Liftoff! The Origin Of The Countdown

What’s the most thrilling part of rocketry? Well, the liftoff, naturally. But what about the sweet anticipation in those tense moments leading up to liftoff? In other words, the countdown. Where did it come from?

Far from being simply a dramatic device, the countdown clock serves a definite purpose — it lets the technicians and the astronauts synchronize their actions during the launch sequence. But where did the countdown  — those famed ten seconds of here we go! that seem to mark the point of no return — come from? Doesn’t it all seem a little theatrical for scientists?

It may surprise you to learn that neither technicians nor astronauts conceived of the countdown. In their book, “Lunar Landings and Rocket Fever: Rediscovering Woman in the Moon”, media scholars Tom Gunning and Katharina Loew reveal that a little-known Fritz Lang movie called Woman In the Moon both “predicted the future of rocketry” and “played an effective role in its early development”.

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Veteran SpaceX Booster Lost Due To Rough Seas

With the notable exception of the now retired Space Shuttle orbiters, essentially every object humanity ever shot into space has been single-use only. But since December of 2015, SpaceX has been landing and refurbishing their Falcon 9 boosters, with the end goal of operating their rockets more like cargo aircraft. Today, while it might go unnoticed to those who aren’t closely following the space industry, the bulk of the company’s launches are performed with boosters that have already completed multiple flights.

This reuse campaign has been so successful these last few years that the recent announcement the company had lost B1058 (Nitter) came as quite a surprise. The 41 meter (134 foot) tall booster had just completed its 19th flight on December 23rd, and had made what appeared to be a perfect landing on the drone ship Just Read the Instructions. But sometime after the live stream ended, SpaceX says high winds and powerful waves caused the booster to topple over.

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Temperature Measurement By Wire

There’s an old joke about how to tell how tall a building is using a barometer. The funniest answer is to find the building owner and offer them a nice barometer in exchange for the information. We wonder if [DiodeGoneWild] has heard that one since his recent video details how to measure temperatures using an ohmmeter.

The idea is that wire changes its resistance based on temperature. So if you know the resistance of a lot of wire — maybe a coil — at room temperature and you can measure the resistance at temperature, it is entirely feasible to calculate the amount of temperature that would cause this rise in resistance.

Of course, there are many ways to measure resistance, too. It’s probably possible to measure parameters like operating current and estimate temperature for at least some circuits. The wire’s material also plays a part, and the online calculator lets you choose copper, aluminum, iron, or tungsten. You also need a lot of wire, a very accurate resistance measurement, or, preferably, both.

There are many ways to accurately measure resistance, of course. Then again, you can also get resistors specifically for the job.

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