Exobiology
Extra-terrestrial Life, I’m Coming for You!!
“Two possibilities exist: either we are alone in the Universe or we are not. Both are equally terrifying.” sci-fi author Arthur C Clarke.
Remember when the internet blew on how everyone would raid Area 51 to find aliens? Or remember when you were young and saw cartoons of aliens? It’s pretty safe to say that at some point in our lives, each one of us has pondered upon the possibility of extra-terrestrial life existing.
“Where is everybody?” This is the famous quote from Enrico Fermi that asks the world to think about the existence of life from other planets. The universe is very old and infinitely huge. We would think that from all this time, there would be a record of meeting extra-terrestrial life, and yet there is none. Now that’s very disappointing, isn’t it? Scientists found it pretty disappointing as well and guess what? They decided to make an entire branch of science dealing with extra-terrestrial life which is none other than…exobiology!
A Very Obvious Definition
Exobiology, or Astrobiology, is a branch of biology concerned with the search for life outside the earth and studies the origins, early evolution, distribution, and future of life in the universe. This field of science considers the question of whether extra-terrestrial life exists, and if it does, how humans can detect it. To investigate the possibility of life outside our planet and help recognize biospheres that might be different from that on Earth, exobiology makes use of molecular biology, biophysics, biochemistry, astronomy, exoplanetology etc.
So, how do I know if a planet supports life? Am I supposed to roam around planets, find a bacterium one day and say hello?
Well, not really. When we look for life on other planets like earth, we make some simplifying assumptions and consider certain factors that ease the task of an exobiologist.
- Our first major assumption is that a vast number of life forms in our galaxy are based on carbon chemistries, as are all life forms on earth. Carbon is the 4th most abundant element in the universe. It can form a variety of molecules because of its properties like Tetravalency and Catenation. Carbon-based life on earth is the ‘gold standard’ by which exobiologists tell us that extra-terrestrial life is ‘possible’.
- Another assumed requirement is the presence of liquid water. This is because it is a very common molecule, and carbon along with liquid water provides an amazing environment for formation of complicated carbon-based molecules which would eventually lead to the formation of life.
- Our next assumption, which increases the probability of extra-terrestrial habitability, is to majorly focus on planets that revolve around stars like that of the sun. The sun is a medium star, neither too large nor too small. Massive stars have a very short lifetime and are often ‘too hot’ which would mean that life wouldn’t get enough time to emerge and evolve; whereas miniscule stars have little energy, thus providing a small amount of heat and warmth to the planets revolving it. In this case, most planets revolving around would be frozen-solid and the ones which are extremely close to the stars would be tidally locked to it.
- Red Dwarfs, which are very common in the universe, have a long lifetime and could allow emergence of life in planets which have thick atmospheres. However, modern evidence shows that existence of life is ‘unlikely’ in red dwarf systems due to their low stellar flux, high probability of tidal locking and very small habitable zones.
A Tiny Problem Here…
So, we made all these assumptions which made the work of exobiologists a lot better. However, we don’t have any evidence to prove the validity of the assumptions we made, as earth is the only known planet to support life.
Also, all these assumptions insist that all life everywhere must always follow the same evolutionary model. We can only know these processes here on earth. Even on earth, there have been many instances where life shouldn’t be possible but it still exists.
Plant life still exists in the absence of photosynthesis; Life living in the heat vents of volcanoes in the South Pacific has been discovered, that has been said to not be possible; In the depths of the oceans, life exists under conditions where life shouldn’t be able to survive. So, we cannot deny the possibility of life existing in a ‘hydrogen’ or a ‘methane’ environment.
Ehh…Aliens don’t know how to speak English
What do we do when we feel alone? We try and talk to someone right? Our poor exobiologists felt lonely as well and decided to make an organisation that could talk to extra-terrestrial life!
The communication with extra-terrestrial intelligence (CETI) is a branch of the search for extra-terrestrial intelligence (SETI) that focuses on composing and deciphering interstellar messages that theoretically could be understood by another technological civilization. It focuses on 4 broad areas for detecting and deciphering “natural” language communication:
- Mathematical Languages
- Pictorial Systems
- Algorithmic communication systems (ACETI)
- Computational approaches
There are multiple organisations and individuals who are engaged in CETI research. The most popular experiment of CETI was the 1974 Arecibo message composed by Frank Drake. It was an interstellar radio carrying basic information about humanity and Earth that was sent to globular star cluster M13 in 1974.
Interestingly, some researchers have come to a conclusion that in order to communicate with extra-terrestrial species, we first must try to communicate with earth’s intelligent animal species. A very popular example of this is John C. Lilly. He worked with interspecies communication by teaching English to the dolphins and he was successful with the rhythms.
Enough with theories; it’s Mission Time!
Exploring the solar system and beyond will help us answer fundamental questions about life beyond our home planet. From studying the habitability of Mars, probing promising “oceans worlds,” such as Titan and Europa, to identifying Earth-size planets around distant stars, scientists are working together with a goal to find unmistakable signs of life beyond Earth.
So now, let us dive deep into some important NASA missions for searching for life in the universe.
Viking 1 and 2
Over 45 years ago, the Viking Project became the first U.S. mission to land a spacecraft safely on the surface of Mars. It was NASA’s 1st attempt to search for life on another planet and also the first mission dedicated to exobiology. Viking 1 and 2, each consisted of an orbiter and a lander. Its experiments revealed unexpected chemical activity in the Martian soil, but failed to provide any clear evidence for the presence of any microorganism.
Cassini
The Cassini spacecraft shared the images of Saturn and its icy moons for more than a decade. Exobiologists were able to see through the thick atmosphere of Titan and study the moon’s surface, where they found lakes and seas filled with liquid hydrocarbons. They are studying what these liquid hydrocarbons could mean for life’s potential on Titan.
Galileo
Galileo orbited Jupiter for about 8 years and returned data such as Jupiter’s icy moon Europa having evidence of a subsurface ocean with more water than the total amount of liquid water found on Earth!
Curiosity
It’s been nearly ten years since Curiosity mars rover touched down on Mars in 2012, and the robot geologist keeps making new discoveries. It is studying whether Mars ever had elements of supporting microbial life. Curiosity provided evidence that freshwater lakes filled Gale Grater billions of years ago. Lakes and groundwater persisted for millions of years and contained all the key elements necessary for life, demonstrating Mars was actually once habitable. Breath-taking, isn’t it!?
Hubble
Ah yes, how can we forget about this legend! Since it launched in 1990, the Hubble Space Telescope has made immense contributions to exobiology. It has been used to make the first measurements of the atmospheric composition of extrasolar planets, and is now vigorously characterizing exoplanet atmospheres with constituents such as sodium, hydrogen, and water vapor. Hubble has also been used to study bodies within the solar system, including asteroids, comets, planets, and moons, such as the intriguing ocean-bearing icy moons Europa and Ganymede. Hubble has provided invaluable insight into life’s potential in the solar system and beyond.
Future of Exobiology
While it is pretty sad to say that there have been no signs of extra-terrestrial life, it doesn’t mean we are alone in this universe. I mean I’m no scientist to say it with 100% certainty but the scientists aren’t giving up hope, so why should we, right?
So, what now? Is there any future to this field of science? Fortunately, the answer to the question is a big YES this time. The answer to the future of exobiology is the formal successor to the Hubble Space Telescope i.e., the James Webb Space Telescope (JWST).
James Webb Space Telescope- A Hero
The James Webb Space Telescope (sometimes called JWST or Webb) is a large infrared telescope with a 6.5-meter primary mirror. The James Webb Space Telescope was launched on 25 December 2021. The Webb telescope will be the premier observatory of the next decade, serving thousands of astronomers worldwide. It will study every phase in the history of our Universe, ranging from the first luminous glows after the Big Bang, to the formation of solar systems capable of supporting life on planets like Earth, to the evolution of our own Solar System.
The Webb telescope will also be capable of making detailed observations of the atmospheres of planets orbiting other stars, to search for the building blocks of life on Earth-like planets beyond our solar system.
The Webb telescope was formerly known as the “Next Generation Space Telescope” (NGST); it was renamed in September 2002 after a former NASA administrator, James Webb. This telescope has a plethora of innovative technologies. Webb’s biggest feature is a tennis court sized five-layer sunshield that attenuates heat from the Sun more than a million times.
The telescope has several key goals out of which the most important one for exobiology is; to study planetary systems and the origins of life.
Conclusion
One simple question asking,” Where is everybody?” and the nature of humans of not wanting to be alone has changed our understanding of life completely. Unless some random civilisation finds us, invades us and destroys us completely, the future of our species in terms of space exploration is looking amazing. If we turn out to be lucky (I mean super lucky), then one day, you might find yourself reading this article with an alien friend of yours sipping a cup of tea.
