Finding The Sun And Moon The New Old-Fashioned Way

The ability to build a robot to take care of a tedious task for you is power indeed. For a few centuries, the task of helping determine one’s location fell to the sextant. Now, you can offload that task to this auto-sextant, courtesy of [Raz85].

To be clear, this robo-sextant doesn’t give you your exact location, but it does find and display the bearing and altitude of the most luminous object around and display them on the LCD — so, the sun and moon. A pair of cheap servos handle the horizontal and vertical movement, an Arduino Uno acts as the brains and nervous system, and a photoresistor acts as the all-seeing eye. Clever use of some cardboard allow [Raz85] to keep the photoresistor isolated from most all light except what the sextant is currently pointed at. Servos have a limited field of movement, so you might need to adjust [Raz85]’s code accordingly if you’re rebuilding this one yourself.

After taking three minutes to make its rounds of the sky, the Uno records the servos’ positions when fixed on the sun or moon, translating that data into usable coordinates. Don’t forget the best part, it runs on batteries making it convenient for all your wave-faring excursions!

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Hacking On Mars In “The Martian”

It’s been 6 years since the hacker’s treat of a book, “The Martian” by Andy Weir, was self-published, and 2 years since the movie came out. We’ve talked about it briefly before, but enough time has passed that we can now write-up the book’s juicier hacks while being careful to not give away any plot spoilers. The book has more hacks than the movie so we’re using the book as the source.

For anyone unfamiliar with the story, Mark Watney is an astronaut who’s left for dead, by himself, on Mars. To survive, he has a habitat designed for six, called the Hab, two rovers, the Mars Descent Vehicle (MDV) they arrived in, and the bottom portion of the Mars Ascent Vehicle (MAV), the top portion of which was the rocket that his five crewmates departed in when they left him alone on the inhospitable desert planet. If you haven’t read it yet, it’s easy to finish over a long weekend. Do yourself a favor and pick it up after work today.

Making Water

Watney’s major concern is food. They sent up some potatoes with the mission which will sprout roots from their eyes. To grow potatoes he needs water.

One component of the precious H2O molecule is of course the O, oxygen. The bottom portion of the MAV doesn’t produce oxygen, but it does collect CO2 from the Martian atmosphere and stores it in liquid form. It does this as one step in producing rocket fuel used later to blast off from the surface.

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Retrotechtacular: The Apollo Guidance Computer

There is so much amazing technology that came out of the space race. For this week’s Retrotechtacular we’re looking at the guidance computer used in the Apollo program undertaken by NASA in the 1960’s.

One of the main components of this system is the Inertial Measurement Unit or IMU. That’s a familiar term for hackers who build quadcopters or other devices for which spacial awareness is paramount. In this case the IMU provided critical information about the motion and orientation of the capsule during it’s trip from the Earth to the Moon and back. But it wasn’t just high tech electronics along for the flight. To determine actual position a sextant was used for triangulating position. Yes, this is the same type of measuring device used for centuries. The method of using the sextant is displayed above. The spacecraft was turned until the sextant pointed at a landmark on Earth. The instrument was the adjusted to line up a star as a landmark, then the computer calculated position based on time and the angles of the two points being sighted. There’s a lot more shown in this thirty-minute film including in-depth assembly and testing of the computer components.

Before we point you to a few related articles we’d like to mention that our stash of really cool Retrotechtacular tips is running low. So if you know of some old footage that’s awesome to watch please send us a tip about it.

Now if you can’t get enough about NASA electronics you should check out the LVDC board which [Fran] got her hands on. Also, it’s worth checking out the unbelievable soldering techniques specified in the NASA manual. There’s a pretty good discussion about that going on in the Reddit thread.

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