> "This proves electronics built around 50 years ago, 12 years before Voyager 1, and far before microprocessors and integrated circuits are still capable of working in the hostile environs of space."
I think in some aspect, it might be even more so (robust), than today's technology: Simpler, more to-the-point technology, leading to greater robustness.
I think today's tech and IT industry has something to learn there, and I'm really happy about the "back to basics" trend in IT, going back to compiled, to-the-point languages like Go, closer-to-the hardware cloud systems etc.
Recently I've been working my way through the PPrune megathread on Concorde: http://www.pprune.org/tech-log/423988-concorde-question-77.h... , in which (somewhere) is a discussion of the control systems. Analog fly-by-wire! A complex set of "synchro" and "resolver" systems connected to op-amps, giving it autostabilisation and autothrottle all the way up to Mach 2. The pilots would just push the throttles full open on the runway and leave them there until it was time to come down.
The F-16 used analog fly by wire, and the F-16's analog computer was very well thought of.[1] Here's what it looks like.[2] All those discrete parts! Note the quadruple redundancy.
AFAIK Concode only uses ~80% thrust on takeoff due to vibrations engines create and risk of overheat. Also fuel gets pumped around to change CG, it is a fascinating piece of machinery.
It's all in that thread :) The 80% limit was only on one engine, due to vortex issues. The others had to be at "100%" and full afterburner to get off the ground. The actual volume of fuel flow for a particular power level was also determined by an analogue computer measuring the inlet air temperature and pressure.
I think the main lesson would be that making your transistors and switching currents enormously large is good for longevity in space, but that's nothing new.
Well, I was also thinking about (but didn't write) that most mission-critical systems aren't written in javascript :) ... but rather something "ancient" like ada or pascal.
Not a satellite, but Deep Space 1 ran on "Remote Agent", which was entirely written in Lisp and even had a remote REPL, which was used to debug and fix a race condition bug while millions of miles away.
Oh, did I misunderstand what he meant by "this era"?
I would assume the proper way to phrase it would be "that era" if he meant the 60's, although he did use "ran" which is the past tense. He also mentioned JavaScript, which didn't even exist in that era, so I guess I'm confused by the entire statement.
Edit: by 'he' I guess I meant 'you'. Which means you did mean to refer to the 60's.
.. on room-sized computers. VLSI hadn't been achieved yet, so Apollo flew with a suitcase-sized computer made from discrete gates and core memory programmed in assembler by Margaret Hamilton and others. https://github.com/chrislgarry/Apollo-11
Not trying to be pedantic or a dick, but you should refer to that language as assembly, not assembler. It is a non trivial difference as assembly refers to the language and assembler refers to the software written to parse assembly commands into machine code (binary strings defined in the given machine's instruction set that are meaningful to the processor).
Otherwise it's similar to referring to the language C as Compiler, which is just silly :)
Also, to your point, agreed. It took several years before we could actually fly high level, compiled languages in space, the first being HAL/S on the Shuttle (completed in 1975).
I dunno how other !English languages handle it, but in German both are simply called Assembler. It would also seem that this distinction isn't generally made, due to the human ability to deduce meaning from context.
Although a few high-level languages existed at the time, compilers back then were not capable of code optimization. The only way to write code tight enough to operate a spacecraft would have been Assembly language.
That's incorrect. Commercial avionics are written in C++ these days. Automotive systems are in C or C++. Ada never got any real use outside the US military, and even there it's dead.
It's probably all legacy stuff. The avionics stuff I worked on was all C++. I got to see some Ada code, but it was all ancient legacy systems that hadn't been replaced yet. I seriously doubt anyone is starting any new projects in it.
Imagine the cadaver was just some person who walked on a treadmill of a windmill when the wind wasn't blowing. The person died on the treadmill, and since this was out in the middle of nowhere, the whole scene was left untouched.
The corpse gets wedged into the gearing and the machine stops until the body rots enough that what's left falls free and the gears start moving again when the wind blows.
One thing about tech in hostile environments is resilience to radiation, which is more or less proportional to number of electrons in junction. With smaller fabrication process we win lower energy consumption and much better integration, but at a cost of radiation resilience.
Unlike this one that never worked properly, two other satellites launched in the same series, LES-8 and LES-9 are still functioning as designed. They were powered by RTGs (radioisotope thermoelectric generator) rather than batteries/solar though.
The reverse is the case. Longevity of satellites had increased over time. This is due to a variety of reasons ranging from materials and design improvements to more advanced electronics and superior stationkeeping thrusters as well as reduced reliance on consumable components.
Early spy satellites, for example, relied on film that was returned to Earth, once the film ran out the satellite was useless. Other satellites simply became obsolete or lost attitude control and were no longer useful. Telstar had a service life of only about a year, the first half dozen TIROS weather satellites had lifetimes of about a year or less. Today satellites with similar missions are expected to last decades, which they often do.
Another reason is that nobody is detonating nuclear bombs in space these days. A major cause of Telstar's short life was intense radiation from high-altitude nuclear tests. I'm not sure how long it would have lasted without that....
I very much doubt anyone would consider something that costs hundreds of millions of dollars to build and fire into space "disposable".
It's not like you can buy a new one for cheaper 5 years later.
Well, you sort of can. The majority of cost is R&D, once that's done and you have a template for a satellite, you can definitely build more of them cheaper than the first one.
There's a certain level of intuition that one can grasp with hardware as opposed to software. I suspect this might contribute to most robustness in design.
Satellite is launched, goes silent after a few years due to electrical problems. Decades later, the onboard batteries have deteriorated such that they're just a short (no storage capacity), and the satellite works intermittently when the solar panels are exposed to enough sunlight.
There's probably some charge control electronics, but that's the gist of things. When the battery is discharged or shorted, the solar panel would need to raise the voltage to power the load. When the battery fails as an open circuit, the solar panel can power the load directly.
In 2013 in North Cornwall, UK, an Amateur Radio Astronomer picked up a signal which he determined to be the LES1 that was built by MIT in 1965.
The date in the URL and article says 2016 though, so I'm still not completely clarified on whether this is 3-year-old news or if the satellite is now transmitting again, again --- actually, looking at the name of the site... I'm leaning towards the former.
Reminds me of: "It is then determined MPU is actually an old spy satellite disguised as a weather satellite, that was programmed to reactivate after a certain period of receiving no commands."
Doesn't this remind anyone of "Star Trek IV: The Voyage Home"? ...Where an alien probe comes into earths orbit wreaking havoc to check on the whales and turns out to be an early satllite from earth...
You are mixing up two different Star Trek movies. The ship from 'The Voyage Home' wasn't a man made satellite, it was an alien "whale" ship. However in the first Star Trek movie, a massive ship threatens Earth but turns out to be Voyager 1 returning home.
You're getting old enough to mix the plots of the 1st and 4th movies together. V'ger was the early earth satellite that the enterprise chased down. The probe seeking humpback whales was of alien origin. According to what I remember of the novelization, the aliens had visited earth before recorded history.
I'm not happy I read the novelization of a Star Trek movie, but there we are.
I think in some aspect, it might be even more so (robust), than today's technology: Simpler, more to-the-point technology, leading to greater robustness.
I think today's tech and IT industry has something to learn there, and I'm really happy about the "back to basics" trend in IT, going back to compiled, to-the-point languages like Go, closer-to-the hardware cloud systems etc.