NASA is Sending Humans Back to the Moon, But it Won't Stop There. Next Comes Mars

NASA recently announced the astronauts that will make up the Artemis II crew. This mission will see the four-person crew conduct a circumlunar flight, similar to what the uncrewed Artemis I mission performed, and return to Earth. This mission will pave the way for the long-awaited return to the Moon in 2025, where four astronauts will fly to the Moon, and two (“the first woman and first person of color“) will land on the surface using the Starship HLS. These missions are part of NASA’s plan to establish a program of “sustained lunar exploration and development.”

As NASA has emphasized for over a decade, the Artemis Program is part of their “Moon to Mars” mission architecture. On Tuesday, April 18th, NASA released the outcomes from its first Architecture Concept Review (ARC 2022), a robust analysis designed to align with its overall mission strategy and define the supporting architecture. This included an Architecture Document and an executive summary that provide a detailed picture of the mission architecture and design process, plus six supporting white papers that addressed some of the biggest questions regarding exploration and architecture.

The agency’s long-term mission architecture includes the hardware needed for human missions to the Moon and Mars, including rockets, spacecraft, rovers, spacesuits, communications relays, and more. It also designates the kinds of operations needed to test these elements and develop the necessary expertise so that everything will function together as a single system. The ARC 2022 also specifies how the mission elements will be incrementally developed and delivered to the Moon and Mars for long-term, human-rated missions in deep space.

Artemis II crew portrait
The Artemis II crew includes, clockwise from left, Christina Koch, Victor Glover, Jeremy Hansen, and Reid Wiseman. Credit: Josh Valcarcel/NASA

The ARC 2022 was conducted by NASA’s Exploration Systems Development Mission Directorate (ESDMD) in January 2023 to review the revised Moon to Mars Objectives. This document, released in September 2022, established guideposts for the allocation of investment by NASA and its commercial and international space agency partners. The agency began developing its ARC in late 2022 to examine how these objectives can be distilled into specific architectural elements that can function together to accomplish human missions.

The process began with Vice President Harris, the Chair of the National Space Council (NSC), asking that NASA develop a plan for an initial lunar surface architecture that includes commercial and international partnerships. As NASA Deputy Administrator Pam Melroy said in a recent NASA press statement:

“Our first Architecture Concept Review is a milestone that will help our Moon to Mars strategy unfold through the objectives in missions both near and long term. We’re aligned with partners toward a future of expanded economic opportunity, scientific discovery, and greater activity on and around the Moon, and with limitless possibilities deeper in the solar system.” 


As per the revised Moon to Mars Objectives, NASA has established four broad categories for meetings its exploration goals. These include Science, Infrastructure, Transportation & Habitation, and Operations, into which 63 objectives were divided into ten goals. These included:

  • Lunar and Planetary Science
  • Heliophysics
  • Human and Biological Science
  • Physics and Physical Science
  • Science Enabling
  • Applied Science
  • Lunar Infrastructure
  • Mars Infrastructure
  • Transportation and Habitation
  • Operations
Artist rendering of an Artemis astronaut exploring the Moon’s surface during a future mission. Credit: NASA

To break these objectives down, NASA emphasized the need for space exploration systems that can ensure astronaut safety during transits to the Moon, Mars, and deep space; the need for bioregenerative life support systems (BRLSS), food production, power generation and distribution (echoing NASA’s Kilopower program), and studies into the long-term physiological effects of microgravity, radiation, and the environment of space, the Moon, and Mars on human physiology.

“Architecting from the Right”

With the objectives for NASA’s Moon to Mars architecture established, the ARC 2022 addresses the specific mission elements and the evolutionary development process to achieve them. This process is called “architecting from the right,” which entails starting with the broadest, long-term goals and working backward to ensure that each goal is traced to the necessary elements (see diagram below). From these Objectives & Goals, the next step (Characteristics & Needs) consists of identifying necessary mission features, activities, and capabilities to satisfy the mission’s goals and objectives.

Next up, there are the interdependent steps known as Functions and Use Cases, which define the actions that a mission architecture would perform to complete the desired Use Case, and the operations that must be executed to produce the desired characteristic and/or need (respectively). From this, NASA derives specific elements, such as rockets, rovers, landers, spacecraft, habitats, and other mission-related vehicles and technology. For the ARC 2022, these elements have been divided into four segments that cover the Artemis Program and how it will lead to the first missions to Mars.

Returning to the Moon (to Stay!)

First, there’s the Human Lunar Return segment, which addresses the initial capabilities, systems, and operations that will establish a human presence on and around the Moon. This includes the Space Launch System (SLS), the Orion spacecraft, the core elements of the Lunar Gateway, the Human Landing System (HLS), the Exploration Extravehicular Activity System (xEVA) spacesuits, and the many communications and other systems that bind them. These elements all come into play for NASA’s proposed return to the Moon, culminating in the Artemis III mission in 2025.

Second, there’s Foundational Exploration, which will continue using capabilities established in the first segment and initiates new systems to expand mission durations and the kinds of surface operations astronauts can perform. This will include the additions of further modules to the Gateway and the delivery of habitation and mobility elements on the surface (the Artemis Basecamp). These will also enable Mars mission simulations and validate technologies used to explore the Martian surface and conduct scientific research.

Artist’s impression of surface operations on the Moon. Credit: NASA

Third, there’s the Sustained Lunar Exploration segment, where NASA aims to build a “future economic opportunity, expanded scientific discovery, and greater participation on and around the Moon” with its international partners. Specific goals in this segment include improved power generation and storage, the local production of propellant, consumables (food and water), construction materials, the large-scale production of goods and services, and developing habitation and support systems to support larger populations.

Missions to Mars

In the fourth segment, Humans to Mars, things get a bit more vague. The Review’s authors acknowledge that the specific elements for sending crews to Mars are not fully distilled and that several options are being explored. The future development of these elements ultimately depends on the mission profile NASA selects, whether it is an “orbit-only” option or a mission involving astronauts traveling to the surface and performing science operations. Nevertheless, the Review stresses that certain assumptions and minimum requirements must be met.

These include an initial mission with a four-person crew traveling to Mars, two crew members descending to the surface, and surface operations for 30 Martian days (sols); sending landers to pre-deploy cargo in advance of crew landings; creating a minimal surface infrastructure (power and communications), but no surface habitat; and a mission where the crew carries all of the propellant they will need for a round-trip journey, meaning that there will be no propellant production on Mars. The Review establishes that other questions regarding mission profiles will be addressed in subsequent analysis cycles.

Said Cathy Koerner, deputy associate administrator for the Exploration Systems Development Mission Directorate at NASA Headquarters in Washington, “NASA now has a goal-based foundation upon which to build our current and future exploration plans. Our approach is designed to ensure exploration of the Moon and Mars has staying power.” 

There are many takeaways from this Review, not the least of which is the lack of definition for the elements needed beyond 2025 and 2028. At this juncture, NASA has prepared and planned for everything leading up to the first crewed mission to the Moon since the Apollo Era. What follows the Artemis III mission is somewhat general, but the essential elements (like completing the Gateway and deploying the Artemis Base Camp) are on the drawing board and on track for development.

Artist’s concept of a Bimodal Nuclear Thermal Rocket in Low Earth Orbit. Credit: NASA

However, the elements required for operations between 2028 and 2033 (when the first mission to Mars is planned) have been in a holding pattern since 2018-2019. These include the Deep Space Transport, the Solar Electric Propulsion (SEP) system it would use, the Mars Base Camp, and other concepts that have been proposed since the NASA Authorization Act of 2010. There is also the unresolved issue of whether or not nuclear propulsion is a viable option, as there is research that indicates it will not be ready by 2033.

As the assumptions and minimum requirements show, an “orbit-only” mission is still possible, though no consensus has been reached on this issue – as indicated by the Achieve Mars (AM) IX Report. And, of course, there’s the issue of the budget environment. According to a 2015 op-ed by two former NASA personnel, the agency’s funding would need to be tripled to achieve the Moon to Mars mission architecture by 2033 (increased from the current 0.5% of the U.S. annual federal budget to 1.5%).

In short, there’s a lot of work that needs to be done if NASA hopes to accomplish its Moon to Mars mission objectives. But with the completion of the SLS, the success of Artemis I, and the announcement of the crew for the Artemis II mission, there’s a lot of excitement in the air. As we get closer to 2033, things will continue to come together, technologies will mature, and a fuller picture of NASA’s mission architecture will emerge.

Further Reading: NASA, ARC 2022