After two false starts, NASA is hoping that the third time will be the charm for the wet dress rehearsal of its Space Launch System (SLS) rocket. The enormous rocket which is intended to carry humans to the moon and, eventually, perhaps even to Mars, is undergoing the final major test before its launch — a rehearsal in which the rocket is brought out to the launch pad, filled with fuel, and a countdown is started and recycled as it would be for an actual launch. The rocket won’t leave the ground, but the rocket’s systems are all powered on and this rehearsal checks that everything is ready for when it does actually launch.
The first test was scheduled for last weekend on Sunday, April 3, and went ahead despite weather including lightning that struck the towers around the rocket. The lightning towers are designed to absorb lightning for just such an occurrence, so no damage was done to the rocket. However, there was a problem with a fan safety system which meant the test had to be called off. NASA tried again the next day on Monday, April 4, but had to scrub for a second time due to a stuck valve.
Now, NASA has confirmed it will try the test once again. The agency had originally said it would test again today, Saturday, April 9. However, now it says the rehearsal will go ahead next week and there will be some changes to the planned test. “NASA is planning to proceed with a modified wet dress rehearsal, primarily focused on tanking the core stage, and minimal propellant operations on the interim cryogenic propulsion stage (ICPS) with the ground systems at Kennedy,” the agency wrote in an update. “Due to the changes in loading procedures required for the modified test, wet dress rehearsal testing is slated to resume with call to stations on Tuesday, April 12 and tanking on Thursday, April 14.”
NASA also shared that engineers have identified a helium check valve that is not working. The small piece of hardware, a few inches long, works by only letting helium flow in one direction for safety reasons. It says it will share more details about the issue and the new test plan next week on Monday, April 11.
