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What Is Mars?
The planet Mars is the fourth from the sun. It is also known as the “red planet” because of its rust-colored hue, created by iron oxide on the ground. It is a terrestrial planet with a surface that combines the impact craters of the moon with Earth-like valleys, deserts, polar ice caps and seasons.
Although Venus is a closer neighbor to Earth, it has scorching temperatures and sulfuric rain that have led scientists and science fiction writers to choose Mars as a focus for humankind’s first interplanetary mission instead.
Why Should Humans Go to Mars?
Mars is alluring as a target for space exploration because it has an atmosphere, water, and geothermal heat—meaning there may be fossils there, or even life itself. Yet so far, we’ve agreed that it has been too dangerous for humans to go look. Even our robotic missions have failed 50% of the time just trying to get there. It’s similar to our attempts to sail the oceans of the world in the 1400s, pushing our technology and understanding to the limit, with many missions failing in the attempt.
But, as technology developed, humans were able to cross the oceans more safely, to great commercial and scientific impact. There are both business and scientific benefits to come from the risks of exploration.
A Brief Timeline of Mars Exploration
Humans have been sending spacecraft into orbit around Mars since the 1960s and onto its surface since the 1970s. Here are some milestones in the history of Mars exploration:
- 1965. NASA’s Mariner 4 probe completes first Mars fly-by, sending photos back to Earth. NASA worked together with its spacecraft development center, the Jet Propulsion Laboratory, on the program.
- 1971. The Soviet landers Mars 2 and Mars 3 becomes the first to contact the Mars surface—but both fail either during descent or shortly upon landing.
- 1976. NASA’s Viking 1 and 2 landers successfully reach the surface and transmit the first color panoramas of Mars.
- 2004. NASA’s Spirit and Opportunity rovers reach Mars and discover evidence that water once flowed on the planet. Opportunity manages to stay operational until 2018.
- 2012. NASA’s more advanced Mars rover, Curiosity, lands at the Gale Crater to search for signs the planet was once habitable.
- 2018. NASA’s InSight lander reaches its landing site in a flat area called Elysium Planitia, with a heat flow probe and seismometer to investigate the deep interior of Mars.
10 Challenges Humanity Must Solve Before Landing on Mars
The technical and engineering challenges of a first manned mission to Mars are daunting. Chris Hadfield has identified 10 areas where we need to make key decisions or develop technologies before humans can land on Mars.
- How to design a long-haul spaceship. Getting to the lunar surface is a three-day trip, so a utilitarian spacecraft will suffice. Going to Mars is a much longer journey, so the spacecraft would need to have more living space, more room for backup systems, equipment for space walks, and— perhaps most importantly—recreation facilities to keep the crew engaged, productive, and sane. Hadfield says to think about ideas put forth in science fiction novels as a window into what the long-haul spacecraft of the future could look like.
- How to cross the solar system. Mars and Earth both orbit the sun, which means the distance between the two planets is constantly changing. If we wait for the optimal alignment and use the best engines we’ve devised, it’s still about five months to get there. That’s a long voyage into the unknown with an unproven ship, hauling everything you need, with no way to resupply critical items. And that’s just the beginning.
- How to weigh time against energy. The path we take between planets needs to be decided. While the Hohmann transfer is the most energy-efficient way of moving between orbits, it is not optimized for speed. Every day we spend in transit is one more day spent eating food, drinking water, breathing the ship’s air, and producing waste, as well as being exposed to interplanetary radiation and the risk of critical systems failures. If we have enough fuel, we could steer a more direct route, brute-forcing the orbital mechanics. If we invent more efficient engines, we could fire them longer and coast less, also decreasing total time. We may continue to decide that it is infeasible to go to Mars with the engines we’ve invented so far.
- How to slow down. On arrival you have to somehow slow to orbital speed, descend through Mars’s very different atmosphere, and safely land. We could fire the engines, but that means we needed to haul that braking fuel as cargo all the way from Earth. We could use Mars’s thin atmosphere to provide braking friction, steering to dip exactly into it to gradually slow to the right speed. But the whole transit ship would need to be tough enough to take the associated heat and pressure.
- How to land. A compromise option might be to jettison the habitat that carried us to Mars, get into a capsule, and ride it directly to the surface. But the Martian atmosphere is much thinner than Earth’s, meaning parachutes don’t work nearly as well. Yet it is thick enough that friction causes heating so the ship needs an appropriate heat shield. The heaviest object humans have landed on Mars (as of 2018) was NASA’s Curiosity Rover, which weighs around one ton (on Earth). A crewed ship would weigh much more. For putting people on Mars, we’ll likely need to use the Martian atmosphere to partially slow down the craft, then fire engines to slow the rate to the surface.
- How to grow food. Growing food in space is a complex proposition; however, solving this problem would provide a sustainable food source and help support the living environment on a spaceship, as plants convert carbon dioxide to oxygen. Experiments are being run on the ISS to explore what types of food can be grown in weightlessness, and eventually on the Moon or Mars. It is likely that a human mission to Mars will have a garden on board and an astronaut trained in horticulture.
- How to deal with weightlessness. Extended weightlessness takes a toll on the human body. We’ve learned from the ISS that there are significant impacts on balance, blood pressure regulation, bone density, and sometimes vision. For astronauts that travel to Mars, there won’t be a ground support team to assist after landing. Depending how long crews need to adapt under Martian gravity (38% of Earth’s), the landing ship may need to function as a rehab facility. The weight and configuration of the Martian spacesuits will also have to allow for this adaptation period.
- How to protect people from the elements. The natural environment on the Martian surface is deadly for human life; very low air pressure, no oxygen, 96% carbon dioxide, and high radiation. The habitat and spacesuits will need to protect the crews from this.
- How to communicate with Earth. Life on Mars will also be psychologically challenging. Even when Earth and Mars are at their closest, 35 million miles apart, it takes radio waves about four minutes to get from here to there. So if the Martian crew transmits “Houston, Hawking Base here,” the quickest they will hear a response is eight minutes later—worst case is 48 minutes later. Real-time communication will thus be impossible, and the Martian crew will need to be self-reliant, technically and mentally. Currently there are simulations looking at possible ways to deal with the communication delay. These include a habitat under the ocean that Hadfield commanded for two weeks, conducting operations with a Martian-representative time delay. One solution that worked well there used recorded video messages sent back and forth, like has often been portrayed in the movies.
- How to do it all in reverse to come home to Earth again. It all sounds very daunting, with a high probability of failure leading to death. But most exploration looked that way at the outset, says Hadfield. It is through incremental improvement of technology and choosing the right moment to take a new risk that explorers have succeeded in the past.
What’s Next for Mars Exploration?
Recent successful Mars missions have provoked discussion about sending humans to the planet in the near future. Current plans include:
- 2020. This is set to be a big year for space exploration, as the European Space Agency, NASA, China and the United Arab Emirates are all planning to launch separate Mars missions, involving either orbiters or rovers.
- 2024. When Vice-President Mike Pence has announced the United States will next put “boots on the moon” as part of a build-up to walking on Mars. This is the same year that Elon Musk has stated his company SpaceX aims to fly the first people to Mars, with the goal of eventually establishing a colony.
- 2033. If the moonwalk succeeds, this is when NASA astronauts will be on track to land on Mars, according to the agency’s administrator, Jim Bridenstine.
Learn more about space exploration in Chris Hadfield’s MasterClass.