There is often discussion about life in space, aliens or Martians or other extra-terrestrials beings, however, it’s not as often asked whether there’s another planet suitable for the human race. As far as we know, the Universe is infinite, meaning there’s likely to be billions of planets and moons and out of these billions, there must be at least one that has conditions so similar to those here on Earth that they’d be suitable for humans to live. The need for another planet is becoming increasingly important too, “I’m afraid we’d better start looking for a new planet” (Robert Shapiro, CEO of the Monsanto Corporation). Human resource consumption, population growth and water scarcity amongst many other things are increasing the strain on the planet we call home. However, since the first man walked on the moon almost 50 years ago, there hasn’t been much of a leap in terms of planetary exploration by foot. So is it too ambitious to start thinking about humans inhabiting another planet? Well, we already are.
In order to find another planet suitable for humans to inhabit, astronomers need to be looking for the right ‘conditions’ for human life. One of the most vital needs for human life to be able to exist and live is oxygen. If the planet has an atmosphere containing oxygen, then we are one step closer in the search for finding the second Earth, however there have not yet been many discoveries of planets, nor moons, oxygen-rich atmospheres. Having said this, there is one planet ‘relatively close’, a mere 39 light-years away, that is believed to have an oxygen-rich atmosphere, Gliese 1132b, but at 450F, it won’t meet the conditions of Earth 2.0 . Nonetheless, if a planet does not have an oxygen-rich atmosphere, technological advancements may soon mean that this won’t be an issue. NASA’s next rover launch to Mars will be able to generate oxygen from the red planet’s atmosphere . If successful, this revolutionary technology may make finding a habitable planet for the human race much easier. It is also important that Earth 2.0 has an atmosphere which contains gases such as carbon dioxide keeping the planet warm and that protect the planet from radiation from its parent star. If the planet (or moon) were to have a molten core, it would be a source of geothermal energy, another way of keeping the planet warm. This would also set up a magnetic field, being another way of protecting it from radiation. For the human race to actually be able to survive on another planet, they will need natural resources such as coal and natural gas. These could then be utilised to provide an energy source on the new planet. However, humans could also utilise ‘Earth 2.0’s’ natural processes such as wind and sunlight to create sustainable sources of energy. If astronomers were to find a moon or planet with all or most of these conditions, it could quite possibly be the perfect Earth 2.0.
Arguably Mars, Earth’s red neighbour, has many of the right conditions for humans to survive. Mars has an atmosphere containing over 90% carbon dioxide and traces nitrogen, but its atmosphere is 100 times less dense than Earth’s meaning it is much thinner and therefore doesn’t retain much, if any, heat from the Sun . Mars is further away from the Sun to Earth, reflected in its temperature ranges from -153°C at the poles to 20°C in the summer at the equator, however, at high latitudes, temperatures can exceed 0°C . Although this is much colder than Earth, the coldest temperature ever recorded on Earth is -89. If appropriate technology was available, the temperature on Mars would be able to support human life. Additionally, essential resources needed to support human life, such as oxygen, nitrogen and water have been found on Mars . For humans to survive, there will need to be an energy source. Potentially, this could be produced by solar and wind power on the planet. Mars is currently the best-known candidate for Earth 2.0, mainly due to its closeness to Earth making it easy to investigate. There have been proposals to send thousands of people to Mars in the next decade or so as part of Elon Musk’s SpaceX plan and believes it may even be possible for humans to fly to “Mars by the mid-2020s” . However, the likelihood of humans stepping foot on Mars in the next 10 years is not very high.
Even though Mars has many of the qualities needed for the human race to survive, the best way to find an Earth 2.0 is searching for exoplanets. Exoplanets are planets orbiting another star, coming in all sizes – some bigger than Jupiter and some smaller than Earth . There are likely to be other planets outside of our solar system that have the right conditions to support human life. For example, Trappist-1, an ultra-cool red dwarf star, has 7 Earth-sized planets orbiting around it, 3 of which are found in the habitable zone. If an exoplanet is found a certain distance away from their parent star (or stars in binary star systems), it may have the right conditions on its surface to support liquid water. This distance is known as the habitable zone. Out of the 3,550 exoplanets that have been discovered (as of 11th February 2017) , 52 are considered habitable. Therefore, if these planets have atmospheres that contain gases such as oxygen or methane, they might have perfect conditions for life as we know it to exist. To date, the most Earth-like exoplanet discovered is Kepler-438b, orbiting the red dwarf star Kepler-438. It has a mean temperature of 3°C, Earth’s mean temperature being 16°C, therefore it is close to that of Earth’s. The planet is orbiting in the habitable zone meaning liquid water could exist. Moreover, on the Earth Similarity Index (ESI), a measurement of how similar planets are to Earth, Kepler-438b measures 0.88, with 1.0 being the most similar. However, it is not considered habitable due to the large amount of radiation it receives from its parent star every 100 days due to solar flares. Additionally, Kepler-438b has an orbit of 35.2 days meaning it is likely to be tidally locked because of this close orbit. It’s also 470 light years from Earth so unlikely to be Earth 2.0 anytime soon .
Another possible candidate for Earth 2.0 is Gliese 581g, an unconfirmed exoplanet, 20 lightyears from Earth, also known as the Goldilocks because of its perfect conditions it is thought to have. It is in the middle of the habitable zone around Gliese 581, a red dwarf star. However, because the temperature of red dwarf stars are much lower than that of our Sun, for example, planets orbit much closer to their parent star compared to here in the Milky Way meaning Gliese 581g is tidally locked meaning one side is in eternal darkness . The temperature is thought to range between -31 to -12 habitable for humans, although a little on the chilly side. It is thought to be tidally locked because of the close proximity to the parent star .
The easiest way to find a planet habitable for the human race is to look for surface water, this is because everywhere there is water, on Earth, there is life. However, maybe another way to find Earth 2.0 is to look for geographical landmarks similar to those on Earth, such as deserts. These landmarks may be another way of providing a link between Earth and other potential worlds. Volcanoes, for example, are found not just on Earth. The largest volcano in the solar system is on Mars. Olympus Mons reaches 26km, over 3 times taller than Everest . There is geological evidence on the sides of Olympus Mons suggesting the existence of lakes 210m, which is relatively recent in terms of geological history. Like Mars, Jupiter’s moon, Io, is thought to have over 400 volcanoes and more than 150 of these are active . Additionally, Triton, one of Neptune’s moons, is active with eruptions of ammonia lava and icy volcanoes. Craters are commonly found on moons, however, because Triton is so geologically active, they are quickly erased. However, volcanic activity is often associated with inhospitable land for humans as well as other forms of life as we know, but volcanoes do offer benefits for life on Earth meaning they may also offer benefits if Earth 2.0 is home to some volcanoes. Volcanic rock is filled with minerals which provide rich nutrients meaning that some of the most fertile soil is found at the base of volcanoes. The fertile land would help during the expansion of the human race on Earth 2.0. Therefore, looking for volcanoes as well as signs of water on other planets could show how habitable the planet is and narrow down the search for Earth 2.0, but this may be a little far-fetched.
We are seeing planets in the past. The Sun is 29 million miles away taking light 8 minutes to travel between Earth and the Sun. Many of the galaxies we know of are light-years away meaning we are seeing them in the distant past. The Earth is 4.568 billion years old meaning if we were looking at Earth from 4 billion light-years away, there would not be any signs of life. Therefore, maybe the technology being used to find habitable planets needs to be updated in order to find the best possible results. Additionally, the transportation methods that will be needed to travel to Earth 2.0 will need to be more advanced then are currently available. In 2015, NASA successfully tested the Space Launch System, which is part of the space exploration of a manned mission to Mars. This is the most powerful rocket ever made, however, it is unknown whether it’ll actually make it to space due to funding issues . The launch date of this mission has already been pushed back from November 2018 to sometime in 2019 reflecting the probability of finding Earth 2.0 anytime soon.
“If everyone on the planet consumed as much as the average US citizen, four Earths would be needed to sustain them” . With need for Earth 2.0 being increasingly more important, the likelihood or finding a planet, or moon, habitable for humans anytime soon is not increasing. However, the chance of there being at least one other planet suitable for the human race to inhabit are very high, considering the number of confirmed exoplanets as well as the thousands still to be discovered. But the likelihood of coming across a planet with the right conditions, especially with our current technology, is not so high. There are several candidates for Earth 2.0 out there, some more likely than others and when we do eventually find a truly habitable planet for the human race, it will be a small step in terms of calling this planet home, but will be the beginning of a process that will be a giant leap for mankind. However, would contaminating another pristine planet be the right solution to the crises developing here on Earth?