Due to repeated delays, cost overruns and the accelerated schedule of the Artemis project, serious doubts were expressed about the availability of the SLS on time. Fortunately, ground crews and engineers at NASA’s Launch Control Center (LCC) – part of the Kennedy Space Center in Florida – recently finished stacking the Artemis I mission. The vehicle is now in the final stages of preparations for this unmanned circumlunar flight in February 2022.
The fully stacked Artemis I the rocket includes the SLS Core Stage, consumable solid rocket boosters, the Orion Multipurpose Crew Vehicle (MPCV) and European Service Module (ESM) – the contribution of the European Space Agency (ESA) to the Artemis program. Now that these systems are all integrated, they will undergo a series of test campaigns that will evaluate them as a fully integrated system for the first time.
Each of these tests will build on the last, culminating in a launch pad simulation that will serve as a “dress rehearsal” for the launch. As Mike Bolger, the head of the Exploration Ground Systems program at LCC, said in a recent press release from NASA:
“It’s hard to articulate what this milestone means, not only for us here at Exploration Ground Systems, but for all of the incredibly talented people who have worked so hard to help us get to this point. Our team showed extraordinary dedication in preparing for the launch of Artemis I. While there is still work to be done for the launch, with ongoing built-in testing and a wet dress rehearsal, see the fully stacked SLS is certainly a reward for all of us. ”
In total, four test campaigns will take place before the “Wet Dress” rehearsal, where the rocket is fully loaded with cryogenic propellant, and a complete pre-launch sequence is performed. These tests include:
Interface check: This campaign will take place in the LCC shooting range, where crews will check the center stage engines, booster thrust control and the interim cryogenic propulsion stage (ICPS). Ground crews will also check the functionality and interoperability of interfaces between the central stage, boosters and ground systems. A final integrated test of all rocket and spacecraft wire harnesses will verify their ability to communicate with each other and with ground systems.
Program specific engineering: Following the interface check test, crews will perform several checks of the center stage and supercharging systems (such as the booster thrust control test) from the VAB. Next, ground crews will perform a technical test of the fully integrated rocket while visiting Launch Complex 39B for the wet dress rehearsal.
End-to-end communications: Next, the crews will conduct an integrated radio frequency test using a radio frequency antenna in the VAB, another near the pad and another based on the Data Tracking Satellite (TDRS) and the deep space network (DSN). These antennas are used by mission control to communicate with SLS, ICPS, and Orion during launch, in orbit, and deep space locations.
Countdown sequencing: The next step will be a simulated launch countdown inside the VAB to demonstrate the ground launch software and ground launch sequencer. The latter system resets the countdown to an automated launch sequencer 30 seconds before launch. While the vehicle is seated on the pad, teams will set up the rocket for launch, run the sequencer at a preset countdown point, and test the rocket and spacecraft responses.
For the Wet dress rehearsal, which will take place several weeks before launch, the rocket will be transferred to the platform at Launch Complex 39B using the crawler transporter. Once there, crews will practice loading and unloading the rocket with cryogenic thruster and performing mock countdowns. This will allow them to practice launching procedures and a launch scrub (followed by detaching).
Before and after the “Wet Dress”, the ground crews will perform the two end-of-flight system tests as well as a final series of inspections and checks inside the VAB. The mission operations team will continue to run launch simulations until February 2022 to stay accurate and ensure they are ready for any scenario that will occur on launch day. NASA will set a specific launch date once the dress rehearsal is successfully completed.
As the first mission of the Artemis program, Artemis I validate the SLS, Orion spacecraft, ESM, and other spaceflight elements for subsequent crewed missions. Artemis II, which is currently scheduled to launch in September 2023, will see four astronauts perform a lunar flyover without landing on the surface. Artemis III, which will be humanity’s long-awaited return to the lunar surface, is still officially scheduled for September 2024.
NASA expects this to be delayed due to issues with the Human Landing System (HLS), a necessary mission element since the previous administration accelerated the schedule for the program. However, that could be a good thing, as the decision to land astronauts on the surface by 2024 has forced all kinds of tough decisions on mission planners, engineers and administrators at NASA.
Among them, the way the lunar gateway was deprioritized and the task of launching its basic elements was given to SpaceX. There were even indications that NASA was ready to contract launch services for the Artemis III mission. A little bit of a break at this point might be just what the agency needs to get everything back on track. With all the work that has gone into building the most powerful rocket since the Saturne V, it would be a shame not to use it!
In the meantime, watch this time lapse video from Artemis I rocket stacked in the vehicle assembly building at NASA’s Kennedy Space Center, courtesy of the European Space Agency:
Further reading: NASA, ESA