Build a Retro Timekeeper That Never Was

Celebrate the first moon landing with a GPS clock that uses Apollo-era panel meters

4 min read
Photo of the three mounted voltmeters on a rack panel.
Photo: David Schneider

Two years ago, on the 48th anniversary of the Apollo 11 landing, a cloth bag that Neil Armstrong used to return the first lunar samples to Earth was sold at a Sotheby’s auction for US $1.8 million. The seller had purchased it online two years earlier for a mere $995—a fantastically good deal for what turned out to be a precious artifact of the Apollo era.

While I wasn’t nearly so fortunate, I, too, got a good deal online for some hardware that probably contributed in some way to the Apollo program, though I don’t know how exactly. I obtained three vintage analog panel voltmeters for $15 each from an eBay seller who had bought them from NASA’s Marshall Space Flight Center, in Huntsville, Ala.

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From WinZips to Cat GIFs, Jacob Ziv’s Algorithms Have Powered Decades of Compression

The lossless-compression pioneer received the 2021 IEEE Medal of Honor

11 min read
Photo of Jacob Ziv
Photo: Rami Shlush

Lossless data compression seems a bit like a magic trick. Its cousin, lossy compression, is easier to comprehend. Lossy algorithms are used to get music into the popular MP3 format and turn a digital image into a standard JPEG file. They do this by selectively removing bits, taking what scientists know about the way we see and hear to determine which bits we'd least miss. But no one can make the case that the resulting file is a perfect replica of the original.

Not so with lossless data compression. Bits do disappear, making the data file dramatically smaller and thus easier to store and transmit. The important difference is that the bits reappear on command. It's as if the bits are rabbits in a magician's act, disappearing and then reappearing from inside a hat at the wave of a wand.

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