Deploy Workaround Code To The Field When “The Field” Is Lunar Orbit

The Apollo missions still inspire people today, decades after they took place. A fortunate side effect of the global public relations campaign is that a lot of information is publicly available for us to review and process. We’re right around the 49th anniversary of Apollo 14 mission, so it was a good time for [Frank O’Brien] to take readers through Apollo Guidance Computer and the hack that saved Apollo 14 (while it was in lunar orbit).

Space fans would already know many parts of this piece, but [Frank] weaves it together into a single narrative around a problematic “Abort” button that was found to be making intermittent contact as the crew were preparing to land on the moon. An inconvenient timing would have unnecessarily aborted the mission, which was obviously Not Good. [Frank] brings us up to speed on AGC fundamentals, just enough to understand the technical constraints for the hack, devised within the time constraints they faced.

For those that prefer a short video summary [Scott Manley] covered this same hack on YouTube. And for another perspective on the scope of this task, remember this was years before we had vi or emacs. When they were contemplating flipping status bits as programs were running, it’s not trivial to do a global search for code that might examine those bits. Look at the tome of source code AGC programmer [Don Eyles] worked with. Space fans who want to learn more can check out [Don]’s book.

For the ultimate AGC talk, check out The Ultimate AGC Talk.

Maybe someday trips to the moon will be a commonplace thing, but Apollo will always be the pioneer.

Books You Should Read: Sunburst And Luminary, An Apollo Memoir

The most computationally intense part of an Apollo mission was the moon landing itself, requiring both real-time control and navigation of the Lunar Module (LM) through a sequence of programs known as the P60’s. Data from radar, inertial navigation, and optical data sighted-off by the LM commander himself were fed into the computer in what we’d call today ‘data fusion.’

The guy who wrote that code is Don Eyles and the next best thing to actually hanging out with Don is to read his book. Don’s book reads as if you are at a bar sitting across the table listening to his incredible life story. Its personal, hilarious, stressful, fascinating, and more importantly for those of us who are fans of Hackaday, it’s relatable.

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Space Escape: Flying A Chair To Lunar Orbit

In the coming decades, mankind will walk on the moon once again. Right now, plans are being formulated for space stations orbiting around Lagrange points, surveys of lava tubes are being conducted, and slowly but surely plans are being formed to build the hardware that will become a small scientific outpost on our closest celestial neighbor.

This has all happened before, of course. In the early days of the Apollo program, there were plans to launch two Saturn V rockets for every moon landing, one topped with a command module and three astronauts, the other one containing an unmanned ‘LM Truck’. This second vehicle would land on the moon with all the supplies and shelter for a 14-day mission. There would be a pressurized lunar rover weighing thousands of pounds. This wouldn’t exactly be a Lunar colony, instead, it would be more like a small cabin in the Arctic used as a scientific outpost. Astronauts and scientists would land, spend two weeks researching and exploring, and return to Earth with hundreds of pounds of samples.

With this, as with all Apollo landings, came a risk. What would happen if the ascent engine didn’t light? Apart from a beautiful speech written by William Safire, there was nothing concrete for astronauts consigned to the deepest of the deep. Later in the Apollo program, there was a plan for real hardware to bring stranded astronauts home. This was the Lunar Escape System (LESS), basically two chairs mounted to a rocket engine.

While the LESS was never built, several studies were completed in late 1970 by North American Rockwell detailing the hardware that would return two astronauts from the surface of the moon. It involved siphoning fuel from a stricken Lunar Module, flying to orbit with no computer or really any instrumentation at all, and performing a rendezvous with an orbiting Command Module in less than one Lunar orbit.

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Hackaday Links: August 20, 2017

Foam core, dollar tree foam board, Adams foam board, or whatever we’re calling a thin sheet of foam sandwiched between two pieces of poster board, is an invaluable hacker’s tool. Everyone should have a few sheets on hand, and not just because each sheet is a dollar each at any Dollar Store. [Eric] has been working on a technique to create compound curves in foam board, and the results look great. It’s a true three-dimensional plane with weird curves, and certainly has applications for something.

The Apollo Lunar Module is the first, and only manned space-only spacecraft ever made. The design of this spacecraft isn’t constrained by trivialities like ‘atmosphere’, and the design didn’t need ‘bulkheads thicker than a stack of paper towels’. It is a beautiful ship, and now a company wants to produce a gorgeous 1/32 scale model of the LEM. The goal is $25k, which is quite high for the real space modeling market, but if this GoFundMe campaign succeeds, this will be one of the finest real space models ever created. It’ll also match the scale of the 1/32 Revell CSM.

Speaking of Apollo-related technology, here’s a slight bit of drama. [Fran] has been working on recreating the DSKY — the user interface for the Apollo Guidance Computer — for a few years now. She’s set up a crowdfunding campaign to recreate the electroluminescent, screen printed segment display, and things are going great. Now there’s a company selling commercial DSKYs (with a stupid TFT display), that potentially uses the same art. Is this copyright infringement? Maybe, but probably not. It is a dick move not to credit [Fran], though.

The Monoprice Mini Delta is phenomenal. More on that in a bit.

There’s a complete solar eclipse happening across the United States tomorrow. Many schools should have started classes by then, but they’re calling tomorrow a snow day. Everyone who is traveling to see the eclipse is probably already where they’re going to be, and there are clouds on the horizon. Literal clouds. Everyone is watching the weather channel to see what the cloud cover will be tomorrow. Some people don’t have to worry: [Dan] is building a high-altitude balloon to get 100,000 feet above any clouds. There’s a 360° camera onboard, and the resulting video will be awesome. At least one person in Charleston will be renting a plane; I question the wisdom of renting a 172 over a Piper or Cirrus or another low-wing plane, but whatever. If you’re working on a project that will look at the eclipse from above the clouds, leave a note in the comments. For those of you looking at clouds tomorrow, Hackaday is doing another eclipse meet up on the Pacific coast of Mexico on April 8, 2024.