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Hackaday Links: April 23, 2023

Mark it on your calendars, folks — this is the week that the term RUD has entered the public lexicon. Sure, most of our community already knows the acronym for “rapid unscheduled disassembly,” and realizes its tongue-in-cheek nature. But given that the term has been used by Elon Musk and others to describe the ignominious end of the recent Starship test flight, it seems like RUD will catch on in the popular press. But while everyone’s attention was focused on the spectacular results of manually activating Starship’s flight termination system to end its by-then uncontrolled flight at a mere 39 km, perhaps the more interesting results of the launch were being seen in and around the launch pad on Boca Chica. That’s where a couple of hundred tons of pulverized reinforced concrete rained down, turned to slag and dust by the 33 Raptor engines on the booster. A hapless Dodge Caravan seemed to catch the worst of the collateral damage, but the real wrath of those engines was focused on the Orbital Launch Mount, which now has a huge crater under it.

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From Table to Orbit: Salt

Saving Martian Colonists Using Table Salt And Rocket Science

Imagine for a moment that you are a member of an early Mars colony. You’re stranded, and the only way to get a message home is to launch a radio well above the surface. To make matters worse, you’ve got no rockets! It was this thought experiment that has motivated [Thoisoi2] to experiment with making a rocket motor using only ingredients and methods available to your average Martian colonist. The methods he has chosen can be seen in the video below the break.

If you skipped Rocketry 101, a quick refresher might help: Rockets work by burning a fuel in an enclosed chamber and then expelling it at high speed in one direction. To get the fuel to burn more quickly (and therefore adding more oomph to the angry end) a complement to the fuel called an Oxidizer is added. It serves to create an oxygen rich environment for the fuel to burn in. It’s the same reason a oxy-propane torch burns hotter than propane by itself.

Sugar Fuels Go Boom
The Sugar Powered Rocket Motor says “Boom!”

Firstly, a stranded Martian would need rocket fuel. If you recall the 1999 movie October Sky, four high school kids used table sugar as their fuel. You might also recall that those tended to get all explody. This volatility caused [Thoisoi2] to eschew sugar as a fuel in favor of a fuel that would also be available to any Martian colonist but be far less likely to cause Rapid Unplanned Disassembly.

What about the oxidizer? In October Sky, the boys experimented with Potassium Chlorate. This is commonly used in rockets but may be more difficult to obtain for your average Mars colonist. But, it turns out that Potassium Chlorate and Sodium Chlorate which can be prepared from table salt will work equally. It’s quite a bit more involved than that however.

Simply adding salt and fuel does not a rocket motor make. The nuances, the science, and the chemistry are all laid out in the wonderful video that [Thoisoi2] has put together, and we are sure you’ll enjoy it as much as we did.

You’ll also get to find out if our stranded Martian ever makes it home or if his potato farming was for naught.

We’d also like to echo the warning in the video: This is an experiment that is pretty dangerous, so don’t try this at home! Definitely try it at somebody else’s house first. Or on the surface of Mars.

Recently Hackaday covered another great attempt at making a rocket motor at home, although this one was a bit less successful, but every bit as interesting! Continue reading “Saving Martian Colonists Using Table Salt And Rocket Science”

Fail Of The Week (in 1996): The 7 Billion Dollar Overflow

The year was 1996, the European Space agency was poised for commercial supremacy in space. Their new Ariane 5 Rocket could launch two three-ton satellites into space. It had more power than anything that had come before.

The rocket rose up towards the heavens on a pillar of flame, carrying four very expensive and very uninsured satellites. Thirty-seven seconds later it self destructed. Seven billion dollars of RUD rained down on the local beaches near the Guiana Space Centre in Southern South America. A video of the failed launch is after the break.

The cause of all this was a single improper type cast in a bit of code that wasn’t even supposed to run during the actual launch. Talk about a fail.

There were two bits of code. One that measured the sideways velocity, and one that used it in the guidance system. The measurement side used a 64 bit variable, but the guidance side used a 16 bit variable. The code was borrowed from an earlier, slower rocket whose velocity would never grow large enough to exceed that 16 bits. The Ariane 5, however, could be described with a Daft Punk song, and quickly overflowed this value.

The code that caused the overflow was actually a bit of pre-launch software that aligned the rocket. It was supposed to be turned off before the rocket firing, but since the rocket launch got delayed so often, the engineers made it timeout 40 seconds into the launch so they didn’t have to keep restarting it.

The ESA never placed blame on a single contractor. The programmers had made assumptions. The engineers had made reasonable shortcuts to make their job easier. It had all made it through inspections, approvals, and finally the launch event.

They certainly learned from the event; the Ariane 5 rocket has flown 82 out of 86 missions successfully since then. It has at least five more launches contracted before it is retired in 2023 for the Ariane 6 rocket being developed now. This event also changed the way critical software and redundant systems were tested, bringing the dangers of code failure to the attention of the public for the first time.

If you want to read more, there is a great discussion on Reddit which tipped us off to this fail, a quite thorough Wikipedia article, and the original article that ran in the New York Times is mirrored here.

Continue reading “Fail Of The Week (in 1996): The 7 Billion Dollar Overflow”