Slider

4829 Articles

Power Grid Stability: From Generators To Reactive Power

July 22, 2025 by 41 Comments

It hasn’t been that long since humans figured out how to create power grids that integrated multiple generators and consumers. Ever since AC won the battle of the currents, grid operators have had to deal with the issues that come with using AC instead of the far less complex DC. Instead of simply targeting a constant voltage, generators have to synchronize with the frequency of the alternating current as it cycles between positive and negative current many times per second.

Complicating matters further, the transmission lines between generators and consumers, along with any kind of transmission equipment on the lines, add their own inductive, capacitive, and resistive properties to the system before the effects of consumers are even tallied up. The result of this are phase shifts between voltage and current that have to be managed by controlling the reactive power, lest frequency oscillations and voltage swings result in a complete grid blackout.

Continue reading “Power Grid Stability: From Generators To Reactive Power” →

Fixing Human Sleep With Air Under Pressure

July 21, 2025 by 68 Comments

By and large, the human body is designed to breathe from birth, and keep breathing continuously until death. Indeed, if breathing stops, lifespan trends relatively rapidly towards zero. There’s a whole chunk of the brain and nervous system dedicated towards ensuring oxygen keeps flowing in and carbon dioxide keeps flowing out.

Unfortunately, the best laid plans of our body often go awry. Obstructive sleep apnea is a condition in which a person’s airways become blocked by the movement of soft tissues in the throat, preventing the individual from breathing. It’s a mechanical problem that also has a mechanical solution—the CPAP machine.

Continue reading “Fixing Human Sleep With Air Under Pressure” →

Why Apple Dumped 2,700 Computers In A Landfill In 1989

July 21, 2025 by 55 Comments

In 1983, the Lisa was supposed to be a barnburner. Apple’s brand-new computer had a cutting edge GUI, a mouse, and power far beyond the 8-bit machines that came before. It looked like nothing else on the market, and had a price tag to match—retailing at $9,995, or the equivalent of over $30,000 today.

It held so much promise. And yet, come 1989, Apple was burying almost 3,000 examples in a landfill. What went wrong?

Continue reading “Why Apple Dumped 2,700 Computers In A Landfill In 1989” →

A Field Guide To The North American Cold Chain

July 17, 2025 by 22 Comments

So far in the “Field Guide” series, we’ve mainly looked at critical infrastructure systems that, while often blending into the scenery, are easily observable once you know where to look. From the substations, transmission lines, and local distribution systems that make up the electrical grid to cell towers and even weigh stations, most of what we’ve covered so far are mega-scale engineering projects that are critical to modern life, each of which you can get a good look at while you’re tooling down the road in a car.

This time around, though, we’re going to switch things up a bit and discuss a less-obvious but vitally important infrastructure system: the cold chain. While you might never have heard the term, you’ve certainly seen most of the major components at one time or another, and if you’ve ever enjoyed fresh fruit in the dead of winter or microwaved a frozen burrito for dinner, you’ve taken advantage of a globe-spanning system that makes sure environmentally sensitive products can be safely stored and transported.

Continue reading “A Field Guide To The North American Cold Chain” →

The DEW Line Remembered

July 16, 2025 by 20 Comments
The DEW line was one of three radar early warning systems of the time.

If you grew up in the middle of the Cold War, you probably remember hearing about the Distant Early Warning line between duck-and-cover drills. The United States and Canada built the DEW line radar stations throughout the Arctic to detect potential attacks from the other side of the globe.

MIT’s Lincoln Lab proposed the DEW Line in 1952, and the plan was ambitious. In order to spot bombers crossing over the Arctic circle in time, it required radar twice as powerful as the best radar of the day. It also needed communications systems that were 99 percent reliable, even in the face of terrestrial and solar weather.

In the end, there were 33 stations built from Alaska to Greenland in an astonishing 32 months. Keep in mind that these stations were located in a very inhospitable environment, where temperatures reached down to -60 °F (-51 °C). Operators kept the stations running 24/7 for 36 years, from 1957 to 1993.

System of Systems

The DEW line wasn’t the only radar early-warning system that the US and Canada had in place, only the most ambitious. The Pinetree Line was first activated in 1951. However, its simple radar was prone to jamming and couldn’t pick up things close to the ground. It was also too close to main cities along the border to offer them much protection. Even so, the 33 major stations, along with six smaller stations, did better than expected. Continue reading “The DEW Line Remembered” →

The Fight To Save Lunar Trailblazer

July 15, 2025 by 42 Comments

After the fire and fury of liftoff, when a spacecraft is sailing silently through space, you could be forgiven for thinking the hard part of the mission is over. After all, riding what’s essentially a domesticated explosion up and out of Earth’s gravity well very nearly pushes physics and current material science to the breaking point.

But in reality, getting into space is just the first on a long list of nearly impossible things that need to go right for a successful mission. While scientific experiments performed aboard the International Space Station and other crewed vehicles have the benefit of human supervision, the vast majority of satellites, probes, and rovers must be able to operate in total isolation. With nobody nearby to flick the power switch off and on again, such craft need to be designed with multiple layers of redundant systems and safe modes if they’re to have any hope of surviving even the most mundane system failure.

That said, nobody can predict the future. Despite the best efforts of everyone involved, there will always be edge cases or abnormal scenarios that don’t get accounted for. With proper planning and a pinch of luck, the majority of missions are able to skirt these scenarios and complete their missions without serious incident.

Unfortunately, Lunar Trailblazer isn’t one of those missions. Things started well enough — the February 26th launch of the SpaceX Falcon 9 went perfectly, and the rocket’s second stage gave the vehicle the push it needed to reach the Moon. The small 210 kg (460 lb) lunar probe then separated from the booster and transmitted an initial status message that was received by the Caltech mission controllers in Pasadena, California which indicated it was free-flying and powering up its systems.

But since then, nothing has gone to plan.

Continue reading “The Fight To Save Lunar Trailblazer” →

Robots Want The Jobs You Can’t Do

July 14, 2025 by 11 Comments

There’s something ominous about robots taking over jobs that humans are suited to do. Maybe you don’t want a job turning a wrench or pushing a broom, but someone does. But then there are the jobs no one wants to do or physically can’t do. Robots fighting fires, disarming bombs, or cleaning up nuclear reactors is something most people will support. But can you climb through a water pipe from the inside? No? There are robots that are available from several commercial companies and others from university researchers from multiple continents.

If you think about it, it makes sense. For years, companies that deal with pipes would shoot large slugs, or “pigs”, through the pipeline to scrape them clean. Eventually, they festooned some pigs with sensors, and thus was born the smart pig. But now that it is possible to make tiny robots, why not send them inside the pipe to inspect and repair?

Continue reading “Robots Want The Jobs You Can’t Do” →