Video: Marc Buie, New Horizons Occultation Team Lead (members only)

SpaceX is targeting Jan. 7 for launch of its first Crew Dragon commercial ferry ship on an unpiloted test flight to the International Space Station, NASA announced Wednesday, a major milestone in the agency’s drive to end its sole reliance on Russian Soyuz crew ships for carrying astronauts to orbit.

The nuclear power generator for NASA’s Perseverance rover has been installed on the spacecraft atop an Atlas 5 rocket at Cape Canaveral, and mission managers gave a green light Wednesday to continue preparations for the rover’s July 30 launch toward Mars.

Scientists examining data from the Cassini mission’s final months reported this week unexpected measurements of Saturn’s gravity field and outer atmosphere, suggesting they may have to revisit theories about the planet’s rings and the forces that generate magnetic fields.