After repeated fuel leaks, two hurricanes and a pair of launch delays, engineers had refueled NASA’s $4.1 billion Space Launch System rocket for aearly Wednesday. The launch would kick off a long-awaited maiden flight to send an uncrewed Orion capsule to circle the moon. NASA set the launch time at 1:47:44 a.m. EST after some delays.
Using a slower, so-called “gentle, gentler” refueling procedure to minimize pressure spikes that have contributed tothe launch team began loading 730,000 gallons of ultra-cold liquid oxygen and hydrogen for the SLS core stage at 3:55 p.m. EST.
Engineers were optimistic that the new procedures would ensure a smooth transition from slow fill to “fast fill”, the point in previous refueling attempts when a large increase in pressure caused disconnect umbilicals to leak. rapid at the base of the rocket’s central stage.
“We are more confident than ever in our loading procedures and how to do it in a way that puts the least stress on the seals,” said Jeremy Parsons, deputy director of exploration ground systems at Kennedy Space Center. . .
This time, the rocket’s fuel tanks were filled without incident. But late in the countdown, a valve used to replenish hydrogen in the core stage developed an intermittent leak. A three-man “red team” was sent to the pad to tighten the bolts around the valve in an effort to minimize leaks and keep the countdown on track.
Another problem that developed late: problem with the data relay from a Space Force eastern range tracking radar. Engineers rushed to replace an Ethernet switch before the opening of the SLS rocket’s two-hour launch window, which closes at 3:04 a.m. EST. Both issues were resolved, but mission leaders had to order a delay while the team made up for lost time.
The last 10 minutes of the countdown were to culminate in the ignition of four hydrogen-powered main engines, followed a few seconds later by the ignition of two solid-fuel boosters inherited from the Shuttle.
At that instant, computer commands will be sent to detonate four massive explosive bolts at the base of each thruster, releasing the 5.7 million pound SLS to rise to the top with 8.8 million pounds of thrust, transforming night into day briefly as it roared skyward on a slightly northeasterly track.
Accelerating rapidly as it consumes propellant and loses weight, the SLS was expected to be moving faster than sound less than a minute after liftoff. A minute after that, both strap thrusters were to shut down and fall, leaving the four engines powering the core stage to continue the climb into space.
Eight minutes after liftoff, the flight plan called for the SLS second stage and attached Orion capsule to separate from the center stage in an initial elliptical orbit inclined 34 degrees to the equator. The central stage, meanwhile, will have to fall back into the atmosphere to break up on an uninhabited part of the Indian Ocean.
Two critical “burns” were needed for the single engine powering the Interim Cryogenic Propulsion Stage, or ICPS: one to raise the low point of the initial orbit and a second to propel the Orion out of the Earth’s gravitational clutch. Earth and on the moon. The 18-minute Trans-Lunar Injection, or TLI, was expected approximately 90 minutes after launch.
The Orion capsule was due to separate from ICPS about two hours after launch, traveling to the Moon for a 60-mile high flyby on Monday, using lunar gravity to propel it into a distant orbit that will carry it farther from Earth than any human-sized spacecraft.
The Artemis 1 mission is the first in a series of SLS/Orion flights intended to establish a sustained presence on and around the moon with a lunar space station called Gateway and periodic landings near the south pole where ice deposits can be accessible in cold weather, permanently shaded craters.
Future astronauts may be able to “mining” this ice if it is present and accessible, converting it into air, water and even rocket fuel to dramatically reduce the cost of deep space exploration.
More generally, Artemis astronauts will conduct extensive exploration and research to learn more about the origin and evolution of the Moon and test the equipment and procedures that will be needed before sending astronauts to Mars.
The goal of the Artemis 1 mission is to put the Orion spacecraft through its paces, testing its solar power, propulsion, navigation and life support systems before returning to Earth on December 11 and diving 25 000 mph through the atmosphere that will subject its protective heat shield to 5,000 hellish degrees.
Testing the heat shield and confirming that it can protect astronauts returning from deep space is the #1 priority for the Artemis 1 mission.
If all goes well with Artemis 1, NASA plans to launch a second SLS rocket in late 2024 to propel four astronauts on a free-loop return trajectory around the moon before landing the first woman and next man on the lunar surface. near the south pole in the Artemis 3 mission.
This flight, scheduled to launch in the 2025-2026 timeframe, depends on the preparation of new NASA moonwalker spacesuits and a SpaceX-built lander that is based on the design of the reusable Starship rocket from the society.
SpaceX is working on the lander under a $2.9 billion contract with NASA, but the company has provided few details or updates and it’s not yet known when NASA and the shipbuilder will Californian rockets will actually be ready for the Artemis 3 lunar landing mission.
But if the Artemis 1 test flight is successful, NASA can verify its need for a superheavy rocket to get initial and moon missions off the ground.