Might just be crazy enough to work
I thought I was being very clever when I thought of combining PCBs with core memory
Basically, you include an iron coated ring in one of the inner layers (or maybe several rings) while a via through the middle takes care of the connections to sense and address leads
Well, someone already thought of it before
Back in 1961
But it does mean this may be a feasible way to create modern core memory without resorting to fiddling with tiny ferrites. Maybe even mass-produce it by iron-plating rings
If we take "ring" or "ferrite" to just mean "iron loop", then printed core memory may actually be fairly straightforward (hah!)
The iron loop can actually be printed as two iron-plated half loops on either surface of a 4 layer, double-sided PCB, with vias through the middle and on each half end of the loop to the one the opposite side
4 layers is also ample to handle addressing, sense, and inhibit lines
Coincidentally, 4 layers are the cheapest multi layer PCB type available from most vendors
I think this is a Crew Return Vehicle concept. There's a lot of space dedicated to provisions and maybe experiments, but not a lot for fuel. I'm guessing there's just enough for a bit of maneuvering and a deorbit burn and nothing else
But that also makes it a feasible build of an orbital spacecraft for a DIY space program that's a bit more exciting than a simple capsule. Geometrically, it's actually an elongated capsule than a "spaceplane", unlike the Shuttle
And you can mount it atop a rocket
Oh that's actually not a Crew Return Vehicle, but a full on space shuttle replacement concept by Lockheed. And it's a lot bigger on the inside than the concepts imply. Which means, it's probably not going to be built any time soon (if at all)
The problem with larger Shuttle* concepts is that they're always going to be semi-reusable as long as rockets are involved
Ironically, the SpaceX Starship is probably the way to go as it's the least "plane-like" of all the reusable systems
This is a pretty nice video of on building a solar cooker with a parabolic reflector. The form is actually made of concrete so you can make many reflectors repeatably with very good accuracy
If I'm building my own radio observatory, I'd probably also use this technique to build hundreds of parabolic dish antennas
Going back to the idea of DIY core memory, I came across this page many moons ago, but lost it. Sadly, the original page is gone, but luckily the Internet Archive has a snapshot
It's a very good primer on the operation of core memory and has a set of demo circuits to operate a small grid of cores (expandable to as many as is practical)
This is an interesting preview of an orbital space station structure (the basics of assembly) from The Gateway Foundation
Their goal is to send an assembly robot with the raw material to build a rotating habitat in space. They'll start with the skeleton structure and the rest can be brought up with subsequent launches
Large scale production of chemicals still require very expensive permits. I know it's to ensure that a large chunk of a neighborhood suddenly doesn't become uninhabitable, but I can't help but feel some of it is just run-of-the-mill bureaucracy
The good news is that I won't need an alcohol permit if I don't produce ethanol
Bad news is that storing several tons of Nitrous Oxide(oxidizer) and Dimethyl Ether(fuel) is a pain and I still need permits
Er... and I need to get said chemicals first
OK, I've had my fill of math for the rest of the decade
Now I actually have to figure out orbital mechanics to the point of being able to model it in the Doom engine, running on a laptop I found on the street back in 2007
Should be good enough to get a spacecraft to the nearest asteroid if I wrap it in some aluminum foil and Silly Putty to protect it from the radiation
This is a concept to incrementally append modules to the ISS with the intention of private use (likely "space hotel", but that idea has its own issues)
The idea itself seems interesting and I think it might be viable now that bigger payloads will soon be possible without the Space Shuttle thanks to SpaceX
This is an animation from a company called Axiom Space
I was looking at the A6/7 Redstone rocket engine and, while the design is decades old, it's one of the simpler variations that can be copied
Probably explains why Copenhagen Suborbitals use it as a reference for their own designs
Also, since the original engine used alcohol + liquid oxygen, it's a tad safer to operate than toxic hypergoic substances. The bigger danger was the high-test hydrogen peroxide used to drive the turbopump
After the high-test peroxide decomposed into a hot gas (H2O and O2), it gets sent through the turbopump turbine and vented out through a giant exhaust (foreground red pipe)
The bulge in the middle is a heat exchanger
But since even the hot gases are cooler than combustion products, I'm wondering if another model can be built which uses film cooling on the interior of the nozzle extension like the process of the original F1 used in the Saturn V
This does add more weight though
Akin's Laws of Spacecraft Design
14 Stood out to me:
"(Edison's Law) "Better" is the enemy of "good"."
"The fact that an analysis appears in print has no relationship to the likelihood of its being correct."
On the ground, the biggest limitation on radio dish size is gravity and I'm not entirely convinced if a dish is the right approach for all signal types
For a narrow beamwidth, I don't think you can beat a parabolic reflector, but for wide field scanning (maybe searching for near-Earth asteroids by radar?) I'd go with an orbital curtain array
It's possible to launch a lightweight folded curtain array antenna into orbit, which can unfold into something roughly the size of a football pitch
Motto of asteroid mining prospectors:
"There's gold in them rocks and I aim to get at it"
Haven't solved the pelletizing problem: I.E. Turning raw asteroid material into floatable chunks, which can be nudged into a usable orbit via ion thrusters
The issue is the limited gravity which lets the back thrust or impact of any lander into a vicious debris cloud. We saw this when Hyabusa2 collected samples on Ryugu
Slow settle + melting/compacting into a 3D printer like extrusion may be an option
@profoundlynerdy Indeed. No matter what, we've been making tiny iron rings for centuries, so worst case scenario, there's room to store at least a few kilobits with some effort
@cypnk Right. That's an 8×8 matrix. Assuming no bits are reserved for parity: 1024 of those will get you 64kB of RAM.
That is plenty of RAM re-start the information age. Relatively fast (10's of MHz) CPU's can be made with scavenged TTL logic chips.
Punched tape as ROM can bootstrap an OS, phonograph cylinders can store a few hundred kB of program data. Long range communication is possible over #shortwave.
@cypnk it seems sometimes like everything worth thinking up was thought up in the sixties
must have been a hell of a time to be alive
@fluffy Before the Internet, people actually had to work hard to send messages of discouragement. Of course, encouragement was harder too, but that also meant fewer distractions overall
@cypnk as boring as capsules are, they turn out to be the aerodynamically most stable solution when it comes to re-entry and landing on planets with atmosphere.
Size is the only reason not to use a capsule in my opinion.
That CRV shape remembers me of the early Starship drafts. They changed it got a few changes recently.
@zem There's also something to be said of design simplicity, at least when it comes to earlier spacecraft going back to the 60s. Hence favoring inherent stability
But I also think we can improve beyond seeking stability in favor of long term occupancy (since we now have computer modeling). Size for one, but also better options for maneuvering and landing on the ground. Splashdowns have their own hazards too
@cypnk hmm that's image is from 2009-ish?
Plane-like or not, sending all the thrusters to LEO and returning them might not be the best idea.
Having a high surface area to weight ratio is good? Having an upper stage return alone/just the engine, would help there..
This stuff is all very much not green no matter how you do it.. (pretty much need an orbital ring/launch loop and industry being diverted away from Earth to be that..)
@jasper This was from 2005-ish and was part of a number or Shuttle replacement concepts from various companies at the time. They were quite adamant to replicate the Shuttle back then
The only way I see are smaller, cheaper, scavenger spacecraft being used to mine asteroids and build infrastructure in orbit
That's a lot less damaging to Earth than launching everything from the surface
I have a book somewhere around here called Heaven's Flame by Joseph Radabaugh(? I think) about making solar cookers from cardboard and aluminum foil. Tried it. Didn't work here because we're too windy. Concrete might work.
@Tay0 I think the solar cooker idea in general might only work with a very sturdy surface, and then only in much warmer climates too. I don't know anyone in these parts who got one to work correctly either
> The asteroid belt is actually farther away from Earth than I remembered
when i saw this thread had started in October of last year, i had the idea you had begun to walk there.
@Nikolai_Kingsley HAHAHA! 😂 Not quite yet. I'll need to send a few drones first
There's gold in them rocks and I aim to get at it
@cypnk ISS is on a high inclination (marginally more expensive per kg) orbit. Looks like they're adding power. They might have to had thrusters too. May as well not connect it to anything, use a better orbit.
@k2civ The orbit was a compromise from the start since they had to build it mostly with the Shuttle and still stay accessible to the Russians. It can probably be incrementally shifted to a higher orbit at a lower inclination with modular thrusters, if NASA is considering deorbiting it (no good to the Russians then anyway)
@confusedcharlot There are *very* strong parallels to that engine. In fact, this is a direct descendant
@confusedcharlot "This A-series of engines utilized a cylindrical combustion chamber design over the spherical V-2 chamber"
@cypnk umbrellas .. so you impact the surface or drill into it,, w/e and the debris is going to follow a predictable path away , have your mining umbrella scoop up the debris and then from the base of the umbrella swing it into your collector / compactor / smelter / w/e
@cypnk yeaaah you’re gonna not want to do this in a residential neighborhood...probably not in a commercial zone either.
@katnjiapus There may still be some companies making bespoke core memory for some hardware which can't be replaced
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