20 Years of Planning, Effort Ready to Culminate in Return to the Moon

The Artemis program, while relatively young, incorporates elements that have had long and winding development histories, which is reflected in the evolution of its earliest mission plans over time. The Space Launch System rocket and Orion spacecraft both trace their stories back to 2004. While congressional support has been very consistent over the past 20 years, stringent budget caps have dragged out development, alongside sometimes lax contract enforcement and novel technical problems. The numerous shifts in hardware timelines have caused drastic replans in the mission that would become Artemis II, but as we stand on the verge of launch, we can look back and appreciate how much work it took to get here.

At the time of the Constellation Program’s cancellation in 2010, Orion had reached a fairly advanced stage of development. However, its reincorporation as the Multi-Purpose Crew Vehicle (MPCV) and redirection towards higher lunar orbit and asteroid missions would result in a delayed completion of design. There was a moderate-fidelity Crew Module in production, likely assigned to the Ares I-Y (or later the rescoped I-X Prime) high-altitude abort test. This vehicle, importantly, had extremely minimal life support systems and generally only what was required to re-enter the atmosphere successfully and operate in space for the 4-hour flight duration. Due to these limited capabilities, after the MPCV transition a new mission was created for it. This mission was named Exploration Flight Test-1 (EFT-1) and set to launch in 2014. EFT-1 would launch this CM and a simulated service module into an eccentric low-earth orbit to demonstrate the thermal protection systems (including newly restarted Avcoat material on the heat shield), the fairings, separation systems, and recovery systems and processes. Performing the mission would also exercise the mission planning, mission control, ground handling, and manufacturing teams for the first time to gain practice and prepare for the first deep-space missions with the final vehicle design. 

After Orion’s Critical Design Review in late 2015, the full uncrewed configuration to be used on Exploration Mission-1 (EM-1, later named Artemis I) entered production and development focus turned to the “Delta CDR“, or a review of the major changes for the crewed configuration that would debut on the second flight. This centered on life support systems such as O2/N2 storage, CO2 filters, and the galley/toilet as well as crew displays. While some degree of displays/crew systems were included on EM-1, they would only be fully integrated for EM-2. 

On the SLS side, while it was designed by teams experienced from Ares 1 and Ares V, there were many challenges getting it to the pad. Congressional funding was not sufficient to develop the full SLS rocket concurrently, so the decision was made to start with the Core Stage. While it looks similar to the Space Shuttle External Tank, it has few similarities besides diameter and color. The aluminum panels that make up its tanks are among the thickest ever friction stir welded, which resulted in random welds being too brittle but undetectably so without destructive testing. These issues, along with the difficulties in standing up an entirely new production facility and workforce (as very little remained from the External Tank project) led to 1-2 years of delays by themselves. They also resulted in the rocket’s Exploration Upper Stage being further delayed, eventually all the way to EM-4. Additional interim upper stages had to be bought piecemeal and human rated after the fact to support the crewed EM-2 and EM-3 missions. Ultimately the first flight, Artemis I in November 2022, was a complete success for SLS, so only minimal improvements and alterations were required for Artemis II. These include the addition of strakes, to control instability caused by air flowing around the booster attach points and reduce vibrations.

One of the most important results of Artemis I was the evaluation of the heat shield’s performance. Unexpected material spalling occurred during entry, and a year-long investigation was performed to understand and remedy the root cause. As shared by NASA in December 2024, the material liberation was due to the skip phase of the entry combining with low material porosity to allow gasses to build up inside the heat shield and crack the outer layers of it. For Artemis III and beyond, the porosity of the material will be increased to allow it to vent properly during the skip, but for Artemis II the skip phase has been eliminated in favor of a more traditional entry profile.

Elements of all of these difficulties have had major impacts on the mission plan itself. The original conception of the mission circa 2012 involved it launching on a Block 1 configuration of SLS to perform several orbits of the moon before returning. 

Later it was changed to a free-return, likely due to adding the longer life support checkout. In March 2013, it was proposed to modify the cislunar phase to include a visit to the asteroid target of the Asteroid Redirect Mission (ARM), which would have been placed in the vicinity of the Moon. In June 2014, after the creation of EUS and Block 1B, EM-2 was changed to use Block 1B to bring EUS implementation forward. With the new mission profile, EM-2‘s secondary role as a component of ARM was no longer workable, and a later flight was designated for that purpose. The proposed EUS development acceleration also proved unworkable due to Core Stage production issues, so EM-2 was reverted to Block 1 while retaining the free-return mission mode, also called the “Hybrid Triple”. In this plan, Orion would launch into a low parking orbit before being boosted by SLS‘s upper stage into a very elliptical checkout orbit. With a period of either 24 or 42 hours, this would allow thorough checkouts of the new crew systems before committing to a weeklong free-return flyby. At the conclusion of the checkout orbit Orion would perform Trans-Lunar Injection and proceed directly past the moon and to reentry. The long checkout period greatly reduced risk for the first crewed flight while also allowing evaluation of crewed deep space operations and lunar observations by the crew. With this, the mission plan essentially reached what will be flown in February.

It has taken 20 years from the award of the first Orion contract to get to this point, with 20 years of decisions and challenges to go with it. While there are many valid criticisms of the Artemis program, inspiration can be taken from Pete Conrad: “I think the Space Shuttle is worth one billion dollars a launch. I think that it is worth two billion dollars for what it does. I think the Shuttle is worth it for the work it does.” The work SLS does is bring humans back to the Moon for the first time in 54 years and prepare us for the potential of decades of routine lunar flights. All in all, it is worth it. Stay tuned for Space Scout’s continuing coverage of Artemis II through launch, its lunar flyby, and splashdown.

Edited by Beverly Casillas