NASA’s Space Launch System’s Latest Woes

ItIt is an orbital fact that the Earth is slowly receding towards the moon. The distance between these two planets increases by 3.78 m (or 1.48 in) each year.It is the same speed as our fingernails grow. That’s not much compared to the overall 384,472 km (238,900 mi.) average distance between the Earth and the moon, and there’s no reason to worry that the moon will be bidding us farewell any time soon. Still, ever since April 1—and especially in the last week—the gap between the Earth and the moon suddenly seems wider than ever. For that, you can thank issues with the Space Launch System (SLS), NASA’s brand new mega-rocket designed to return American astronauts to the lunar surface sometime this decade.

It was on March 17 that the towering 98 m (322 ft.) rocket emerged from its hangar in the Kennedy Space Center’s Vehicle Assembly Building (VAB) and began its slow creep out to its launch pad. The rocket wasn’t getting set to fly, but rather to undergo what NASA calls a wet dress rehearsal. That involves filling the giant machine’s tanks with 2.8 million liters (730,000 gal.) This involves filling up the tanks of the massive machine with liquid oxygen and hydrogen fuel. After running a simulation for 45 hours, the engine will stop at the T-minus 9.3 mark. Then, the SLS is drained and returned to the VAB. The initial steps of the exercise began on April 1, and let’s just say that if a Broadway-bound show had a dress rehearsal anything like what the SLS has had, the whole production would close out of town.

NASA has a very candid blog that reports on the 15 days spent at launchpad 39B. There have been numerous breakdowns, forcing NASA to stop the countdown. Among the most serious problems is a stuck helium valve on the rocket’s second stage that has prevented that stage from being loaded with fuel. The problem can’t be repaired on the pad, but only back in the VAB—meaning that even if the rest of the work went perfectly, the wet-dress rehearsal would still not be run to its planned completion.

The rest of the work is not going as planned. Among the other problems to beset the giant rocket over the past two weeks: a liquid hydrogen leak in one of the vehicle’s umbilical cords; temperature fluctuations in the supercold liquid oxygen fuel which must be kept at -182º C (-297º F); and a troubling pressure surge in the liquid hydrogen flow line. This has made it impossible for ground controllers to fill the liquid hydrogen tanks with more than 5 percent of their capacity, and to refill the liquid oxygen tanks with more than 49%.

NASA does not know how many wet-dress rehearsals it will continue to attempt before giving up. How it works It hasIt is certain that it will continue to do its job, and the SLS will eventually fly. NASA is blessed with a lot of history to back up its optimistic outlook. As veteran space reporter Bill Harwood of CBS reports, back in the 1960s, an intended six-day countdown of the venerable Saturn V rocket took 17 days to complete—longer than the SLS has so far been at it. History records that the Saturn V flew and took nine astronauts to orbit the moon. We wish the SLS the same luck.

The original version of this story appeared in TIME Space. This weekly newsletter covers all things space. Sign up now

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