Hackaday Links: November 20, 2022

Lots of space news this week, with the big story being that Artemis I finally blasted off for its trip to the Moon. It was a spectacular night launch, with the SLS sending the crew-rated but vacant — well, mostly vacant — Orion spacecraft on a week-ish long trip to the Moon, before spending a couple of weeks testing out a distant retrograde orbit. The mission is already returning some stunning images, and the main mission goal is to check out the Orion spacecraft and everything needed for a crewed Artemis II lunar flyby sometime in 2024. If that goes well, Artemis III will head up in 2025 with a crew of four to put the first bootprints on the Moon in over 50 years.

Of course, like the Apollo missions before it, a big part of the crewed landings of the Artemis program will likely be the collection and return of more lunar rock and soil samples. But NASA likes to hedge its bets, which is perhaps why they’ve announced an agreement to purchase lunar regolith samples from the first private company to send a lander to the Moon. The Japanese start-up behind this effort is called ispace, and they’ve been issued a license by the Japanese government to transfer samples collected by its HAKUTO-R lander to NASA. Or rather, samples collected on the lander — the contract is for NASA to take possession of whatever regolith accumulates on the HAKUTO-R’s landing pads. And it’s not like ispace is going to return the samples — the lander isn’t designed to ever leave the lunar surface. The whole thing is symbolic of the future of space commerce, which is probably why NASA is only paying $5,000 for the dirt.

On the slightly more expensive side, a few weeks ago the $10 billion James Webb Space Telescope was having some trouble with one of its main instruments. Telemetry from MIRI, the Mid-Infrared Instrument, indicated that one of the wheels that rotate various filters into the optical path was experiencing higher-than-expected friction. Operators shut down MIRI, and while science continued on the other instruments aboard JWST, engineers looked over the telemetry data and came up with a plan to get MIRI back online. They determined that the friction is likely “increased contact forces between sub-components of the wheel central bearing assembly,” which we take to mean the filter wheel is just a little wonky. Since it only happens under certain conditions, they should be able to avoid this becoming a full-blown problem, and MIRI is slowly being returned to operation.

Bad news for KrakenSDR fans — no more passive radar for you! The five-channel coherent SDR receiver used to have a passive radar option, but an unnamed regulatory agency apparently decided that passive radar in the hands of plebes is a no-go. The KrakenRF folks are hashing it out with lawyers, but they say things aren’t looking good so far. On the plus side, they’re doing the right things and offering refunds to anyone who bought a KrakenSDR specifically for passive radar, so hats off to them for that.

And finally, passive radar depends on receiving reflections of high-powered broadcast signals off moving objects — something like the signals emanating from the 1,000,000 Watt super tower seen in this video. The acrophobic need not worry — this isn’t one of those POV videos made by a tower climber. Rather, Jeff Geerling and his dad take us on a tour of the really interesting bit: the stuff in the buildings at the foot of the tower. This particular tower hosts hundreds of customers, including several FM radio stations, and the engineering that goes into radiating that much power in a controlled manner is breathtaking. The amount of copper that went into those hardline coax sections alone is a little staggering, but those combiner boxes in the basement? Wow! We really enjoyed the fact that there’s a 50,000-Watt dummy load, too, and that it had to be mounted outdoors to save the building’s HVAC system. Really cool stuff.