Back in the hazy olden days of the pre-2000s, navigating between two locations generally required someone to whip out a paper map and painstakingly figure out the most optimal route between those depending on the chosen methods of transport. For today’s generations no such contrivances are required, with technology having obliterated even the a need to splurge good money on a GPS navigation device and annual map updates.
These days, you get out a computing device, open Google Maps or equivalent, ask it how you should travel somewhere, and most of the time the provided route will be the correct one, including the fine details such as train platform and departure times. Yet how does all of this seemingly magical route planning technology work? It’s often assumed that Dijkstra’s algorithm, or the A* graph traversal algorithm is used, but the reality is that although these pure graph theory algorithms are decidedly influential, they cannot be applied verbatim to the reality of graph traversal between destinations in the physical world.
Recently, a company by former SpaceX employee Ben Nowack – called Reflect Orbital – announced that it is now ready to put gigantic mirrors in space to reflect sunshine at ground-based solar farms. This is an idea that’s been around for a hundred years already, both for purposes of defeating the night through reflecting sunshine onto the surface, as well as to reject the same sunshine and reduce the surface temperature. The central question here is perhaps what the effect would be of adding or subtracting (or both) of solar irradiation on such a large scale as suggested?
We know the effect of light pollution from e.g. cities and street lighting already, which suggests that light pollution is a strongly negative factor for the survival of many species. Meanwhile a reduction in sunshine is already a part of the seasons of Autumn and Winter. Undeniable is that the Sun’s rays are essential to life on Earth, while the day-night cycle (as well as the seasons) created by the Earth’s rotation form an integral part of everything from sleep- and hibernation cycles, to the reproduction of countless species of plants, insects, mammals and everyone’s favorite feathered theropods.
With these effects and the gigantic financial investments required in mind, is there any point to space-based mirrors?
Solid state electronics have provided lighter weight night vision units that work better than the old-fashioned gear that used photomultiplier tubes, but there was an even older technology as [Our Own Devices] shows us in a recent video. The Metascope Type B was a first-generation passive night vision viewer that relied on moonlight.
The video shows a 1946 technical paper from the Office of Scientific Research and Development with [Vannevar Bush] credited as the institute’s director. If that name sounds familiar, you may remember that he foresaw hypertext (inspiring both [Doug Englebart] and the creation of the Web).
The Type B was an improvement over the older Type A, which had been tested during the invasion of North Africa in 1942. The type A weighed less than two pounds and was much smaller than the type B. However, it didn’t work very well, so they stopped making them and did a redesign, which is what you see in the video. The type B weighed almost 5 pounds.
To use the metascope, you had to “charge” it with light and then wait. Eventually, you’d need to charge it again. The type B allowed you to charge one phosphor plate while using another one. When that plate became weak, you could swap the plates to continue using the device.
If you aren’t keen on the history, you can skip to just before the 15-minute mark of the video for the hardware examination. He doesn’t open the device, but that’s probably wise, given the nature, age, and rarity of the metascope.
Modern image sensors are very sensitive to infrared, and normal cameras usually have filters to keep them out. Not that you can’t remove it, of course. If you want to see something more modern, [Nick] built his own AN/PVS-14 night vision scope and you can too.
We are always fascinated when someone can take something and extend it in a clever way without changing the original thing. In the computer world, that’s old hat. New computers improve, but can usually run old software. In the real world, the addition of stereo to phonograph records and color to photography come to mind.
But there are few stories as strange or wide-ranging as the path to provide color TV. And it had to be done in a way that a color set could still get a black and white picture and black and white sets could still watch a color signal without color. You’d think there would be a “big bang” moment where color TV burst on the scene — no pun involving color burst intended. But there wasn’t. Instead, there was a long, twisted path with many competing interests and ideas to go from a world in black and white to one tinted with color phosphor.
Background
In 1928, Science and Invention magazine had plans for building a mechanical TV (although not color)
It is hard to imagine, but John Logie Baird transmitted color images as early as 1928 using a mechanical scanner. Bell Labs had a demonstration system, also mechanical, in 1929. Baird broadcast using his system in 1938. Even earlier, around 1900, there were attempts to create mechanical color image systems. Those systems were fickle or impractical, though.
Electronic scanning was the answer, but World War II froze most consumer electronics development. Baird showed an electronic color system in late 1944. However, it would be 1953 before NTSC (the National Television System Committee) adopted the standard color TV signal for the United States. It would be almost 20 years later before SECAM and PAL were standardized in other parts of the world.
Of course, these are all analog standards. The world’s gone digital now, but for nearly 50 years, analog color TV was the way people consumed TV in their homes. By 1941, NTSC produced a standard in the United States, but not for color TV. TV adoption didn’t really take off until after the war. But by 1950, the US had some 6 million TV sets.
This was both a plus — a large market — and a negative. No one wanted to obsolete those 6 million sets. Well, at least, the government regulators and consumers didn’t. But most color systems would be incompatible with those existing black and white sets. Continue reading “The Long Strange Trip To US Color TV”→
Every 26 months, Earth and Mars come tantalizingly close by virtue of their relative orbits. The closest they’ve been in recent memory was a mere 55.7 million kilometers, a proximity not seen in 60,000 years when it happened in 2003.
However, we’ve been playing close attention to Mars for longer than that. All the way back in 1924, astronomers and scientists were contemplating another close fly by from the red planet. With radio then being the hot new technology on the block, the question was raised—should we be listening for transmissions from fellows over on Mars?
Today, if you want to send a message to a distant location, you’ll probably send an e-mail or a text message. But it hasn’t always been that easy. Military commanders, in particular, have always needed ways to send messages and were early adopters of radio and, prior to that, schemes like semaphores, drums, horns, Aldis lamps, and even barrels of water to communicate over distances.
One of the most reliable ways to pass messages, even during the last world war, was by carrier pigeon. Since the U.S. Army Signal Corps handled anything that included messages, it makes sense that the War Department issued TM 11-410 about how to use and care for pigeons. Think of it as the network operations guide of 1945. The practice, though, is much older. There is evidence that the Persians used pigeons in the 6th century BC, and Julius Caesar’s army also used the system.
You wouldn’t imagine that drawing an assignment in the Signal Corps might involve learning about breeding pigeons, training them, and providing them with medical attention, but that’s what some Signal Corps personnel did. The Army started experimenting with pigeons in 1878, but the Navy was the main user of the birds until World War I, when the U.S. Pigeon Intelligence Service was formed. In World War II, they saw use in situations where radio silence was important, like the D-Day invasion.
The Navy also disbanded its earlier Pigeon Messenger Service. It then returned to avian communications during the World Wars, using them to allow aviators to send messages back to base without radio traffic. The Navy had its own version of the pigeon manual.
These days, paying for TV programming is a fact of life. You pay your cable company or some streaming service and the only question is do you want Apple TV and Hulu or would you rather switch one out for NetFlix? But back in the 1960s, paying for TV seemed unthinkable and was quite controversial. Cable TV systems were rare, and the airwaves were a public resource, so allowing someone to charge to watch TV on the public airwaves was hard to imagine. That was the backdrop behind the Telemeter — an early attempt to monetize TV programming that was more like a pay phone than a modern streaming service.
Rear view of the telemeter and coin box
[Lothar Stern] wrote about the device in the November 1959 issue of Popular Mechanics (see page 220). The device looked like a radio that sat on top of your TV. It added a whopping three pay-TV channels, and inside was a coin box, and — no kidding — a tape punch or recorder. These three channels were carried from a Telemeter studio over what appears to be a dedicated cable strung on existing phone poles.
Of course, TVs with coin boxes were nothing new. But those TVs were found in public places, airports, and hotels. The money was simply to turn the TV on for a set amount of time. This was different. A set-top box unscrambled channels delivered over a dedicated cable. Seems like old hat today, but a revolutionary idea in 1959.
