Any discussion on aliens and extra-terrestrial life is incomplete without odd questions, doubts stemming from science fiction, and conspiracy theories. "Yes, there may be aliens out there," said Dr Henry Throop, senior scientist with the Planetary Science Institute, while promptly warning us that they may not resemble the extra-terrestrial beings we know from pop culture. But Dr Throop, who has worked with NASA on its New Horizons and Cassini missions, doesn't mind the questions; he says that it is just indicative of how curious people are about astrobiology and the world around them. "Lay people, filmmakers and scientists have this curiosity. A lot of the subjects that films talk about are tackled by scientists in their research. If you look at films like The Martian, Gravity or Interstellar, these are new science fiction films which have a lot of overlap with the questions that science is seeking to answer," he says.
At a recent talk organised by Awestrich and Space Geeks Mumbai, which asked the question 'Are we alone in the universe?' Dr Throop shed light on where we stand in terms of research about extra-terrestrials. He said that despite the fact that there are 10 raised to 22 stars in our galaxy, 100 billion such galaxies, we have not found aliens thus far, and the sobering truth is that it will take many years for us to reach the star nearest to the Earth outside of our own solar system. "No bacteria has been found, neither have any credible radio signals been received," he said. But enthusiasts should not be dismayed, because NASA and astrobiologists are making progress when it comes to finding planets where life could survive.
Dr Throop took a dive into the history of astrobiology to give a look into how our understanding of planetary bodies outside of the earth and extra-terrestrial life has evolved. Before the theory of heliocentrism was accepted, it was assumed that the Earth was at the centre of the universe. As time passed, humans learnt that there are more stars in the galaxy which resemble the Sun, and that many individual, spiral-shaped galaxies exist in the universe. By the '90s, scientists found that there could possibly be 10 raised to 23 other planets, many of which may be similar to our own. In a gist, he explained how the Earth is not as unique as it was thought to be.
This leads us to the next question: Where should we look for life? Dr Throop cancelled out blackholes (citing the lack of gravity) and the centre of the universe (the pressure levels are too high). One approach could be to consider the factors that are necessary to life on Earth, and find places where these factors are present. "But the issue with such an approach is that exceptions do exist to these rules — as is proved in the case of extremophiles like thermophilic bacteria in the Yellowstone National Park, sea floor bacteria that exist at the bottom of the ocean, cryophilic bacteria that survive and thrive in Antarctic ice," he explained.
However, one of these factors cannot be ruled out — the presence of liquid water. "The search for liquid water is the search for life," said Dr Throop. He explained that life processes involve complex chemistry, which can take place the fastest in solvents, which are liquids (because the molecules can move at a quicker rate). He also said that water is the most commonly found solvent because hydrogen and oxygen are the most reactive elements. "This means that the search for life is ultimately the search for water which exists at the right temperature. Sort of like what Goldilocks did with the porridge — not too hot, not too cold," he said.
According to Dr Throop, there are three places within our own solar system which could be hospitable environments. The first of these is Mars; explorations have shown that it used to have massive water bodies. "This water either evaporated or turned into ice, and we now know that evaporation was the most likely cause of the disappearance of this water. In the recent past, there have been occasional findings of water sources. Debateable fossilised evidence has also been found from Mars," he said. The Mangalyaan launched by ISRO in 2013 looked for methane on the planet, because the presence of methane is indicative of volcanism or biological processes, and the latter is pertinent to our search for life. "The Lonar crater in Maharashtra is the closest analog to Mars on Earth, and inferences about the Red Planet can be drawn from it," he said, "It is a crater formed in a basalt rock system where the salts have leeched out and interacted with the water. Erosion in this crater can teach us about Mars."
The second place is Saturn's moon Enceladus, which has been photographed by the Cassini mission probe, which recently crashed into the atmosphere of Saturn. "Massive plumes of erupting water have been found on Enceladus, which means that there is a heat source there. The third is Jupiter's moon Europa, which was recently found to have a liquid surface. Icy rafts have been found on a smooth surface, which means that there may be a warm ocean underneath this icy shell, where life can grow and evolve," he said. Enceladus and Europa's 'wet and warm' state make them more likely candidates for supporting life than Mars.
But it is possible that life on other planets may not even remotely resemble life on Earth? Dr Throop warned that we must be careful in our biases, but that some things can be said with certainty. "Chemistry cannot take place at 10,000 degrees Celsius! Life can't exist at such high temperatures," he explained. He mentioned that solvents other than water, such as hydrogen fluoride, are also viable, and that while carbon is the building block of life on Earth, it could possibly be composed of other elements. "There's nothing as good as carbon, but that's a carbon-based creature saying this!" he observed. How much of what we know is an educated guess, and how much of it is based on evidence? "Zero percent is proof-based. It's all a guess, because we've never actually found any life. When we detected exoplanets, we realised that all our predictions were wrong," he informed.
He talked about how The Martian was a realistic representation of what Mars is like, adding that it is actually possible to grow potatoes on this planet like Matt Damon did in the film. However, he pointed out that there was one major plot flaw. "The powerful sandstorm which is the reason why Matt Damon gets left behind on Mars cannot occur, because the planet's atmosphere is too thin," he said.
When asked if he thinks multiverses and parallel dimensions exist, Dr Throop said that it is possible for them to exist in theory. "But equations also allow us to have three-humped camels!" he quipped. Does he, like Stephen Hawking, believe that it is better for the human race to relocate to another hospitable planet? "Does it make sense to uproot ourselves and spend a massive amount of money to settle on another planet, instead of fixing what is wrong with the Earth? I don't think so," he said. He said that even if we look closer home within our own solar system, Enceladus and Europa are not suitable for humans, because they don't have any atmosphere, and they're very cold. "But they may be good for whale-like creatures, because they do have warm water! Could life of some sort live and evolve there? Certainly. We have no idea what the state of evolution is on these moons; it could be nothing, or it could be at a nascent stage. We also don't know how similar the chemistry on these moons will be to chemistry on Earth," he explained.
Another question that is always on people's minds is what scientists will do if alien life is found. "I'm sure there is protocol in place, but mainly they will begin their research and publish papers. It also poses a huge philosophical question," he said, adding that the widely held notion that NASA is hiding information about extra-terrestrials is wrong. "It is our job to tell people our findings, and if we do find something, we will be excited to tell you!" he said.
Updated Date: Jan 29, 2018 17:48 PM