2

Defining the Science for Campaigns

Designing and prioritizing science campaigns requires the development of a broad set of tools and concepts before progress on the campaigns themselves can begin. This chapter defines a Mars campaign and describes the architectures considered by the committee before explaining how the candidate science objectives were developed and themselves prioritized. Crafting campaigns from these science objectives required several assumptions and caveats, including crew size, exploration zone definition and size, and planetary protection. A final section lists enabling technologies for human exploration of Mars.

2.1 WHAT COMPRISES A CAMPAIGN TO MARS?

A campaign in the context of this study is a set of missions encompassing the first three landings of human-scale landers on Mars (Figure 2-1). Long-term Mars exploration could be implemented as a succession of several campaigns. Not every landed mission within a campaign would necessarily carry humans to the surface of Mars; a cargo mission delivering substantial infrastructural elements for humans would qualify as the landing of a human-scale lander. The campaigns in this report are each guided by a different concept, and the three missions in each case carry the humans or cargo and complete the concept.

Multiple Mars landings maximize the return on investment associated with the significant cost of hardware development and operations support needed to enable humans to safely journey from Earth to Mars, land on Mars, be productive explorers on Mars, ascend from Mars, journey back to Earth, and analyze their scientific return. Planning a campaign of several missions is more cost-effective than planning single missions individually. The lessons learned and progress of technology inherent in the first missions to Mars mean that any longer series of human-scale landings would be difficult to define and plan in detail, especially if later missions are to be allowed to evolve in design and scope.

While the technology available to a campaign will change with time, and potential precursor missions, such as sample return, will shape the ways future explorers will pursue their science, this study aims to be agnostic to the timing of the first human missions to Mars. Instead, the campaigns focus on the community’s top science themes, independent of timing and execution.

NASA has conducted several design reference mission studies for the human exploration of Mars. Two reference mission scenarios were provided by NASA for this study, and they define the building blocks used to assemble the report’s campaigns: the “long-stay” 300-sol mission scenario and the “short-stay” 30-sol mission scenario (Hoffman and Kaplan 1997; Portree 2001; Hoffman et al. 2022; Needham and Rucker 2024) (Figure 2-2).

These long-stay and short-stay scenarios are determined by orbital dynamics and can be considered as being fixed constraints. They are combined into campaigns in two ways:

• The 30-30-30 campaign scenario comprises three 30-sol crewed surface missions deployed consecutively at up to three different locations on Mars.
• The 30-Cargo-300 campaign scenario comprises three landed missions to the same location on Mars: one 30-sol crewed surface mission, followed by one uncrewed cargo surface mission to robotically deliver and deploy infrastructure to enable a much longer stay, followed by one 300-sol crewed surface mission. The purpose of each of the missions is determined by the campaign’s science priorities (see additional detailed discussion of campaigns in Chapter 3).

2.1.1 Advantages and Disadvantages of the Two Campaign Architectures

The two architectures have both short-term and long-term advantages and shortcomings, particularly in how science fits into the architectures, and what their budget and schedule needs would be.

The cadence of the 30-30-30 campaign scenario is similar to a chaptered book: each site visited reveals a different act in Mars’s story. The 30-30-30 campaign scenario allows up to three different landing sites to be explored, which means that the planet’s diversity could be broadly sampled. Owing to the relatively short stays, the exploration zone associated with each landing site will be limited in extent. The 30-30-30 campaign scenario may leave behind a global network of instruments suitable for long-term monitoring of global and regional activity and phenomena on Mars, but this scenario is not immediately conducive to long-term studies of human health, microbial populations, plant growth, and animal behavior and/or reproduction. However, one or more missions could have a more substantive biological and physical sciences and human factors component. The 30-30-30 campaign architecture requires fewer extreme technological advances than the 30-Cargo-300 campaign because of the special needs of a 300-sol human stay on Mars. Additionally, unforeseen events may force NASA into a 30-30-30 scenario, making its planning and consideration a key activity.

In contrast, the 30-Cargo-300 campaign scenario targets a single landing site, entailing only two crewed missions, with a human scale but uncrewed cargo landed mission dedicated to infrastructure deployment in between the 30- and 300-sol crewed missions. Owing to the establishment of this infrastructure, the third mission in the campaign is a long-stay, 300-sol mission, enabling the scientific investigation of a large exploration zone. This architecture allows science targets tens to hundreds of kilometers distant to be investigated, including via multiple visits to allow iterations, multiple sampling opportunities, and the establishment of long-baseline instrument networks. By the end of the 30-Cargo-300 campaign, an initial human science and exploration infrastructure has been established on Mars, which may serve as the basis for follow-up campaigns that could further expand the infrastructure and the exploration zone.

The 30-Cargo-300 architecture therefore delivers greater depth of scientific study at one site, because the 300-sol period allows the crew to be discovery responsive, with enough time for task and measurement iterations (see Box 1-1, “Discovery-Driven Science”). The 30-Cargo-300 strategy forces the consideration of establishing a fixed base. Establishing a base is a proven strategy in scientific field exploration, for example, in the Antarctic and Arctic (e.g., Lee et al. 2022; Lee 2024a, 2024b). Establishing a fixed base has long-term benefits for repeat visits and providing a source of inspiration to Earth, but it has the disadvantage of focusing upon a single exploration zone.

2.1.2 Overview of the Four Prioritized Notional Campaigns

The campaigns presented here for consideration (Figure 2-3) are described in detail in Chapter 3. In priority order, they are as follows:

• Mars Science Across an Expanded Exploration Zone (30-Cargo-300) in Section 3.3,
• Synergy of Mars Science Measurements (30-Cargo-300) in Section 3.4,
• Seeking Life Beneath the Martian Icy Crust (30-Cargo-300) in Section 3.5, and
• Investigating Mars at Three Sites (30-30-30) in Section 3.6.

For each campaign, the committee was tasked with describing a science “roadmap” that includes the highest priority science objective(s) addressed, secondary science objectives that are also achievable, measurements needed to address the objectives, and key assets and major equipment emplaced at each phase of the campaign (before, during, between, or after crew missions; see Appendix A for the statement of task). Because of the roadmap’s similarity to standard NASA science traceability matrices (STMs) (Weiss et al. 2005), the report refers to them as STMs (see Appendix J).

To identify the science objectives for each campaign, the committee agreed upon a common understanding that a science objective is a science aim that is as large as possible but still answerable by a series of measurements and their interpretation. Each campaign includes a selection of science objectives, as well as a selection of measurements for those science objectives, as shown schematically in Figure 2-4.

2.2 SCIENCE OBJECTIVES AND THEMES

The committee created science objectives, relying on input from the four disciplinary panels and its own broad viewpoint. The committee’s final objective list does not necessarily map one-to-one with the panel STMs but rather is intended to capture the highest priority science across themes and disciplines, broken into achievable objectives.

The committee received input from the four disciplinary panels in the form of presentations on their science objectives, comprehensive science traceability matrices—including potential robotic precursor observables and samples—and additional pages of written commentary (see Appendixes B–E and J). Incorporating input from the panels, the community, invited speakers, and published sources (see References section), and through months of conversations and exercises, the committee created a combined, prioritized list of science objectives, shown in Table 2-1.

Every campaign consists of science objectives selected from this ranked list and the key measurements needed to address the objectives. Some campaigns also contain additional crucial science objectives from the longer lists provided by the four panels. Primary science objectives for each campaign are those that are the most important to complete and are tied to the landing site choice. Secondary science objectives are those that can be conducted at any landing site and/or are decoupled from the primary science objectives of the campaign.

As the committee considered the scientific objectives advanced by each panel, several common themes emerged as major thrusts of the highest-impact research. The committee identified themes common across disciplines—Life: Past and Present; Life: Habitability; Climate: Weather, Processes, and History; Human Experience and Habitation; and Enabling Future Missions (Table 2-1). Furthermore, the committee identified derivative areas of study that affect research on Mars. These are expanded below.

2.2.1 Life: Past and Present

The detection of life on Mars is a persistent top priority for explorers of many disciplines, and it is the top science objective in this report. The work that goes into understanding the context and meaning of a possible life detection requires, however, a network of information gleaned from multiple objectives and, thus, the broader theme discussed here emerged. Furthermore, detection of life on Mars, whether extant or extinct, necessarily relies on multiple lines of evidence and cannot be viewed as a simple binary yes-no answer (Green et al. 2021), but as a progressive scale where claims of life detection are reported in terms of the level of confidence and using metrics that are discussed and refined within the astrobiology community. This includes concepts like biosignature assemblages (Mustard et al. 2013), the Ladder of Life Detection (Neveu et al. 2018), and nested astrobiological approaches to deciphering the preservation of biosignatures and the presence of life (Chan et al. 2019).

The committee endorses a “decision tree” approach, where the next set of measurements is dynamically defined based on the results from previous measurements (see Box 1-1). The search for life cannot return a definitive “no,” but only a spectrum from “no evidence yet” to higher levels of evidence, and—as humans have wished for centuries—the possible answer of yes, there is life on Mars.

If evidence of life were discovered, any information gained on the surface about the nature of the purported martian life would be most helpful in dealing with the returned samples, and the astronauts would need a detailed search plan prepared in advance. Community efforts to communicate issues of life detection could emphasize the uncertainty of interpretations to different audiences (Green et al. 2021).

2.2.2 Life: Habitability

Part of astrobiology is exploring new conditions under which life can exist and thrive. Mars offers the closest and most accessible means of exploring whether life can exist in a substantially different way than it does on Earth. Habitability is defined as environments or conditions where life could persist. Habitability can also be viewed as a matter of degree, to differentiate between conditions where life merely persists versus where life thrives or is most likely to be found in abundance. The report An Astrobiology Strategy for the Search for Life in the Universe (NASEM 2019) also defined the concept of “dynamic habitability,” which refers to the changing degree of habitability of a planet over time. This is particularly important for Mars because its climate has changed dramatically in the past 4 billion years from its warmer and wetter past to the cold and dry present.

TABLE 2-1 Scientific Themes and Prioritized Science Objectives

The geologic record on Mars contains evidence of martian environments and their evolution. The framework for correlating specific events or transitions that are widely separated across time and space (e.g., impacts, volcanism, and sedimentary resurfacing) is created by establishing local and regional stratigraphic relationships, constrained by estimated timelines derived from crater densities and/or radiometrically dated samples. By incorporating observations of morphological, textural, spectral, and chemical properties at well-selected sites, an emerging stratigraphic context can be used to develop working hypotheses about the global environmental evolution of the entire planet through time.

2.2.3 Climate: Weather, Processes, and History

Measurements of the present-day atmospheric state and processes, in concert with measurements of solar radiation, are needed to understand the present climate of Mars. Profiling near-surface atmospheric water vapor and its exchange with the upper regolith is important for determining the sources and sinks of atmospheric water and their role in the transport of water across the planet. Similar measurements are also needed for CO₂ and other volatiles such as CH₄.

Atmospheric effects that still need to be better understood include physical weathering and material transport, planetary temperature variations, chemical weathering, mineral formation, and their impact on habitability. Interactions of the atmosphere with sand, dust, exposed bedrock, and the shallow subsurface form archives of past climate and geologic processes that can be studied (e.g., polar layered deposits, ice cores, and layered rock strata) to understand the past climate of Mars (Figure 2-5). Both the atmosphere and the rock record hold information on the past and present radiation environment of Mars.

2.2.4 Human Experience and Habitation

The “human exploration system” on the martian surface will consist of living components (plants, microbes, and animals, including humans), the inhabited environment (lander, habitat, rover, extravehicular activity suit, and launch vehicle), and systems operated by the crew (e.g., in situ resource utilization payloads). It is undeniable that the function of this human exploration system will determine overall mission success. Consequently, an overarching goal is to improve its performance to increase science return.

As stated in Section 1.1, maintaining the health and safety of the crew is an inviolate expectation for any human space mission. Meeting this requirement when the continuity of medical care is broken by time and

distance poses special challenges for Mars. The enhancements in medical capabilities that will be required during Mars transit and surface operations pose a formidable challenge for health professionals that is beyond this committee’s remit.

From a human factors perspective, the development and validation of new methods to monitor and maintain human physical and behavioral performance is necessary translational research that can and needs to be part of Mars science campaigns. Hardware reliability overall needs be a mission priority, including considerations of redundancy, repairability, and early warning, with particular focus on systems critical for health and human safety.

The complexity, dynamism, and uniqueness of the human exploration system is characterized collectively as the integrated longitudinal martian environment. It includes environmental stressors such as dust, radiation, diurnal cycles, and psychosocial factors such as isolation, task difficulty, and team cohesion, whose potential impact is individual, interactive, longitudinal, and cumulative. The resultant strain disturbs allostasis and will affect crew health and performance on Mars and potentially long after return.¹ Therefore, developing effective primary and secondary strategies to optimize the human exploration system in response to those demands is a cross-cutting theme and a long-term goal for planetary exploration. For more information on implementation during early missions, see Section 3.2, “Common Biological and Physical Sciences in Space and Human Factors Requirements for All Campaigns.”

2.2.5 Enabling Future Missions

All new knowledge of martian environmental conditions, including the existence of water and carbon dioxide, temperatures, winds, dust, and many others under the themes of Life: Past and Present, Life: Habitability, and

To manage risks from acute, chronic, and nuclear technology radiation exposure, NASA adopts the “as low as reasonably achievable” principle (Francisco 2023). Short-term radiation exposure to solar particle events is limited to an effective dose of 250 mSv per event to minimize acute effects. Total career effective radiation dose is not to exceed 600 mSv, regardless of age and sex. These limits are based on an increased likelihood of cancer-related radiation exposure–induced death above an estimated population baseline level, which is currently set at 3 percent greater than the mean—comparable to lifestyle effects such as physical inactivity and smoking (NASEM 2021; OCHMO 2022).

Direct quantification of the radiation environment in deep space and on the martian surface has helped reduce uncertainty about the absorbed radiation dose that humans will receive on Mars. Galactic cosmic rays would produce an average dose-equivalent rate of 1.84 mSv/day in deep space and 0.64 mSv/day at the surface of Mars (Zeitlin et al. 2013; Hassler et al. 2014). Solar energetic particle events, however, are highly variable, and could inflict a dose-equivalent of 1.2–19.5 mSv/event in deep space and of 0.025 mSv/event on Mars (Hassler et al. 2014).

The Radiation Assessment Detector (RAD) on the Mars Science Laboratory mission has continuously measured the most energetic part of the deep-space radiation field within the spacecraft during the cruise and surface phases of the mission since Curiosity’s landing in August 2012 and confirms for this time period the more general numbers given above. RAD data indicate dose equivalent on the order of 1–2 mSv/day in deep space and 0.3–0.9 mSv/day on the surface of Mars (Guo et al. 2021). These data have been essential to inform models to predict radiation risks for future Mars missions; however, total radiation dosages will need to be characterized over an entire solar cycle to be more comprehensive and predictive.

Recent efforts to improve radiation risk assessment for human missions use a multimodal ensemble framework (Simonsen and Slaba 2020) to integrate research data from interrelated sources with the aim to characterize crew exposure during all phases of a mission and estimate biological effects (both cancer and noncancer) of particles at the whole-body and tissue levels.

As illustrated in Figure 2-6, cumulative dose estimates for a 30-day surface campaign and total mission duration of 870–1250 days range from about 685 mSv to >1,700 mSv, depending on the trajectory (Simonsen 2024).

These exposure levels fall well outside the existing base of human spaceflight and exceed the current career limit of 600 mSv. As previously stated in Space Radiation and Astronaut Health, “Unless technological advancements and engineering controls provide improved radiation shielding or other protections to astronauts, for a mission to Mars to proceed, NASA would need to seek waivers to the radiation health standard both for the mission and for each astronaut” (NASEM 2021).

Current knowledge gaps include characterization of neutron spectrum dosimetry ranges, risk characterization between average cumulative doses on the International Space Station (ISS) (~300 mSv) and potential Mars exposures (>1200 mSv), estimation of relative biological effect (e.g., cancer, cardiovascular, cognitive) for exotic parts of the radiation spectrum, understanding interactions of particles with their immediate and nearby surroundings (regolith, spacecraft, and tissues), determination of the effectiveness of shielding strategies, and improving forecasting of infrequent solar particle events (Simonsen 2024). Consequently, the Panel on Biological and Physical Sciences and Human Factors prioritized validating advanced passive and active dosimeters to measure dose rate and composition of the radiation field, understanding stochastic and deterministic radiation effects in plants, animals, and humans, and validating risk biomarkers such as DNA damage, oxidative stress, and inflammation.

Human–Agent Teaming

An operational goal of any expedition is to maximize both the quality and quantity of science that can be successfully completed. These metrics vitally depend on human factors in a human-tended mission, whereas in a robotic mission they do not.

Human operations on a planetary body as remote as Mars will require a different cadence than operations in low Earth orbit (LEO) or on the Moon. At distances from Earth of ~400 km for the ISS in LEO and ~400,000 km for the Moon, both are relatively close; thus, humans can be assisted by mission controllers and investigators. Uploads and downloads are frequent; verbal communication approximates normal conversation but is impaired by the one-way time delay of 1.28 seconds to the Moon. In contrast, Mars averages 225,000,000 km from Earth—three orders of magnitude greater than the distance from the Moon. One-way communication delays can be as great as 22 minutes, hampering regular communication. Thus, a higher degree of crew self-sufficiency will be required than is typical of current space operations, relying heavily on collaboration and coordination among human crew and constructed assistants.

Human–agent teaming refers to the collaborative effort between one or more humans and artificial agents² to achieve common goals (O’Neill et al. 2022). It is distinct from “autonomy,” where software and hardware operate independently of crew expertise or decision making. The abilities of each agent, whether they are robotic or human, vary in how they gather information from the environment, evaluate feedback, learn new patterns, and develop meaningful verbal and nonverbal responses (Meimandi et al. 2023).

While future martian explorer-scientists will likely carry large compendiums of human knowledge, if this information is not in an easily accessible form, its utility will be limited. Human–agent teaming utilizes concepts from diverse fields such as psychology, human factors engineering, cognitive sciences, neuroscience, computer science, and robotics to enable crew autonomy far from Earth. Functional capabilities that offload routine science and mission management tasks such as science sample processing and data analysis from humans can enable crew members to reallocate time and expertise, improving situational awareness for more complex and independent tasks such as field geology, hypothesis evolution when novel findings require follow-up, and search-and-rescue operations.

Rapid advances in artificial intelligence (AI) and machine learning hold promise for a larger role of artificial agents in human–agent teaming. However, human operators working alongside AI frequently encounter partners who excel in certain areas but lack fundamental skills in others (Dellermann et al. 2019). AI requires extensive machine learning based on large, well-established, carefully curated, and ecologically relevant training sets. Better definition of the surface activities on Mars will be needed so that AI agents can be appropriately trained

The impact of this type of research is twofold: First, it provides granular insight into the psychosocial and biomedical performance of the crew, which is valuable to mission designers and planners. This consideration is captured in Science Objective 4. Second, it offers the public a window into life on Mars similar to the way ISS astronauts share their lives on social media today. The need to capture, summarize, and understand the impact of Mars landings on human behavior and social dynamics in an increasingly connected world is recognized in the “inspiration” pillar underpinning NASA’s Moon to Mars Architecture (NASA 2025b). The intrinsic value of social science as one of the three branches of science (along with physical and life science) is that it brings rigor to the study of enigmatic topics such as inspiration (e.g., Thrash et al. 2014).

Finding: The committee notes that social science is not included as a scientific domain in NASA’s Moon to Mars strategy. However, some mission-critical aspects of social science are captured in crew health and performance objectives.

Conclusion: The first human landings on Mars will cause some of the largest individual, societal, and ethnographic impacts on humanity in modern history. These impacts will be a rich area for scientific research, and NASA’s Moon to Mars Strategy and Objectives could be expanded to better include this research area both for the astronauts on Mars and for the inspirational impacts on humanity more broadly.

2.3 ASSUMPTIONS AND CAVEATS FOR CAMPAIGN PLANNING

In the time between completion of this study and the first human Mars campaign, a wide range of technical advances are possible. To create the campaigns presented in this report, the committee adopts certain bounding assumptions while simultaneously attempting to present the boldest and clearest vision possible. This section presents the assumptions and caveats used in all campaigns. Additional assumptions and caveats specific to a particular campaign scenario are detailed within that scenario’s section.

2.3.1 Crew Size and Utilization

Estimating the crew size needed to implement science investigations depends upon a detailed knowledge of the tasks and time needed to achieve the science, which is a complex issue relying in part upon technologies that have yet to be developed (Stuster et al. 2019). In Chapter 3, each campaign outlines the role of the crew and how that role impacts possible crew size estimates. The number of crew members was not a factor in the committee’s prioritization of science objectives; rather the science objectives drive the estimates of crew size for each campaign. Generally, crewed missions will have lower utilization fractions (the portion of the sol available for science work activity) than robotic missions because humans sleep, eat, and perform other mission-relevant tasks that are not science objectives (NASA 2021a, 2021b; Stromgren et al. 2022). However, there are sophisticated science tasks that only humans can complete, or that humans can complete far more effectively than robots.

Estimating the hours needed for humans to complete the science outlined in these proposed campaigns is not yet possible for missions that will occur many years in the future. The campaigns do distinguish between what can be done in 30 days versus 300 days on the surface, but parsing time into individual labor hours is beyond the scope of this report. Currently, astronauts are estimated to spend about 20 percent of each sol performing science tasks (HEOMD 2022). This value is consistent with utilization fractions of 5–20 percent empirically recorded on previous space missions (Mattfeld et al. 2015) and on polar expeditions (Hoffman 2012; Lee 2015).

The fraction of time available for science may change, but far more uncertainty surrounds how many hours doing the science itself would take. The demands of science tasks depend upon the instruments being used (which are beyond the scope of this report); the integration of automation, artificial intelligence, and robotic assistance; the amount of training that has occurred; the nature of the landscape; and many more variables. Appendix J contains detailed distinctions for science that must be done on the surface versus what can be done back on Earth using returned samples. As tasks and equipment grow in complexity and scope, so too will the demand on crew time for maintenance and repair (Stuster et al. 2019).

Between this report and the launch of the missions, significant time has to be spent on determining exactly how the science will be achieved, calculating the necessary time allocation, and reconciling these calculations with the mission plan. This iterative process will necessarily result in changing the exact science measurements performed. Table 3-1 provides examples of measurements that could achieve science objectives acceptably, better, or best to guide these decisions.

2.3.2 Landing Sites and Exploration Zones for Science Objectives

NASA’s First Landing Sites/Exploration Zones (LS/EZ) Workshop for Human Missions to the Surface of Mars, held in Houston, Texas, in October 2015, provided constraints in latitude and elevation where humans could land on Mars (Figure 2-7). Latitudes greater than 50°N or 50°S were excluded, as well as terrain at elevations greater than 2 km. This meant that Mars’s polar regions and their polar layered deposits, for instance, were off limits. An exploration zone was defined as a 100-km-radius area surrounding a landing site, accessible via some mobility solution.

Such mission constraints reflected specific assumptions about logistical, engineering, and operational capabilities that the current study was instructed to ignore. The current study was also instructed to not propose or consider any specific landing site or exploration zone on Mars.

Instead, LSs and EZs are characterized only by the set of scientific criteria that need to be met to optimally address science priorities, depending on the campaign scenario considered. The committee used its own experience, that of the panels, and published results to inform its recommendations, and all campaigns proposed here are believed to have suitable landing sites on Mars available in which to carry them out. The Moon to Mars community is already planning workshops for determining landing sites, and these workshops will provide information for architectural and technological investment decisions.

Science Objective 1: Determine if, in the exploration zone, evidence can be found for any of the following: habitability, indigenous extant or extinct life, and/or indigenous prebiotic chemistry.

Science Objective 1 addresses broadly the search for signs of indigenous life on Mars, via four possible lines of evidence: (1) habitability, past or present; (2) extant life; (3) extinct life; and (4) prebiotic chemistry, past or present.

All four lines of evidence may be pursued simultaneously only at an LS/EZ allowing access to present water and ideally also to a record, as extensive and diverse as possible, of past aqueous activity, including cycles thereof. Organics as remnants of life would be better preserved in ice; however, extant life would be better found in a habitable environment, e.g., with liquid water. Liquid water can lead to hydrolysis of organics, and sampling ice reduces the risks of uncontrolled forward or backward contamination of a water reservoir (see Section 2.3.4 for additional discussion of planetary protection). Liquid water on or near the surface of Mars today is expected to be found mainly in the form of brines, including perchlorate-rich brines (Martinez et al. 2013; Fischer et al. 2014; Renno et al. 2021), which could limit but not preclude the possibility of extant life (Trüper and Galinski 1986; Murray et al. 2012). Deep subsurface aqueous environments may be a desirable setting to search for extant life and are expected to be encountered at depths of 2–5 km at low- to mid-latitudes (Clifford 1993; Wright et al. 2024).

Water ice might serve as a transient habitat for life and/or could capture a record of extant or ancient life deposited on ice as dust, snow, or ejecta from distant impacts. Beyond water ice, additional locally accessible habitable niches (e.g., caves, gullies, light-toned deposits, mud volcanoes, recurrent slope linear, salt deposits) could be sampled for evidence of extant life.

Ancient sedimentary rocks could also be sampled for evidence of ancient life (MEPAG E2E-iSAG 2011; Beaty et al. 2019). A record of indigenous prebiotic chemistry might also be found in ancient (Noachian) rocks having experienced only limited alteration or in settings showing hydrothermal redox gradients implying different degrees of heating. Signatures of recent prebiotic chemistry might also be found. However, while important to characterize, organics associated with recent indigenous prebiotic chemistry would have to be distinguished from meteoritic organics.

Science Objective 2: Characterize past and present water and CO₂ cycles and reservoirs within the exploration zone to understand their evolution.

Present atmosphere–surface exchanges of these volatiles occur continuously while being modulated daily, seasonally, annually, and on obliquity variation and geological timescales everywhere on Mars, so the characterization of ongoing volatile cycling may be considered, to first order, landing site agnostic. Past exchanges, however, are best recorded in the geologic record. Among options for the latter, Mars’s present repositories of water and/or CO₂ ices may be considered the highest priority, as they would allow bridging the gap between ongoing volatile cycles and those of the past, albeit the geologically recent past.

Although polar layered deposits are expected to present the best preserved and most comprehensive records of recent to ongoing water and CO₂ cycling on Mars, they are not considered optimal for addressing Science Objective 1. Instead, a suitable alternative for addressing Science Objective 2 would be a layered glacier water ice deposit located at lower latitude.

Science Objective 3: Characterize and map the geologic record and potential niche habitats within the exploration zone to reveal Mars’s evolution and to provide geologic context to other investigations, including the study of bolide impacts, volcanic and intrusive igneous activity, the sedimentary record, landforms, and volatiles, including liquids and ices.

Science Objective 3 entails revealing Mars’s impact, volcanic and/or igneous, sedimentary, and environmental evolution by investigating the geologic record and potential niche habitats in the EZ. A niche habitat is an organism’s functional role within an environment reflecting both habitability and available resources. For example, two microbes in a habitable environment may each be able to grow and reproduce but may specialize in their resource utilization, metabolism, spatial distribution (e.g., in microenvironments), or temporal dynamics driven by available resources, competition, and interactions. Meeting this objective means that the selected LS/EZ has to present diverse geology, allowing examination and near-surface sampling of a suite of geologic materials and their geochemically altered or degraded products, to include multiple impact, volcanic and igneous, and sedimentary units spanning ideally a maximum swath of Mars’s history. An LS/EZ presenting contrasting environments exhibiting different degrees of degradation is important to allow relatively pristine and degraded materials from different times to be sampled and compared, and to help reconstruct environmental evolution. Comparisons between ancient (>3.5 billion years and recent lavas may for instance indicate changes in Mars’s radiation environment, which in turn may reveal when Mars’s magnetic field decayed.

Characterizing potential niche habitats and Mars’s environmental evolution requires access to, and sampling of, a geologic record ideally reflecting multiple past and/or present water activity within the EZ as well. To complement the characterization of Mars’s environmental evolution, aeolian deposits (dust bowls and sand dunes) which may incorporate materials having originated within or beyond the EZ would be important to access and sample also, although less dusty settings are better for rock exposure and multispectral mapping. Understanding Mars’s geologic and environmental evolution is also key to providing context for other campaign science objectives.

Science Objective 4: Determine the longitudinal impact of the integrated martian environment on crew physiological, cognitive, and emotional health, including team dynamics, and confirm effectiveness of countermeasures.

Science Objective 4 would be carried out for any mission regardless of location.

Science Objective 5: Determine what controls the onset and evolution of major dust storms, which dominate present-day atmospheric variability.

Science Objective 5 does not require selecting an LS in an area where major dust storms originate, but the EZ would be required to give access to an area known to frequently experience the passage of dust storms (e.g., Wang

However, while muons do penetrate deeply, the dose they deliver is lower than other forms of ionizing radiation except at depths below 10–15 m, where other forms of radiation do not penetrate. Because the dose at 10 m is quite low, the muon dose is ignored in some studies (Charpentier et al. 2024). Indeed, muon doses can be ignored beneath 10 m for the purposes of organic survival when background radiation (e.g., radioactive isotopes in bedrock, potassium-40 in salts) is taken into consideration (see also Section 2.2.6).

Sampling Depth to Preserved Organics

Amino acids are the building blocks of proteins. Amino acids are a common target for astrobiological investigation owing to their widespread abiotic production in space and planetary systems, their persistence over millions to billions of years, their use in all known life as the basis for metabolic machinery, and their potential use by life beyond Earth in a similar capacity. For example, the Murchison meteorite is rich in amino acids despite its age of 4.6 billion years, including some of the same amino acids used by life (see, e.g., Cronin et al. 1981; Koga and Naraoka 2017). It also contains many diverse amino acids not found in life. The astrobiology community has proposed measuring amino acid abundance, chirality (handedness), and complexity as ways to distinguish organic material derived from life as opposed to abiotic processes. Therefore, measuring amino acids is useful both to characterize the abiotic background and to seek evidence of life.

Radiation, however, damages organic molecules such as amino acids and obscures their origin and history. Recent work with meteoritic amino acids using gamma irradiation as an analog of space radiation demonstrated limited amino acid survival near the surface. Degradation was enhanced by the presence of silica and even more by the presence of 1 percent perchlorates (Pavlov et al. 2022). After 80 Ma in a silica matrix, none of the amino acid isovaline would still exist at the surface, and only 40–60 percent of the original concentration at 2 m depth. After an exposure time of 500 Ma, only one part in 10³ to 10⁵ would remain at 2 m depth under the studied conditions. Thus, even the planned Rosalind Franklin Rover (ExoMars) may be unable to sample deep enough to recover undamaged amino acids unless under ideal conditions (low exposure age, specific preservation conditions).

Pavlov et al. (2022) estimate that an original ~100 ppb of amino acids (a number based on martian meteorite analysis) would have been reduced to 0.1 ppb in 70 Ma of exposure at Mars Sample Return sample depths, below the detection limits of the best liquid chromatography mass spectrometry methods on Earth. Therefore, sampling needs to be done at significantly greater depths than 2 m to reduce degradation by the orders of magnitude needed for meaningful analysis; to abrogate the impact of space radiation on radiolysis of organics entirely, depths greater than 10 m may be needed.

The presence of diverse amino acids in Murchison and other meteorites might be taken to imply that at least some amino acids can survive space radiation for billions of years. However, there are several important caveats: most meteorites are derived from a few recent collisions in the asteroid belt (Broz et al. 2024), and organic-rich CM/CI meteorites typically have exposure ages of 7 Ma or less (Takenouchi et al. 2014). Samples collected from the surfaces of asteroids can have low exposure ages (e.g., 0–10 Ma) owing to impact gardening of asteroid surfaces (Matsuoka et al. 2023) and selection of young sites such as craters (Welten et al. 2024).

Although the prior text focuses on amino acids, a few words about nucleic acids are warranted. The first-order decay kinetics of DNA are affected by temperature (which affects the rates of hydrolysis) and other in situ characteristics such as pH (Allentoft et al. 2012). While DNA has been recovered from ice dated to ~8 million years old in Beacon Valley on Earth (Bidle et al. 2007), modeling of the soil and ice-rich permafrost suggests seasonal maximum temperatures would permit partial melt of liquid veins in ice and permit microbial activity. This may explain why the oldest DNA sequenced on Earth is widely considered to be 2 million years old, obtained from marine sediments in Greenland (Kjaer et al. 2022), whose clay component is likely to have aided preservation by inhibiting enzymatic degradation for mineral-bound DNA.

While there is no expectation of recovery of DNA beyond many millions of years on Earth, Mars’s significantly colder temperatures could extend DNA’s potential survival; natural radioactivity may ultimately be the limitation on DNA survival. Studies of the synergistic effects of desiccation and freezing on microbial survival to irradiation (Horne et al. 2022) suggest that at greater than 10 m depth on Mars, the extremophile Deinococcus radiodurans could survive an equivalent of more than 100 million years. Life in the near subsurface of Mars could therefore

The United States is a signatory to the treaty. Specific operating principles and requirements are regulated by national space agencies, including NASA (Figure 2-9).

Within NASA, the Office of Planetary Protection oversees planetary protection from within the Office of Safety and Mission Assurance. Current rules are governed by NASA Procedural Requirements 8715.24, Planetary Protection Provisions for Robotic Extraterrestrial Missions, and NASA Interim Directive 8715.129, Biological Planetary Protection for Human Missions to Mars; this Interim Directive expired on September 30, 2025 (Benardini 2025).

The COSPAR guidelines (March 20, 2024) state that “planetary protection goals should not be relaxed to accommodate a human mission to Mars” but recognize that specific implementation guidelines will be different (COSPAR 2024; Spry et al. 2024).³ However, one of the accompanying guidelines states: “Neither robotic systems nor human activities should contaminate Special Regions on Mars, as defined by this Committee on Space Research (COSPAR) policy” (NASEM 2018a, p. 29). “Special Regions” are defined as locations on Mars that might possibly harbor indigenous martian life or terrestrial life brought there by astronauts or otherwise. At present, there are only candidate Special Regions. With current human exploration system capabilities, this guideline would essentially preclude responding to the top scientific objective identified by this committee, which is to search for life. However, ways to meet these guidelines have been suggested, for example (NASA 2005, 2025c) and further technology development and operational assessment could help to quantify and reduce forward contamination risks while preserving the

scientific integrity of studies in Special Regions. The risks of contamination will never be zero, and, as a result, it is important to develop explicit plans to address this contingency. As highlighted in Section 5.2.1, human–robotic partnerships for remotely operated science could reduce human impact in Special Regions, where needed.

Special Regions on Mars are also relevant to the possibility of backward contamination, that is, bringing martian organisms back to Earth. Minimizing the chance of backward contamination is a key goal of planetary protection policy. No policy could entirely eliminate the possibility of backward contamination, but visiting Special Regions with astronauts would clearly increase it. However, not visiting Special Regions would also minimize or eliminate the chance of finding extant martian life. This committee does not presume to have the authority to resolve this debate: the committee instead points out that it needs to be well studied before any crewed Mars missions are launched, or even completely planned. One factor reducing the chance of backward contamination, as compared to the Apollo missions to the Moon, is the much longer return time: 6 months, as opposed to 3 days. This gives the crew more time to better understand the potential for backward contamination through collaboration with Earth-based researchers and crew-performed onboard analysis. Backward contamination remains a more serious concern for Mars than it was for the Moon, as by almost any measure Mars is more likely to be inhabited.

Planetary protection guidelines have a dual purpose. They protect both the integrity of scientific measurements and human health. While many life-detection methods are sensitive to potential Earth contamination, others are unlikely to be affected; for example, DNA sequencing can identify known Earth contaminants by comparison with controls and databases of known organisms and likely contaminants. Metagenomic studies of low-biomass environments need to address contaminants owing to a wide range of contaminant sources including personnel and reagents used in sample processing. Current best practices integrate positive and negative controls at multiple stages to identify potential contaminants, alongside screening of sequencing data for contamination (Fierer et al. 2025).

Planetary protection guidelines are dynamic, not static, and are modified as knowledge grows. As the community continues to learn about mechanisms of organism death, dispersal, and reproductive potential or lack thereof, as well as transport phenomena in the martian atmosphere and subsurface, there needs to be continuing community dialogue. Improved knowledge about interactions of environmental challenges including vacuum, solar

Omics—referring to a group of sciences that study entire sets of biological molecules to understand their roles in an organism’s structure, function, and dynamics (examples are genomics, proteomics, transcriptomics, and metabolomics)—approaches have widespread biological applications such as diagnosis of genetic diseases, molecular stratification of disease risk, identification of environmental pathogens, elucidating the molecular basis of organismal response and adaptation to spaceflight (microbes, plants, and animals), and population metagenomics.

Typical workflows for nucleic acids require extraction, quality control steps, library preparation, sequencing, and data analysis (Figure 2-10). Other omics often require extraction, enzymatic digestion, separation and analysis (typically using mass spectrometry), and subsequent bioinformatic data analysis. The capabilities to utilize these methods in real time in spaceflight environments (i.e., “point-of-care” applications) are evolving rapidly, particularly because of small (palm-size), low-power devices (for example, nanopore sequencing, which eliminates the requirement for polymerase chain reaction amplification). The feasibility of onboard real-time genetic analysis has been demonstrated on the ISS (Castro-Wallace et al. 2017), as have robust workflows for real-time microbial profiling (Stahl-Rommel et al. 2021). Successful nanopore sequencing has also been demonstrated under martian gravity conditions (Carr et al. 2020).

Such capabilities need not replicate the complete range of terrestrial facilities but can be focused to provide analyses needed for time-sensitive measurements and those needed to decide on next steps in a decision tree. Maturation of these tools offers an opportunity for cross-field development of Mars analytical capabilities. Advancements in computational capabilities to support these tools will also enhance the ability to conduct sophisticated bioinformatic and other computational analyses on the surface.

2.3.6 Mars Sample Return from Crewed Missions

Return of martian samples and biological specimens collected from crew, model organisms, and the built environment is important for the advancement of human knowledge. Samples that might contain evidence of extinct or extant life are a unique case that could answer one of the greatest questions facing humanity—“Are we alone?”—and thus will be among the most valuable.

Skilled humans on Mars will be able to understand the landscape and its rocky materials better than any remotely operated robot (e.g., Yingst et al. 2009; Antonenko et al. 2013) and will be able to conduct real-time analysis and prioritize sample collection much faster than any robotic system (Glass 2013; Cohen et al. 2015). Thus, human explorers are essential for the best possible sample selection and contextual understanding at the martian surface.

Similarly, experts on Earth are needed for the most comprehensive sample analysis. Although longer-stay missions will have more time for analysis on the martian surface, the needs for Earth-based specialist expertise, better Earth instrumentation, and multiple laboratories necessitate the return of samples. For example, biological techniques such as single-cell spatial analysis (DNA, mRNA, or protein), which provide positional context of cells in an organism, require sample preparation and processing (e.g., fixation, sectioning, imaging, microdissection, and in situ hybridization and sequencing) that are time and labor intensive.

Measurements utilizing phase-specific stable and radiogenic isotopes, trace elements, nanometer-scale composition and texture, and precise organics characterization cannot be done remotely or entirely on Mars because they require sample preparations and analytical precisions only possible in specialized laboratories (NRC 2011; NASEM 2023a). The infrastructure supporting such facilities represents a required complexity on Earth that is currently impractical for early Mars missions.

Beyond the initial complex measurements, divergent scientific interpretations will require measurements in multiple laboratories and interpretation by multiple research groups. Replication of results similarly requires multiple analyses in different laboratories. The extensive analyses performed on EET 84001 (Righter 2024) and planned measurements for the Mars Sample Return mission (Beaty et al. 2019; Whetsel et al. 2025) are examples of the scientific need for materials to be analyzed by multiple techniques and multiple groups, simultaneously solving questions and creating new avenues of inquiry.

Curating samples for future analysis—a standard practice—begins at the moment of collection. Documenting context is crucial, as is any required specific pretreatment (e.g., stabilization and fixation) and storage conditions (e.g., temperature, pressure, and atmospheric composition) to preserve detail at the molecular level. Last, sample return will allow for future analyses by instruments and techniques not yet in existence, as has recently been demonstrated with curated Apollo samples.

Conclusion: Sample masses of the order of tens of kilograms are desired for a wide range of dissimilar analysis by independent groups, but the exact amount depends on the science objectives and evolving analytical techniques. This estimate also includes the need for duplicate samples for long-term archiving and to be shared for education and public outreach purposes.

Recommendation: Samples from every human mission to Mars should be returned to Earth. NASA should engage the science community to determine the number, type, mass, and environmental conditioning required for samples before the first human missions commence. Sample return guided by human interpretation of in situ measurements should be a priority for all human missions.

2.4 ENABLING TECHNOLOGIES

Technologies required to enable human science exploration fall into two categories: technologies needed for long human surface stays, and technologies to better enable the science discovery, as referenced in panel STMs to enhance science return in any of the architectures or campaigns. Discussion of certain enabling technologies is