why do we travel to mars quizlet

Why we explore Mars—and what decades of missions have revealed

In the 1960s, humans set out to discover what the red planet has to teach us. Now, NASA is hoping to land the first humans on Mars by the 2030s.

Mars has captivated humans since we first set eyes on it as a star-like object in the night sky. Early on, its reddish hue set the planet apart from its shimmering siblings, each compelling in its own way, but none other tracing a ruddy arc through Earth’s heavens. Then, in the late 1800s, telescopes first revealed a surface full of intriguing features—patterns and landforms that scientists at first wrongly ascribed to a bustling Martian civilization. Now, we know there are no artificial constructions on Mars. But we’ve also learned that, until 3.5 billion years ago, the dry, toxic planet we see today might have once been as habitable as Earth.

Since the 1960s, humans have set out to discover what Mars can teach us about how planets grow and evolve, and whether it has ever hosted alien life. So far, only uncrewed spacecraft have made the trip to the red planet, but that could soon change. NASA is hoping to land the first humans on Mars by the 2030s—and several new missions are launching before then to push exploration forward. Here’s a look at why these journeys are so important—and what humans have learned about Mars through decades of exploration.

Why explore Mars

Over the last century, everything we’ve learned about Mars suggests that the planet was once quite capable of hosting ecosystems—and that it might still be an incubator for microbial life today.

Mars is the fourth rock from the sun, just after Earth. It is just a smidge more than half of Earth’s size , with gravity only 38 percent that of Earth’s. It takes longer than Earth to complete a full orbit around the sun—but it rotates around its axis at roughly the same speed. That’s why one year on Mars lasts for 687 Earth days , while a day on Mars is just 40 minutes longer than on Earth.

Despite its smaller size, the planet’s land area is also roughly equivalent to the surface area of Earth’s continents —meaning that, at least in theory, Mars has the same amount of habitable real estate. Unfortunately, the planet is now wrapped in a thin carbon dioxide atmosphere and cannot support earthly life-forms. Methane gas also periodically appears in the atmosphere of this desiccated world, and the soil contains compounds that would be toxic to life as we know it. Although water does exist on Mars, it’s locked into the planet’s icy polar caps and buried, perhaps in abundance, beneath the Martian surface .

Today, when scientists scrutinize the Martian surface, they see features that are unquestionably the work of ancient, flowing liquids : branching streams, river valleys, basins, and deltas. Those observations suggest that the planet may have once had a vast ocean covering its northern hemisphere. Elsewhere, rainstorms soaked the landscape, lakes pooled, and rivers gushed, carving troughs into the terrain. It was also likely wrapped in a thick atmosphere capable of maintaining liquid water at Martian temperatures and pressures.

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Somewhere during Martian evolution, the planet went through a dramatic transformation, and a world that was once rather Earthlike became the dusty, dry husk we see today. The question now is, what happened? Where did those liquids go, and what happened to the Martian atmosphere ?

Exploring Mars helps scientists learn about momentous shifts in climate that can fundamentally alter planets. It also lets us look for biosignatures, signs that might reveal whether life was abundant in the planet’s past—and if it still exists on Mars today. And, the more we learn about Mars, the better equipped we’ll be to try to make a living there, someday in the future.

Past missions, major discoveries

Since the 1960s, humans have sent dozens of spacecraft to study Mars . Early missions were flybys, with spacecraft furiously snapping photos as they zoomed past. Later, probes pulled into orbit around Mars; more recently, landers and rovers have touched down on the surface.

But sending a spacecraft to Mars is hard , and landing on the planet is even harder. The thin Martian atmosphere makes descent tricky, and more than 60 percent of landing attempts have failed. So far, four space agencies—NASA, Russia’s Roscosmos, the European Space Agency (ESA), and the Indian Space Research Organization (ISRO)—have put spacecraft in Martian orbit. With eight successful landings, the United States is the only country that has operated a craft on the planet’s surface. The United Arab Emirates and China might join that club if their recently launched Hope and Tianwen-1 missions reach the red planet safely in February 2021.

Early highlights of Mars missions include NASA's Mariner 4 spacecraft , which swung by Mars in July 1965 and captured the first close-up images of this foreign world. In 1971, the Soviet space program sent the first spacecraft into Martian orbit. Called Mars 3 , it returned roughly eight months of observations about the planet's topography, atmosphere, weather, and geology. The mission also sent a lander to the surface, but it returned data for only about 20 seconds before going quiet.

Over the subsequent decades, orbiters returned far more detailed data on the planet's atmosphere and surface, and finally dispelled the notion, widely held by scientists since the late 1800s, that Martian canals were built by an alien civilization. They also revealed some truly dramatic features: the small world boasts the largest volcanoes in the solar system, and one of the largest canyons yet discovered—a chasm as long as the continental United States. Dust storms regularly sweep over its plains, and winds whip up localized dust devils.

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In 1976, NASA’s Viking 1 and 2 became the first spacecraft to successfully operate on the planet’s surface, returning photos until 1982. They also conducted biological experiments on Martian soil that were designed to uncover signs of life in space—but their results were inconclusive , and scientists still disagree over how to interpret the data.

NASA’s Mars Pathfinder mission , launched in 1996, put the first free-moving rover—called Sojourner—on the planet. Its successors include the rovers Spirit and Opportunity , which explored the planet for far longer than expected and returned more than 100,000 images before dust storms obliterated their solar panels in the 2010s.

Now, two NASA spacecraft are active on the Martian surface: InSight is probing the planet’s interior and it has already revealed that “ marsquakes” routinely rattle its surface . The Curiosity rover , launched in 2012, is also still wheeling around in Gale Crater, taking otherworldly selfies, and studying the rocks and sediments deposited in the crater’s ancient lakebed.

Several spacecraft are transmitting data from orbit: NASA’s MAVEN orbiter , Mars Reconnaissance Orbiter , and Mars Odyssey ; ESA’s Mars Express and Trace Gas Orbiter ; and India’s Mars Orbiter Mission .

Together, these missions have shown scientists that Mars is an active planet that is rich in the ingredients needed for life as we know it—water, organic carbon , and an energy source. Now, the question is: Did life ever evolve on Mars , and is it still around?

Future of Mars exploration

Once every 26 months , Earth and Mars are aligned in a way that minimizes travel times and expense , enabling spacecraft to make the interplanetary journey in roughly half a year. Earth’s space agencies tend to launch probes during these conjunctions, the most recent of which happens in the summer of 2020. Three countries are sending spacecraft to Mars during this window: The United Arab Emirates, which launched its Hope spacecraft on July 20 and will orbit Mars to study its atmosphere and weather patterns; China, which launched its Tianwen-1 on July 23 , and the United States, currently targeting July 30 for the launch of its Perseverance rover .

Perseverance is a large, six-wheeled rover equipped with a suite of sophisticated instruments. Its target is Jezero Crater, site of an ancient river delta , and a likely location for ancient life-forms to have thrived. Once on the surface, Perseverance will study Martian climate and weather, test technologies that could help humans survive on Mars, and collect samples from dozens of rocks that will eventually be brought to Earth. Among its goals is helping to determine whether Mars was—or is—inhabited, making it a true life-finding Mars mission.

All of the robotic activity is, of course, laying the groundwork for sending humans to the next world over. NASA is targeting the 2030s as a reasonable timeframe for setting the first boots on Mars, and is developing a space capsule, Orion , that will be able to ferry humans to the moon and beyond.

Private spaceflight companies such as SpaceX are also getting into the Mars game. SpaceX CEO Elon Musk has repeatedly said that humanity must become “ a multiplanetary species ” if we are to survive, and he is working on a plan that could see a million people living on Mars before the end of this century.

Soon, in one way or another, humanity may finally know whether our neighboring planet ever hosted life—and whether there’s a future for our species on another world.

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Why go to Mars?

Mars is an obvious target for exploration because it is close by in our Solar System, but there are many more reasons to explore the Red Planet. The scientific reasons for going to Mars can be summarised by the search for life, understanding the surface and the planet’s evolution, and preparing for future human exploration.

Searching for life on Mars Understanding whether life existed elsewhere in the Universe beyond Earth is a fundamental question of humankind. Mars is an excellent place to investigate this question because it is the most similar planet to Earth in the Solar System. Evidence suggests that Mars was once full of water, warmer and had a thicker atmosphere, offering a potentially habitable environment.

Understanding the surface of Mars and its evolution

While life arose and evolved on Earth, Mars experienced serious climate change. Planetary geologists can study rocks, sediments and soils for clues to uncover the history of the surface. Scientists are interested in the history of water on Mars to understand how life could have survived. Volcanoes, craters from meteoroid impacts, signs of atmospheric or photochemical effects and geophysical processes all carry aspects of Mars’ history.

Samples of the atmosphere could reveal crucial details on its formation and evolution, and also why Mars has less atmosphere than Earth.

Mars can also help us to learn more about our home. Understanding martian geophysical processes promises to uncover details of the evolution and history of Earth and other planets in our Solar System.

Human exploration

To reduce the cost and risk for human exploration of Mars, robotic missions can scout ahead and help us to find potential resources and the risks of working on the planet.

Before sending astronauts, we need to understand the hazards. Inevitably, astronauts would bring uncontained martian material when they return to Earth, either on their equipment or on themselves. Understanding any biohazards in the soil and dust will help the planning and preparation of these future missions.

Going to Mars is hard and it is even harder for humans because we would need to pack everything to survive the trip to our neighbouring planet and back. Designing a Mars mission would be easier if we could use resources that are already available locally. Water is a valuable resource for human expeditions, both to consume by astronauts and for fuel. Samples gathered by robots could help to evaluate where potential resources are available for future human explorers and how to exploit them.

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Mars Exploration Science Goals

The key to understanding the past, present or future potential for life on Mars can be found in NASA’s four broad, overarching goals for Mars Exploration.

Determine Whether Life Ever Arose on Mars

Conditions needed for life to thrive.

On Earth, all forms of life need water to survive. If life ever evolved on Mars, it likely did so in the presence of a long-standing water supply. That's why our search for evidence of life on Mars focuses on areas where liquid water was once stable, below the surface where it still might exist, or in current "hot spots" where hydrothermal pools (like those at Yellowstone) might be habitable. Data from multiple NASA Mars missions suggest the presence of liquid water just below the surface in rare places, and on water ice at the Martian poles. Mars missions also search for energy sources other than sunlight, since life on the Mars surface is unlikely because "superoxides" break down organic (carbon-based) molecules on which life is based. We find life on Earth in many places without sunlight--dark ocean depths, inside rocks, and deep below the surface. Chemical and geothermal energy, for example, are also energy sources for life forms on Earth. Perhaps tiny, subsurface microbes on Mars could use such energy sources, too.

Looking for Life Signs

Differentiating life from non-life is a challenge, no matter where one finds it. On Earth, we know which markers, or biosignatures, to look for, but life on another planet might be very different in chemistry, structure, and other characteristics. Life detection technologies under development will help us define life in non-Earth-centric terms, to detect it in all the forms it might take. In the meantime, NASA Mars missions look for telltale biosignatures of current and past life. Knowing the location and form on Mars of the element carbon, a fundamental building block of life, would tell us a lot about where life might have developed. The current Martian atmosphere consists mostly of carbon dioxide. Any discovery of carbonate minerals formed on the Martian surface by chemical reactions between water and the atmosphere would be a clue that water had been present for a long time--perhaps long enough for life to have developed. By studying fossils in sedimentary rock on Earth that leave a record of past life, we know that only certain environments and types of deposits preserve fossils well. We look for lakes and streams on Mars that may have left behind similar deposits. 

Characterize the Climate of Mars

What's the martian climate like today.

The current Martian climate is regulated by seasonal changes of carbon dioxide ice caps, atmospheric movement of large amounts of dust, and water vapor exchange between the surface and atmosphere. One of Mars' most dynamic weather patterns is the generation of dust storms, generally in the southern spring and summer. These storms can grow to encompass the whole planet. Understanding how these storms develop and grow is one science goal.

What Can the Current Climate on Mars Reveal about the Past?

A better understanding of Mars' current climate helps scientists more effectively model its past behavior. To do this, they need Mars weather maps and information about quantities of dust and water vapor in the atmosphere. Monitoring the planet for this information over one full Martian year (687 Earth days) and repeated years helps us understand how Mars behaves over its seasonal cycle and guides us toward understanding how the planet changes over millions of years. The layered terrain of Martian polar regions also holds clues about the planet's past, much as a tree's rings provide a record of its history. When and how were these polar layers deposited? Was the climate of Mars ever like that of Earth? And if so, what happened to change the planet into the dry, cold, barren desert it is today? Our current missions are striving to answer those important questions.

Characterize the Geology of Mars

How did Mars become the planet we see today? What accounts for the differences and similarities between Earth and Mars? Studying Mars' geology helps answer these questions.  We work to understand the relative roles of wind, water, volcanism, tectonics, cratering, and other processes in forming and modifying the Martian surface. For example, Mars hosts incredibly large volcanoes, which can be 10 to 100 times larger than those on Earth. One reason for this difference is that the Mars crust doesn't move the way it does on Earth, so the total volume of lava piles up into one very large volcano.

The Magnetism of Mars Gives Clues to the Planet's Interior and More

The discovery of large areas of magnetic materials on Mars indicates that the planet once had a magnetic field, much as Earth does today. Because magnetic fields in general shield planets from many forms of cosmic radiation, this discovery has important implications for the prospects for finding evidence of past life on the Martian surface. Study of the ancient magnetic field also provides important information about Mars' past interior structure, temperature, and composition. The presence of magnetic fields also suggests that Mars was once more of a dynamic Earth-like planet than it is today.

Rocks on Mars Can Tell Us About the Planet's History and Its Potential for Harboring Life

Of fundamental importance are the age and composition of different types of rocks on the Martian surface. Geologists use the age of rocks to determine the sequence of events in a planet's history. Information about rock composition tells them what happened over time. Particularly important is identifying rocks and minerals formed in the presence of water. With an ongoing series of Mars orbiters, landers, and rovers, with increasingly sophisticated tools, we are helping to answer numerous questions, such as what other materials might be trapped in rock with information about Mars' history, and how different rock types are distributed on the surface.

Seeking Signs of Life in Ancient Martian Rocks

NASA’s Perseverance Mars rover is caching rock samples for a future mission to collect and return to Earth. For Mars 2020 Deputy Project Scientist at NASA-JPL Katie Stack Morgan, studying rocks is not only important in the search for ancient life, but it’s also a hobby Credits: NASA 360

Prepare for Human Exploration

Studies are underway to determine how humans might safely journey to Mars and back to Earth. This extremely difficult engineering challenge requires a thorough understanding of the Martian environment, which is critical to the safe operation of equipment and the health of  humans.

Astronaut Safety in the Harsh Martian Environment

The safety of astronauts is of paramount importance to NASA. Mars lacks an ozone layer, which on Earth shields us from lethal doses of solar ultraviolet radiation. We are seeking to expand our information about how much ultraviolet radiation reaches the Martian surface. We need a more detailed understanding of the radiation environment to assess ultraviolet effects on astronauts and help engineers design protective space suits and habitats. In the presence of UV radiation, "superoxides" in Martian soil break down organic molecules. This would probably not affect astronauts seriously, but the impact of this and any other unique chemical aspects of the Martian soil must be assessed before human exploration of Mars can begin. NASA missions have already begun to analyze the Mars radiation environment on Mars and search for water resources that could support future human explorers. Those resources could be accessed eventually by robotic spacecraft, rovers, and drills. In addition, advanced entry, descent, and landing techniques that reduce the G-forces on landers are planned for spacecraft and astronaut safety.

Much of the necessary scientific and technological work for the goal of sending humans to Mars is carried out by NASA's Johnson Space Center. For more information about eventual human Mars missions, visit NASA's Human to Mars webpage.

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Subscribe to the center for technology innovation newsletter, darrell m. west darrell m. west senior fellow - center for technology innovation , douglas dillon chair in governmental studies.

August 18, 2020

The recent launch of the Mars rover Perseverance is the latest U.S. space mission seeking to understand our solar system. Its expected arrival at the Red Planet in mid-February 2021 has a number of objectives linked to science and innovation. The rover is equipped with sophisticated instruments designed to search for the remains of ancient microbial life, take pictures and videos of rocks, drill for soil and rock samples, and use a small helicopter to fly around the Jezero Crater landing spot .

Mars is a valuable place for exploration because it can be reached in 6 ½ months, is a major opportunity for scientific exploration, and has been mapped and studied for several decades. The mission represents the first step in a long-term effort to bring Martian samples back to Earth, where they can be analyzed for residues of microbial life. Beyond the study of life itself, there are a number of different benefits of Mars exploration.

Understand the Origins and Ubiquity of Life

The site where Perseverance is expected to land is the place where experts believe 3.5 billion years ago held a lake filled with water and flowing rivers. It is an ideal place to search for the residues of microbial life, test new technologies, and lay the groundwork for human exploration down the road.

The mission plans to investigate whether microbial life existed on Mars billions of years ago and therefore that life is not unique to Planet Earth. As noted by Chris McKay, a research scientist at NASA’s Ames Research Science Center, that would be an extraordinary discovery. “Right here in our solar system, if life started twice , that tells us some amazing things about our universe,” he pointed out. “It means the universe is full of life. Life becomes a natural feature of the universe, not just a quirk of this odd little planet around this star.”

The question of the origins of life and its ubiquity around the universe is central to science, religion, and philosophy. For much of our existence, humans have assumed that even primitive life was unique to Planet Earth and not present in the rest of the solar system, let alone the universe. We have constructed elaborate religious and philosophical narratives around this assumption and built our identity along the notion that life is unique to Earth.

If, as many scientists expect, future space missions cast doubt on that assumption or outright disprove it by finding remnants of microbial life on other planets, it will be both invigorating and illusion-shattering. It will force humans to confront their own myths and consider alternative narratives about the universe and the place of Earth in the overall scheme of things.

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As noted in my Brookings book, Megachange , given the centrality of these issues for fundamental questions about human existence and the meaning of life, it would represent a far-reaching shift in existing human paradigms. As argued by scientist McKay, discovering evidence of ancient microbial life on Mars would lead experts to conclude that life likely is ubiquitous around the universe and not limited to Planet Earth. Humans would have to construct new theories about ourselves and our place in the universe.

Develop New Technologies

The U.S. space program has been an extraordinary catalyst for technology innovation . Everything from Global Positioning Systems and medical diagnostic tools to wireless technology and camera phones owe at least part of their creation to the space program. Space exploration required the National Aeronautics and Space Administration to learn how to communicate across wide distances, develop precise navigational tools, store, transmit, and process large amounts of data, deal with health issues through digital imaging and telemedicine, and develop collaborative tools that link scientists around the world. The space program has pioneered the miniaturization of scientific equipment and helped engineers figure out how to land and maneuver a rover from millions of miles away.

Going to Mars requires similar inventiveness. Scientists have had to figure out how to search for life in ancient rocks, drill for rock samples, take high resolution videos, develop flying machines in a place with gravity that is 40 percent lower than on Earth, send detailed information back to Earth in a timely manner, and take off from another planet. In the future, we should expect large payoffs in commercial developments from Mars exploration and advances that bring new conveniences and inventions to people.

Encourage Space Tourism

In the not too distant future, wealthy tourists likely will take trips around the Earth, visit space stations, orbit the Moon, and perhaps even take trips around Mars. For a substantial fee, they can experience weightlessness, take in the views of the entire planet, see the stars from outside the Earth’s atmosphere, and witness the wonders of other celestial bodies.

The Mars program will help with space tourism by improving engineering expertise with space docking, launches, and reentry and providing additional experience about the impact of space travel on the human body. Figuring out how weightlessness and low gravity situations alter human performance and how space radiation affects people represent just a couple areas where there are likely to be positive by-products for future travel.

The advent of space tourism will broaden human horizons in the same way international travel has exposed people to other lands and perspectives. It will show them that the Earth has a delicate ecosystem that deserves protecting and why it is important for people of differing countries to work together to solve global problems. Astronauts who have had this experience say it has altered their viewpoints and had a profound impact on their way of thinking.

Facilitate Space Mining

Many objects around the solar system are made of similar minerals and chemical compounds that exist on Earth. That means that some asteroids, moons, and planets could be rich in minerals and rare elements. Figuring out how to harvest those materials in a safe and responsible manner and bring them back to Earth represents a possible benefit of space exploration. Elements that are rare on Earth may exist elsewhere, and that could open new avenues for manufacturing, product design, and resource distribution. This mission could help resource utilization through advances gained with its Mars Oxygen Experiment (MOXIE) equipment that converts Martian carbon dioxide into oxygen. If MOXIE works as intended, it would help humans live and work on the Red Planet.

Advance Science

One of the most crucial features of humanity is our curiosity about the life, the universe, and how things operate. Exploring space provides a means to satisfy our thirst for knowledge and improve our understanding of ourselves and our place in the universe.

Space travel already has exploded centuries-old myths and promises to continue to confront our long-held assumptions about who we are and where we come from. The next decade promises to be an exciting period as scientists mine new data from space telescopes, space travel, and robotic exploration. Ten or twenty years from now, we may have answers to basic questions that have eluded humans for centuries, such as how ubiquitous life is outside of Earth, whether it is possible for humans to survive on other planets, and how planets evolve over time.

The author would like to thank Victoria E. Hamilton, staff scientist at the Southwest Research Institute, for her helpful feedback on this blog post.

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Why do we care so much about Mars? Johns Hopkins scientist explains

Credit: istock

By Greg Rienzi

Mars is not red—it's blushing from humanity's profusion of attention. At present, a small fleet of robotic spacecraft and vehicles probe the planet, among them a car-sized rover called Curiosity that roams the Gale crater to send back dazzling images and oodles of scientific data. And then there's the MAVEN spacecraft, which orbits the planet to survey the atmosphere. In 2016, NASA will launch InSight to study the planet's deep interior. More missions are on tap in 2020 and beyond, paving the way for possible future human exploration.

Mars has long inspired authors to tell tales, from the benign ( My Favorite Martian ) to the heroic (DC Comics' Martian Manhunter) to the ridiculous ( Mars Attacks! ). And there's more to come. Mars will provide the backdrop for the upcoming Ridley Scott film The Martian about an astronaut (Matt Damon) stranded on the planet.

Being curious about all things Red Planet, we turned to Kevin Lewis, an assistant professor in Earth and Planetary Sciences and a participating scientist with NASA's current Curiosity mission. Lewis works with images and topography of sedimentary rocks to evaluate the Martian landscape and geological features, all in an effort to determine the planet's past climate.

Can you explain the appeal of Mars to writers who dream up scenarios of colonization and signs of life?

Mars is a dynamic place. It's almost like visiting Egypt's pyramids. We know amazing things happened here once. But where did all the water go, and why is it now a dead planet? It's the only other planet in our solar system that had liquid water on its surface, yet something went wrong along the way that made the planet diverge pretty strongly from the Earth. There's a bit of mystery novel to the planet. It's also very similar to what we're used to. Maybe Mars was not Miami Beach, but it probably felt a lot more like home at some point in its history. It's also, relatively speaking, easy to get to. So while we're homing in on other Earth-like planets in our universe that may harbor evidence of life, we're not getting to those anytime soon. Mars is within our reach.

What are Curiosity's most significant findings to date?

One of the really amazing discoveries came just after we landed. The first sample of rocks we took showed us these perfectly rounded pebbles. It's pretty clear they were formed by ancient rivers. We've known for some time—from pictures taken from orbit—that Mars had what looked like river networks, but this is the first time we saw basically a preserved stream bed like one you'd find on Earth. We've also found fine-grained sediments, very likely evidence of lake beds. All this has helped us feel more secure that there was standing water on the surface during a more habitable period in the planet's history.

What are the prevailing notions on past climates?

Current atmospheric pressures [thin, mostly carbon dioxide] and temperatures [average -81 F] don't support standing water. There are some challenges to getting Mars to be warm and stay warm over geological time. Clearly the planet had a radically different atmosphere and climate than it has today. Very possibly there was liquid water on the surface for just a blip of time, but how long? And what volume? These are some of the questions we're looking to answer and that will help us learn more about the climate conditions necessary.

But what of "Martians," or any form of life there?

First, consider that macroscopic life became dominant just in the past 10 percent of Earth's history—and after that period of climate transition that happened on Mars. So it's totally plausible we had some early biological activity on Mars, but almost certainly it would have been on the microbial level, like bacteria. Don't expect fossilized bird bones, tree trunks, or Martian skeletons. But it's important to keep in mind that deep surface exploration is not possible with this mission. There might be more signs of life buried deep away that we can't currently get to.

Clearly NASA is invested in exploring Mars, but what of possible manned missions?

A dedicated program needs to be in place, one that will require an effort on an international scale. It would be a big project, but potentially hugely scientifically rewarding and totally inspiring for humanity. A project of this size and scope is not currently feasible given the NASA budget, but we can start to lay the groundwork for the technology needed. [Note Dec. 5 Orion launch.] We need a rocket big enough to get us and our instruments there, with a return rocket, like we did on the moon. And then we have to protect the astronauts once they're on the surface, thus the need for more information about the current Mars conditions.

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•  • Planetary Nebulae 
•  • Novae & Supernovae 
•  • Star-Forming Regions 
•  • Galactic Center 
•  • Milky Way Structure 
•  • The Local Group 
•  • Types of Galaxies 
•  • How Many Galaxies? 
•  • Powers of Ten 
•  • Galaxy Evolution 
•  • Hubble's Law 
•  • Dark Matter 
•  • Dark Energy 
•  • What Is the Universe Made of? 
•  • Particle Physics 
•  • History of the Universe 

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13.7 Cosmos & Culture

Why do 202,586 people want to leave our planet for mars.

Barbara J. King

This Viking 1 orbiter image shows the rocky surface and thin atmosphere of Mars. NASA hide caption

This Viking 1 orbiter image shows the rocky surface and thin atmosphere of Mars.

"You could say that most people would rather lose a leg than live the rest of their life on a cold, hostile planet, having said goodbye to friends and family forever, the best possible video call suffering from a seven minute delay—one way."

True enough, I thought upon encountering this statement on the website of Mars One . Mars One is a Dutch non-profit organization that intends to establish a human colony on Mars by 2025. (You can follow Mars One's plans on Twitter ).

For 202,586 people, though, the idea of living forever on that "cold hostile planet" is apparently no nightmare but rather a cherished dream. That's precisely how many applications Mars One says it received during its open call (April through August 2013) for future Mars residents. The hopefuls hailed from 140 countries, with the United States (24 percent), India (10 percent) and China (6 percent) leading the pack .

This massive group has now been whittled down to 1,058 finalists, ranging from a woman who is a first lieutenant in the United States Army to a man who is a student at Rutgers University in New Jersey.

Next, a final group of 24 astronauts — the ones who will establish human life on Mars — will be chosen.

If these plans to launch for Mars become reality, the interplanetary journey will take 7 to 8 months. So why the one-way ticket? An obvious constraint is the ability to assemble the right-stuff technology, on Mars, to launch a rocket back home again. There's also an intense 8-year training period, and thus a big investment in these 24 individuals. Mars One explains that the astronauts, before leaving Earth:

"will be isolated from the world for a few months every two years in groups of four in simulation facilities, to learn how they respond to living in close quarters while isolated from all humans except for the three crew members. In addition to the expertise and work experience they must already possess, they have to learn quite a few new skills: physical and electrical repairs to the settlement structures, cultivating crops in confined spaces, and addressing both routine and serious medical issues such as dental upkeep, muscle tears and bone fractures."

Perhaps, also, it makes sense to seek only those hardy souls who are prepared to make a permanent commitment — no escape clauses! — to life on Mars.

I don't know a single one of the applicants. I do admire their courage. Yet might there be an elephant-in-the-room type of question that needs to be asked?

Mars One CEO Bas Landorp told The Huffington Post earlier this year that "the most important skill" considered in the selection process is an applicant's "ability to function in a team." (The full selection criteria is available online .)

Still, my question is this: Are people eager to leave behind everyone they love — for the rest of their lives — good candidates to succeed at forging a tight-knit colony on Mars? A colony that surely will require great sociability, shared good feelings and cooperation to succeed?

Of course, explorers, pioneers and emigrants from one land to another have, throughout human history, engaged in some version of making this commitment; we are the beneficiaries today of their adventurous spirit.

No one before, though, has opted to live "off world" in the way that the Mars One mission requires. The record for the longest continuous time in space, as far as I can determine, is held by cosmonaut Valeri Polyakov , who spent 437 days in space flight aboard the Mir space station. It was big news even in 2012 when plans for a future one-year stay on the International Space Station were announced.

A scenario in which 24 people, previously unknown to each other, leave the Earth in order to live and die elsewhere is truly unprecedented.

Later this month I'll be writing a second post about the future of human life on Mars. For now, I'm going to try and think this one issue through.

I invite your thoughts.

Barbara's most recent book on animals will be released in paperback in April. You can keep up with what she is thinking on Twitter: @bjkingape

• anthropology
• Bas Landorp

Mars: how scientists prevent Earth’s microbes from contaminating other planets

Lecturer of Space Governance, The Open University

Disclosure statement

Thomas Cheney is affiliated with the Centre for a Spacefaring Civilization. AstrobiologyOU has received funding from Research England (Expanding Excellence in England).

The Open University provides funding as a founding partner of The Conversation UK.

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There are two planned Mars landings in 2021. First, Nasa’s Perseverance rover is due to land on the planet later this month. Then China’s Tianwen rover will follow in May. Both missions intend to search the planet for signs of life.

But how do we make sure when our landers touch down on the red planet’s surface, nothing unwanted is landing with them? If we aren’t careful, we could be spreading all sorts of life – like in 2019, when a spacecraft crashed onto the moon’s surface with a cargo of tiny, almost indestructible lifeforms called tardigrades.

The good thing is, we have policies and laws to prevent this from happening. In fact, there’s an entire section of space law, called planetary protection, designed to prevent planets, moons, comets and asteroids from being contaminated.

For 50 years, governmental organisations have stuck to the generally accepted rules and laws. But they are no longer the only players in the game. An increasing number of commercial space missions are taking off.

Planetary protection

There are two variants of planetary protection, called forwards and backwards. The former concerns the contamination of other planets by material taken from Earth. This protects any life that may be on those planets, of course. But it also means scientists can be reasonably certain any signs of life they discover are actually signs of “extraterrestrial” life and not transplanted from Earth.

To achieve this, the rooms in which spacecraft are made and put together are some of the cleanest places on Earth. The facilities are regularly tested for any biological contamination, and often throw up surprising results. In 2013 a completely new type of bacteria was found in two clean rooms around 4,000km (2,500 miles) apart. The life form, which survives on eating very little, was found nowhere else on Earth.

Backwards contamination is preventing Earth being contaminated by extraterrestrial material that has hitched a ride back. In 1969, when the Apollo 11 astronauts landed back on Earth, they spent three weeks in quarantine to make sure they didn’t bring anything dangerous back from the moon. Neil Armstrong even celebrated his 39th birthday in there.

We have since learnt much more about the moon, and it’s generally considered to be microbe free. The chances of bringing anything back to Earth would be much greater if missions were to bring samples, or humans, back from Mars.

Planetary protection has a long history. The committee on space research (COSPAR), an international non-governmental organisation, began discussing it as early as the 1950s, when planned missions to the moon raised concerns about the potential for contamination to effect later scientific investigations.

Since then COSPAR’s planetary protection policy, with its scientific guidelines and recommendations, has become the internationally recognised “gold standard”. It categorises planets and moons based on their potential for life or signs of life, past or present. The greater the potential for life, the greater the protective measures. By this categorisation, Mars is better protected than the moon.

This means missions to higher category bodies require more sterilisation to ensure fewer potential contaminates travel. It can also affect end-of-life-plans for missions. Nasa’s Juno probe will be crashed into Jupiter this July in order to avoid potential contamination of Europa or any of the other moons.

But as the product of a non-governmental organisation, the COSPAR policy is not legally binding. It’s what lawyers refer to as “soft law” . This means it doesn’t have the force of a legally binding agreement but is still recognised as an important guideline that should be followed.

That said, we do have an obligation under international law to avoid the harmful contamination of outer space, the moon and other celestial bodies, as well as the Earth. This is due to the Outer Space Treaty of 1967.

While the treaty states “harmful contamination” should be avoided, it does not define what this means. However, the past 50 years establishes a fairly strong expectation that future missions will also comply with these principles.

On top of this, there’s a social and moral aspect to the obligation. Space scientists expect missions to comply with the planetary protection principles. To not do so risks condemnation from the scientific community.

Non-governmental spaceflight

The days of space beyond Earth orbit only being explored by government scientific operations are coming to a close. Private companies are increasingly venturing further away from our planet. The lunar landing attempt in 2019 that potentially contaminated the moon was by a private company, called SpaceIL. Elon Musk’s SpaceX is aiming to launch missions to Mars.

This doesn’t mean space will become a lawless wild west, because states are responsible for the activities of their nationals in outer space. They’re required to authorise and continually supervise these activities. If damage is done, it’s the state that is liable, not the private company. But many states include insurance policies as part of granting a licence.

It’s difficult to predict how this will play out, particularly given the limited directly relevant precedent. However, the general approach taken so far by the US government is encouraging. Recently, Nasa updated its planetary protection policy to explicitly stipulate it is the implementation of the US’ obligations under the Outer Space Treaty.

Based on this, it’s reasonable to assume any licence granted by the US would require they adhere to the Nasa planetary protection policy, which broadly aligns with the COPSAR policy.

This isn’t guaranteed to be maintained forever. Attempts in the US Congress to potentially exempt private actors from planetary protection requirements have already happened , as part of a bill in 2018 to reduce the “regulatory burden” on the commercial space industry. The efforts failed, but those who supported it may try again.

Planetary protection is important for maintaining the scientific value of outer space. But scientific interest is not the only reason for exploring outer space – there are many others. Where the balance lies will need to be considered, but it’s a debate that needs wide participation.

• Contamination

Head of School, School of Arts & Social Sciences, Monash University Malaysia

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Why Do We Care About Water on Mars?

The first spacecraft from Earth to visit Mars was Mariner 4 in 1965. Since then, several robotic spacecraft have flown by, orbited, or landed on Mars and sent back lots of information about this world so different from our own.

Mars is a cold, bleak wasteland, with very thin air that we Earthlings could never breathe. However, many of the pictures our telescopes, orbiters, and rovers have sent back show signs that liquid water might have been on the surface of Mars long ago. Also, we can see ice caps at the north and south poles.

Image of Martian ice clouds. Credit: NASA/Hubble Heritage Team (STScI/AURA)

Artist's depiction of Mars Global Surveyor. Credit: NASA

All these signs of water are very exciting. Why? Because on Earth, almost everywhere there is water, there is life. Whether the water is boiling hot or frozen, some sort of creature seems to thrive in it. Is it the same on other planets? If water once flowed on Mars, did life once thrive there too? Or, maybe there is still water on Mars, only it has gone underground. Could there be tiny life forms—like bacteria—on Mars even now?

A comparison of Arizona’s Grand Canyon, left, with Mars’ Nanedi Valles, right. The images suggest that a river once cut through Nanedi Valles much like the Colorado River cuts through the Grand Canyon. Credit: NASA/JPL

NASA's four goals in exploring Mars:

Find out if life ever existed on mars..

NASA scientists will look for water and places where living things might use heat energy from under ground. They will also look for signs of carbon, which is an element needed for life as we know it.

Learn about the climate on Mars.

Martian dust storm. Credit: Malin Space Science Systems, MGS, JPL, NASA

Scientists who study the Martian climate will look at the melting and freezing of the polar ice caps. They'll also study the many dust storms on Mars, such as the storm shown in this image.

Learn about the geology on Mars.

Olympus Mons. Credit: NASA/USGS

Geologists will study Martian rocks, volcanoes, craters, valleys, ridges, cracks, crannies, and other land formations to try to figure out how they were formed. The Martian volcano shown in this image, Olympus Mons, is the largest volcano in the solar system!

Prepare for humans to go to Mars!

Mars explorers poster. Credit: NASA/KSC

NASA will develop technologies to help humans survive and explore the harsh Martian environment.

Mars Games:

Explore Mars!

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What is microgravity (grades 5-8), nasa stem team, is there gravity in space, why do objects float in orbit, how can spacecraft fall around earth, why does nasa study microgravity, can microgravity be found on earth, more about microgravity.

This article is for students grades 5-8.

Microgravity is the condition in which people or objects appear to be weightless. The effects of microgravity can be seen when astronauts and objects float in space. Microgravity can be experienced in other ways, as well. “Micro-” means “very small,” so microgravity refers to the condition where gravity seems to be very small. In microgravity, astronauts can float in their spacecraft – or outside, on a spacewalk. Heavy objects move around easily. For example, astronauts can move equipment weighing hundreds of pounds with their fingertips. Microgravity is sometimes called “zero gravity,” but this is misleading.

Gravity causes every object to pull every other object toward it. Some people think that there is no gravity in space. In fact, a small amount of gravity can be found everywhere in space. Gravity is what holds the moon in orbit around Earth. Gravity causes Earth to orbit the sun. It keeps the sun in place in the Milky Way galaxy. Gravity, however, does become weaker with distance. It is possible for a spacecraft to go far enough from Earth that a person inside would feel very little gravity. But this is not why things float on a spacecraft in orbit. The International Space Station orbits Earth at an altitude between 200 and 250 miles. At that altitude, Earth’s gravity is about 90 percent of what it is on the planet’s surface. In other words, if a person who weighed 100 pounds on Earth’s surface could climb a ladder all the way to the space station, that person would weigh 90 pounds at the top of the ladder.

____________________________________________________________________________________________

Words to Know

free fall: the condition of moving freely in an environment in which gravity, and nothing else, is causing acceleration

vacuum: the absence of all matter, including air

mass: the measurement for the amount of matter in an object

If 90 percent of Earth’s gravity reaches the space station, then why do astronauts float there? The answer is because they are in free fall . In a vacuum , gravity causes all objects to fall at the same rate. The mass of the object does not matter. If a person drops a hammer and a feather, air will make the feather fall more slowly. But if there were no air, they would fall at the same acceleration. Some amusement parks have free-fall rides, in which a cabin is dropped along a tall tower. If a person let go of an object at the beginning of the fall, the person and the object would fall at the same acceleration. Because of that, the object would appear to float in front of the person. That is what happens in a spacecraft. The spacecraft, its crew and any objects aboard are all falling toward but around Earth. Since they are all falling together, the crew and objects appear to float when compared with the spacecraft.

What does it mean to fall around Earth? Earth’s gravity pulls objects downward toward the surface. Gravity pulls on the space station, too. As a result, it is constantly falling toward Earth’s surface. It also is moving at a very fast speed – 17,500 miles per hour. It moves at a speed that matches the way Earth’s surface curves. If a person throws a baseball, gravity will cause it to curve down. It will hit the ground fairly quickly. An orbiting spacecraft moves at the right speed so the curve of its fall matches the curve of Earth. Because of this, the spacecraft keeps falling toward the ground but never hits it. As a result, they fall around the planet. The moon stays in orbit around Earth for this same reason. The moon also is falling around Earth.

NASA studies microgravity to learn what happens to people and equipment in space. Microgravity affects the human body in several ways. For example, muscles and bones can become weaker without gravity making them work as hard. Astronauts who live on the space station spend months in microgravity. Astronauts who travel to Mars also would spend months in microgravity traveling to and from the Red Planet. NASA must learn about the effects of microgravity to keep astronauts safe and healthy. In addition, many things seem to act differently in microgravity. Fire burns differently. Without the pull of gravity, flames are more round. Crystals grow better. Without gravity, their shapes are more perfect. NASA performs science experiments in microgravity. These experiments help NASA learn things that would be hard or perhaps impossible to learn on Earth.

For the same reason microgravity exists in orbit, it can also be found on Earth. NASA uses airplanes to create microgravity for short periods of time. The airplane does this by flying in up-and-down parabolas. At the top of the parabola, people and objects inside the airplane are in free fall for about 20-30 seconds at a time. For the same reasons, a person can even experience free fall very briefly going over a large hill, like on a roller coaster. Microgravity also can be experienced in amusement park free-fall rides. NASA also uses drop towers to study microgravity. Objects are dropped using special equipment from the top of these tall towers, experiencing free fall as they drop.

NASA Microgravity Site for Students and Educators Fun in Microgravity Picture Gallery NASA – What Is Microgravity? NASA Edge at Physics Day With Microgravity Man Video Podcast

Read What Is Microgravity? (Grades K-4)

Why the US can't send humans to Mars

• Humans have long imagined life on Mars , though our understanding of the planet has changed a lot.
• Some of the US's earliest plans assumed humans could reach the Red Planet by the 1980s.
• Over the decades, technology and funding challenges have hampered the nation's hopes of crewed flights.

Earlier this month, NASA announced it was funding a revolutionary high-thrust rocket — called a Pulsed Plasma Rocket — that could make crewed missions to Mars in just two months.

That's seven months faster than it'd take with current technology, and it would drastically reduce the risk and cost of a crewed Mars mission, according to Howe Industries, which is developing the concept. It "holds the potential to revolutionize space exploration," NASA said in a statement.

The PPR is just one of the latest developments in the US's decadeslong discussion to send humans to Mars . In the early '60s, for example, nuclear-bomb-powered spaceships were proposed for the trip.

Since well before NASA landed the first humans on the moon, the US has poured money and time into proposals for a crewed Mars mission , only to see its attempts never leave the ground. But technology isn't the only thing standing in the way. Politics also plays a big role .

"That's kind of like a joke within the space community or the Mars community," Matthew Shindell, a curator with the National Air and Space Museum, told Business Insider. "Putting humans on Mars is always 20 years away."

He said it was short enough to seem tangible but long enough that the political situation would change before it could be realized.

To fully understand why the US hasn't sent humans to Mars despite sending more robots there than any other country, it just takes a trip down memory lane. Here's a history of the US's most promising crewed Martian missions that never were.

1950s: The Mars Project

In the '40s and '50s, no one really knew what they might find on Mars, but they knew getting there would be tricky. One of the first to seriously tackle the problem was Wernher von Braun.

During World War II , von Braun was a member of the Nazi party and created V-2 missiles . After the war, he continued his work on missiles with the US Army as part of Operation Paperclip while also working on a novel called "The Mars Project." In it, he laid out the first detailed plan to send humans to the Red Planet.

He envisioned a 260-day mission that would launch in 1985 with 10 spaceships and 70 crew members. "He sat down and did the math and created a whole story around it," Shindell said.

In the late '50s, von Braun consulted on NASA's very first 10-year plan, which included sending the first probes to Mars. (Sending humans to Mars would come later.) What started as fiction got closer to reality when von Braun started working at NASA a couple of years later.

1960s: Mars by 1965

In the late 1950s, Theodore Taylor, who worked on nuclear weapons at Los Alamos , and the theoretical physicist Freeman Dyson embarked on an ambitious plan to build a nuclear-explosion-powered spaceship.

Named Project Orion, the resulting ship would take 12 years to develop, cost $100 million a year, and comfortably hold 150 people. Their motto was "Mars by 1965, Saturn by 1970." But NASA was concerned about what would happen if any of the hundreds of bombs required to fuel the rocket exploded.

By 1963, the team was having trouble getting increased funding. That same year, the Limited Test Ban Treaty was signed, hampering the team's ability to test its vehicle.

The project was canceled a year later.

1965: Mars' first close-up

Though NASA was feverishly working toward the moon in the '60s, it didn't fully abandon its plans for Mars.

In 1962, the German rocket scientist Ernst Stuhlinger was working at NASA on a project to get five crewed ships to the Red Planet by the early 1980s.

Stuhlinger's planned ships were huge, almost 500 feet long. For comparison, NASA's Space Shuttles are under 200 feet. But as NASA raced to land the first humans on the moon, it shifted focus to smaller, lighter spacecraft. This helped speed things along toward the moon, but it was a step back for Mars.

This pivot "reduced Apollo's utility as a technological stepping stone to Mars," David S. F. Portree wrote in "Humans to Mars: Fifty Years of Mission Planning, 1950-2000."

In the meantime, NASA knew it needed more information about Mars before it landed humans there. So, in 1964, NASA's Jet Propulsion Laboratory launched the very first probe to fly by Mars: Mariner 4 .

The images the probe transmitted to Earth were fuzzy and showed a desolate, barren planet. But they were the first close-up images of Mars's surface that anyone on Earth had seen.

1970s: The post-Apollo plans

NASA had just landed the first people on the moon in 1969 as part of its Apollo Program and was ready for the next big step. That same year, a Space Task Group appointed by President Richard Nixon issued a report that supported human flights to Mars in 1982.

But Nixon ignored most of the 1969 report's suggestions in favor of what would become the Space Shuttle program , which didn't involve going to Mars. It was a turning point for NASA.

During the height of the Apollo era, NASA didn't have to compete for funding, Shindell said. Now, Nixon's administration started cutting its budget.

This was during the Vietnam War , and many Americans wanted the government to focus on poverty, the environment, and other domestic issues.

"If you're a proponent of human Mars exploration, this is the problem you've faced ever since the 1970s," Shindell said. Sending humans to the moon was already incredibly expensive, and it's a lot closer than Mars.

1980s: Sally Ride's report

In 1985, President Ronald Reagan appointed the National Commission on Space to envision the next 50 years of space travel, which involved the possibility of piloted vehicles to Mars.

But then NASA's Space Shuttle Challenger exploded. The disaster affected how the agency thought about human space travel as a whole.

"In general, there was a great deal of soul-searching within NASA about the use of expensive and risky human-rated launch vehicles like the shuttle," William Sheehan and Jim Bell wrote in "Discovering Mars: A History of Observation and Exploration of the Red Planet."

Just a year later, though, NASA's administrator tasked the astronaut Sally Ride with laying out the agency's future space explorations. In her report, she explained what it would take for the US to land an astronaut on Mars by 2005.

To meet that timeline, NASA would need to triple its current budget in the next decade. That didn't happen.

1989: 20 years to Mars

By 1989, a crewed mission to Mars seemed back on the table, according to a speech by the newly elected president, George H.W. Bush.

" Why Mars?" he asked. "Because it is humanity's destiny to strive, to seek, to find. And because it is America's destiny to lead."

NASA's response was the Space Exploration Initiative, an analysis of Bush's space-exploration goals, which would cost an estimated $400 billion to $500 billion.

At that point, Mars was still a long way off. The missions weren't expected to begin until after 2010.

But Sheehan and Bell said a lack of congressional funding and political support led to the demise of Bush's Martian mission a few years later in 1993.

1990s: "Better, faster, cheaper"

By the 1990s, Mars enthusiasts were dreaming of getting humans there by the end of the millennium. The aerospace engineer Robert Zubrin formed the Mars Society, an advocacy group pushing for the planet's exploration and eventually establishing a human settlement there.

NASA was meanwhile trying to figure out how to study Mars after losing contact with the robotic probe Mars Observer in 1993. With so much still unknown about the planet, uncrewed missions continued to be the focus.

The agency's new administrator, Daniel Goldin, was pursuing a new mantra for the robotic missions: "better, faster, cheaper."

This decade saw success with the uncrewed Pathfinder and Mars Global Surveyor missions. Pathfinder delivered Sojourner, the first operational Mars rover, while MGS sent back incredible images and data from the planet .

Just a couple of years later, though, NASA lost two more uncrewed spacecraft, the Mars Polar Lander and the Mars Climate Orbiter.

2000s: But first, the moon

Despite the setbacks of the Polar Lander and MCO, NASA again had success in 2004 with rovers Spirit and Opportunity .

Though NASA had recently suffered another tragedy with the loss of the Space Shuttle Columbia and its crew in 2003, the agency's rovers seemed to reignite some of the desire for human missions to Mars.

In 2004, 15 years after his father's space speech, President George W. Bush announced what would become the Constellation Program. The ultimate goal was to put people on Mars, though there was no exact date given for this part of the plan.

A large part of Bush's vision involved returning to the moon before heading to the Red Planet. In 2010, President Barack Obama canceled Constellation but set a timeline of getting astronauts to Mars by the 2030s.

2010s: Mars goes commercial

In the 2010s, private space companies — such as SpaceX — started planning projects to get crews to Mars.

SpaceX's founder, Elon Musk, said in 2016 that he'd get people there in less than a decade . He later revised the date to 2029 with robust colonization by 2050.

So far, SpaceX hasn't sent anything to Mars.

President Donald Trump meanwhile reversed the Obama administration's space-exploration plans. NASA was again planning for a moon-first agenda .

Established in 2017 under the Trump Administration, NASA's Artemis Program is its latest and current mission for crewed deep-space exploration. It aims to return humans to the moon and create a lunar space station where astronauts can live for weeks or months at a time.

But this moon-first agenda doesn't completely rule out Mars. Dayna Ise, who leads NASA's Mars Campaign Office, said it would actually help us get to the Red Planet.

"You learn a lot by going to the moon, but you learn even more by staying at the moon," she said. "And so whatever we learn there will help with Mars."

She also said private space companies had a role to play. "It's all hands on deck," she said. "It is such a difficult engineering problem that we cannot exclude anybody from helping."

2020s: Simulating life on Mars

The private space companies have been busy this decade. This year, SpaceX had its first mostly successful Starship launch after several fiery attempts. The mega-rocket is set to play a huge role in Musk's plans to colonize Mars.

The Biden Administration has meanwhile continued to support the Artemis lunar missions. There have been a few setbacks, though.

Citing safety and technical challenges, NASA recently pushed back its first crewed Artemis mission to the moon, which is now scheduled for 2025.

Artemis IV, NASA's mission to deliver part of a lunar space station to the moon, is still scheduled for 2028.

Ise said having a long-term presence on the moon would help experts learn more about how crews could survive on a different world for longer than a few days.

The agency is also studying how people will fare in isolation. NASA's CHAPEA missions put volunteers in a simulated Mars habitat for a year. The "analog astronauts" follow strict schedules, have limited contact with loved ones, and are closely monitored. The first crew is set to emerge from the habitat this year on July 6.

2030s and beyond: Getting humans to Mars

Despite its moon-first agenda, NASA knows Mars has its own challenges that the lunar surface can't prepare them for. In addition to taking a lot of time and fuel to get there, the trip is expected to result in communication delays of at least 20 minutes between the crew and Earth.

Ise said the travelers would need to be able to take care of their own health emergencies and fix hardware issues. But NASA is also working on making some systems more autonomous . "If there is an issue, they don't have time to troubleshoot with someone on the ground to fix their life support system," she said. "So we need those life support systems to be smarter."

Other problems include keeping the crew safe from radiation, dealing with the planet's skin-irritating dust, and developing a food source . "We have to build an ecology inside a transit vehicle to keep everyone alive and healthy," Ise said.

All that will take time. NASA's administrator, Bill Nelson, has said there's potential for the agency to send humans to Mars by 2040 . Ise compared it to eating an entire elephant. "We're doing it one bite at a time and building on everything that we learn," she said.

It remains to be seen whether private US companies will reach Mars first.

Correction — May 28, 2024: An earlier version of this story misstated Virgin Galactic's space exploration goals. Virgin Galactic has not announced plans to send robots or humans to Mars.

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