Space debris, which consists of pieces of spent rocket stages, satellites, and other objects launched into orbit since 1957 – is a growing concern. According to the ESA Space Debris Office, there are roughly 40,500 objects in LEO larger than 10 cm (3.9 inches) in diameter, an additional 1.1 million objects measuring 1 and 10 cm (0.39 to 3.9 inches) in diameter, and 130 million objects 1 mm to 1 cm (0.039 to 0.39 inches). The situation is projected to worsen as commercial space companies continue to deploy “mega-constellations” of satellites for research, telecommunications, and broadband internet services.
To address this situation, researchers from the University of Kyoto have developed the world’s first wooden satellite. Except for its electronic components, this small satellite (LingoSat) is manufactured from magnolia wood. According to a statement issued on Tuesday, November 5th, by the University of Kyoto’s Human Spaceology Center, the wooden satellite was successfully launched into orbit atop a SpaceX Falcon 9 rocket from NASA’s Kennedy Space Center in Florida. This satellite, the first in a planned series, is designed to mitigate space debris and prevent what is known as “Kessler Syndrome.”
In 1978, NASA scientists Donald J. Kessler and Burton G. Cour-Palais proposed a scenario in which the density of objects in Low Earth Orbit (LEO) would become high enough that collisions between objects would cause a cascade effect. This would lead to a vicious cycle in which collisions caused debris, which would make further collisions more likely, leading to more collisions and more debris (and so on). For decades, astronomers and space agencies have feared that we are approaching this point or will be shortly.
Animation of Kyoto University’s prototype wooden satellite in space. Credit: Kyoto UniversityBy manufacturing satellites out of wood, the University of Kyoto scientists expect they will burn up when they re-enter Earth’s atmosphere at the end of their service. This will prevent potentially harmful metal particles from being generated when a retired satellite returns to Earth. The small satellite measures just 10 cm (4 in) on a side and weighs only 900 grams, making it one of the lightest satellites ever sent to space. Its name comes from the Latin word for wood (“lingo”) and CubeSat, a class of small satellites with a form factor of 10 cm cubes.
Before launch, the science team installed LingoSat in a special container prepared by the Japan Aerospace Exploration Agency (JAXA). According to a spokesperson for Sumitomo Forestry, LignoSat’s co-developer, the satellite will “arrive at the ISS soon and will be released to outer space about a month later.”
Once the satellite reaches the ISS, it will dock via the Kibo Japanese Experiment Module (JEM) before deployment. It will then spend the next six months in space, and data will be sent from the satellite to researchers who will monitor it for signs of strain. Ultimately, the goal is to determine if wooden satellites can withstand the extreme temperature changes and conditions in space. A second satellite, LingoSat 2, is a double-unit CubeSat currently scheduled for launch in 2026.
Further Reading: The Guardian
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If I ask you to picture a radio telescope, you probably imagine a large dish pointing to the sky, or even an array of dish antennas such as the Very Large Array. What you likely don’t imagine is something that resembles a TV dish in your neighbor’s backyard. With modern electronics, it is relatively easy to build your own radio telescope. To understand out how it can be done, check out a recent paper by Jack Phelps.
He outlines in detail how you can construct a small radio telescope with a 1-meter satellite dish, a Raspberry Pi, and some other basic electronics such as analog-to-digital converters. It’s a fascinating read, and one of the most interesting features is that his design is tuned to a frequency of 1420.405 MHz. This is the frequency emitted by neutral hydrogen. Since it has a wavelength of about 21 centimeters, the hydrogen emission line is sometimes called the 21-cm line. Neutral hydrogen comprises the bulk of matter in the Universe. The 21-cm emission isn’t particularly bright, but because there is so much hydrogen out there, the signal is easy to detect. And wherever there is matter, so too is the hydrogen line.
Observations of hydrogen in the Milky Way (red dots). Credit: Jack PhelpsThe emission is caused by a spin flip of the hydrogen’s electron. It’s a hyperfine emission, which means the line is very sharp. If you see the line shifted a bit, you know that’s because of relative motion. Astronomers have used the line to map the distribution of matter in the Milky Way, and have even used it to measure our galaxy’s rotation. Early observations of the line pointed to the existence of dark matter in our galaxy. And now you can do it at home.
There are other radio objects you can observe in the sky. The Sun is a popular target given its strong radio signal. Jupiter is another somewhat bright source. It’s a cool hobby. Even if you don’t intend to build a radio telescope of you’re own, it’s worth checking out the paper just to see how accessible radio astronomy has become.
Reference: J. Phelps. “Galactic Neutral Hydrogen Structures Spectroscopy and Kinematics: Designing a Home Radio Telescope for 21 cm Emission.” arXiv preprint arXiv:2411.00057 (2024).
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