NASA Taps Webb To Help Study 2032 Asteroid Threat

February 13, 2025 by Tom Nardi 1 Comment

In all likelihood, asteroid 2024 YR4 will slip silently past the Earth. Based on the data we have so far, there’s an estimated chance of only 2.1% to 2.3% that it will collide with the planet on December 22nd, 2032. Under normal circumstances, if somebody told you there was a roughly 98% chance of something not happening, you probably wouldn’t give it a second thought. There’s certainly a case to be made that you should feel that way in regards to this particular event — frankly, it’s a lot more likely that some other terrible thing is going to happen to you in the next eight years than it is an asteroid is going to ruin your Christmas party.

That being said, when you consider the scale of the cosmos, a 2+% chance of getting hit is enough to raise some eyebrows. After all, it’s the highest likelihood of an asteroid impact that we’re currently aware of. It’s also troubling that the number has only gone up as further observations of 2024 YR4’s obit have been made; a few weeks ago, the impact probability was just 1%. Accordingly, NASA has recently announced they’ll be making time in the James Webb Space Telescope’s busy scientific schedule to observe the asteroid next month.

So keeping in mind that we’re still talking about an event that’s statistically unlikely to actually occur, let’s take a look at what we know about 2024 YR4, and how further study and analysis can give us a better idea of what kind of threat we’re dealing with.

Continue reading “NASA Taps Webb To Help Study 2032 Asteroid Threat” →

Budget-Minded Synthetic Aperture Radar Takes To The Skies

February 13, 2025 by Dan Maloney 7 Comments

Unless you work for the government or a large corporation, constrained designs are a fact of life. No matter what you’re building, there’s likely going to be a limit to the time, money, space, or materials you can work with. That’s good news, though, because constrained projects tend to be interesting projects, like this airborne polarimetric synthetic aperture radar.

If none of those terms make much sense to you, don’t worry too much. As [Henrik Forstén] explains, synthetic aperture radar is just a way to make a small radar antenna appear to be much larger, increasing its angular resolution. This is accomplished by moving the antenna across a relatively static target and doing some math to correlate the returned signal with the antenna position. We saw this with his earlier bicycle-mounted SAR.

For this project, [Henrik] shrunk the SAR set down small enough for a low-cost drone to carry. The build log is long and richly detailed and could serve as a design guide for practical radar construction. Component selection was critical, since [Henrik] wanted to use low-cost, easily available parts wherever possible. Still, there are some pretty fancy parts here, with a Zynq 7020 FPGA and a boatload of memory on the digital side of the custom PCB, and a host of specialized parts on the RF side.

The antennas are pretty cool, too; they’re stacked patch antennas made from standard FR4 PCBs, with barn-door feed horns fashioned from copper sheeting and slots positioned 90 to each other to provide switched horizontal and vertical polarization on both the receive and transmit sides. There are also a ton of details about how the radar set is integrated into the flight controller of the drone, as well as an interesting discussion on the autofocusing algorithm used to make up for the less-than-perfect positional accuracy of the system.

The resulting images are remarkably detailed, and almost appear to be visible light images thanks to the obvious shadows cast by large objects like trees and buildings. We’re especially taken by mapping all combinations of transmit and receive polarizations into a single RGB image; the result is ethereal.

A Transparent BB-8 Build Using Christmas Ornaments

February 13, 2025 by Lewin Day 4 Comments

The cool thing about the droids of Star Wars is that they’re not that hard to recreate in real life. R2-D2 is a popular choice, but you can even build yourself a neat little BB-8 if you’re so inclined. [Piyush] has built a particularly compelling example that’s transparent, which lets you see the internals and how it all works.

The build makes creative use of a pair of Christmas ornaments. They are perhaps the cheapest and easiest way to source a clear plastic sphere. One serves as the “head”, while the other serves as the larger spherical body. Inside, an Arduino Pro Micro is running the show. It’s hooked up to a L293D motor driver which runs the drive motors and the reaction wheel motor which provides stability, while a separate MOSFET is on hand to run the gear motor which controls the head.

There’s also an HC-05 module for Bluetooth communication, and a BNO055 sensor for motion tracking and ensuring the robot stays the right way up. 3D printed components are used prodigiously to cram everything together tightly enough to fit. There’s even a printed charging base to juice up the little droid. Controlling the robot is as simple as using a smartphone with an app created in the MIT App Inventor.

If you’ve never built a spherical rolling robot before—and few of us have—this design is a great reference for your own work. We’ve seen a few BB-8s over the years, most of which dropped shortly after the movie was released. Continue reading “A Transparent BB-8 Build Using Christmas Ornaments” →