What are some of the grand challenges in space exploration that remain to be solved?

"Before he went to Cape, he invited me down to spend a little time with him," said Dean. "[Neil] said, 'Why don't you and I, once the boys go to bed, why ... Jul 13, 2019 ... What did Neil Armstrong really say when he took his first step on the moon? Millions on Earth who listened to him on TV or radio heard this ... Aug 27, 2012 ... As Armstrong said, “that's one small step for man, one giant leap for mankind.” Or did he? Let's clear that up first. Aug 25, 2012 ... They set out to show the world that the American spirit can see beyond what seems unimaginable - that with enough drive and ingenuity, anything ... Jan 26, 2003 ... What Neil Armstrong meant to say as he descended from the ladder of Apollo 11's Lunar Excursion Module (LEM) and stepped onto the lunar ... ... say we had not been complete in our description of his testimony. He's right. When you look at what Armstrong said to Congress you see that while he was ... Nov 14, 2019 ... Did Neil Armstrong flub the first sentence ever delivered from the surface of the moon, or did we misunderstand what he really said? Jul 3, 2019 ... ... Neil Armstrong marked the arrival with an eight-word message back home. “Houston,” Armstrong said. ... did the job of actually flying the missions ... Dec 10, 2020 ... Following their historic walk on the moon, Neil Armstrong, Buzz Aldrin and Michael Collins visited the monarch at Buckingham Palace. Jul 14, 2019 ... He said there was a lost word in his famous one-liner from the moon: “That's one small step for 'a' man.” It's just that people just didn't hear it.