February 2024 workshop: white-paper briefing, Key Mars Architecture Decisions¶
Document: 09-2024-architecture-workshop-white-paper-mars-decisions.pdf, 15 slides, 3,609,325 bytes, from
https://www.nasa.gov/wp-content/uploads/2024/02/, fetched 2026-10-01T18:28:04Z (sources/manifest.csv). Title
slide: "Key Mars Architecture Decisions" (slide 1). No presenter or date. Footer: "2024 Moon to Mars Architecture
Workshops". Listed on the Architecture Workshops page under
"February 2024". Text: sources/text/docs/2024-02-09-2024-architecture-workshop-white-paper-mars-decisions.txt;
images in sources/raw/slides/2024-02-09-2024-architecture-workshop-white-paper-mars-decisions/.
Rank and method. A briefing, not the architecture of record (SCHEMA, "Workshop slides"), older than Rev B and Rev C. It briefs a 2023 white paper, "Key Mars Architecture Decisions", which the wiki doesn't hold; the 2025 "Architecture Definition" paper supersedes it (source page). All 15 slides were read in the text layer. The images of the text-poor slides 3, 5, 6 and 15 were viewed, and of slides 4, 7, 9 and 13 (a network figure and pictures); the title card (slide 1) wasn't. The text has no "Moon Base", "CUI" or "Pre-Decisional" (searched).
Summary. The seven Mars decisions that became MD-01 to MD-07, each on its own slide with the "Needed Decision Outcome" and its "Context", two years before Rev C closed four of them. It adds to the wiki: "nearly 100 key architecture decisions" in the preliminary analysis (slide 4), where the same workshop's opening deck says "nearly 90"; the crew decision as two (surface, vicinity), each with its own slide; the target-state question as first framed, "Science missions to different sites, excursions from an established base at one site, or something else?" (slide 8); and a timeline of Mars studies since 1986 headed "We need to move beyond studies… and start making decisions" (slide 3).
Slides¶
| Slide | Title (as printed) | Content |
|---|---|---|
| 1 | "Key Mars Architecture Decisions" | Title card |
| 2 | "Architecture Segments" | The four segments and Future Segments, one line each |
| 3 | "To send Humans to Mars…" | Timeline of studies (image) |
| 4 | "Decision Space Modeling" | Nearly 100 decisions |
| 5 | "Decision Time Criticality" | Seven first (image) |
| 6 | "Mars Priority Architecture Decisions" | The seven hexagons (image) |
| 7–13 | "Candidate Key Mars Architecture Decision" (slide 11: "Candidate Key Decision") | One per decision |
| 14 | "Key Take-Aways" | Take-aways |
| 15 | "White Paper" | Thumbnails of the paper's four pages and a QR code (image) |
The timeline (slide 3)¶
Read from the image. "WE NEED TO MOVE BEYOND STUDIES…" over a timeline from "APOLLO 11" to 2020, with report covers above and below; "…AND START MAKING DECISIONS" at the foot. As far as the small print can be read:
- Above the line: 1986 "Pioneering the Space Frontier"; 1989 "Exploration Studies Technical Report"; 1991 "America at the Threshold"; 2005 "Exploration Systems Architecture Study"; 2007 "Lunar Architecture Team Report"; 2009 "Mars Design Reference Architecture 5.0"; 2009 "Human Spaceflight Plans Committee"; 2011 "Constellation Program Lessons Learned"; 2022 "2021 Strategic Analysis Cycle Report".
- Below the line: 1987 "Leadership and America's Future"; 1989 "90-Day Study on Human Exploration"; 1998 "Mars Design Reference Mission 3.0"; the Global Exploration Roadmap of 2011, 2013 and 2018 and its supplements of 2020 and 2022 (bracketed "International Studies"); 2023 "Mars Transportation Assessment Study".
- On the line: "1986 Space Shuttle Challenger Disaster", "1989 Speech President George H. W. Bush", "2003 Space Shuttle Columbia Disaster", "2004 Speech President George W. Bush", "2010 Speech President Barack Obama", "2019 Speech Vice President Mike Pence".
NASA's Mars Architecture Studies page lists seven historical studies (1989–2014); the slide is a longer list with a point to make. None of the reports is among the wiki's sources.
Decision modeling (slides 4–5)¶
Slide 4, "Decision Space Modeling": "NASA is developing a decision modeling process and tools.
- Preliminary analysis identified nearly 100 key architecture decisions.
- NASA is currently refining the catalog of needed decisions and modeling in a decision trade space that maps linkages between decisions.
Seven key decisions recommended for priority analysis in the 2024 analysis cycle."
Beside it, a network of nodes read from the image: propulsion, power and thermal choices, each labeled "Compound Choice", "Discrete Dimension" or "Trade Space" ("Main Propulsion System : Compound Choice", "Electric Propellant Type", "Chemical Engine Type", "Power System : Compound Choice" with "Solar" and "Nuclear Power", "Thermal" with "ZBO" and "RBO", "Stage : Trade Space"), with green and red lines between some of them. No key explains the colors.
Slide 5, "Decision Time Criticality" (image): "7 PRIORITY DECISIONS" as seven colored pins in a circle, a road of many more pins to a Mars marker ("ROAD TO MARS"), "EVERY DECISION WILL GET MADE. NOT EVERY DECISION CAN BE MADE FIRST." and "Modeling precedence relationships helps sort the full catalog of decisions by time criticality." The pins use the five colors of slide 6's key; this slide has no key.
Nearly 90 or nearly 100. The same workshop's opening deck says "NASA catalogued nearly 90 needed decisions" (Overview and Updates, slide 12); this deck's "Preliminary analysis identified nearly 100", with the catalog still being refined, and so does the 2025 "Architecture Definition" paper ("nearly 100 candidate definition tasks"). Both figures appear at one workshop and neither deck says how they relate, so the wiki can't read 2024 to 2025 as a change in either direction (the wiki's comparison; open question 54).
The seven decisions (slides 6–13)¶
Slide 6, "Mars Priority Architecture Decisions" (image): seven hexagons beside a vertical label "Crewed Mars Mission Priorty Architecture Decisions" (as printed), and a "Color Key" of five: "Why we will go", "When we will go", "What we will do there", "Who will be involved", "How we will get there and back". The hexagons and colors are those of the opening deck's slide 12. Slides 7–13 take one each, with the hexagon in the corner:
| Slide | Hexagon (color) | Slide title | Needed decision outcome | Context |
|---|---|---|---|---|
| 7 | "Mars Science Priorities" (Why) | "Science Priorities for Initial Human Mars Segment" | "Identify the highest science priorities for the initial human Mars segment — Includes both planetary and biological science priorities" | "Picking where before considering why may force us to revisit our how decisions"; "Science priorities are why and what decisions, not how (implementation) decisions — but they can anchor the how" |
| 8 | "Initial Human Mars Segment Target State" (What) | "Initial Human Mars Segment Target State" | "What is the target state ('vision') for the initial human Mars segment? — Science missions to different sites, excursions from an established base at one site, or something else?" | "Segment scope should focus on the target state, not just a first mission — Apollo focused on getting to the Moon and back, so architecture wasn't suited for more crew, longer stays, larger exploration radii, or ambitious infrastructure"; a Chesley Bonestell painting, "The Exploration of Mars, 1953" |
| 9 | "Initial Human Mars Segment Cadence" (When) | "Initial Human Mars Segment Mission Cadence" | "What is the cadence of missions for the initial human Mars segment?" | "Initial Mars Segment Target State key decision will establish the segment scope — How many unique missions (including robotic precursors, cargo, and demonstrations) are necessary to achieve desired scope?"; "What does a Mars-equivalent campaign look like?" over a lunar campaign picture |
| 10 | "Mars Loss of Crew Risk Posture" (How) | "Mars Architecture Loss of Crew (LOC) Risk Posture" | "Define probability LOC risk posture for a Mars mission." | "Human spaceflight programs typically develop an understanding of the overall LOC risk for the candidate operations and define a minimum level of acceptable risk (i.e., safety threshold) for the mission." |
| 11 | "Number of Crew to Mars Surface" (Who) | "Crew Complement to Mars Surface per Crewed Mission" | "How many crew will descend and land on the Mars surface per crewed mission? — Minimum number for first mission and upper limit for subsequent missions in the initial segment — Note that number of crew to surface is not necessarily the same as number of crew to Mars vicinity" | "Crew complement is the most common study constraint across all architectures and elements, with implications for virtually every crewed element, plus logistics and operations." |
| 12 | "Number of Crew to Mars Vicinity" (Who) | "Crew Complement to Mars Vicinity per Mission" | "How many crew will travel to Mars vicinity per crewed mission? — Minimum number for first mission and upper limit for subsequent missions" (and the same note) | "… with implications for transit and Earth launch/land vehicles." |
| 13 | "Mars Surface Power Generation Tech" (How) | "Mars Primary Surface Power Generation Technology" | "Select primary surface power generation technology." ("primary" underlined) | "Extensive robotic mission experience has made clear that reliable surface power is mission critical in Mars' challenging environment. Primary power source selected will be a scalability driver for human Mars missions."; pictures labeled "Example of Nuclear Surface Power Technology" and "Example of Non-Nuclear Surface Power Technology" |
The lunar campaign picture on slide 9 (read from the image) is captioned "Lunar South Pole Target Site", with "Lunar Reconnaissance Orbiter", "Artemis I", "Artemis II", "Gateway begins science operations with launch of Power and Propulsion Element and Habitation and Logistics Outpost", "Artemis III-V: Deep space crew missions; cislunar buildup and initial crew demonstration landing with Human Landing System", "Early South Pole Robotic Landings", "Volatiles Investigating Polar Exploration Rover" and "Humans on the Moon—21st Century".
Key take-aways (slide 14)¶
"The order in which key decisions are made heavily influences exploration architectures." "NASA endeavors to identify a logical order for decision making by modeling the decision trade space for human Mars exploration." "Every decision is important, but not every decision can be first." "Methodology allows decision makers to understand the integrated impacts of each individual decision on the overarching architecture." "Application of the new process and tools resulted in seven key Mars architecture decisions to focus on in the current analysis cycle. These decisions affect every subsequent decision." "Mars serves as a test case for this approach. Lessons will inform future decisions for the Moon and subsequent exploration." "As architecture decisions are made, updates will be reflected in NASA's Moon to Mars Architecture Definition Document. The Architecture Definition Document is updated annually."
The paper (slide 15)¶
Thumbnails of four pages, read from the image as far as the print allows: the first page headed "Key Mars Architecture Decisions" with "2023 Moon to Mars Architecture" down the side and "2023 Moon to Mars Architecture Concept Review" in the footer; a page with a figure titled "Priority Human Mars Architecture Decisions" (the seven hexagons and a color key); and the decision network of slide 4. So the paper's own title is the one the 2023 overview uses, not the opening deck's "Mars Priority Decisions" (the wiki's reading of a thumbnail). The text layer of slide 15 holds only "White Paper".
What changed by Rev C¶
These comparisons are the wiki's.
- The seven are MD-01 to MD-07, by title, as on Key definition tasks. Slide 13's title, "Mars Primary Surface Power Generation Technology", is the heading ADD Rev C gives MD-07 (p. 192). Slide 11's title, "Crew Complement to Mars Surface per Crewed Mission", is not Table One's "Number of Crew to Mars Surface".
- Four are closed: power at the 2024 review; target state, loss-of-crew method and crew to surface at the 2025 review. MD-03 (cadence), MD-01 (science) and MD-06 (crew to vicinity) are still open in Rev C.
- The target state was narrowed, not chosen. Slide 8 offered "Science missions to different sites, excursions from an established base at one site, or something else". Rev C's down-select left three options, all with more than one mission: short stays at one site, long stays at one site, or short stays at different sites (p. 193; Key definition tasks).
- Loss of crew: a posture became a method. Slide 10 asks for a "probability LOC risk posture"; Rev C closed MD-04 as a "Risk Methodology".
- Crew to the surface was settled as a minimum: "no fewer than four (4) crew to the surface, with consideration for no fewer than six (6)" (pp. 76, 193; the Update says "up to six"). The vicinity decision, MD-06, is still open (Key definition tasks).
Oddities¶
As printed, images checked:
- "Priorty" in slide 6's vertical label.
- Slide 11 is headed "Candidate Key Decision"; the other six say "Candidate Key Mars Architecture Decision".
- "Decision Outcome Needed" on slide 13; the other six say "Needed Decision Outcome".
- Slide 6's hexagon says "Cadence"; slide 9's title says "Mission Cadence".
Related pages¶
Key definition tasks · Humans to Mars · Architecture definition process · Overview and Updates, February 2024 · Mars challenges briefing, February 2024 · 2024 executive overview · "Architecture Definition" white paper (2025)