Science

1012 Articles

Crowdsourcing Ionosphere Data With Phones

November 18, 2024 by 19 Comments

How do you collect a lot of data about the ionosphere? Well, you could use sounding rockets or specialized gear. Or maybe you can just conscript a huge number of cell phones. That was the approach taken by Google researchers in a recent paper in Nature.

The idea is that GPS and similar navigation satellites measure transit time of the satellite signal, but the ionosphere alters the propagation of those signals. In fact, this effect is one of the major sources of error in GPS navigation. Most receivers have an 8-parameter model of the ionosphere that reduces that error by about 50%.

However, by measuring the difference in time between signals of different frequencies, the phone can estimate the total electron current (TEC) of the ionosphere between the receiver and the satellite. This requires a dual-frequency receiver, of course.

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The Laser Shadow Knows

November 18, 2024 by 31 Comments

Normally, you think of things casting a shadow as being opaque. However, new research shows that under certain conditions, a laser beam can cast a shadow. This may sound like nothing more than a novelty, but it may have applications in using one laser beam to control another. If you want more details, you can read the actual paper online.

Typically, light passes through light without having an effect. But using a ruby crystal and specific laser wavelengths. In particular, a green laser has a non-linear response in the crystal that causes a shadow in  a blue laser passing through the same crystal.

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The Diablo Canyon NPP in California. This thermal plant uses once-through cooling. (Credit: Doc Searls)

US DOE Sets New Nuclear Energy Targets

November 14, 2024 by 63 Comments

To tackle the growing electrification of devices, we’ll need to deploy more generation to the grid. The US Department of Energy (DOE) has unveiled a new target to triple nuclear generating capacity by 2050.

Using a combination of existing Generation III+ reactor designs, upcoming small modular and micro reactors, and “legislation like the ADVANCE Act that streamlines regulatory processes,” DOE plans to add 35 gigawatt (GW) of generating capacity by 2035 and an additional 15 GW installed per year by 2040 to hit a total capacity of 200 GW of clean, green atom power by 2050.

According to the DOE, 100 GW of nuclear power was deployed in the 1970s and 1980s, so this isn’t an entirely unprecedented scale up of nuclear, although it won’t happen overnight. One of the advantages of renewables over nuclear is the lower cost and better public perception — but a combination of technologies will create a more robust grid than an “all of your eggs in one basket” approach. Vehicle to grid storage, geothermal, solar, wind, and yes, nuclear will all have their place at the clean energy table.

If you want to know more about siting nuclear on old coal plants, we covered DOE’s report on the matter as well as some efforts to build a fusion reactor on a decommissioned coal site as well.

Microfluidic Motors Could Work Really Well For Tiny Scale Tasks

November 14, 2024 by 8 Comments

The vast majority of motors that we care about all stick to a theme. They rely on the electromagnetic dance between electrons and magnets to create motion. They come in all shapes and sizes and types, but fundamentally, they all rely on electromagnetic principles at heart.

And yet! This is not the only way to create a motor. Electrostatic motors exist, for example, only they’re not very good because electrostatic forces are so weak by comparison. Only, a game-changing motor technology might have found a way to leverage them for more performance. It achieves this by working with fluid physics on a very small scale.

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The Life Cycle Of Nuclear Fission Fuel: From Stars To Burn-Up

November 14, 2024 by 48 Comments

Outdone only by nuclear fusion, the process of nuclear fission releases enormous amounts of energy. The ‘spicy rocks’ that are at the core of both natural and artificial fission reactors are generally composed of uranium-235 (U-235) along with other isotopes that may or may not play a role in the fission process. A very long time ago when the Earth was still very young, the ratio of fissile U-235 to fertile U-238 was sufficiently high that nuclear fission would spontaneously commence, as happened at what is now the Oklo region of Gabon.

Although natural decay of U-235 means that this is unlikely to happen again, we humans have learned to take uranium ore and start a controlled fission process in reactors, beginning in the 1940s. This can be done using natural uranium ore, or with enriched (i.e. higher U-235 levels) uranium. In a standard light-water reactor (LWR) a few percent of U-235 is used up this way, after which fission products, mostly minor actinides, begin to inhibit the fission process, and fresh fuel is inserted.

This spent fuel can then have these contaminants removed to create fresh fuel through reprocessing, but this is only one of the ways we have to extract most of the energy from uranium, thorium, and other actinides like plutonium. Although actinides like uranium and thorium are among the most abundant elements in the Earth’s crust and oceans, there are good reasons to not simply dig up fresh ore to refuel reactors with.

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Intuition About Maxwell’s Equations

November 13, 2024 by 13 Comments

You don’t have to know how a car engine works to drive a car — but you can bet all the drivers in the Indy 500 have a better than average understanding of what’s going on under the hood. All of our understanding of electronics hinges on Maxwell’s equations, but not many people know them. Even fewer have an intuitive feel for the equations, and [Ali] wants to help you with that. Of course, Maxwell’s gets into some hairy math, but [Ali] covers each law in a very pragmatic way, as you can see in the video below.

While the video explains the math simply, you’ll get more out of it if you understand vectors and derivatives. But even if you don’t, the explanations provide a lot of practical understanding

Understanding the divergence and curl operators is one key to Maxwell’s equations. While this video does give a quick explanation, [3Blue1Brown] has a very detailed video on just that topic. It also touches on Maxwell’s equations if you want some reinforcement and pretty graphics.

Maxwell’s equations can be very artistic. This is one of those topics where math, science, art, and history all blend together.

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The Constant Monitoring And Work That Goes Into JWST’s Optics

November 11, 2024 by No comments

The James Webb Space Telescope’s array of eighteen hexagonal mirrors went through an intricate (and lengthy) alignment and calibration process before it could begin its mission — but the process is far from being a one-and-done. Keeping the telescope aligned and performing optimally requires constant work from its own team dedicated to the purpose.

Alignment of the optical elements in JWST are so fine, and the tool is so sensitive, that even small temperature variations have an effect on results. For about twenty minutes every other day, the monitoring program uses a set of lenses that intentionally de-focus images of stars by a known amount. These distortions contain measurable features that the team uses to build a profile of changes over time. Each of the mirror segments is also checked by being imaged selfie-style every three months.

This work and maintenance plan pays off. The team has made over 25 corrections since its mission began, and JWST’s optics continue to exceed specifications. The increased performance has direct payoffs in that better data can be gathered from faint celestial objects.

JWST was fantastically ambitious and is extremely successful, and as a science instrument it is jam-packed with amazing bits, not least of which are the actuators responsible for adjusting the mirrors.