The Space Launch System Is Moving On To Artemis 1
For many years now NASA has been working towards returning humans to the surface of the Moon. Through Artemis, the agency plans to prepare a large amount of infrastructure and set up a more permanent human presence. A big part of this plan revolves around the Space Launch System which is expected to transport both crew and cargo over the next few years.
In recent months the next generation launch vehicle has been working on finishing its wet dress rehearsal. While it encountered a lot of problems along the way. NASA is finally confident in the result and moving on to the next step. This next step is the long awaited Artemis 1 mission which will see the Space Launch System take off for the first time and head to the Moon.
This test will also show off the Orion spacecraft with no crew as it flies by the Moon and attempts to safely return to Earth. All of which are very important for the future of Artemis and general plans on the Moon. Here I will go more in-depth into some of the recent updates from the agency, the expected date of this launch, and more.
Recent Updates
In the last few days, both the Space Launch System and NASA have been very busy. Just two days ago on June 26th, NASA tweeted saying, “Here is your latest Moon rocket update. The wet dress rehearsal has been completed! SLS and @NASA_Orion will soon roll back to the Vehicle Assembly Building at @NASAKennedy to fix a liquid hydrogen leak and prepare for launch.” More specifically, NASA analyzed the data from the wet dress rehearsal conducted Monday, June 20th, and determined the testing campaign was complete. The agency will roll the SLS and Orion back to the Vehicle Assembly Building (VAB) at Kennedy next week to prepare the rocket and spacecraft for launch.
“During the wet dress rehearsal activities, we have incrementally added to our knowledge about how the rocket and the ground systems work together, and our teams have become proficient in launch procedures across multiple sites. We have completed the rehearsal phase, and everything we’ve learned will help improve our ability to lift off during the target launch window,” said Tom Whitmeyer, deputy associate administrator for common exploration systems at NASA Headquarters. “The team is now ready to take the next step and prepare for launch.” During Monday’s rehearsal, teams were able to validate the timelines and procedures for launch, including loading cryogenic – or supercold – propellant into the rocket’s tanks, performing the launch countdown through the handover to the automated launch sequencer, and draining the tanks. The rehearsal focused on two primary objectives and several secondary objectives to help ensure the team will be ready to launch on the Artemis I flight test. In addition to some of the tweets posted by the agency, they also included a graphic of the Artemis 1 checklist. This showed off all but one step complete before the launch is ready to happen.
The main objectives of the recent test that NASA is confident with are to demonstrate cryogenic loading operations through all phases of propellant loading and proceed into terminal countdown, perform a recycle to T-10 minutes, a second terminal countdown, scrub, and perform propellant drain operations and safing activities. Also, demonstrate Kennedy facilities Launch Complex-39 and Launch Control Center in launch countdown configuration and demonstrate operations and connectivity required on the day of launch with launch control team, support launch team, 45th Delta Space Force Eastern range, network, and design center support.
By reaching deep into the final phase of the countdown, known as the terminal count when many critical activities occur in rapid succession, teams exercised all the assets and capabilities of the entire system: the SLS rocket, the Orion spacecraft, and Exploration Ground Systems including at Launch Complex 39B and other supporting locations. NASA points out that despite a liquid hydrogen leak detected earlier in the day when increasing pressure to condition the engines, teams were able to develop a plan to proceed into the terminal count with the expectation the countdown would stop after handover to the flight software for the automated launch sequencer. The software performs checks to confirm the engine temperatures are within an acceptable range up to the point of the engine start sequence at T minus 9.34 seconds and operated correctly to halt the countdown at any point if temperatures fall outside that range, just as it would during an actual launch attempt.
“The team continues to impress me with their and creative thinking and resourcefulness,” said Charlie Blackwell-Thompson, Artemis launch director at Kennedy. “Our Artemis launch team has worked quickly to adapt to the dynamics of propellant loading operations. With each milestone and each test, we are another step closer to launch.” The launch director elected to do a single run through the terminal count due to the length of the day for the launch teams. With experience from loading operations and simulations, it is not necessary to perform a retest to demonstrate the ability to recycle and reset for another run through the terminal count. Additionally, as part of the normal procedures after the cut-off of the countdown, teams successfully completed a set of steps to “safe,” or stabilize and reconfigure, the rocket. Engineers reviewed the few commands that would have been included within the remaining seconds of the countdown before the engine start sequence and determined those activities had been previously validated in other recent tests. The remaining commands were not part of the objectives, but the team has decided to incorporate additional checks earlier in the countdown as they fine-tune procedures, such as for engine purge bleed parameters and propellant feedline heaters used for conditioning the engines to a specific temperature range for launch. Performing these checkouts earlier in the countdown will provide the team with the best position to make the target launch window.
Artemis 1
Now that we know more about the recent wet dress rehearsal test and SLS’s progress, we can take a closer look at what is next and when Artemis 1 is expected to happen. As of right now, before returning to the VAB, engineers will also add a checkout of the booster hydraulic power unit to provide additional data for the countdown schedule. The units contain hydrazine powered turbines attached to pumps that provide pressure to pivot the booster nozzles used for steering the rocket during ascent. The automated launch sequencer sends the command to start the hydraulic power unit at T minus 28 seconds, which would have occurred just after the point the flight software cut off the countdown at T minus 29 seconds.
Once inside the VAB, teams will replace a seal on the quick disconnect of the tail service mast umbilical to address a liquid hydrogen leak detected during the rehearsal. NASA plans to return SLS and Orion to the pad for launch in late August, and will set a specific target launch date after replacing hardware associated with the leak. Based on NASA’s estimate to return SLS to the pad in late August, we can expect the launch to happen in September or a bit later realistically. Artemis I will be the first integrated test of NASA’s deep space exploration systems: the Orion spacecraft, SLS rocket and supporting ground systems. As the first in a series of increasingly complex missions, Artemis I will pave the way for long-term exploration at the Moon in preparation for human missions to Mars. During this flight, the spacecraft will launch on one of the most powerful rockets in the world and fly farther than any spacecraft built for humans has ever flown. It will travel 280,000 miles from Earth, thousands of miles beyond the Moon over the course of about a four to six-week mission. Orion will stay in space longer than any ship for astronauts has done without docking to a space station and return home faster and hotter than ever before. At the start, SLS and Orion will blast off from Launch Complex 39B at NASA’s modernized spaceport at Kennedy Space Center in Florida. The SLS rocket will produce 8.8 million pounds of thrust during liftoff and ascent to loft a vehicle weighing nearly six million pounds to orbit. Propelled by a pair of five segment boosters and four RS-25 engines, the rocket will reach the period of greatest atmospheric force within ninety seconds. After jettisoning the boosters, service module panels, and launch abort system, the core stage engines will shut down and the core stage will separate from the spacecraft. This will be very exciting to watch just a few months from now based on NASA’s estimates.
Conclusion
The Space Launch System has been going through practically constant tests for a long time now. Over the past few months alone it has been attempting to finish the wet dress rehearsal. Thankfully, only a few days ago NASA announced they have completed the test and are moving on to Artemis 1. We will have to wait and see how it progresses and the impact it has on the space industry.