Big NASA Press Conference Wednesday on "Discovery Beyond our Solar System"NASA has scheduled a major

Discussion in 'Astronomy, Exobiology, & Cosmology' started by Yazata, Feb 22, 2017.

  1. Yazata Valued Senior Member

    NASA has scheduled a major press conference concerning a "Discovery Beyond our Solar System" for 1pm EST on Wednesday Feb 22 in Washington DC . Nature has a paper associated with whatever is to be announced, but it's embargoed until after the announcement. Nothing seems to have leaked about what the announcement is about. (How is that Possible in Washington DC?)

    Here's the announcement:

    I wondered if I could perhaps figure out what this is about by examining the research areas of the participants.

    One is a NASA administrator. Another is the guy in charge of the orbiting Spitzer space telescope at Cal Tech.

    Another is Sara Seager of MIT who says that she is searching for "another earth" including signs of life by detection of "biosignature gases". If that's what this is about, it could be huge (or at least controversial).

    Another one is Nikole Lewis of the Space Telescope Science Institute at Johns Hopkins. Her research is once again into exoplanet atmospheric composition.

    The last one is Michael Gillon of the University of Liege in Belgium. He too has an interest in the search for extraterrestrial life. His research concerns transiting exoplanets around small dwarf stars, detection of "super earths" and their physicochemical characterization.

    This is going to be interesting.

    Somehow I expect that's whatever is announced will be more disappointing than the discovery of "another earth" showing possible signs of life in its atmosphere. That's too much to hope for.

    My guess/speculation is that they've found a rocky exoplanet with an atmosphere that might include oxygen. We'll know tomorrow.
    Last edited: Feb 22, 2017
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  3. Walter L. Wagner Cosmic Truth Seeker Valued Senior Member


    if they've found an abundance of oxygen, that will prove exciting indeed.
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  5. DaveC426913 Valued Senior Member

    Yeah, I'm not holding my breath. They make these "major announcements" a couple of times a year.

    It'll be cool, but it won't be cool!
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  7. Yazata Valued Senior Member

    A writer at CNET says that he's seen the news (so yes, it's leaked, everything leaks) and while he won't reveal it before the news conference, he says it could provide new settings for future science fiction novels. So it sounds like it has something to do with locating extrasolar planets that could sustain earth-life as we know it.
  8. Yazata Valued Senior Member

    I just watched the streamed press conference.

    It concerns a red dwarf star called Trappist - 1. It was already known that it had 3 rocky planets. The announcement today is that 4 more exoplanets have been discovered in this system, bringing the total to 7. All of them are rocky planets roughly the same size as Earth, none are gas giants. And three of the planets are in the star's habitable zone. Possibly more, since the habitable zone isn't completely characterized and things like atmospheric greenhouse effects might have to be factored in.

    The Trappist - 1 star is very small, only about 11% of the diameter and 8% of the mass of the sun and quite red and cool. The star's planetary system is very close to the star compared to our solar system. The planets' orbital periods (years) vary from 1.5 to 20 days. The innermost ones are probably tidally-locked to the star. All seven are closer to their star than the Earth is to the Sun.

    It's unknown how old the system is, though minimum estimates are 1 billion years. Red dwarves are very long lived compared to the Sun, so it could be a lot more than that. But red dwarves can be unstable in their early phases, so it's unclear whether solar flares might have fried the planets and stripped them of atmospheres early in their histories. The star seems to be quiescent now.

    The planets are crammed close to one another in their orbits and would only be about 2x the Earth-Moon distance at closest approach to each other. So from one of these planets, the other planets wouldn't just be dots of light in the sky like Venus, they would be discs like the Moon and perhaps even bigger. A very science-fictionish sky.

    One of the questions asked is whether material could be transferred from one planet to another (that's been known to happen in our much larger solar system), making them one giant ecosystem assuming there's any life there. The answer was we don't know.

    There's still no word on the planets' atmospheric composition or on whether they have signs of liquid water. That research is apparently awaiting the new James Webb space telescope to be lofted in a few years. It will include very powerful spectroscopes. The excitement is that this is a wonderful target system for the new telescope and it should be possible to get chemical characterization of these new planets with the means that will soon be available.

    I should probably say that being in a star's habitable zone doesn't necessarily mean that a planet is habitable. There are three planets in our solar system's inhabitable zone too, Venus, Earth and Mars. Venus is uninhabitable due to a run-away greenhouse effect, and Mars doesn't have enough greenhouse effect to make it warm enough for liquid water. (These exoplanets' larger Earthlike mass might help with that.)
    Last edited: Feb 22, 2017
  9. DaveC426913 Valued Senior Member

    Some factoids from the broadcast.

    Trappist 1 is about 40ly away in Aquarius.

    Trappist 1e's year is about 1.5 Earth days.
    Trappist 1g's year is about 9 Earth days.

    Trappist 1e and Trappist 1f are both slightly smaller than Earth.
    Trappist 1g is about 13% larger than Earth.

    Trappist 1e receives about as much light as Earth.
    Trappist 1f receives about as much light as Mars.

    Arrangement and possible history of planets in system suggests they they might have formed much farther out and migrated inward. The implication is that they may have formed where there should be lots of water. According to the announcers, they may well be "super water rich" (that's a quote).

    They are quite close to each other, being at closest, a few times farther than the Moon is from us. (That will make for some spectacular skies).
    So while it is unlikely that they have moons (because of their proximity both to their sun and to each other), they do have resonances between each other. This opens the possibility that they may yet have tides.
  10. Walter L. Wagner Cosmic Truth Seeker Valued Senior Member

    so sara seager is likely looking for abundant oxygen; water is just about everywhere on habitable-zone planets.
  11. youreyes amorphous ocean Valued Senior Member

    I am amazed by this discovery, I really hope they will do a Starshot like project for Trappist system
  12. Yazata Valued Senior Member

    I seem to have made an error in post #5. All seven of the Trappist 1 planets are closer to their star than Mercury is to the Sun. It's a tightly wound little stellar system, not a whole lot bigger than Jupiter's collection of moons. Which is good if the planets are expected to be warm enough for liquid water, given that Trappist 1 is a red dwarf star. A planet as far away as Earth from the Sun would be a Pluto-like snowball. (Everything's relative, I guess.)

    As Dave notes in post #6, the planets do interact gravitationally with each other and appear to have formed into resonances.

    Trappist 1 is about 40 light years away, so I don't know of any feasible way to get a spaceprobe (let alone a crew) there in a realistic period of time.
    Last edited: Feb 23, 2017
  13. ElectricFetus Sanity going, going, gone Valued Senior Member

    These worlds are very different from anything we know of.

    "Notably, planets c, d, and f have stellar irradiations very close to those of Venus, Earth, and Mars, respectively (Fig. 2). However, even at these low insolations, all seven planets are expected to be either tidally synchronized23, or trapped in a higher-order spin-orbit resonance, the latter being rather unlikely considering the constraints on the orbital eccentricities24 (Table 1). Using a 1D cloud-free climate model accounting for the lowtemperature spectrum of the host star25, we infer that the three planets e, f, and g could harbour water oceans on their surfaces, assuming Earth-like atmospheres. The same inference is obtained when running a 3D climate model26 assuming that the planets are tidally synchronous. For the three inner planets (b,c,d), our 3D climate modeling results in runaway greenhouses. The cloud feedback that usually decreases the surface temperatures for synchronous planets is rather inefficient for such short period objects27. Nevertheless, if some water survived the hot early phase of the system28, the irradiation received by planets (b,c,d) are still low enough to make possible for limited regions on their surfaces to harbour liquid water1,7."

    Basically being tidallocked pushed up their habitablity zone because of much harder it is is to move heat around via air and water rather than a turning planet. These worlds would only be habitable across a small percentage of their surface. The node facing the sun would be too hot and dark side would obviously be to cold and like a light for photosynthesis, only near the terminator would be temperate.

    Photosynthesis is a whole other problem. This star is much dimmer and redder then our sun, its peak emission spectra according to a black body calculator is ~1140 nm, compared to our sun which has a peak emission of 500 nm (blue-green light). Using its total luminosity (0.000525) verse its visible light luminosity (0.00000373) means it give off 1/140 as much visible light verse all light compared to our sun. That means even though these planets would be warmed by all the inferred light they would still be at least 1/140 as dim in visible light. Obviously that would be very red light too. Plant life there would need to conduct photosynthesis with very VERY little blue light, very little red light and mostly NIR light. The problem is for oxygenic photosnythesis (cracking water into oxygen) need higher energy photons to do the deed, it is possible to take two NIR photons and put them together to get the energy of one visble photon ( Photosynthesis here on earth utilizes manganese in chlorophyll, the artificial two photon phosphor system uses primarily Yttrium which is a little more rare than manganese but still possible to come by, but also Yb and Er which is significantly more rare. Biology given billions of years may find some kind of system to feed off IR light, here on earth though it has not happened because visible light is much easier to work with and likely the biochemical energy expended to maintain an IR photosynthetic system is not worthwhile, but in the TRAPPIST-1 system with so little visible light, utilizing lower quality IR light might makes sense. None the less because of the lower quality light, life on the TRAPPIST planets are likely to have much lower carriage capacity to life on earth.

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