Mars Crew Complement Considerations (ACR24 white paper)¶
Document: Mars Crew Complement Considerations, a four-page white paper headed "2024 Moon to Mars
Architecture" and footed "2024 Moon to Mars Architecture Concept Review". No date is printed beyond
the year; the download path is 2024/12. Files: text
sources/text/docs/2024-12-acr24-mars-crew-complement.txt; raw
sources/raw/docs/2024-12-acr24-mars-crew-complement.pdf (fetched 2026-10-01T07:22:46Z from
https://www.nasa.gov/wp-content/uploads/2024/12/acr24-mars-crew-complement.pdf, per
sources/manifest.csv). Page numbers: the printed numbers (1–4) match the PDF pages and the text
file's [page N] markers. PDF pages 2 and 3 were checked against the text.
Which paper this is. NASA's White Papers web page lists it under the 2024 Architecture Concept Review: "Weighs the factors, risks, and opportunities that affect how many astronauts NASA will send to the Red Planet during the first human missions" (White Papers page, fetched 2026-10-01). The 2024 executive overview lists it among its four "Mars-focused" papers (2024 overview, PDF p. 8). It is 2024 context, older than ADD Rev C and older than the decision it prepares: the floor of four crew to the Mars surface came at the 2025 review (MD-05; ADD Rev C, pp. 76, 193).
Summary. "Crew complement — or the number of astronauts on a mission to accomplish set responsibilities — is a key driver for human exploration architectures, with flow-down impacts on most elements and sub-architectures" (p. 1). The paper lists what drives the number (crew health and performance, responsibilities, workload, concept of operations, complexity and value), shows three concepts of operations (crew to Mars vicinity only, split crew, all crew to the surface), and says NASA will bring "an integrated decision package" to agency leadership (p. 3). It gives no number of crew. The content is on Key definition tasks.
Contents¶
| Page | Section | Wiki home |
|---|---|---|
| 1 | Introduction (why crew complement drives the architecture; "architecting from the right"; vicinity and surface "may be different values"); Crew Health and Performance Considerations | Key definition tasks |
| 2 | Figure 1, "Notional Crew Time Allocations"; Crew Responsibility Considerations; Crew Workload Considerations | same |
| 3 | Mission Concept of Operations Considerations; Mission Complexity and Value Considerations; Summary and Forward Work; Figure 2, three crew concepts of operations | same |
| 4 | Key Takeaways; References 1–5 | this page |
What the PDF shows that the text layer loses¶
- Figure 1 (p. 2) is a pie chart headed "Notional Crew Time Allocations for a Humans to Mars surface mission", with ten labels: Training, Planning, System Operations and Maintenance, Science & Exploration, Public Engagement, Sleep, Personal Time, Meals, Exercise, Medical Care. It prints no values, and a footnote says "*All values notional. Assumptions based on NASA historical and trade study data." The wiki gives the labels only and doesn't size the slices.
- Figure 2 (p. 3) shows three diagrams of Mars with a crew marker: "Crew to Vicinity Only" (marker in orbit only), "Split Crew" (markers in orbit and on the surface) and "All Crew to Surface" (marker on the surface only). The text layer keeps the three headings but separates them from the caption.
Key takeaways (p. 4)¶
- "The number of crew an architecture must support has flow-down impacts on most sub-architectures and elements, with profound implications for key exploration systems, including launch vehicles, transit systems, ascent vehicles, communications infrastructure, and power generation."
- "Splitting a crew between locations (e.g., in space, inside habitat, on EVA, etc.) significantly impacts the architecture necessary to support them."
- "Key considerations for establishing the number of crew to the vicinity and the surface of Mars include balancing crew health, performance, operations, safety, utilization, technology integration, and exploration objectives."
- "Due to these flow-down impacts, it is critically important that NASA makes a decision regarding crew complement early in the stages of architecture development."
- "NASA will continue to analyze the trade space in support of a decision on crew complement, developing a decision package for review by agency leadership."
What changed by Rev C¶
These comparisons are the wiki's. In short: the decision the paper prepares has been made for the surface (MD-05, ACR25), but not for Mars vicinity (MD-06, still open), and the 2025 reasoning repeats several of the paper's considerations. Details are on Key definition tasks. The paper doesn't settle whether the ADD's "no fewer than six" or the Update's "up to six" is meant (open question 28).
References that are other architecture documents¶
The paper cites five references (p. 4). As printed:
| Ref. | Title, as printed | Among the wiki's sources? |
|---|---|---|
| 1 | Key Mars Architecture Decisions, 2023 Moon to Mars Architecture White Paper | no |
| 2 | Mars Communications Disruption and Delay, 2023 Moon to Mars Architecture White Paper | no |
| 3 | NASA's Moon to Mars Strategy and Objectives Development | yes, Strategy and Objectives Development (2023) (the link is a go.nasa.gov short link; matched by title) |
| 4 | Moon to Mars Objectives | yes, Moon to Mars Objectives (2022) (same file name in the link) |
| 5 | Human Health and Performance: Keeping Astronauts Safe & Productive On a Mission to Mars, 2023 Moon to Mars Architecture White Paper | no |
References 1, 2 and 5 are among the 13 papers of January 2024 that the 2023 executive overview lists
(2023 overview).
"No" means no file in sources/manifest.csv or sources/text/pages/ has a matching name.
Oddities¶
As printed, PDF checked:
- A different title for the power paper. "For an example of a key driving decision made using this process, see the 2024 Mars Initial Surface Power Decision white paper published concurrently to this paper" (p. 3). The paper published with it is titled "Mars Surface Power Technology Decision" (source page).
- Two semicolons where commas belong: "The more crew on a mission; the more that duties may be shared" (p. 2) and "Due to the distances and communications delays associated with a Mars mission; the crew must also have the capability" (p. 2).
See open question 66.
Related pages¶
Key definition tasks · Humans to Mars · Human Systems · RT-4 Crew Time · Mars Surface Power Technology Decision (ACR24)