Astronomy and space exploration

Discussion in 'General Discussion' started by eloyc, Apr 10, 2017.

  1. eloyc

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    Welcome home, astronomy/space lovers! :) :cool2:

    I hope we can gather here to share interesting news and comments regarding this subject.

    I'll start things up by mentioning... the space warp drive! As you may know, this was a concept made popular in Star Trek, but the Alcubierre drive (https://en.wikipedia.org/wiki/Alcubierre_drive) may make some truth out of it. There have been some experiments. This is one of them: http://www.spacewarpdynamicsllc.com/ They even have a facebook profile where they share updates, etc. What do you think of this?

    By the way, I will soon start a free course (in Coursera) on this subject, Imagining new worlds, and I'm pretty excited about it.

    Sorry for the crappy/kind of empty OP, but I'm in a hurry. :p
     
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  2. Davros

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    Requires a substance with negative mass, good luck creating that.
    As for using the casimir effect, you'd be better off asking the astronaut to fart out of the window the casimir effect is incredibly weak.

    Reminds me of the EM Drive
     
    #2 Davros, Apr 10, 2017
    Last edited: Apr 10, 2017
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  3. eloyc

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    I haven't heard about that before, and I'm not sure if that sentence made my ignorance worse. Was Casimir a man whose farts were incredibly weak?

    Thanks for the video. :) I will watch it later.
    -------------------------------------
    Trappist-1: https://science.nasa.gov/seven-worlds-trappist-1

    I was so excited when I heard of this discovery! But I guess you also know how the story ends:
    http://www.sciencealert.com/bad-news-humans-trappist-1-is-not-the-alien-paradise-we-were-hoping-for

    It was beautiful, while it lasted. :-/
     
  4. Clukos

    Clukos Bloodborne 2 when?
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    Give it a listen

    Edit: It's a long discussion about many things, the most relevant info to this topic starts at around 1 hour 47 minutes
     
    #4 Clukos, Apr 12, 2017
    Last edited: Apr 12, 2017
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  5. eloyc

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    ^^ Thank you! I'm quite busy, now. I'll watch it later. :)
     
  6. Davros

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    No the Casimir effect is very weak, so weak that a fart would produce millions of times more thrust. You ruin the joke when you make me explain it.

    It's only slightly relevant

    Try this (its in bitesize peices)
    http://www.worldscienceu.com/scienc...be-environments-with-extremely-strong-gravity
     
    #6 Davros, Apr 12, 2017
    Last edited: Apr 12, 2017
  7. Clukos

    Clukos Bloodborne 2 when?
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    I'd say that's right on the money, especially the part about a multiverse and our understanding of the universe, and it definitely falls under the "interesting comment" category. He also holds a Ph.D. in physics from MIT so his comments regarding this subject should hold some value :)
     
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  8. Davros

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    #8 Davros, Apr 12, 2017
    Last edited: Apr 12, 2017
  9. eloyc

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    Sorry? :???:

    And astronomy. ;-)

    Thanks again. Videos are starting to stack up in my playlist. :-D
    ----------------------------------------------------------
    https://astronomynow.com/2017/04/11/possible-venus-twin-discovered-around-dim-star/
     
  10. nutball

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    Ugh, please take any Kepler press release with a huge pinch of salt.
     
  11. eloyc

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    I know. A mountain of salt, maybe. But, could you explain why?
     
  12. Davros

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    Nasa arnt above adding a lot of speculation to their press conferences.
    see my video about the EM drive from the 15min mark
     
    #12 Davros, Apr 13, 2017
    Last edited: Apr 13, 2017
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  13. nutball

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    A couple of reasons.

    Firstly, Kepler is a NASA mission, and the NASA PR machine is very aggressive. You wouldn't know that the rest of the world did astronomy going by NASA press releases. The Kepler team are worse than most for this as they have a bit of a chip on their shoulder - they know now that the mission they designed those decades ago has turned out the wrong one, and that TESS and ultimately PLATO are what we really need to advance the field.

    Secondly the way that Kepler detects planets doesn't directly yield a measurement of the mass (in most cases). Follow-up observations (radial velocity) are required to obtain a precise mass measurement, and these observations are very difficult for typical Kepler planets as they tend to be quite faint. So the Kepler team have started using certain statistical and model-dependent techniques to assign masses to their planets. Some of these are quite robust, eg. transit timing variations in multiple planet systems, others are distinctly dodgy in the sense that you get out what you put in.

    These statistical estimates may or may not be correct, but they are not substitutes for a proper measurement, particularly when speaking about individual objects. Without an proper mass measurement it's not possible to be definitive about the planetary nature of the transiting object. There have been a slew of high-profile public news stories about the discoveries of "Earth-like" planets in habitable zone orbits, most of which only have radius measurements not mass measurements. The argument is basically "it's 1 Earth radius, so what else can it be??". Well either measure the mass to prove it's a super-Earth, or STFU. High-profile PR stunts publicising results that later turn out to be wrong doesn't do exoplanet science any favours.
     
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  14. eloyc

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    I understood everything you said. I invite you again to further explain on some points, as I intend this thread to be as informative as possible (so I'm glad that my crappy piece of news about a Kepler discovery is generating a discussion):
    - Why is mass that important in order to assess if a planet is similar to Earth with regard to the possibility to host life?
    - Could you share more info about TESS and PLATO and why those projects are more suitable?

    Thanks.
     
  15. Davros

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    knowing the size and mass gives you a better chance of predicting what the planet is made of. Is it rocky, is it gaseous ?
     
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  16. eloyc

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    [​IMG]
    Enceladus’ sea floor has hydrothermal vents like ours

    ...

    Enceladus, which is a tiny moon, took Cassini researchers by surprise when they discovered what seemed to be geysers of water emitting from the south pole in 2005. Subsequent investigations built a picture of the origin: liquid water under the surface of Enceladus, which led to the idea of an entire ocean under the surface. The heating mechanism, to date, has not been discovered.

    The Ion Neutral Mass Spectrometer on the craft made the observation of molecular hydrogen in the ejecta from these geysers. According to principal investigator Hunter Waite of the Southwest Research Institute and his co-investigators, the source almost certainly has to be hydrothermal vents at Enceladus’ sea floor. This means there’s plenty of geological activity, increasing the chances for life.
    ...​
    http://www.astronomy.com/news/2017/04/enceladus-sea-floor-has-hydrothermal-vents

    Hopefully, some of the planned exploration missions will eventually launch and go there with the needed tools to check if the moon can actually support life/already has some kind of life form.
     
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  17. nutball

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    One of the key techniques for characterising the atmospheres of transiting exoplanets is transmission spectroscopy, ie. studying the absorption by the planet atmosphere of the starlight that shines through it during transit. This is spectacularly difficult to do, it gets more difficult as the planet and hence the scale-height of its atmosphere gets smaller. We need capture sufficient photons that passed through the atmosphere to make a statistically significant detection of chemicals in the planet atmosphere. For the smallest planets, eg. Earth-like rocky planets which in our current world view are the best place to search for biomarkers, this can only be achieved for the brightest stars.

    So what we are really after are small planets around bright stars. Bright stars are rare in the sky, so to find enough small planets around bright stars we need to survey a lot of the sky. Kepler has a tiny field-of-view (100 sq. deg) compared to the whole sky. TESS and PLATO are optimised to have much larger field-of-view, and moreover their survey strategy will involve multiple pointings which Kepler did not. TESS will cover about 85% of the sky, typically with baselines of a few months, up to one year. PLATO is optimised to detect true Earth analogues, ie. Earth-sized planets in a 1 year orbit about a G-type star. PLATO will stare for up to three years at each of its fields, to catch multiple transits of this type of planet.
     
    #17 nutball, Apr 15, 2017
    Last edited: Apr 15, 2017
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  18. eloyc

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    That's so exciting! Unfortunately, I just read that it won't launch until 2025. :-(
     
  19. nutball

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    At the earliest.

    Look at it this way though, will you still be alive in 2045? If PLATO really delivers as promised you will be privileged to see the fruits of its discoveries. For me it's touch and go - I am working on the mission, I will be close to retirement age at the end of its life (2035). Proper confirmation of biomarkers in the Earth 2.0 that it discovers will take maybe a decade. But there is quite high probability that you will see it if you can hang on that long :)

    TESS is probably launching next year, if Elon can manage to stop blowing up his customers payloads. If TESS can deliver on its promise there will still be some exciting science to keep you interested in the meantime.
     
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  20. Davros

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    Ah, Elon not immune to believing his own hype

     
    #20 Davros, Apr 15, 2017
    Last edited: Apr 15, 2017
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