It was all smiles and thumbs-up on March 30, at 5:28 PM local time, when NASA astronaut Mark Vande Hei and Russian cosmonauts Anton Shkaplerov and Pyotr Dubrov thumped down in the steppes of Kazakhstan aboard a Russian Soyuz spacecraft—and with good reason. For one thing, Vande Hei had just completed a marathon 355 consecutive…

The Age of the Private Space Station Is Upon Us