Live coverage: New Horizons returns first close-up image

Researchers at MIT, the University of Colorado and elsewhere have found that very low-frequency electromagnetic waves in the Earth’s upper atmosphere form a shield, protecting the planet’s surface from the Van Allen belt’s high-energy radiation.

Scientists announced Thursday that measurements from NASA’s Cassini spacecraft detected hydrogen gas, a key energy source for microbial life, in a plume gushing from a vast liquid water ocean buried beneath the icy shell of Saturn’s moon Enceladus.

A balky interplanetary seismic instrument that ran into technical problems in 2015, forcing a two-year delay in the launch of NASA’s InSight lander to Mars, cleared a major test last month after engineers redesigned part of the sensor package, boosting confidence that the mission will be ready to blast off in May 2018.