It’s 2024, and there’s no getting around it. Grid energy is expensive. [Darrell] realized that a lot of his money was going on water heating, and he came up with a neat solution. What if he could hack in some solar power to slash his bills at a minimum of fuss? It worked so well for him, he’s whipped up a calculator to help others do the same.

[Darrell]’s idea was simple enough. He hooked up solar panels to just the bottom heating element of his hot water heater. This cut his power bill in half. His calculator is now up at pvh20.com, and it’s designed to help you figure out if it’s feasible for you. It takes into account your location, local power prices, and the amount of sun your area tends to get on a regular basis. It also takes into account the solar panels you intend to use and your water heater to determine how many panels you’ll need for properly hot water. Key all that in, and you’re well on your way to speccing a decent solar hot water setup. From there you’ll just need to buy the right stuff and wire it all up properly.

If you live in an area where the sun shines freely and the power is more expensive than printer ink, this could be a project well worth pursuing. Cheaper hot water is a grand thing, after all. [Darrell’s] calculator is really only the first step, and it doesn’t deal with the practicalities of installation, but that’s half the fun of a good project, right? Happy hacking!

One of the most sought after substances in the Universe is water – especially in its liquid form – as its presence on a planet makes the presence of life (as we know it) significantly more likely. While there are potentially oceans worth of liquid water on e.g. Jupiter’s moon Europa, for now Mars is significantly easier to explore as evidenced by the many probes which we got onto its surface so far. One of these was the InSight probe, which was capable of a unique feat: looking inside the planet’s crust with its seismometer to perform geophysical measurements. These measurements have now led to the fascinating prospect that liquid water may in fact exist on Mars right now, according to a paper published by [Vashan Wright] and colleagues in PNAS (with easy-read BBC coverage).

InSight’s mission lasted from November 2018 to December 2022 by which time too much dust had collected on its solar panels and communication was lost. During those active years it had used its seismometer (SEIS) to use the vibrations from natural marsquakes and similar to map the internals of the planet. Based on rock physics models and the data gathered by InSight, there is a distinct possibility that significant liquid water may exist in Mars’ mid-crust, meaning at a depth of about 11.5 to 20 km. Most tantalizing here is perhaps that at these depths, more liquid water may exist today than may have filled Mars’ past oceans.

Since we’re talking about just a single lander with a single instrument in a single location, it would be highly presumptuous to draw strong conclusions, and at these depths we would have no means to access it. Even so, it would offer interesting ideas for future Mars missions, not to mention underground Mars bases.