Liftoff! The Origin Of The Countdown

What’s the most thrilling part of rocketry? Well, the liftoff, naturally. But what about the sweet anticipation in those tense moments leading up to liftoff? In other words, the countdown. Where did it come from?

Far from being simply a dramatic device, the countdown clock serves a definite purpose — it lets the technicians and the astronauts synchronize their actions during the launch sequence. But where did the countdown¬† — those famed ten seconds of here we go! that seem to mark the point of no return — come from? Doesn’t it all seem a little theatrical for scientists?

It may surprise you to learn that neither technicians nor astronauts conceived of the countdown. In their book, “Lunar Landings and Rocket Fever: Rediscovering Woman in the Moon”, media scholars Tom Gunning and Katharina Loew reveal that a little-known Fritz Lang movie called Woman In the Moon both “predicted the future of rocketry” and “played an effective role in its early development”.

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Classic Chat: Arko Takes Us Inside NASA’s Legendary JPL

Started by graduate students from the California Institute of Technology in the late 1930s, the Jet Propulsion Laboratory (JPL) was instrumental in the development of early rocket technology in the United States. After being tasked by the Army to analyze the German V2 in 1943, the JPL team expanded from focusing purely on propulsion systems to study and improve upon the myriad of technologies required for spaceflight. Officially part of NASA since December of 1958, JPL’s cutting edge research continues to be integral to the human and robotic exploration of space.

For longtime friend of Hackaday Ara “Arko” Kourchians, getting a job JPL as a Robotics Electrical Engineer was a dream come true. Which probably explains why he applied more than a dozen times before finally getting the call to join the team. He stopped by the Hack Chat back in August of 2019 to talk about what it’s like to be part of such an iconic organization, reminisce about some of his favorite projects, and reflect on the lessons he’s learned along the way.

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Apollo DSKY Display Glows Again

We love seeing old technology brought back to life, especially when it’s done in the context of how the device was originally intended to be used. And double points when it’s space gear, like what [Curious Marc] and his usual merry band of cohorts did when they managed to light up a couple of real Apollo DSKY displays.

The “Display and Keyboard” formed the human interface to the Apollo Guidance Computer, the purpose-built machine that allowed Apollo missions to fly to the Moon, land safely, and return to Earth. Complete DSKYs are hard to come by, but a lucky collector named [Marcel] was able to score a pair of the electroluminescent panels, one a prototype and one a flight-qualified spare. He turned them over to AGC guru [Carl Claunch], who worked out all the details of getting the display working again —¬† a non-trivial task with a device that needs 250 volts at 800 Hertz.

The first third of the video below mostly concerns the backstory of the DSKY displays and the historical aspects of the artifacts; skip to around the 12:30 mark to get into the technical details, including the surprising use of relays to drive the segments of the display. It makes sense once you realize that mid-60s transistors weren’t up to the task, and it must have made the Apollo spacecraft a wonderfully clicky place. We were also intrigued by the clever way the total relay count was kept to a minimum, by realizing that not every combination of segments was valid for each seven-segment display.

The video has a couple of cameos, like [Ben Krasnow], no slouch himself when it comes to electroluminescent displays and DSKY replicas. We also get a glimpse of well-known component slicer and MOnSter 6502-tamer [TubeTime] too. Continue reading “Apollo DSKY Display Glows Again”

Space Shuttle Program: 40th Anniversary Of The First Launch Of Columbia

For those who grew up watching the endless coverage of the Apollo program in the 60s and 70s, the sight of OV-102, better known as the Space Shuttle Columbia, perched on pad 39A at the Kennedy Space Center was somewhat disconcerting. Compared to the sleek lines of a Saturn V rocket, the spacecraft on display on April 12, 1981, seemed an ungainly beast. It looked like an airplane that had been tacked onto a grain silo, with a couple of roman candles attached to it for good measure. Everything about it seemed the opposite of what we’d come to expect from spaceflight, but as the seconds ticked away to liftoff 40 years ago this day, we still had hope that this strange contraption wouldn’t disappoint.

At first, as the main engines ignited, it seemed that Columbia would indeed disappoint. The liquid hydrogen exhaust plume seemed anemic, at least compared to the gout of incandescent kerosene that had belched out from every rocket I’d ever seen launched. But then those magnificent — and as it later turned out, deadly dangerous — solid rocket boosters came to life, and Columbia fairly leaped off the launchpad. Americans were on their way to space again after a six-year absence, and I remember cheering astronauts John Young and Bob Crippen on as I watched the coverage with my dad that early Sunday morning.

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Engine Trouble Delays SpaceX’s Return To The ISS

A crewed mission to the International Space Station that was set to depart from Kennedy Space Center on Halloween has been pushed back at least several weeks as NASA and SpaceX investigate an issue with the company’s Merlin rocket engine. But the problem in question wasn’t actually discovered on the booster that’s slated to carry the four new crew members up to the orbiting outpost. This story starts back on October 2nd, when the computer aboard a Falcon 9 set to carry a next-generation GPS III satellite into orbit for the US Space Force shut down the engines with just two seconds to go before liftoff.

The fact that SpaceX and NASA have decided to push back the launch of a different Falcon 9 is a clear indication that the issue isn’t limited to just one specific booster, and must be a problem with the design or construction of the Merlin engine itself. While both entities have been relatively tight lipped about the current situation, a Tweet from CEO Elon Musk made just hours after the GPS III abort hinted the problem was with the engine’s gas generator:

As we’ve discussed previously, the Merlin is what’s known as an “open cycle” rocket engine. In this classical design, which dates back to the German V-2 of WWII, the exhaust from what’s essentially a smaller and less efficient rocket engine is used to spin a turbine and generate the power required to pump the propellants into the main combustion chamber. Higher than expected pressure in the gas generator could lead to a catastrophic failure of the turbine it drives, so it’s no surprise that the Falcon 9’s onboard systems determined an abort was in order.

Grounding an entire fleet of rockets because a potentially serious fault has been discovered in one of them is a rational precaution, and has been done many times before. Engineers need time to investigate the issue and determine if changes must be made on the rest of the vehicles before they can safely return to flight. But that’s where things get interesting in this case.

SpaceX hasn’t grounded their entire fleet of Falcon 9 rockets. In fact, the company has flown several of them since the October 2nd launch abort. So why are only some of these boosters stuck in their hangers, while others are continuing to fly their scheduled missions?

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Blow Dryers And Metal Shears: Hacks Of Early Falcon 9 Flights

Orbiting over our heads right now are two human beings who flew to the International Space Station in a SpaceX Crew Dragon vehicle on top of a Falcon 9. The majority of coverage focused on the years since human spaceflight last launched from Florida, but [Eric Berger] at Ars Technica reminds us it also makes for a grand ten-year celebration of the SpaceX workhorse rocket by sharing some stories from its early days.

Falcon 9 is a huge presence in the global space launch industry today, but ten years ago the future of a young aerospace company was far from certain. The recent uneventful launch is the result of many lessons learned in those ad-hoc days. Some early Falcon 9 flights were successful because the team decided some very unconventional hacks were worth the risk that paid off. A bit of water intrusion? Dry it out with a blow dryer and seal it back up. Small tear in a rocket nozzle? Send in someone to trim a few inches with shears (while the rocket was standing vertical on the launchpad).

Industry veterans appalled at “a cowboy attitude” pounced on every SpaceX failure with “I told you so.” But the disregard for convention is intentional, documented in many places like this old Wired piece from 2012. Existing enshrined aerospace conventions meant the “how” was preserved but the “why” was reduced to “we’ve always done it this way” rarely re-evaluated in light of advancements. Plus the risk-averse industry preferred staying with flight-proven designs, setting up a Catch-22 blocking innovation. SpaceX decided to go a different way, rapidly evolving the Falcon 9 and launching at a high cadence. Learning from all the failures along the way gave them their own set of “why” to back up their “how” growing far beyond blow dryers and metal shears. We’re happy to see the fail-learn-improve cycle at the heart of so many hacker projects have proven effective to send two astronauts to the space station and likely beyond.

[Photo: SpaceX Crew Demo-2 on the launch pad]

Displaying HTML Interfaces And Managing Network Nodes… In Space!

The touchscreen interface aboard SpaceX Crew Dragon is just one of its many differences from past space vehicles, but those big screens make an outsized visual impact. Gone are panels filled with indicator needles in gauges, or endless rows of toggle switches. It looked much like web interaction on everyday tablets for good reason: what we see is HTML and JavaScript rendered by the same software core underlying Google’s Chrome browser. This and many other details were covered in a Reddit Ask Me Anything with members of the SpaceX software team.

Various outlets have mentioned Chromium in this context, but without answering the obvious follow-up question: how deep does Chromium go? In this AMA we learn it does not go very deep at all. Chromium is only the UI rendering engine, their fault tolerant flight software interaction is elsewhere. Components such as Chromium are isolated to help keep system behavior predictable, so a frozen tab won’t crash the capsule. Somewhat surprisingly they don’t use a specialized real-time operating system, but instead a lightly customized Linux built with PREEMPT_RT patches for better real-time behavior.

In addition to Falcon rocket and Dragon capsule, this AMA also covered software work for Starlink which offered interesting contrasts in design tradeoffs. Because there are so many satellites (and even more being launched) loss of individual spacecraft is not a mission failure. This gives them elbow room for rapid iteration, treating the constellation more like racks of servers in a datacenter instead of typical satellite operations. Where the Crew Dragon code has been frozen for several months, Starlink code is updated rapidly. Quickly enough that by the time newly launched Starlink satellites reach orbit, their code has usually fallen behind the rest of the constellation.

Finally there are a few scattered answers outside of space bound code. Their ground support displays (visible in Hawthorne mission control room) are built with LabVIEW. They also confirmed that contrary to some claims, the SpaceX ISS docking simulator isn’t actually running the same code as Crew Dragon. Ah well.

Anyone interested in what it takes to write software for space would enjoy reading through these and other details in the AMA. And since it had a convenient side effect of serving as a recruiting event, there are plenty of invitations to apply if anyone has ambitions to join the team. We certainly can’t deny the attraction of helping to write the next chapter in human spaceflight.

[Photo credit: SpaceX]