Magic Mirror Isn’t Transparent Metal

August 22, 2022 by Al Williams 20 Comments

One of the Star Trek movies has a McGuffin called “transparent aluminum.” While magic mirrors aren’t really transparent, it appears that way to a casual observer. If you haven’t seen one of these, they are polished metal mirrors with a pattern embossed on the back. When you shine a point source of light on the mirror, however, the reflection matches what is on the back of the mirror. Is it transparent? No, and the video by [Steve Mould] below explains what’s really going on.

The reality is that very subtle variations of the surface produce the image. You need some understanding of optics and calculus to fully understand what’s going on.

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Unpacking The Stowaway Science Aboard Artemis I

August 22, 2022 by Tom Nardi 40 Comments

NASA’s upcoming Artemis I mission represents a critical milestone on the space agency’s path towards establishing a sustainable human presence on the Moon. It will mark not only the first flight of the massive Space Launch System (SLS) and its Interim Cryogenic Propulsion Stage (ICPS), but will also test the ability of the 25 ton Orion Multi-Purpose Crew Vehicle (MPCV) to operate in lunar orbit. While there won’t be any crew aboard this flight, it will serve as a dress rehearsal for the Artemis II mission — which will see humans travel beyond low Earth orbit for the first time since the Apollo program ended in 1972.

As the SLS was designed to lift a fully loaded and crewed Orion capsule, the towering rocket and the ISPS are being considerably underutilized for this test flight. With so much excess payload capacity available, Artemis I is in the unique position of being able to carry a number of secondary payloads into cislunar space without making any changes to the overall mission or flight trajectory.

NASA has selected ten CubeSats to hitch a ride into space aboard Artemis I, which will test out new technologies and conduct deep space research. These secondary payloads are officially deemed “High Risk, High Reward”, with their success far from guaranteed. But should they complete their individual missions, they may well help shape the future of lunar exploration.

With Artemis I potentially just days away from liftoff, let’s take a look at a few of these secondary payloads and how they’ll be deployed without endangering the primary mission of getting Orion to the Moon.

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Is This The Oldest Open Source HVAC Project In Existence?

August 22, 2022 by Dave Rowntree 19 Comments

Homebrew HVAC systems are one of those projects that take such a big investment of time, effort and money that you’ve got to be a really dedicated (ideally home-owning) hacker with a wide variety of multidisciplinary skills to pull off an implementation that can work in reality. One such HVAC hacker is [Vadim Tkachenko] with his multi-zone Home Climate Control (HCC) project that we covered first back in 2007. We now have rare opportunity to look at the improvements fifteen years of part-time development can produce, when a project is used all day, all year round in their own home. At the start, things were simple, just opening and closing ventilators with none of those modern MQTT-driven cloud computing stuff. Continue reading “Is This The Oldest Open Source HVAC Project In Existence?” →

SSB In Your Pocket

August 22, 2022 by Al Williams 66 Comments

In the old days, a shortwave radio was a major desk fixture. These days, you can get truly diminutive radios. However, most of them only have AM capability (that is, no simple way to receive single-sideband or SSB signals) and — maybe — the ability to pick up FM broadcast. Small radios also often have no provision for an external antenna which can be crucial for shortwave radios. [Farpoint Farms] shows off the Raddy RF7860 which is a palm-sided radio, but it has the elusive sideband modes and an external antenna port and wire antenna. It even has a rechargeable battery.

Reading the comments, it appears this is a rebadged version of a HanRongDa HRD 747 radio. Of course, there are other smaller radios with sideband reception like the Tecsun PL368, but they aren’t this small. If you are in the market for a really tiny shortwave radio, this might be the thing for you.

Of course, the question is what you want to listen to on the shortwave bands these days. There are fewer and fewer broadcasters on shortwave, especially those that broadcast to a general audience. However, if there is something you want to hear, pairing this radio with a good portable antenna, would do the job.

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