Supercon 2023: Restoring The Apollo Guidance Computer

November 6, 2024 by Lewin Day 17 Comments

Humans first visited the Moon in 1969. The last time we went was 1972, over 50 years ago. Back then, astronauts in the Apollo program made their journeys in spacecraft that relied on remarkably basic electronics that are totally unsophisticated compared to what you might find in an expensive blender or fridge these days. Core among them was the Apollo Guidance Computer, charged with keeping the craft on target as it travelled to its destination and back again.

Marc Verdiell, also known as CuriousMarc, is a bit of a dab hand at restoring old vintage electronics. Thus, when it came time to restore one of these rare and storied guidance computers, he was ready and willing to take on the task. Even better, he came to the 2023 Hackaday Supercon to tell us how it all went down!

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Polaris Dawn, And The Prudence Of A Short Spacewalk

October 3, 2024 by Tom Nardi 40 Comments

For months before liftoff, the popular press had been hyping up the fact that the Polaris Dawn mission would include the first-ever private spacewalk. Not only would this be the first time anyone who wasn’t a professional astronaut would be opening the hatch of their spacecraft and venturing outside, but it would also be the first real-world test of SpaceX’s own extravehicular activity (EVA) suits. Whether you considered it a billionaire’s publicity stunt or an important step forward for commercial spaceflight, one thing was undeniable: when that hatch opened, it was going to be a moment for the history books.

But if you happened to have been watching the live stream of the big event earlier this month, you’d be forgiven for finding the whole thing a bit…abrupt. After years of training and hundreds of millions of dollars spent, crew members Jared Isaacman and Sarah Gillis both spent less than eight minutes outside of the Dragon capsule. Even then, you could argue that calling it a spacewalk would be a bit of a stretch.

Neither crew member ever fully exited the spacecraft, they simply stuck their upper bodies out into space while keeping their legs within the hatch at all times. When it was all said and done, the Dragon’s hatch was locked up tight less than half an hour after it was opened.

Likely, many armchair astronauts watching at home found the whole thing rather anticlimactic. But those who know a bit about the history of human spaceflight probably found themselves unable to move off of the edge of their seat until that hatch locked into place and all crew members were back in their seats.

Flying into space is already one of the most mindbogglingly dangerous activities a human could engage in, but opening the hatch and floating out into the infinite black once you’re out there is even riskier still. Thankfully the Polaris Dawn EVA appeared to go off without a hitch, but not everyone has been so lucky on their first trip outside the capsule.

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Hackaday Links: June 9, 2024

June 9, 2024 by Dan Maloney 32 Comments

We’ve been harping a lot lately about the effort by carmakers to kill off AM radio, ostensibly because making EVs that don’t emit enough electromagnetic interference to swamp broadcast signals is a practical impossibility. In the US, push-back from lawmakers — no doubt spurred by radio industry lobbyists — has put the brakes on the move a bit, on the understandable grounds that an entire emergency communication system largely centered around AM radio has been in place for the last seven decades or so. Not so in Japan, though, as thirteen of the nation’s 47 broadcasters have voluntarily shut down their AM transmitters in what’s billed as an “impact study” by the Ministry of Internal Affairs and Communications. The request for the study actually came from the broadcasters, with one being quoted in a hearing on the matter as “hop[ing] that AM broadcasting will be promptly discontinued.” So the writing is apparently on the wall for AM radio in Japan.

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The Fake Moon Landing Quarantine

June 15, 2023 by Al Williams 43 Comments

We aren’t much into theories denying the moon landing around here, but [Dagomar Degroot], an associate professor at Georgetown University, asserts that the Apollo 11 quarantine efforts were bogus. Realistically, we think today that the chance of infection from the moon, of all places, is low. So claiming it was successful is like paying for a service that prevents elephants from falling through your chimney. Sure, it worked — there hasn’t been a single elephant!

According to [Degroot], the priority was to protect the astronauts and the mission, and most of the engineering money and effort went towards that risk reduction. The — admittedly low — danger of some alien plague wiping out life on Earth wasn’t given the same priority.

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Hackaday Links: May 14, 2023

May 14, 2023 by Dan Maloney 13 Comments

It’s been a while since we heard from Dmitry Rogozin, the always-entertaining former director of Roscosmos, the Russian space agency. Not content with sending mixed messages about the future of the ISS amid the ongoing war in Ukraine, or attempting to hack a mothballed German space telescope back into action, Rogozin is now spouting off that the Apollo moon landings never happened. His doubts about NASA’s seminal accomplishment apparently started while he was still head of Roscosmos when he tasked a group with looking into the Apollo landings. Rogozin’s conclusion from the data his team came back with isn’t especially creative; whereas some Apollo deniers go to great lengths to find “scientific proof” that we were never there, Rogozin just concluded that because NASA hasn’t ever repeated the feat, it must never have happened.

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Add A Little Quindar To Your Comms For That Apollo-Era Sound

April 30, 2023 by Dan Maloney 9 Comments

If there’s one thing that ties together all the media coming out of the Apollo era, it’s probably the iconic Quindar tones. These quarter-second beeps served as control tones for the globe-spanning communications network needed to talk to the Apollo astronauts, and any attempt to recreate the Apollo-era sound would be glaringly wrong without them. And that’s why [CuriousMarc] whipped up this Quindar tone system.

The video below starts with a detailed treatment of what Quindar tones are and why they were used, a topic we’ve covered ourselves in the past. To recap, Quindar tones are a form of in-band signaling, with a 2,525-Hz pure sine wave intro tone that signaled the transmitters connected to Mission Control in Houston over leased telephone lines to key up. The 2,475-Hz outro tone turned off the transmitters and connected the line to the receivers.

To recreate the sound quality of the original circuitry, and to keep in the retro vibe, [Marc]’s Quindar homage avoided digital circuitry as much as possible, opting instead to generate the two tones with an XR-2206 function generator chip. The chip can rapidly switch back and forth between two frequencies, making it perfect for FSK applications or, in this case, reproducing the two slightly different tones. [Marc] added a dual mono-stable multi-vibrator to pulse the tone, giving the 250-ms pulse, and an audio gate, which uses a MOSFET to switch the tone into an audio stream. All this got soldered up to a piece of perf board and stuffed in the base of a cheap intercom microphone, which while not period accurate still has a cool retro look — and now, a retro sound, too.

Hats off to [CuriousMarc] and his merry band for probing the mysteries of Apollo-era comms and keeping the accomplishments of all those engineers alive. The methods they used are still relevant after all these years, and there seems to be no end to what we can learn from them.

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The Nixie Clock From Outer Space

March 13, 2023 by Al Williams No comments

Nixie clocks are nothing new. But [CuriousMarc] has one with a unique pedigree: the Apollo Program. While restoring the Apollo’s Central Timing Equipment box, [Marc] decided to throw together a nixie-based clock. The avionics unit in question sent timing pulses and a mission elapsed time signal to the rest of the spacecraft. Oddly enough, while it had an internal oscillator, it was only used during failures. It normally synched to the guidance computer’s onboard clock.

There is a detailed explanation of the unit, along with some of the ancillary equipment and panels. Much of what the output from the unit is driving counters to display timers, although some of the clocks drive other pieces of equipment, like the telemetry commutator, which time stamps each telemetry frame.

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