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Chaitanya GIRI
Astro-bio-chemist @European Space Agency's historic Rosetta Mission

Hello there! My name is Dr. Chaitanya Giri.

I am an astro-bio-chemist – someone whose research interests are interwoven in astronomy, biology and chemistry – and I work as a scientist within the framework of European Space Agency’s Rosetta mission to comet 67P/Churyumov-Gerasimenko. If you could recall the science fiction movie Deep Impact you would be able to comprehend what landing on a comet is like! Unlike the comet in the movie, comet 67P is not set to collide with the Earth and neither Rosetta is a manned mission! Rosetta’s motivation was to get familiarized with the enigmatic comets from very close proximities.

I had a rare opportunity of working on the Cometary Sampling and Composition Experiment (COSAC), a custom-built miniature analytical instrument on board the Philae Lander of Rosetta mission that is aimed at examining the organic (molecules predominantly containing carbon, oxygen, nitrogen, & hydrogen) ingredients of comet’s surface. Our team, with COSAC, has successfully identified 16 organic molecules from the comet’s surface. These are some of the first organic molecules to have been identified on comet’s surface. 4 out of these 16 molecules were identified for the very first time on any comet. Some of them are known chemical precursors of prebiotic species such as sugars, amino acids, nucleotides and nucleosides. These prebiotic species are known to be the basic building blocks of biological life on Earth.

How were these biologically significant molecules created on comets? When were these molecules synthesized, ten, thousand, million or billion years ago? Do these comets deliver any such material and water on Earth today? How do these comets come from peripheries of interstellar space to near-Earth space? Did these comets play any role in the origin of life and oceans on Earth?

Happy to share my knowledge with you and answer all these and more questions! Space exploration, missions, technologies, science, career! AskMeAnything!

What are your thoughts on NASA's discovery that Mars had a long-lasting series of lakes? http://www.latimes.com/science/sciencenow/la-sci-sn-mars-lakes-curiosity-20151008-story.html

I was very happy to see this confirmative discovery. Kudos to the principlal investigating team! This discovery has greatly rejuvenated the will to explore Mars.

Some five years ago, I participated in a geological expedition (led by renowned geologists Goro Komatsu and Takafumi Matsui) where we deemed Lonar Crater in Maharashtra, India as an analogue of Dogana Crater on Mars. Both these craters, located on two different planets, appear morphologically similar! Our team demonstrated that Dogana has features - drainages on the slope of the crater, incised valley, a delta, and a flat floor - all created due to water-driven geological processes. We purported, Dogana apparently hosted a lake at the bottom of its crater in the past as Lonar does today. The recent discovery has demonstrated water-driven activities on the surface of Mars. Our and other similar findings are now supported by this confirmation!

Water on Mars could be a driving force for the 'possibly-existing' life on Mars. The NASA Mars Science Laboratory and the upcoming ESA-Roscosmos ExoMars rover (launch in 2018) will have much to say about any signatures of life on Mars. My colleagues here at the Max Planck Institute for Solar System Research, led by Dr. Fred Goesmann, would be contributing with a payload called Mars Organic Molecule Analyzer (MOMA) for the ExoMars rover. MOMA is the next-generation version of COSAC that identified organics on comet 67P. MOMA would try to override the perchlorate-related detection issues (a major hurdle towards identification of Martian organics) and if all goes well it would be able to identify Martian organics in a much better way. Water on Mars is also a great prospect for future human habitation, however much needs to be studied before that actually happens.

Do you think it's possible for a different kind of life that's very different than our (meaning they are not carbon-based or they don't need H2O but drink something else) to exist somewhere out there?

Like most of us, I believe there could be many distinct alien lives existing out there. But I do not have a definite answer on the 'possibilities' of such lives existing! The latter needs extensive details. Presently several non-carbon chemistries consisting of elements like silicon, boron, and arsenic are being hypothesised. Regarding the drinks, alien lives could share similar affinity for water or they could have a different taste altogether! They could prefer drinking (I liked that word!) hydrogen cyanide, ammonia, methane or ethane. Scientists therefore presently are researching to know more about the last common ancestor of all life forms on Earth, the clues from which could help us contemplate over the chemistry of alien lives. Of the several biochemistries presently studied, one of the most mature is that of 'alternative chirality'. I had the privilege of working on alternative chirality with my PhD supervisor Uwe Meierhenrich, who happens to be a well-known authority on this subject. The concept stems from the fact that the carbon-based life on Earth is exclusively made up of left-handed amino acids and right-handed sugars, but we do not know the phenomena that led to this exclusivity. There are many theories attempting to answer this quest. One of the strongest being the following. In 1998, astronomers observed that 'birthplaces' of stars emit certain types of radiation that have the ability to create a bias towards a certain handedness. Prof. Meierhenrich's team, including me, tried to simulate this process at a high-tech radiation facility near Paris. We bombarded a starting mixture, containing 50% each of both left- and right-handed amino acids, with varying radiation. On bombardment we were successfully able to create biases towards a certain handedness i.e. using left-handed radiation we destroyed right-handed amino acids, which led to abundance of left-handed amino acids and vice versa. We thus have an inkling that sometime in the past before the origin of life, Earth possibly could have received already-biased molecules. On Earth few bacterial species utilise right-handed amino acids, however it is restricted only to these simple life-forms. As we go higher up the ladder of life, complex organisms like us dominantly utilise the left-handed amino acids for biochemical functions. Therefore, if we encounter complex life-forms - like mammals/reptiles/plants - with right-handed amino acids and left-handed sugars, they would be deemed biochemically alien to us. Simply putting, our mirror-images would be alien to us!

What is your team working on next? What happens to the the rocket that is currently circling the comet?

My team is currently trying to revisit the data that we gathered in November 2014. Our first interpretations (the sixteen organic molecules) are out in the public domain. By revisiting we aim to identify those molecules that we were less confident...This knowledge is worth millions but signing up is free
What are your thoughts on Elon Musk's ambition to Colonize Mars?
Ambition, Plan, Proposal, Design - these are the four consecutive initial stages in realising any exploratory project. As for the human colonisation of Mars, most of the space agencies have been ceasing to move beyond their respective mission desi...This knowledge is worth millions but signing up is free
Given the theory that water and other material was delivered to earth by commets, is it possible that the first life form was delivered to earth through these commets as well?
The question you’ve asked is one of the most profound questions troubling us. And it is being investigated currently from different school of thoughts. Scientists are breaking down this enormous question into minor questions and pursuing them ...This knowledge is worth millions but signing up is free
Can you tell us more about the theory that water in the oceans came from comets? Also if it did, it wont be exclusive to earth. What other bodies in our solar system have water?
Water exists within our atmosphere, on surface, as well as a few hundred miles within the Earth's interiors. It is widely believed that a certain volume (and not the entire volume) of water on Earth came from comets, mostly arriving around 4.3 to ...This knowledge is worth millions but signing up is free