An icy satellite of Saturn, Enceladus, has been a subject of increasing interest in recent years since Cassini captured jets of water and other material being ejected out of the south pole of the moon. One particularly tantalizing hypothesis supported by the sample composition is that there might be life in the oceans under the ice shells of Enceladus. To evaluate Enceladus' habitability and to figure out the best way to probe this icy moon, scientists need to better understand the chemical composition and dynamics of Enceladus' ocean.

Specifically, an appropriate salinity could be important for habitability. Like the porridge of the Three Bears, the salt level of the water must be just right for life to thrive. Too high a salinity could be threatening to life, and too low a salinity may indicate a weak water-rock reaction, limiting the amount of energy available to life.

In an alternate reality playing out at this year's international Planetary Defense Conference, a fictional asteroid crashes over Europe, 'destroying' a region about 100 km wide near the Czech Republic and German border. The scenario was imagined, but the people who took part are very real, and the lessons learnt will shape our ability to respond to dangerous asteroids for years to come.

The interaction of two doomed stars has created this spectacular ring adorned with bright clumps of gas—a diamond necklace of cosmic proportions. Fittingly known as the "Necklace Nebula," this planetary nebula is located 15,000 light-years away from Earth in the small, dim constellation of Sagitta (the Arrow).

A pair of tightly orbiting sun-like stars produced the Necklace Nebula, which also goes by the less glamorous name of PN G054.203.4. Roughly 10,000 years ago, one of the aging stars expanded and engulfed its smaller companion, creating something astronomers call a "common envelope." The smaller star continued to orbit inside its larger companion, increasing the bloated giant's rotation rate until large parts of it spun outwards into space. This escaping ring of debris formed the Necklace Nebula, with particularly dense clumps of gas forming the bright "diamonds" around the ring.

The pair of stars which created the Necklace Nebula remain so close together—separated by only several million miles—that they appear as a single bright dot in the center of this image.

Mars missions, astronauts coming and going at the International Space Station, China's increasingly ambitious space program. Space-related news is flowing, and not just from the world's richest, biggest nations. Take Latin America.

On Feb. 17, the congress in Nicaragua, one of the region's poorest, most conflict-prone nations, approved a law creating a space agency. Costa Rica, known for relative growth and stability, did the same on Feb. 18, the day that the NASA rover Perseverance landed on Mars to look for signs of ancient life.

SpaceX safely returned four astronauts from the International Space Station on Sunday, making the first U.S.