Talking with an engineer from NASA, I learned that there is little difference in the learning process used by NASA engineers and that used by many UX and Conversion Rate Optimization (CRO) professionals.
Two Sides of the Same Coin

Although this is only a minuscule glimpse into what NASA engineers do, it gives enough insight for the purpose of this article.
Before launching anything into space, and only after they have formulated a detailed plan to do so, engineers at NASA gather lots of data from all kinds of sources, then carefully calculate their next moves – basically, they make very educated guesses. In other words, they don’t have a magic wand they can wave to solve every conceivable problem before sending an object to perform specific functions on other planets. Author’s note: I was sure they did, and I guess that is why I got excited about writing this article.
What UX Professionals Do
When faced with questions like, “Can we land our craft at those speeds, or at that angle?”, NASA engineers crunch numbers and guesstimate by looking at previous data, mixing in some creativity, and running their ideas through computer simulations. Once an idea passes those initial tests, it is ready for the first live test. This is exactly what UX designers do – they run tests and analyze data to draw a reasonable conclusion. This is not, however, the end of the story for NASA, nor is it for a business looking to accomplish great things.
What CRO Professionals Do

When NASA puts its contraptions to a live test, it finds out just how well its research, data and ideas hold up. Like running an A/B or multivariate test, NASA collects the data from the test and learns something about it, even if the contraption they are testing fails. What you might not realize is that those live tests often fail not just once, but many times before they are successful – much like A/B tests.
Using their data, both NASA engineers and CRO pros modify the subject of the test – whether it be a landing page or landing gear for the next Mars Rover. The next test will (hopefully) account for the shortcomings of the previous test, and at some point your iteration will produce a successful result.
So Do We Need Both UX and CRO?
A UX team develops the personas and provides council and direction to product development teams, but what is the purpose of CRO? Think of these roles as two sides of the same coin: UX handles things before live testing while CRO handles the live testing itself.
While it is true you can run tests through simulators or labs, you can never truly know how a user will react to your shiny new website until the numbers come rolling in from real users experiencing it in their own environment. All you need are some Data scientists and plenty of time to test, and you can launch your website redesign or update – or even a NASA mission – with confidence.