Human Exploration Architecture

Why Moon and Mars: Building an Evolutionary Architecture

Explores how NASA is using an evolutionary crawl-walk-run approach to steadily build capabilities that can overcome the challenges of deep space exploration, expanding on the incremental approach the agency used to build up to the Apollo lunar landings.

Architecture Definition

Updates two previous white papers to summarize the six major questions that make up an exploration architecture and how NASA defines the Moon to Mars Architecture to answer those questions. 

Architecture-Driven Planetary Protection Considerations

Surveys NASA’s approach to planetary protection, the process by which NASA safeguards both exploration destinations and the Earth from contamination, and highlights key considerations for human missions to Mars.

Architecture-Driven Data Gaps

Introduces the new catalog of architecture-driven data gaps, areas where NASA requires additional information to achieve its exploration goals.

Integrated Lunar Power Strategy Considerations

Identifies the key factors that affect generating, storing, and sharing power on the lunar surface, a key capability as exploration expands to increasingly complex operations.

Communications and Navigation Needs for the Foundational Exploration Segment

Explains how NASA’s communications and navigation needs will expand beyond those of initial Artemis missions as it explores more of the lunar surface and undertakes increasingly ambitious activities there.

Lunar Surface Cargo

Analyzes projected needs and capability gaps for transportation of cargo to the lunar surface.

Lunar Mobility Drivers and Needs

Discusses the need to move cargo and assets on the lunar surface and factors that will significantly impact mobility systems.

Priority Science Enabled through Architecture

Surveys landmark studies that inform NASA’s science goals and how the Artemis program is realizing those goals.

Lunar Reference Frames

Offers considerations for developing an architecture that supports multiple reference frames to meet diverse positioning, navigation, and timing needs.

Mars Crew Complement Considerations

Weighs the factors, risks, and opportunities that affect how many astronauts NASA will send to the Red Planet during the first human missions.

Mars Surface Power Technology Decision

Presents NASA’s selection of nuclear fission power as the primary surface power generation technology for initial missions to Mars.

Mars Entry, Descent, and Landing Challenges

Examines the challenges of landing on the Red Planet and considerations for crewed entry, descent, and landing capabilities.

Mars Ascent Propellant Considerations

Explores the challenges of transport, or in-situ manufacture, of fuel needed to ascend to Mars orbit after a surface mission.

Architecture-Driven Technology Gaps

Explains how NASA identifies technology gaps for needed architecture capabilities and encourages innovation to close them.

Humans in Space to Accomplish Science Objectives

Describes unique capabilities of human explorers and how humans and robots can work together to maximize scientific returns.

International Partnerships

Policies, Opportunities, and Engagement: Elaborates on how NASA engages and collaborates with space agencies from around the world.

Responsible Exploration

Dives into the ethical, legal, and societal implications of space exploration and how NASA explores in the interest of all humanity.

Lunar Communications and Navigation Architecture

NASA’s return to the Moon will require reliable communications services and accurate navigation data. A network of ground stations, space relay satellites, and surface-to-surface communications equipment provided by NASA, industry, and international partners will keep Artemis astronauts connected with Earth.

Lunar Site Selection

Exactly where Artemis missions land when humans return to the Moon will depend on a wide variety of factors. Surface conditions, science objectives, the lighting environment, communications availability, system capabilities, and more can affect landing site selection.

Analytical Capabilities In-situ vs. Returned

Samples collected on the lunar surface may be analyzed by science instruments launched to the Moon or at laboratories on Earth. In-situ analysis is limited by the capabilities of instruments that can be launched to the Moon, whereas samples returned to Earth can benefit from more refined analyses. However, returning pristine samples — those kept in the environment in which they were collected — to Earth presents technological challenges.

Safe and Precise Landing at Lunar Sites

Precision lunar landings will become increasingly important as space agencies and private companies explore more of the Moon. More precise landings enhance crew safety, minimize site contamination risks, and enable missions to reach specific, scientifically significant sites.

Surface Extravehicular Activity Architectural Drivers

When humans return to the Moon, they won’t simply land — they’ll explore the lunar surface during extravehicular activities, or spacewalks. NASA and its partners will need to address the unique challenges of walking on the Moon. The lessons learned on the lunar surface will directly influence plans for crewed Mars missions.

Lunar Logistics Drivers and Needs

To support crewed missions, the missions need numerous logistics items — the equipment and supplies necessary to sustain life, maintain systems, and conduct science — supplied to the lunar surface. The composition and amount of these items vary significantly based on mission requirements.

Mars Communications Disruption and Delay

Communications blackouts and delays are unavoidable for crewed Mars missions, though blackouts can be mitigated through thoughtful design. Crewed Mars exploration must respond to the unique constraints of the Red Planet; to account for disruption and delays, system and crew autonomy must be a significant focus in mission planning.

Mars Mission Abort Considerations

Crewed Mars missions have more challenging abort factors than lunar missions due to the sheer distance from Earth. An abort in transit to Mars will take months, not days. Early Mars missions will have limited abort options from the surface.This paradigm shift will require fundamental changes in mission planning.

Mars Surface Power Generation

The first human explorers on Mars will need energy to power the systems they use to live and work on the surface and ascend back to orbit. The Martian environment poses unique challenges for generating power and power requirements will vary significantly based on mission profile. 

Round-Trip Mars Mission Mass Challenges

Round-trip Mars missions are much more difficult than one-way trips. Mars “gear ratios” are multipliers of the mass required to launch any given payload from Earth’s gravity well to Mars’ and then return it home. The mass requirements for each leg of a round-trip mission will affect mission cost, schedule, and complexity.

Human Health and Performance for Mars Missions

Astronauts on missions to Mars will face a series of interrelated risks to their health and performance, including radiation exposure, changing gravity, isolation, distance from Earth, and environmental factors on the surface. Mission architecture and equipment design should consider these risks and minimize them wherever possible.

Exploration Lessons Learned from the Space Station

The International Space Station is humanity’s testbed in low Earth orbit. The orbiting laboratory is advancing capabilities in life support, navigation, extravehicular activities, and human health. Lessons learned on the space station are enabling deep space exploration.

Why NRHO: The Artemis Orbit

The programs and systems comprising Artemis have evolved from a series of agency initiatives. These systems have been determined through feasibility analyses and assessments of mission design and architecture conducted over many years. One of the key architectural features is the staging orbit from which Artemis will operate: Near-Rectilinear Halo Orbit (NRHO). (PDF)

Why Artemis will Focus on the Lunar South Pole Region

The lighting conditions in the south polar region contribute to unique scientific and operational opportunities. Sites of permanent darkness are not exposed to the solar wind and could preserve volatiles collected throughout the Moon’s past. Conversely, long exposure to sunlight creates environments suitable for long-term survival of hardware and solar power generation. (PDF)

Gateway: The Cislunar Springboard for International and Sustainable Deep Space Exploration

A key need for the lunar architecture – derived from the Moon to Mars objectives – is a long-duration, multi-purpose cislunar platform. That Gateway is a critical element of deep space infrastructure, empowering the Artemis program, serving as a stepping-stone to Mars, and establishing a permanent, U.S.-led outpost in cislunar space. (PDF)

Mars-Forward Capabilities to be Tested at the Moon

NASA and its partners have identified a series of risk-reduction activities to practice, improve, and refine exploration systems at the Moon before sending a crew to Mars. These operational constructs are combined in various ways to accomplish mission goals as we expand our reach beyond the International Space Station to the lunar vicinity and on to Mars. (PDF)

Mars Transportation

One of the most visible portions of the Mars architecture is the Earth to Mars transportation system. Four propulsion systems are currently under consideration: nuclear thermal, hybrid nuclear electric/chemical, hybrid solar electric/chemical, and all chemical. This paper orients the greater community to their breadth, variations, and associated risks. (PDF)