A Martian panorama taken by the Mars Exploration Rover Opportunity.
Though details of Mars' surface are difficult to see from Earth, telescope observations show seasonally changing features and white patches at the poles. For decades, people speculated that bright and dark areas on Mars were patches of vegetation, Mars was a likely place for advanced life forms, and water might exist in the polar caps. When the Mariner 4 spacecraft flew by Mars in 1965, photographs of a bleak, cratered surface shocked many - Mars seemed to be a dead planet. Later missions, however, showed that Mars is a complex planet and holds many mysteries yet to be solved. Chief among them is whether Mars ever had the right conditions to support small life forms called microbes.
Mars is a rocky body about half the size of Earth. As with the other terrestrial planets - Mercury, Venus, and Earth - volcanoes, impact craters, crustal movement, and atmospheric conditions such as dust storms have altered the surface of Mars.
Mars has two small moons, Phobos and Deimos, that may be captured asteroids. Potato-shaped, they have too little mass for gravity to make them spherical. Phobos, the innermost moon, is heavily cratered, with deep grooves on its surface.
Like Earth, Mars experiences seasons due to the tilt of its rotational axis. Mars' orbit is about 1.5 times farther from the sun than Earth's and is slightly elliptical, so its distance from the sun changes. That affects the length of Martian seasons, which vary in length. The polar ice caps on Mars grow and recede with the seasons. Layered areas near the poles suggest that the planet's climate has changed more than once. Volcanism in the highlands and plains was active more than 3 billion years ago. Some of the giant shield volcanoes are younger, having formed between 1 and 2 billion years ago. Mars has the largest volcano in the solar system, Olympus Mons, as well as a spectacular equatorial canyon system, Valles Marineris.
Mars has no global magnetic field today. However, NASA's Mars Global Surveyor orbiter found that areas of the Martian crust in the southern hemisphere are highly magnetized, indicating traces of a magnetic field from 4 billion years ago that remain.
Scientists believe that Mars experienced huge floods about 3.5 billion years ago. Though we do not know where the ancient flood water came from, how long it lasted, or where it went, recent missions to Mars have uncovered intriguing hints. In 2002, NASA's Mars Odyssey orbiter detected hydrogen-rich polar deposits, indicating large quantities of water ice close to the surface. Further observations found hydrogen in other areas as well. If water ice permeated the entire planet, Mars could have substantial subsurface layers of frozen water. In 2004, Mars Exploration Rover Opportunity found structures and minerals indicating that liquid water once existed at its landing site. The rover's twin, Spirit, also found the signature of ancient water near its landing site, halfway around Mars from Opportunity's location.
The cold temperatures and thin atmosphere on Mars do not allow liquid water to exist at the surface for long. The quantity of water required to carve Mars' great channels and flood plains is not evident today. Unraveling the story of water on Mars is important to unlocking its climate history, which will help us understand the evolution of all the planets. Water is an essential ingredient for life as we know it. Evidence of long-term past or present water on Mars holds clues about whether Mars could ever have been a habitat for life.
In 2008, NASA's Phoenix Mars lander was the first mission to touch water ice in the Martian arctic. Phoenix also observed precipitation (snow falling from clouds), as confirmed by Mars Reconnaissance Orbiter. Soil chemistry experiments led scientists to believe that the Phoenix landing site had a wetter and warmer climate in the recent past (the last few million years). NASA's Mars Science Laboratory mission, with its large rover Curiosity, is examining Martian rocks and soil at Gale Crater, looking for minerals that formed in water, signs of subsurface water, and carbon-based molecules called organics, the chemical building blocks of life. That information will reveal more about the present and past habitability of Mars, as well as whether humans could survive on Mars some day.
Mars was named by the Romans for their god of war because of its red, bloodlike color. Other civilizations also named this planet from this attribute; for example, the Egyptians named it "Her Desher," meaning "the red one."
NASA is on a journey to Mars, with a goal of sending humans to the Red Planet in the 2030s. That journey is already well under way.
For decades, the agency and its partners have sent orbiters, landers and rovers, dramatically increasing our knowledge about the Red Planet and paving the way for future human explorers. The Curiosity rover has gathered radiation data to help us protect future astronauts, and the upcoming Mars 2020 rover will study the availability of Martian resources, including oxygen.
There is more to learn as we expand humanity's presence into the solar system: Was Mars once home to microbial life or is it today? Can it be a safe home for humans? What can the Red Planet teach us about our own planet's past, present and future?
Building on the robotic legacy, the human exploration of Mars crosses three thresholds, each with increasing challenges as humans move farther from Earth: Earth Reliant, the Proving Ground, and Earth Independent.
Earth Reliant exploration is focused on research aboard the International Space Station. The orbiting microgravity laboratory serves as a world-class test bed for the technologies and communications systems needed for human missions to deep space. Astronauts are learning about what it takes to live and work in space for long periods of time, increasing our understanding of how the body changes in space and how to protect astronaut health.
We're also working with our commercial crew and cargo partners to provide access to low-Earth orbit and eventually stimulate new economic activity, allowing NASA to continue using the station while preparing for missions beyond.
Next, we move into the Proving Ground, conducting a series of missions near the moon -- we call it "cislunar space" -- that will test the capabilities we will need to live and work at Mars. Astronauts on the space station are only hours away from Earth, but the proving ground is days away, a natural stepping stone to a Mars mission, which will be months away from home.
The first of these missions will launch NASA's powerful new rocket, the Space Launch System, from NASA’s Kennedy Space Center in Florida. The mission will carry the Orion spacecraft (without astronauts) thousands of miles beyond the moon during an approximately three week mission. Next up, astronauts will climb into Orion for a similar mission, traveling farther than humans have ever traveled before. .
Also in the 2020s, we'll send astronauts on a yearlong mission into this deep space proving ground, verifying habitation and testing our readiness for Mars.
Another proving ground milestone is the Asteroid Redirect Mission. NASA will send a robotic spacecraft to capture an asteroid boulder and put it in a safe orbit around the moon. Astronauts on Orion will then explore the asteroid, returning to Earth with samples. This two-part mission will test both deep space spacewalking and sampling techniques and Solar Electric Propulsion, which we’ll need to send cargo as part of human missions to Mars.
Finally, we become Earth Independent, building on what we've learned on the space station and in deep space to send humans to low-Mars orbit in the early 2030s.
This phase will also test the entry, descent and landing techniques needed to get to the Martian surface and study what's needed for in-situ resource utilization or "living off the land." NASA is already studying potential "Exploration Zones" on Mars that would offer compelling science research and provide resources our astronauts can use.
Science missions are already in the Independent phase, with the next rover due in 2020. We will also conduct a round-trip robotic demonstration mission with sample return in the late 2020s.
Mars is the next tangible frontier for human exploration, and it's an achievable goal. There are challenges to pioneering Mars, but we know they are solvable. We are well on our way to getting there, landing there, and living there.
NASA is leading our nation and our world on a journey to Mars. Like the Apollo Program, we embark on this journey for all humanity. Unlike Apollo, we will be going to stay. This is a historic pioneering endeavor — a journey made possible by a sustained effort of science and exploration missions beyond low Earth orbit with successively more capable technologies and partnerships.
This pioneering endeavor carries out the direction given to us in the 2010 NASA Authorization Act and in the U.S. National Space Policy. It engages all four NASA Mission Directorates and all NASA Centers and Laboratories. It enlists the best of academia and industry across the nation and builds on our existing international partnerships while embracing new ones. And like pioneering efforts before it, the journey to Mars will foster and attract new commercial enterprises.
Why Mars? Mars is the horizon goal for pioneering space; it is the next tangible frontier for expanding human presence. Our robotic science scouts at Mars have found valuable resources for sustaining human pioneers, such as water ice just below the surface. These scouts have shown that Mars’ geological evolution and climate cycles were comparable to Earth’s, and that at one time, Mars had conditions suitable for life. What we learn about the Red Planet will tell us more about our Earth’s past and future, and may help answer whether life exists beyond our home planet. Together with our partners, we will pioneer Mars and answer some of humanity’s fundamental questions:
Mars is an achievable goal. We have spent more than four decades on the journey to Mars, with wildly successful robotic explorers. The first human steps have been taken through science and technology research aboard the International Space Station (ISS) and in laboratories here on Earth. We are taking the next steps by developing the Space Launch System (SLS) and the Orion crewed spacecraft, demonstrating new operations to reduce logistics, and preparing for human missions into cislunar space, such as exploring a captured asteroid. There are challenges to pioneering Mars, but we know they are solvable. We are developing the capabilities necessary to get there, land there, and live there.
Technology drives exploration and many of the technologies we need are in various stages of conceptualization, development, or testing. Consequently, NASA will continue to make key decisions and further define steps on this journey as technology and knowledge mature. This is a good thing, as it allows new ideas, new technologies, and new partnerships to be developed during the next two decades of this journey.
This document communicates our strategy and shares our progress. It reflects the ongoing discussion with our stakeholders and partners, and an update on current plans and activities within an evolving architecture. It identifies the challenges facing future pioneers and our strategy for addressing these challenges. NASA’s strategy provides an evolutionary, resilient framework for defining future missions. We are making progress on the journey to Mars using current missions to advance technologies and systems for the next decade, and we are conducting the technical analyses needed to plan for the decades beyond.
We are on a journey to Mars. We have already taken the first steps. We are excited by the challenges that remain, knowing they will only push us further. Come join us on the journey!
NASA aims to extend human presence deeper into the solar system and to the surface of Mars. In doing so, our human and robotic explorers will expand knowledge and discover the potential for life beyond Earth. Our goal is not bound by a single destination. We seek the capacity for people to work, learn, operate, and sustainably live safely beyond Earth for extended periods of time. We will achieve this goal with a growing number of international and commercial partners, realizing economic benefits and strengthening America’s leadership on Earth and in space.
As pioneers, we seek to blaze the trail for others, establishing a presence that leads to economic progress and broad societal benefit. We pioneer space to discover life, identify resources, foster economic growth, inspire and educate, protect ourselves from space-based threats, and leave a better future for the next generation. This goal is embodied in the idea of a human and robotic journey to Mars. It is time for the next steps, and the agency is actively developing the capabilities that will enable humans to thrive beyond Earth for extended periods of time, leading to a sustainable presence in deep space.
NASA’s efforts build upon the proven international and commercial partnerships at the core of the ISS. Our activities align with the Global Exploration Roadmap (GER), a product of 12 space agencies committed to expanding human presence in space. We will continue to build on partnerships with U.S. industry, academia, and our stakeholders. Our partners are developing technologies, systems, and missions to meet individual objectives, such as lunar surface operations, while contributing to the journey to Mars. The commonality between exploration capabilities, related scientific investigations, and the range of potential activities, allows partners to target individual objectives while working together to achieve pioneering goals.
While far away, Mars is a goal within our reach. We are closer to sending humans to Mars than at any point in NASA’s history. We will journey in phases, leveraging our experience on the space station to step out into the Proving Ground of cislunar space — the volume of space around the moon featuring multiple stable staging orbits for future deep space missions. Over the next decade, NASA and our partners will use this Proving Ground to practice deep-space operations with decreasing reliance on the Earth, gaining the experience and systems necessary to make pioneering space and the journey to Mars a reality.
NASA's approach to pioneering is embodied in a set of guiding principles that will increase our successes and benefits over the coming decades. These key principles are the basis for a sustainable, affordable space program and provide overarching guidance to ensure NASA’s investments efficiently and effectively enable the journey to Mars. These principles are:
Implementable in the near term with the buying power of current budgets and in the longer term with budgets commensurate with economic growth
Exploration enables science and science enables exploration, leveraging scientific expertise for human exploration of the solar system
Application of high Technology Readiness Level (TRL) technologies for near-term missions, while focusing sustained investments on technologies and capabilities to address challenges of future missions
Near-term mission opportunities with a defined cadence of compelling and integrated human and robotic missions, providing for an incremental buildup of capabilities for more complex missions over time
Opportunities for U.S. commercial business to further enhance the experience and business base
Resilient architecture featuring multi-use, evolvable space infrastructure, minimizing unique major developments, with each mission leaving something behind to support subsequent missions
Substantial new international and commercial partnerships, leveraging current International Space Station partnerships and building new cooperative ventures for exploration
These principles are integrated throughout NASA’s strategy and are exemplified in current plans and activities. This document highlights a few example applications of these principles, as indicated in relevant sections by the icons above.
The journey to Mars passes through three thresholds, each with increasing challenges as humans move farther from Earth. NASA and our partners are managing these challenges by developing and demonstrating capabilities in incremental steps.
Earth Reliant exploration is focused on research aboard the ISS. On the space station, we are testing technologies and advancing human health and performance research that will enable deep-space, long-duration missions.
In the Proving Ground, NASA will learn to conduct complex operations in a deep space environment that allows crews to return to Earth in a matter of days. Primarily operating in cislunar space, NASA will advance and validate capabilities required for human exploration of Mars.
Earth Independent activities build on what we learn on ISS and in cislunar space to enable human missions to the Mars vicinity, including the Martian moons, and eventually the Martian surface. With humans on Mars, we will be able to advance science and technology in ways only dreamed of with current robotic explorers. Future Mars missions will represent a collaborative effort among NASA and its partners — a global achievement that marks a transition in humanity’s expansion as we go to Mars not just to visit, but to stay.