A launch webcast hosted by Stephen Colbert begins at 10:30 a.m. EDT (1430 GMT). When you purchase through links on our site, we may earn an affiliate commission. Here’s how it works. Update 12:57 p.m.

The impressive flight cadence of Virgin Galactic's VSS Unity space plane won't last much longer. Unity flew for the sixth time in as many months last week, carrying two research scientists and another ...