NASA Set to Update Moon to Mars Architecture with ACR24

NASA is developing the latest version of its overarching vision for space exploration: the Moon to Mars Architecture. Amid an environment of questions about the Artemis Program, the agency’s year-long Strategic Analysis Cycle is drawing to a close this November with the 2024 Architecture Concept Review, called ACR24. While not focused on the near-term execution of upcoming missions, this review is expected to provide some clarity about the long-term direction of NASA’s human spaceflight ambitions as they currently stand.

NASA should release the products of ACR24 sometime in December, and they are a must-see for anyone hoping to understand the shape of crewed Lunar and Martian exploration. These decisions may also become especially relevant as the incoming Trump administration contemplates its vision for the agency. Space Scout will cover these details as they become available, but we already have a good idea of what to expect.

The Products:

The essential formulation of this Moon to Mars Architecture is the Architecture Definition Document, or ADD, a comprehensive publication packed with details about NASA’s exploration framework. This includes a breakdown of the spacecraft, systems, and mission concepts that make up the architecture, and how they help accomplish the agency’s goals and objectives. It is organized chronologically according to the four architecture segments: Human Lunar Return, Foundational Exploration, Sustained Lunar Evolution, and Humans to Mars.

The ADD is a “living document” updated each year; ACR24 will produce ADD Revision B. This will be the key source to learn about any new architecture “elements,” meaning distinct spacecraft or systems, such as landers and rovers. The ADD is also something of a weather vane for NASA’s Mars plans; while no major decisions have yet been made, the ADD describes the agency’s current priorities and rationale, which yields insight into what the first crewed Mars missions will look like.

The architecture process also produces a varying number of White Papers, shorter documents which focus on a specific topic, problem, or decision. These often identify the next challenge the architecture will need to address as the analysis cycle continues. They can be released at any point in the process, but a large batch usually accompanies the product release. Additionally, an Executive Overview may be included that briefly summarizes the work across all other products.

What We’re Expecting To See

Tidbits of information have trickled in from agency sources throughout the year, providing clues about what ACR24 will cover.

The most obvious of these was a pair of White Papers released over the summer, which described gaps in NASA’s lunar surface capabilities. They highlighted a need to land mid-sized cargo on the Moon, as well as to move cargo from point to point across the surface. At a meeting of the NASA Advisory Council’s Human Exploration and Operations committee in August, Nujoud Merancy, deputy associate administrator for NASA’s Strategy & Architecture Office, confirmed that two new elements would be added to the architecture in response to these needs. Space Scout previously speculated that these elements are likely an uncrewed utility rover, perhaps provided by the Canadian Space Agency and MDA Space, and a mid-sized cargo lander, which could come from any number of sources. These elements will appear in the ADD.

The ADD may also include a third new element: initial lunar surface habitation, provided by the Italian Space Agency’s Multi-Purpose Habitat (MPH). This small, cylindrical module would represent the first dedicated lunar “outpost” in history, providing space for two crew to live and work on the Moon for up to 30 days at a time. The MPH will complement living space provided by SpaceX and Blue Origin’s Human Landing Systems and JAXA’s Pressurized Rover. The MPH passed its Mission Concept Review in September, indicating it has already been initiated as an architecture element. More details are known about MPH than either of the other two elements which may appear, but its inclusion in the ADD could still provide a seminal reference for its planned capabilities.

Other details that might appear in Revision B of the ADD include updates about NASA’s Mars planning process. Last year, NASA released a White Paper outlining the first seven key architecture decisions that will need to be made for a human mission to Mars. Since then, NASA has identified five more architecture decisions that are next in line to be addressed. These could appear in ADD Rev B or in one of this year’s White Papers, and the ADD should indicate NASA’s current stance on these decisions. It’s important to note that these decisions have only been identified, not actually made, though a few, such as “Mars Surface Power Generation Tech,” have enough consensus that they could be formalized this year.

We also know the subjects of two White Papers which will be released. The first will cover NASA’s lunar surface strategy. Compared to the now-cancelled Constellation Program, the Artemis Program is lacking in detail about some important logistics operations, such as the way cargo will be aggregated and transported around surface sites. The program’s emphasis on commercial and international partnerships creates welcome diversity, but demands additional attention to integration across elements. This White Paper may shed light on Artemis’ approach to this challenge.

Finally, another White Paper will identify a gap in lunar sample return upmass capabilities. While much focus has been placed on delivering cargo to the surface, equally important is the ability to return samples and other payloads to Earth. The Apollo program returned 382 kg (842 lb) of samples across six landings, and Artemis hopes to greatly expand that legacy. This “upmass” may be returned alongside the crew, via the Human Landing System and Orion spacecraft, or through robotic means, potentially leveraging Gateway as a waypoint. NASA will address these considerations in the upcoming White Paper.

As the new year dawns, the Artemis campaign faces an uncertain future. While key milestones occurred in 2024, the program’s execution and delays have come under scrutiny, including both government-led and commercial elements. The Strategic Analysis Cycle which produces architecture products is designed to be resilient to changes in administration and even, to an extent, in its overall direction. Should ACR24 prove to be the last such review for Artemis in its current form, the underlying architecture principles will likely emerge unscathed, ensuring that a strong foundation for American leadership in human space exploration is preserved.

Edited by Nik Alexander