Nasa must complete a “wet dress rehearsal” for launch before actually sending its SLS rocket into orbit for the first time
美国国家航空航天局 will roll its massive Moon rocket back out to the launch pad in early June for a fourth attempt at a critical fueling test of the launch vehicle the space agency hopes will propel astronauts back to the lunar surface in 2025.
Nasa plans to wheel its Space Launch System (SLS) rocket and Orion Spacecraft back out to Launch Complex 39B at Kennedy Space Center, in Florida, sometime in early June, according to a space agency blog. Nasa had rolled the rocket back into the cavernous Vehicle Assembly Building at Kennedy Space Center on 25 April after five weeks and three incomplete tests at the launch pad.
Nasa associate administrator for exploration systems development Jim Free now says the space agency has fixed the problems that cropped up in the first attempts at the test, known as a “wet dress rehearsal”.
A wet dress rehearsal consists of a simulated countdown and filling the rocket with cryogenic liquid oxygen and hydrogen propellant, the “wet” portion of the test. Nasa’s first attempt to run the test on 3 April was foiled by malfunctioning fans designed to manage hazardous gasses on the rocket’s mobile launcher platform, while the second 4 April attempt was scrubbed halfway through when a pressure valve on the mobile launcher platform malfunctioned.
Following the aborted 4 April test, Nasa technicians also discovered a faulty helium pressure valve on the rocket’s upper stage.
一种 third attempt at the wet dress rehearsal 14 April failed due to a liquid hydrogen leak in the connection fueling the rocket.
While Nasa has yet to announce the exact day the SLS will roll out to the launch pad again, the space agency did state it will take about 14 days from the time it gets the rocket in place to when the test can begin.
Nasa must complete the wet dress rehearsal before it can launch the first flight of its Artemis moon program, Artemis I. An uncrewed test flight of the SLS and Orion spacecraft, Artemis I will see Orion fly beyond the Moon and back to Earth.
Artemis II, a crewed lunar flyby is scheduled for 2024, while Artemis III, the mission that will land two astronauts on the lunar surface, is scheduled for 2025.
Nasa has declined to schedule an Artemis I launch date until completing the wet dress rehearsal test, and the space agency recently published a calendar of possible launch dates reaching into 2023. The earliest launch window runs from 26 July through 10 八月, and the next window opening from 23 August through 6 九月.
The exact date of launch, and the alignment of the Earth and Moon, will determine how long the Artemis I mission lasts, ranging from 26 至 42 days from liftoff to splash down.