Rod joins Leo to talk about the Space Launch System, which NASA plans to use to go back to the moon by 2027. This week, there was a successful test of the SLS main engines, which ran for over eight minutes straight. Rod says the Saturn V was very robust, and it only flew a few times before it was man-rated. That was known as "all-up testing," where they were testing everything all at once - a gutsy way to do it. NASA is taking a more incremental approach this time.