A team of researchers affiliated with institutions in Australia, the U.S. and France has found evidence of relatively recent water movement in meteorites that only recently collided with the Earth. In their paper published in the journal Science, the group describes their study of carbonaceous chondrite (CC) meteorites that landed on the surface of the Earth within the past century and what they found.

A lot of scientists believe that the water present on Earth came from meteorites. This theory has been difficult to prove because the meteorites recovered to date do not contain water and because chemical reactions that might have involved comet-borne water occurred millions of years ago. In this new effort, the researchers took a look at the idea from another angle—they studied isotopes in meteorites that have landed on Earth over just the past century.

Prior research has suggested that most, if not all, CC meteorites were formed approximately 4.5 billion years ago as part of larger asteroids. To find out if recent arrivals might have evidence of a water history, the researchers looked at uranium and thorium distributions in samples—the former is water-soluble while the latter is not.

A cubesat, largely built by undergraduate students and scheduled to launch on Sunday, will explore the feasibility of a new propulsion method that could enable very small satellites to move around Earth's orbit without carrying fuel. This could pave the way for tiny satellites that stay in orbit for long periods and operate in swarms, monitoring storms and natural disasters, for example.

A cubesat is about the size of a loaf of bread, designed to hitch a ride into space with a major mission. Cubesats are low-cost ways to test out new technologies or enable students to get hands-on experience with space exploration. MiTEE is scheduled to fly from the Mojave Air and Space Port on Virgin Orbit's Launch Demo 2.

While Earth's atmosphere is much thicker on the ground, a scattering of air particles stretch all the way up to low Earth orbit—the territory of about 60 percent of Earth-orbiting satellites. Small satellites are more strongly affected by the drag of the upper atmosphere than large satellites, slowing their orbits and causing them to drop toward the Earth.

"These smaller spacecraft just don't last very long, maybe even days to weeks, or a few months, dependent upon how high they are," said Brian Gilchrist, a professor of electrical engineering and computer science, who supervised the team.

These 366 images of the sun were made by ESA's Proba-2 satellite in 2020.

This satellite is continuously monitoring the changing activity of the sun. One image was selected to represent each day of the year (including leap day 29 February in 2020). Click here for an animated version.

The images were taken by the satellite's SWAP camera, which works at extreme ultraviolet wavelengths to capture the sun's hot turbulent atmosphere (the corona) at temperatures of about a million degrees Celsius.

In two images—21 June and 14 December—a partial solar eclipse is visible from Proba-2's point-of-view.

2020 marked the start of a new solar activity cycle—cycle 25—which lasts about 11 years on average. At the beginning of the year the sun still showed low levels of activity, but at the end of the year it already showed signs of waking up.

In the images of November and December, multiple active regions are visible. These regions represent areas of intense magnetic activity that can produce some of the most dramatic space weather events, such as solar flares and coronal mass ejections.