The six Apollo lunar landing missions demonstrated the value of manned exploration of planetary surfaces. The astronauts were able to set up scientific instruments, choose the most interesting samples for collection, and study the geology of the lunar surface.
An Apollo 11 astronaut carries a small scientific instrument station to be set up away from the Lunar Module. This station and several others are still transmitting data to Earth. Since the first Mars rover Sojourner traversed the rocky plain of Ares Valles, increasingly sophisticated vehicles have explored the hills and plains of Mars.
Marie Curie is the flight spare, or backup vehicle, for the Sojourner rover that operated on Mars in Sojourner traveled about meters feet across the Martian surface with a top speed of 1 centimeter 0.
It was the first to test a "rocker bogie" mobility system, designed to prevent rovers from tipping over in their exploration of the rocky surface of Mars.
Mars makes a complete orbit around the Sun a year in Martian time in Earth days. Mars is a rocky planet. Its solid surface has been altered by volcanoes, impacts, winds, crustal movement and chemical reactions. Mars has a thin atmosphere made up mostly of carbon dioxide CO 2 , argon Ar , nitrogen N 2 , and a small amount of oxygen and water vapor. Several missions have visited this planet, from flybys and orbiters to rovers on the surface. The first true Mars mission success was the Mariner 4 flyby in At this time, Mars' surface cannot support life as we know it.
Current missions are determining Mars' past and future potential for life. Mars is known as the Red Planet because iron minerals in the Martian soil oxidize, or rust, causing the soil and atmosphere to look red. In the late s when people first observed the canal-like features on Mars' surface, many speculated that an intelligent alien species resided there.
This led to numerous stories about Martians, some of whom invade Earth, like in the radio drama, "The War of the Worlds. Countless stories since have taken place on Mars or explored the possibilities of its Martian inhabitants.
Movies like "Total Recall" and take us to a terraformed Mars and a struggling colony running out of air. A Martian colony and Earth have a prickly relationship in "The Expanse " television series and novels.
And in the novel and its movie adaptation, "The Martian," botanist Mark Watney is stranded alone on the planet and struggles to survive until a rescue mission can retrieve him. Mars is a cold desert world. It is half the size of Earth. Mars is sometimes called the Red Planet. It's red because of rusty iron in the ground.
Like Earth, Mars has seasons, polar ice caps, volcanoes, canyons, and weather. In JPL's clean rooms, we found evidence of microbes that have the potential to be problematic during space missions. These organisms have increased numbers of genes for DNA repair, giving them greater resistance against radiation, they can form biofilms on surfaces and equipment, can survive desiccation and thrive in cold environments.
It turns out that clean rooms might serve as an evolutionary selection process for the hardiest bugs that then may have a greater chance of surviving a journey to Mars. These findings have implications for a form of planetary protection called "forward contamination".
This is where we might bring something accidentally or on purpose to another planet. It is important to ensure the safety and preservation of any life that might exist elsewhere in the Universe, since new organisms can wreak havoc when they arrive at a new ecosystem.
Humans have a poor track record of this on our own planet. Smallpox, for example, was spread on blankets given to Indigenous people of North America in the 19th Century. Forward contamination is undesirable from a scientific perspective too. Scientists need to be sure that any discovery of life on another planet is genuinely native there, rather than a false identification of an alien-looking, but Earth-grown, contamination.
Microbes could potentially hitchhike their way to Mars, even after pre-launch cleaning and exposure to radiation in space. Their genomes may change so much that they look truly otherworldly.
We have recently seen that novel microbes have evolved on the International Space Station. Although Nasa's engineers work hard to avoid introducing such species into the Martian soil or air, any signs of life on Mars would have to be carefully examined to ensure it did not originate here on Earth.
Not doing so could potentially spark misguided research into the universal features of life or Martian life. Microbes carried into space can also be of more immediate concern to astronauts — posing a risk to their health and perhaps even causing life-support equipment to malfunction if they become gummed up with colonies of microorganisms. But planetary protection is bidirectional. The other component of planetary protection is avoiding "backward contamination", where something brought back to Earth presents a potential risk to life on our own planet, including to humans.
This is the theme of many science-fiction movies, where some fictional microbe threatens all life on Earth. But when a Nasa and the European Space Agency Esa mission is launched towards Mars in , it could become a very real consideration — if all goes according to current plans, the Mars Sample Return Mission will bring back the first Martian samples to Earth in Past studies have indicated that Mars samples are very unlikely to contain active, hazardous biology — and Perseverance is looking for any signs that might have been left by ancient microbial life on the planet.
But Nasa and Esa say they are taking additional precautions to ensure all samples returned from Mars will be safely contained in a multi-layered isolation system. There is a chance, however, that if we do detect signs of life on Mars, it could have come from Earth in the first place. Ever since the first two Soviet probes landed on the Martian surface in , followed by the US Viking 1 lander in , there likely have been some fragments of microbial, and maybe human DNA, on the Red Planet.
Given the global dust storms and trace amounts of DNA that might have gone with these spacecraft, we have to be sure we don't fool ourselves that the life we find isn't originally from Earth.
But even if Perseverance — or the missions that preceded it — did accidentally carry organisms or DNA from Earth to Mars, we have ways of telling it apart from any life that is truly Martian in origin. Hidden within the DNA sequence will be information about its provenance.
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