Looking at the marvellous Chesley Bonestell paintings of spacecraft done in the late 40’s and early 50’s made me question wether spaceflight, say to Mars, would have been possible in craft without electronic computers.
Would it be possible to fly to the Moon or Mars and land on the surface without modern computers, using perhaps only a radar altimeter and “the right stuff” ?
If you read Bonestell-era SF, like Robert Heinlein’s **Rocketship Galileo[/B or Gerge O. Smith’s Venus Equilateral, they talk about “programming” the flight of the ships by cutting cams". There were still lengthy calculations using mechanical computing devices, then the instructions were encded in mechanical devices. (There was a special session at last year’s Arisia convention in Boston about just such anachronisms). So there was pre-digital computer-controlled spaceflight, at least in theory. The hitch was that it couldn’t respond in real time. One reason you needed human astronauts on the job.
Sorry, I should have made it clear that I did mean manned spaceflight.
Neil Armstrong took over the final stages of the Apollo 11 landing of eagle, using, I believe, just the radar altimeter data (though I may be wrong) and landed ok.
Surely if you know in advance enough about the enviroment you’re going to land in (effects of Mascons on your orbit; the martian atmosphere, etc.): then it should be possible to do an entirely manual approach and landing.
Also I can’t remember the references but didn’t Gemini astronauts test orbital rendevous by “manual” means?
I should have made it clear that in each of those cases the ship was manned. The “cam” evidently took car of most of the flight. People were there for corrections. If you watch the movie Destination Moon (loosely based on Rocket Ship Galileo, with a script by Heinlein and set desgn by Bonestell himself), youll see the kind of flight I mean. They don’t show th cam, but they have scenes of mechanical Differential Analyzers computing the course.
One consequence of using mechanical or electro-mechanical computers rather than purely electronic computers is that your spaceship would have to be much bigger.
In terms of complexity, a comparable problem to landing a spacecraft is directing the fire of naval guns. If you ever get a chance to visit a WW2-era large warship, visit the Directing (or Plotting) room. There will likely be several massive mechanical computers used to take input from the ship’s radars, direction and range finders, gun mounts, and helm, and compute firing solutions for the main battery. If you had to fit something comparable on your spacecraft, it would have to be at least ten times bigger than Apollo was.
Because the mechanical computers are so large, you would have to do what NASA did with Apollo; do your computational “heavy lifting” on the ground, and put the bare minimum of computers on the spacecraft. This would probably work for the moon, where the communications lag is short, but it might make a far side of the Moon landing difficult, and a Mars trip impossible.