"Search for Life Part 2" Tweet Chat, November 2014
In November of 2014, MIT's Dr. Sara Seager answered questions about exoplanets, the search for life, and the next technologies (like JWST!). Here are some exerpts.
The answers are very succint due to Twitter's 140 character limit (and we also added the #search4life hashtag to each answer). Often the questions are rephrased in the answers so that our Twitter followers would know what we were giving the answer to.
Q: Biomarkers may be indicative of life, but are there observations that will really *prove* the existence of extraterrestrial life?
A: Biosignatures in exoEarth atmospheres will not prove life. Enough planets with biosigs will be convincing.
Q: [follow-up] Unless 'biosigs' can have another, unknown cause/origin of course (i'd guess).
A: Biosigs can have non-life causes but some are more robust than others. O2 is still a favorite.
Q: What's the most promising ground-based set-up for future discoveries of possibly life-bearing planets?
A: Planned 20+30 m optical telescopes GMT/TMT/ELT will have a shot at observing several Earth atms transiting M stars.
Q: Can that be scaled up w/ bigger telescopes to see them around sun-like stars?
A: Yes, but ground observatories are limited by the blurring effect of Earth's atmosphere. At some point space is easier.
Q: How long until we can detect (or not) earths/superearths around nearby M stars? Do current observations neglect their existence?
A: Some superEarths around M stars already known. TESS (launch 2017) will find many more http://tess.gsfc.nasa.gov. #search4life on superEarths transiting M stars will be done with #JWST.
Q: What do we expect to see with the #JWST that we can't see with the #Hubble in the area of exoplanets?
A: #JWST will reach down to small rocky planets transiting M stars. Hubble works mostly for hot giant planets.
Q: What mass planet would you hope to find life developing on? (ex. Jupiter mass or earth mass, etc.)
A: For #search4life predominantly rocky planets with a thin atmosphere. Massive rocky planets OK if they have thin atmospheres. We thought rocky planets were limited to 1.75 Earth masses until Kepler 10 c at 17 Earth masses.
Q: Thin in comparison to Venus, but thick in comparison to Mars?
A: In addition to a thin atm composition is important. Venus's atm might be OK if it was far from the star and colder.
Q: Showing an O/N atmosphere with some methane and H20 vapor?
A: Exoplanets are so diverse we are open to any possibility for exoplanet atmospheres.
Q: You can tell whether it has a thin atmosphere from transits or direct imaging?
A: Yes, based on the depth of spectral features a thin atmosphere can be identified --- with good enough data.
Q: And what about exomoons? How long til we get to observe them? Will any incoming mission be accurate enough?
A: Kepler should have found moons if they are large and plentiful. None found, so we may have to wait awhile.
Q: Based on what we know about exoplanets today, what is one of the most exciting discoveries we could potentially make w/ #JWST?
A: #JWST will inaugurate "en force" the characterization of rocky exoplanets. The most exciting discovery by #JWST would be biosigs in a rocky exoplanet atmosphere--but we have to get lucky.
Q: Could be possible to find habitable exoplanets around brown or white dwarf stars?
A: Astronomers are trying to find habitable planets all possible star types but often only few are accessible.
Q: Are we missing out on discovery parameter space with no space UV capabilities post HST? (astronomeara)
A: Beyond JWST studies for a UVOIR 10 m telescope are ongoing but it will be awhile. For exoplanets UV is so important for understanding the host star UV radiation that destroys biosignature gases.
Q: What comes after finding biosigs in a rocky exoplanet atmosphere? (starshipbuilder)
A: We need to observe the atmosphere in detail for "false positives" might need next generation telescopes.
Q: Should we also be developing technologies to send probes to relatively near exoplanets while searching? (scientificscott)
A: Hopefully others are working on exoplanet probes but for now the search for exoplanets needs to stay focused.
Q: Can we detect Water on Exoplanets?(gordysocceruk)
A: @Hubble has already found water vapor on a number of hot giant exoplanets
Q: At the present time how many exo planets compatible with life have been discovered ? (gnk_fans)
A: Speculation is several planets in their star's HZ. But no planets are known for sure that would be life compatible.
Q: Can #JWST find/differentiate carbon, water, organics on exoplanets? What resolution? (dirknc)
A: @NASAWebb can find water vapor and carbon compounds in exoatmospheres, R~3000
Q: What's the expected lifetime of #JWST? Limited by propulsion, power, damage? (dirknc)
A: #JWST has a 5 year lifetime but hopes for 10. Limited by fuel and other things.
Q: Do we have the ability to accurately detect the makeup of exoplanet's atmospheres? (demon_113)
A: For now we can approximately but not accurately inventory exo atmopsheres. #JWST will nail giant planet atmospheres.
Q: Is it plausible that intelligent life has been observing our planet, but we're too stupid as a species for them to be intrstd? (trianglecity)
A: If a nearbyciviliation exists and has $ and space capability like ours they could see O2 and speculate on life.