Reflecting On Margaret Hamilton: 50 Years After Apollo 11

In celebration of the 50th anniversary of the first Apollo moon landing, Google created a 1.4-square-mile portrait of NASA software developer Margaret Hamilton using more than 107,000 mirrors from the Ivanpah Solar Facility in the Mojave Desert, a solar thermal power plant with a gross capacity of 392 megawatts.

The fields of heliostat mirrors (173,500 in total) ordinarily focus sunlight on receivers located on the solar power towers, which subsequently generate steam to drive steam turbines. The facility was first connected to the electrical grid in September 2013 before formally opening in February 2014, during which it was the world’s largest solar thermal power station. Ivanpah was developed by BrightSource Energy and Bechtel, with Google contributing $168 million towards its $2.2 billion in costs. Google no longer invests in the facility, however, due to the decline of the price of photovoltaic systems.

The facility has historically taken steps to avoid disrupting the natural wildlife, which includes desert tortoises. The effect of mirror glare on airplane pilots, water concerns, and collisions with birds has also been addressed by the operators of the installation.

According to Google, the image was larger than Central Park and could be seen a mile above sea level. The mirrors are all attached to a rotating mount that maneuvers the mirrors in order to create lighter and darker shades to make up the image.

The Apollo 11 mission, manned by Buzz Aldrin, Neil Armstrong, and Michael Collins, was the first to bring humans to the moon in 1969. Hamilton‘s role in the team included programming the in-flight software for all of NASA’s Apollo missions. She had also worked on satellite tracking software for the Air Force through Lincoln Lab (started by the Massachusetts Institute of Technology) and later joined the Charles Stark Draper Laboratory. It was, however, her work on creating computer systems to predict and track weather systems for use in anti-aircraft air defenses that made her a candidate for a lead developer role at NASA.

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Keeping Birds At Bay With An Automated Spinning Owl

There’s nothing wrong with building something just to build it, but there’s something especially satisfying about being able to solve a real-world problem with a piece of gear you’ve designed and fabricated. When all the traditional methods to keep birds from roosting on his mother’s property failed, [MNMakerMan] decided to come up with a more persuasive option: a solar powered spinning owl complete with expandable batons.

We imagine the owl isn’t strictly necessary when you’re whacking the birds with a metal bar to begin with, but it does add a nice touch. Perhaps it will even serve to deter some of the less adventurous birds before they get within clobbering distance, which is probably in their best interest. [MNMakerMan] says the rotation speed of the bars seems low enough that he doesn’t think it will do the birds any physical harm, but it’s still got to be fairly unpleasant.

At first glance you might think that this contraption simply spins when the small 10 watt photovoltaic panel next to it catches the sun, but there’s actually a bit more to it than that. Sure he probably could just have it spin constantly whenever the sun is up, but instead [MNMakerMan] is using a ATtiny85 to control the 11 RPM geared DC motor with a IRF540 MOSFET. By adding a DS3231 RTC module into the mix, he’s able to not only accurately control when the spinner begins and ends its bird-busting shift, but implement timed patterns rather than running it the whole time. All of which can of course be fine-tuned by adjusting a couple variables and reflashing the chip.

We’ve seen plenty of automated systems for keeping cats away, and of course squirrels are a common target for such builds as well, but devices to deter birds are considerably less common among these pages. So it would seem that, at least for now, [MNMakerMan] has the market cornered on solar bird smashing gadgets. We’re sure Mom’s very proud.

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Dark Absorbing Diodes Are No DAD Joke

We will confess that the authors of the Applied Physics Letters article “Experimental Demonstration of Energy Harvesting from the Sky using the Negative Illumination Effect of a Semiconductor Photodiode” never used the acronym DAD or the phrase “dark absorbing diode.” But we thought it was too good to pass up. The research work uses a type of diode to generate small amounts of power from darkness. Admittedly, the amount of power is small, but it is still an important result and could result in — another coined phrase — negative solar cells providing energy by taking advantage of the temperature differential between the cell and the night sky.

In theory — and with no atmosphere — the technique could only result in about 4 watts per square meter. Not only is this low compared to a solar panel’s 100 to 200 watts per square meter, but it is also far from the prototype’s 64 nanowatts per square meter. Clearly, this technology has a ways to go to become practical.

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Dollar Store Garden Lights As ATtiny Power Supplies

Solar garden lights are just another part of the great trash pile of our age, electronics so cheap as to be disposable. Most of you probably have a set lurking somewhere at home, their batteries maybe exhausted. Internally though they are surprisingly interesting devices. A solar cell, a little boost converter chip, and a little NiCd battery alongside the LED. These are components with potential, as [Randy Elwin] noted with a mind to his ATtiny85 projects.

The YX805A chip he references in his write-up is one of several similar chips that function in effect as joule thieves, extending the available charge in the battery to keep the LED active as long as possible when their solar panel is generating nothing, and turning it off in daylight when the panel can charge. Their problem is that they are designed as joule thieves rather than regulators, so using them as a microcontroller PSU without modification can result in overvoltage.

His solution is to use the device’s solar panel input as a feedback pin from his ATtiny, allowing the microcontroller to keep an eye on its supply voltage and enable or disable the converter as necessary while it keeps running from the reservoir capacitor. Meanwhile the solar panel now charges the NiCd cell through a single diode. It’s not perfect and maybe needs a clamp or something, he notes that there is a condition in which the supply can peak at 8 volts, a level which would kill an ATtiny. But still, we like simple hacks on dollar store parts, so it’s definitely worth further investigation.

This isn’t the first garden light hack we’ve shown you, there was this flashlight, and some LED hacks.

Solar light picture: Leon Brooks [Public domain].

Solar Power Is Set To Get More Expensive

The sun constantly bathes half the planet with energy. The energy may be free, but the methods for converting it to electricity cost money. Last year, the Chinese government cut subsidies to their solar panel manufacturers to shrink the industry which was perceived as bloated. This forced Chinese solar panel makers to cut prices to clear inventory. This drove down prices about 30%, making solar power cheaper than ever.

Reuters is reporting that Eric Luo, president of one of the largest solar panel makers in China, predicts that “the party is definitely over.” Speaking at the World Economic Forum, Luo said that prices have quit dropping and he expected industry consolidation to cause prices to rise by as much as 15% over the next two years.

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Spend All Day On The Lake

Solar vehicles are getting more and more common as the price of solar panels comes down, and the availability of motors and controllers for all of these vehicles rises. Making a solar-electric bike from a kit is one thing, but this solar-powered boat is a master class in hacking at all levels, from the solar drive train to the pontoons, and even the anchor.

[J Mantzel] has many videos about his boat on his channel, and watching them all will likely leave you wanting to build your own. He builds almost everything on his boat from scratch from things he has lying around. For example, the anchor was hand-built from fiberglass and then filled with concrete, and his steering system is a semi-complex system of ropes, pulleys, and shafts. Most of the boat’s shell was hand-built from fiberglass as well, and everything that can be repurposed is saved for later use.

The ten panels, batteries, inverter, and other miscellaneous part of the system were about half of the cost of the whole vessel, but he reports that he also uses the boat as a backup power source for his house, and can use the system to run other things like an electric chainsaw for example. He also uses the boat for camping and construction, and without having to worry about fuel it has been very useful to him.

If you get into the videos on the channel, you’ll find that this isn’t his only solar-powered boat. He recently completed a solar speedboat as well with a custom-built propeller that can really move across the water. His videos are apparently very popular as well, since they have been linked to repeatedly by readers in some of the recent solar vehicle write-ups we’ve published.

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Go Up A Creek Without A Paddle

Kayaks are a some of the most versatile watercraft around. You can fish from them, go on backpacking trips, or just cruise around your local lake for a few hours. They’re inexpensive, lightweight, don’t require fuel, and typically don’t require a license or insurance to operate. They also make a great platform for a solar-powered boat like this one with only 150 watts of panels and a custom-built motor with parts from an RC airplane.

[William Frasier] built his solar-powered kayak using three solar panels, two mounted across the bow of the boat using pontoons to keep them from dipping into the water, and the other mounted aft. Separating the panels like this helps to prevent all three of them being shaded at once when passing under bridges. They’re all wired in parallel to a 12V custom-built motor which is an accomplishment in itself. It uses custom-turned parts from teak, a rot-resistant wood, is housed in an aluminum enclosure, and uses an RC airplane propeller for propulsion.

Without using the paddles and under full sun, the kayak can propel itself at about 4 knots (7 kmh) which is comparable to a kayak being propelled by a human with a paddle. With a battery, some of the shading problems could be eliminated, and adding an autopilot to it would make it almost 100% autonomous.

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