SpaceX launched four astronauts to the International Space Station for NASA on Wednesday, less than two days after completing a flight chartered by millionaires.

It's the first NASA crew comprised equally of men and women, including the first Black woman making a long-term spaceflight, Jessica Watkins.

"This is one of the most diversified, I think, crews that we've had in a really, really long time," NASA's space operations mission chief Kathy Lueders said on the eve of launch.

The high efficiency, light weight and flexibility of the latest solar cell technology means photovoltaics could provide all the power needed for an extended mission to Mars, or even a permanent settlement there, according to a new analysis by scientists at the University of California, Berkeley.

Most scientists and engineers who've thought about the logistics of living on the surface of the Red Planet have assumed that nuclear power is the best alternative, in large part because of its reliability and 24/7 operation. In the past decade, miniaturized Kilopower nuclear fission reactors have advanced to the point where NASA considers them to be a safe, efficient and plentiful source of energy and key to future robotic and human exploration.