A Better Way to Turn Solar Sails

Illustration of a solar sail. (Credit: NASA)

Solar sails are space's ultimate free ride, they get their propulsion from the Sun, so they don't need to carry propellant, but they come with their own challenges. A sail has a large surface area but a low mass, which creates a huge moment of inertia and makes it difficult to control, especially with reaction wheels. A team of engineers have cracked it though with "smart mirrors" that can instantly switch their reflectivity on command, transforming sunlight from an unruly force into a precision steering tool.

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Researchers Match Up 12 Meteorites with the Near-Earth Asteroids They Came From

Every day meteoroids blast through our planet’s atmosphere to hit the ground as meteorites. A team of researchers in Italy traced twelve of them to progenitor asteroids that orbit in near-Earth space. Scientists treasure meteorites because they reveal information about their parent bodies. In an arXiv paper, two Italian researchers—Albino Carbognani and Marco Fenucci—analyze the characteristics of the parent bodies of 20 selected meteorites. They were able to track all but eight back to their parent asteroids. Based on their work, the pair says at least a quarter of meteorites come from collisions that happened in near-Earth space and not in the Main Belt. Meteorites from Near-Earth Asteroids: How They Got Here Many meteorites are chondritic, similar to asteroids in the Main Belt (or came from it). In their paper, the authors point out that progenitor meteoroids (including many that fall to Earth and become meteorites) formed millions of years ago following collisions between main-...

JWST Takes a Detailed Look at Jupiter’s Moon Ganymede

Nature doesn’t conform to our ideas of neatly-contained categories. Many things in nature blur the lines we try to draw around them. That’s true of Jupiter’s moon Ganymede, the largest moon in the Solar System. The JWST took a closer look at Ganymede, the moon that’s kind of like a planet, to understand its surface better. Ganymede is basically a planet, except it doesn’t orbit the Sun. If it did orbit the Sun instead of Jupiter, it would be indistinguishable from a planet. It has a differentiated internal structure with a molten core that produces a magnetic field. It has a silicon mantle much like Earth’s, and has a complex icy crust with a deep ocean submerged beneath it. It has an atmosphere, though it’s thin. It’s also larger than Mercury, and almost as large as Mars. According to the authors of a new study, it’s an archetype of a water world. But even with all this knowledge of the huge moon, there are details yet to be revealed. This is especially true of its complex surface...

What Blew Up the Local Bubble?

In our neighborhood of the Milky Way, we see a region surrounding the solar system that is far less dense than average. But that space, that cavity, is a very irregular, elongated shape. What little material is left inside of this cavity is insanely hot, as it has a temperature of around a million Kelvin. from Universe Today https://ift.tt/KvVDeiC via IFTTT

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