Key Takeaways
- Life search tops priority list for Mars missions.
- Three-mission campaigns maximize scientific return.
- Human-robotic teams enable adaptive exploration.
Introduction
The release of A Science Strategy for the Human Exploration of Mars by the National Academies of Sciences, Engineering, and Medicine marks a pivotal moment in the planning of future space exploration. This consensus study report, commissioned by NASA, articulates a comprehensive vision for the scientific value of sending humans to the Red Planet. It asserts that the primary motivation for such an endeavor must be scientific discovery, specifically the search for life and the understanding of planetary evolution. The report represents the collective expertise of leading scientists and engineers who have evaluated the current state of knowledge and identified the most pressing questions that only human explorers can answer.
Humanity stands at the threshold of a new era. After decades of robotic exploration which has fundamentally altered our understanding of Mars – revealing a world that was once wet and potentially habitable – the next logical step involves the direct presence of human scientists on the surface. Robots have been essential pathfinders, mapping the planet and analyzing its surface chemistry, but they face inherent limitations in mobility, decision-making, and sample handling. Humans possess the cognitive flexibility to recognize the unexpected, the dexterity to manipulate complex tools in real-time, and the ability to traverse difficult terrain that would trap a rover. The strategy outlined in this report leverages these unique human capabilities to accelerate scientific discovery by orders of magnitude.
The report focuses on the first three human landings, defining them not as isolated sorties but as a cohesive “campaign” designed to build up infrastructure and scientific capacity over time. This approach recognizes that the cost and risk of human spaceflight require a high return on investment, measured in scientific knowledge. The strategy integrates inputs from four specialized panels – Astrobiology, Atmospheric Science and Space Physics, Biological and Physical Sciences in Space and Human Factors, and Geosciences – to create a unified roadmap. This roadmap does not merely list objectives; it proposes specific mission architectures, or “campaigns,” that optimize the balance between scientific breadth and depth.
Central to this strategy is the concept of “discovery-driven” science. Unlike robotic missions, which often follow a pre-determined sequence of commands, human missions must be designed to adapt. If a crew finds a potential biosignature on the first day of a mission, the schedule for the remaining days must be flexible enough to allow for immediate, detailed follow-up. This adaptability requires a fundamental shift in how missions are planned and executed, moving away from rigid timelines toward a capability-driven approach that empowers the crew to act as autonomous scientists.
The Priority of Science: Eleven Objectives
The committee identified eleven high-priority science objectives that should guide the human exploration of Mars. These objectives were ranked based on their scientific importance and the degree to which human presence aids in their achievement.
1. Search for Life and Habitability
The unequivocal top priority is to determine if evidence of habitability, indigenous extant (living) or extinct life, or prebiotic chemistry exists within the exploration zone. This objective is the primary driver for landing site selection and mission design. The search encompasses two distinct possibilities: finding ancient fossilized life in sedimentary rocks, similar to the mission of the Perseverance rover, or finding extant life in subsurface aquifers or ice deposits.
The strategy emphasizes that searching for extant life requires accessing environments that are protected from the harsh surface radiation and oxidizing conditions. This implies a need for deep drilling capabilities to reach liquid water tables that may exist kilometers below the surface. The detection of life would be a singular event in human history, fundamentally changing our understanding of the universe. Consequently, the report places this objective above all others, arguing that the unique capabilities of human explorers – specifically their ability to select samples and perform complex analyses in situ – are essential for a definitive answer.
2. Water and Carbon Dioxide Cycles
The second priority is to characterize the past and present cycles of water and carbon dioxide. These two volatiles are the master variables of the Martian climate system. Understanding their reservoirs and fluxes is essential for reconstructing the planet’s history. The report calls for investigating how these cycles have evolved over billions of years, transitioning Mars from a wet world to a dry desert.
Human explorers can contribute to this objective by drilling into polar layered deposits or mid-latitude ice sheets, which serve as climate archives similar to ice cores on Earth. By analyzing the isotopic composition of the ice and trapped gases, scientists can unravel the history of atmospheric loss and climate change. This knowledge also informs the availability of resources for future human settlement, as water ice is a critical feedstock for life support and propellant production.
3. Geologic Record and Evolution
The third objective focuses on characterizing and mapping the geologic record to reveal the planet’s evolution. Mars preserves a geological record of the early solar system that has been largely erased on Earth by plate tectonics. By studying the Martian crust, specifically its igneous and sedimentary rocks, scientists can gain insights into the processes of planetary formation and differentiation.
A key task within this objective is establishing an absolute chronology for Martian events. Currently, the ages of Martian surfaces are estimated using crater counting methods, which have significant uncertainties. Humans can collect igneous rock samples from known stratigraphic contexts for radiometric dating, which would calibrate the cratering timescale and anchor the history of the entire inner solar system. This objective also includes studying the impact of bolides (meteorites) and volcanic activity, which have shaped the surface over eons.
4. Human Health and Performance
The fourth priority addresses the “human element” directly: determining the longitudinal impact of the integrated Martian environment on crew physiological, cognitive, and emotional health. This objective recognizes that the success of the science mission depends entirely on the well-being of the explorers. The Martian environment presents a unique combination of stressors, including partial gravity (0.38 g), radiation, isolation, and confinement.
The report calls for a comprehensive research program to monitor crew health and performance throughout the mission. This includes studying the effects of isolation on team dynamics and the efficacy of countermeasures designed to mitigate physical deconditioning. Unlike missions to the International Space Station (ISS), a Mars crew will face communication delays of up to 20 minutes, requiring a high degree of autonomy and psychological resilience.
5. Dust Storm Dynamics
Determining what controls the onset and evolution of major dust storms is the fifth objective. Dust storms on Mars can grow from local events to planet-encircling tempests that obscure the surface for months. Understanding the mechanisms that trigger these storms is vital for atmospheric science and for the safety of human operations.
Dust affects atmospheric temperature, water vapor transport, and surface operations. It can block solar power generation and damage mechanical systems through abrasion. Human explorers can deploy networks of meteorological stations and use lidar (light detection and ranging) to profile the vertical structure of dust storms, providing data that orbiters cannot observe.
6. In Situ Resource Utilization (ISRU)
Characterizing the Martian environment for ISRU applications is the sixth objective. This involves identifying and mapping resources such as water ice, hydrated minerals, and atmospheric carbon dioxide that can be processed to support human habitation. The ability to produce water, oxygen, and methane propellant on Mars is a cornerstone of sustainable exploration architectures.
The report emphasizes the need to move beyond theoretical models and conduct ground-truth measurements of resource availability. This includes drilling to verify the purity and depth of ice deposits and testing extraction technologies in the actual Martian environment. Successful ISRU reduces the mass that must be launched from Earth, making long-term exploration economically feasible.
7. Biological Adaptation
The seventh objective investigates whether the Martian environment affects reproduction or the functional genome across multiple generations in model organisms. This research uses plants and small animals (like nematodes or fruit flies) to study the long-term biological effects of Martian gravity and radiation.
Understanding if terrestrial life can reproduce and thrive on Mars is a prerequisite for any concept of permanent settlement. This objective looks for subtle genetic changes or developmental abnormalities that might not be apparent in a single generation but could accumulate over time.
8. Microbial Dynamics
Determining the stability of microbial population dynamics in biological systems and habitable volumes is the eighth priority. This refers to the microbiome of the crew and their habitat. In a closed environment, the balance of microbes can shift, potentially leading to the proliferation of pathogens or the failure of biological life support systems.
Monitoring these dynamics ensures crew health and the integrity of life support functions. It also relates to planetary protection, as understanding the “human cloud” of microbes is essential for preventing the contamination of pristine Martian environments.
9. Dust Effects on Humans and Hardware
Characterizing the effects of Martian dust on human physiology and hardware is the ninth objective. Martian dust is chemically reactive, containing perchlorates and other oxidizers that can be toxic to humans if inhaled or ingested. It is also electrostatically charged and abrasive, posing a threat to seals, bearings, and spacesuits.
The report calls for detailed toxicological studies using actual Martian dust samples to establish exposure limits and mitigation strategies. This research is vital for the design of EVA (extravehicular activity) suits and habitat filtration systems.
10. Integrated Ecosystems
The tenth objective studies the impact of the Martian environment on an integrated ecosystem of plants, microbes, and animals. This extends the biological research to the community level, investigating how different species interact and support each other in a bioregenerative life support system.
This objective explores the feasibility of creating self-sustaining biological loops where plants provide food and oxygen, microbes recycle waste, and humans complete the cycle. Understanding the resilience of these ecosystems to Martian stressors is key to reducing dependence on Earth resupply.
11. Radiation Environment
The final prioritized objective is to characterize the primary and secondary radiation environment at key locations. This includes measuring the flux of galactic cosmic rays (GCRs) and solar energetic particles (SEPs) on the surface and within subsurface shelters.
Accurate radiation data is needed to validate risk models and design effective shielding. The interaction of cosmic rays with the Martian atmosphere and regolith produces secondary radiation (neutrons) that can be particularly damaging. Characterizing this environment contextualizes the biological risks and informs the interpretation of samples collected for astrobiology.
Strategic Campaigns
To operationalize these objectives, the committee developed four distinct mission campaigns. These campaigns represent different strategic approaches to exploration, varying in their architectural requirements and scientific focus. They are presented in priority order.
Campaign 1: Mars Science Across an Expanded Exploration Zone
This campaign is the highest-ranked option because it offers the most comprehensive scientific return. It utilizes the “30-Cargo-300” architecture, which consists of three landings at a single site.
- Mission 1 (30 Sols): A short-stay crewed mission to validate the landing site, conduct initial reconnaissance, and deploy preliminary instruments. This mission serves as a pathfinder, ensuring the site is safe and scientifically valuable before committing to a long stay.
- Mission 2 (Cargo): An uncrewed delivery of heavy infrastructure, including a large habitat, a pressurized rover, a power station, and advanced laboratory equipment. This mission builds the capacity for the subsequent long-duration stay.
- Mission 3 (300 Sols): A long-stay crewed mission where astronauts utilize the pre-deployed infrastructure to conduct deep and wide-ranging exploration.
Scientific Focus:
The campaign targets a site with diverse geology and accessible water ice. This allows the crew to address all eleven science objectives. They can search for life in near-surface ice, study the geologic history of the region, monitor the climate over changing seasons, and conduct long-term biological experiments. The “Expanded Exploration Zone” concept implies a operational radius of over 100 kilometers, enabled by pressurized rovers, allowing access to a variety of terrain types.
Operational Concept:
The key asset is the pressurized rover, which allows multi-day excursions away from the habitat. This mobility is essential for accessing the diverse geological units required to reconstruct the planet’s history. The campaign also prioritizes a high-capability surface laboratory, allowing the crew to perform sophisticated analyses (e.g., DNA sequencing, isotopic analysis) on site, which informs the selection of samples for return to Earth.
Campaign 2: Synergy of Mars Science Measurements
This campaign also uses the 30-Cargo-300 architecture but prioritizes the type of data collected over the specific location. It focuses on maximizing the synergy between different measurements to create a holistic view of the Martian system.
Scientific Focus:
The goal is to collect a comprehensive dataset that links surface, subsurface, and atmospheric processes. This includes deep drilling to profile the crust, tall meteorological towers to profile the boundary layer atmosphere, and extensive surface sampling. The campaign is less dependent on a specific “perfect” landing site and more focused on deploying a powerful suite of instruments that can generate value anywhere.
Operational Concept:
The cargo mission delivers heavy drilling equipment capable of reaching depths of 1 kilometer or more, along with a tall (30+ meter) meteorological mast. The 300-sol crew focuses on vertical profiling – studying the atmosphere upwards and the crust downwards. This vertical dimension is missing from most robotic missions and provides critical data on volatile transport and subsurface stratigraphy.
Campaign 3: Seeking Life Beneath the Martian Icy Crust
This campaign is specifically designed to address the top-priority objective: the search for life. It recognizes that the best chance of finding extant life is likely deep underground, below the cryosphere where liquid water might be stable.
Scientific Focus:
The campaign targets a site where deep aquifers are suspected to exist, likely in the mid-latitudes or near the equator. The primary scientific activity is deep drilling (2 to 5 kilometers) to reach these liquid water zones. The samples retrieved from these depths would be analyzed for biosignatures, metabolic activity, and organisms.
Operational Concept:
This is a technically demanding campaign centered around a heavy drilling rig. The cargo mission would deliver the drill and the power systems needed to operate it. The 300-sol crew would be composed largely of drilling engineers and geobiologists. Their time would be dominated by drilling operations, core retrieval, and the careful handling of samples to prevent contamination. While highly focused, this campaign carries higher risk; if the deep drilling fails or the subsurface is sterile, the primary objective is lost.
Campaign 4: Investigating Mars at Three Sites
This campaign utilizes the “30-30-30” architecture. Instead of a single long stay, it involves three separate short-stay (30 sol) missions to three different landing sites.
Scientific Focus:
The goal is to explore the diversity of Mars. By visiting three distinct geologic provinces (e.g., an ancient crater, a volcanic plain, and a polar layered deposit), the campaign can address questions about global heterogeneity. It is particularly well-suited for calibrating the cratering record by collecting samples from surfaces of vastly different ages.
Operational Concept:
Each mission is a “sprint,” with the crew maximizing their time on EVA (extravehicular activity) to collect samples and deploy autonomous monitoring stations that will continue to report data after they leave. This architecture reduces the risk of a single point of failure (like a bad landing site) but sacrifices the depth of science that comes with a long-duration stay. It is less effective for biological research that requires observing multigenerational effects.
Enabling Technologies and Challenges
The execution of these campaigns requires significant technological advancements. The report identifies several key areas where current capabilities are insufficient.
Deep Drilling
Accessing the subsurface is a recurring theme in the science objectives. While current rovers scratch the surface (centimeters), the search for life and the understanding of climate history require drilling meters, or even kilometers, deep. The report highlights the need for a drill capable of reaching at least 10 meters for the Expanded Zone campaign and up to several kilometers for the Seeking Life campaign. Technologies like the “RedWater” coiled tubing drill and the “RodWell” (Rodriguez Well) for melting ice are identified as promising candidates requiring further development.
In Situ Resource Utilization (ISRU)
Living off the land is not just a convenience; it is a necessity for the “30-Cargo-300” architecture. The production of oxidizer and fuel for the return journey reduces the landed mass requirement. The extraction of water from ice or hydrated minerals supports the crew and enables the “closed-loop” life support systems envisioned for long stays. The report notes that ISRU technology must be demonstrated at a relevant scale before human missions rely on it.
Human-Agent Teaming
The strategy emphasizes that humans will not work alone. They will be part of integrated teams involving robots and artificial intelligence (AI) agents. “Human-Agent Teaming” is distinct from simple automation; it implies a collaborative relationship where the AI system can anticipate crew needs, manage routine tasks, and even participate in scientific decision-making. The report recommends establishing a recurring summit to advance this field, ensuring that the cognitive load on astronauts is managed effectively.
Planetary Protection
Perhaps the most significant non-technical challenge is planetary protection – the prevention of forward contamination (bringing Earth microbes to Mars) and backward contamination (bringing Martian microbes to Earth). The report acknowledges a fundamental conflict: the regions most likely to harbor life (“Special Regions”) are also the regions where human presence is most scientifically valuable but most restricted by current regulations.
Humans are biologically “dirty” and cannot be sterilized like a robot. The report recommends that NASA collaborate with international bodies like COSPAR (Committee on Space Research) to evolve these guidelines. New strategies, such as zoning exploration areas or using robotic intermediaries for sampling sensitive sites, must be developed to allow human exploration while preserving the scientific integrity of the search for life.
Synergy with Moon to Mars Architecture
The Mars science strategy is explicitly linked to NASA’s broader “Moon to Mars” (M2M) architecture. This framework treats the Moon not just as a destination but as a proving ground for Mars.
The Artemis program is critical for validating technologies like life support, habitats, and spacesuits in a deep-space environment. The Lunar Gateway provides a platform for studying radiation effects and testing autonomous operations. However, the report also identifies gaps where the lunar experience is insufficient. For instance, the toxicity of Martian dust (perchlorates) is different from the abrasive nature of lunar dust, requiring specific mitigation strategies that cannot be fully tested on the Moon. Similarly, the aerodynamic entry and descent through the Martian atmosphere have no lunar analog and require specific development.
The report argues that while the Moon provides a foundation, specific investments in Mars-unique capabilities – such as deep drilling and dust mitigation – must run in parallel to avoid delays. The scientific objectives for Mars should influence the design of lunar missions, ensuring that Artemis activities yield data relevant to the future Red Planet campaigns.
Summary
The report A Science Strategy for the Human Exploration of Mars establishes a clear directive: science must lead the way. It argues that the immense effort of sending humans to Mars is justified by the potential for transformative scientific discovery. By prioritizing the search for life, the understanding of planetary evolution, and the study of human adaptation, the strategy ensures that these missions will leave a legacy of knowledge that benefits all of humanity.
The proposed campaigns offer a flexible but focused pathway forward. Whether through the depth of a long-stay mission at a single diverse site or the breadth of multiple short visits, the goal remains the same: to utilize the unique capabilities of human explorers to answer the fundamental questions of our existence. The integration of advanced technology, rigorous planetary protection, and international collaboration will be the pillars upon which this historic endeavor rests.
Appendix: Top 10 Questions Answered in This Article
What is the primary scientific goal of human missions to Mars?
The top priority is to search for evidence of life, including extant or extinct organisms, habitability, and prebiotic chemistry. This goal drives mission design and landing site selection.
Why are human explorers necessary for Mars science?
Humans possess adaptability, real-time decision-making, and dexterity that robots lack. They can perform “discovery-driven” science, rapidly changing plans based on new findings, which accelerates discovery.
What are the two main mission architectures proposed?
The report proposes a “30-Cargo-300” model (short stay followed by cargo and a long 300-sol stay) and a “30-30-30” model (three short 30-sol stays at different sites).
How does the strategy address the risk of contamination?
It recommends evolving planetary protection guidelines to balance the need for exploration with the prevention of biological contamination. This includes developing new zoning strategies and robotic partnerships.
What is the “Expanded Exploration Zone” campaign?
This is the highest-ranked campaign, involving a long-duration stay at a single, geologically diverse site with access to ice. It aims to address all eleven science objectives comprehensively.
Why is deep drilling important for Mars exploration?
Deep drilling (up to kilometers) is necessary to reach subsurface zones below the cryosphere where liquid water – and potentially extant life – may exist protected from surface conditions.
What role does the Moon play in this strategy?
The Moon serves as a testbed for technologies like life support and operations. However, the report notes that unique Mars challenges, like dust toxicity, require specific separate development.
What is “discovery-driven” science?
This is an operational approach where mission activities are not fully pre-planned but evolve based on real-time findings, leveraging the crew’s ability to react to new data immediately.
How will Martian dust affect human explorers?
Dust poses risks to health (toxicity) and hardware (abrasion). The strategy prioritizes understanding dust storm dynamics and developing mitigation technologies for crew safety.
Will samples be returned to Earth?
Yes, the report recommends returning samples from every human mission. Terrestrial laboratories are required for the high-precision analyses needed to confirm biosignatures or date rocks.
Appendix: Top 10 Frequently Searched Questions Answered in This Article
Is there life on Mars?
We do not know yet. The search for evidence of past or present life is the highest priority scientific objective for human missions outlined in the report.
How long does a trip to Mars take?
While transit times vary, the report discusses mission architectures involving surface stays of 30 days (“short stay”) and 300 days (“long stay”), plus months of travel time.
Can humans breathe on Mars?
No, the atmosphere is mostly carbon dioxide. The strategy includes In Situ Resource Utilization (ISRU) objectives to test producing oxygen from the Martian atmosphere for breathing and fuel.
What are the dangers of radiation on Mars?
Radiation from cosmic rays and solar particles is a major hazard. One of the science objectives is to characterize this environment to improve shielding and risk models for astronauts.
Will astronauts grow food on Mars?
The strategy includes objectives to study biological adaptation and integrated ecosystems, which investigates growing plants as part of bioregenerative life support systems.
What is the temperature on Mars?
Mars is very cold. The report emphasizes the need to understand the climate history and current weather patterns, including the thermal cycles that affect habitability and ice stability.
How much does a Mars mission cost?
The report does not provide a cost estimate but focuses on maximizing the scientific “return on investment” by ensuring that expensive human missions achieve high-value science goals.
Can we terraform Mars?
The report focuses on exploration and scientific study, not terraforming. It prioritizes understanding the current environment and its history rather than changing it on a planetary scale.
What is a “sol”?
A “sol” is a Martian solar day, approximately 24 hours and 39 minutes long. Mission durations in the report are often defined in sols (e.g., 30 sols, 300 sols).
Why do we need to send humans instead of just robots?
Humans can think creatively, react instantly, and perform complex tasks like deep drilling much faster than robots. They act as “force multipliers” for scientific discovery.
