STEVE INSKEEP, HOST:
NASA is not sending a spacecraft toward the moon today after all. The flight director called off today's launch due to multiple problems, including an issue with one of the rocket engines. Brendan Byrne of member station WMFE is at the Kennedy Space Center in Florida covering a story that, to many people, must seem like a bummer. Hey there, Brendan.
BRENDAN BYRNE, BYLINE: How are you, Steve?
INSKEEP: What went wrong?
BYRNE: Well, the SLS rocket relies on four main engines to give it that big lift off the ground, and one of those engines failed to get down to the right temperature for launch, so mission managers called it off. The vehicle also had some issues fueling earlier today. They detected a hydrogen leak. And engineers spent some time this morning investigating a crack in the foam insulation of the fuel tank. So they have to wait until at least Friday to try to launch once more. But, Steve, what's a few more days when NASA's been waiting since 1972 to launch this mission? That's the last time people stepped on the lunar surface.
INSKEEP: Yeah. Yeah, I can imagine. But weren't there something like 200,000 people expected to watch this launch this morning?
BYRNE: That's right. There were quite a few people that were here. There were traffic jams coming in close to the space center. Hotels were sold out. But, you know, I think people here - we're experienced rocket chasers here in Florida, Steve, and we know that scrubs happen. During the space shuttle program, scrubs happened multiple times. So I think people understand why NASA's calling it safe here.
INSKEEP: Yeah, definitely better than the alternative. And needless to say, the mission itself is not called off. So once they resume in coming days or whenever, what is the idea here?
BYRNE: So it's essentially a test flight. So NASA built this brand-new rocket called SLS, the most powerful the agency's ever created. The teams conducted simulated launch countdowns back in June. There were some problems back then. But this thing has yet to fly. Another critical test will come with the Orion capsule. Its job is to get astronauts to lunar orbit, keep them alive and then safely return them back to Earth. So NASA's going to be stress testing this capsule to the max, spending six weeks in space orbiting the moon. There'll be some mannequins on board that will measure the stresses on future astronauts, including how much radiation they'll be exposed to. And NASA's going to test key systems like communication, navigation and the heat shield.
Before the launch, I spoke with - the launch attempt, I spoke with Doug Hurley about this kind of testing. He was the final space shuttle pilot and then went on to command the first human mission from the U.S. after shuttle on SpaceX's Crew Dragon. He now works for Northrop Grumman, the company that builds the two solid rocket boosters on SLS.
DOUG HURLEY: You want to see the ground team, of course, the contractor team, integration team, all those teams - mission control - coming together and kind of hitting their stride. And I think we're ready for that now, and this is that next test is the uncrewed test flight.
INSKEEP: OK, so sometime in the next few days, they send up the crash test dummies, the ultimate crash test dummies.
HURLEY: (Laughter).
INSKEEP: And assuming all goes well with that, what happens next?
BYRNE: Well, the next mission is Artemis 2, which will take a crew of astronauts on a trip around the moon and back. Artemis 3 is when astronauts will take a lander to the surface and step foot on the moon once more - up to, I mean, (ph) three years. But there's a lot more than just this test flight that needs to go right. NASA's working with private company SpaceX to build that first lander, which is still under development. And the agency also needs new spacesuits for lunar exploration. NASA has a lot to prove with these missions, and there's a lot on the horizon.
INSKEEP: Well, Brendan, we'll check in with you again. Thanks so much.
BYRNE: You got it, Steve.
INSKEEP: Brendan Byrne of WMFE. Transcript provided by NPR, Copyright NPR.