Extrasolar Planet Discussion - Now Discussing: KEPLER announces hundreds of candidates

Discussion in 'Archive: The Senate Floor' started by Lowbacca_1977, May 9, 2010.

  1. Lowbacca_1977 Force Ghost

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    Ohhhh dang it. I need to get busy, I think.
  2. SithLordDarthRichie London CR

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    Geothermal activity surely will be a key factor in searching for an Earth-like planet. After all, one of the problems with trying to inhabit any of the other planets in the Solar System other than their distance from The Sun is that they are geologically inactive.
    In other words, dead. Dead worlds are no good.

    Mars was active but died and lost its atmosphere. The only active bodies other than Earth now are moons of Saturn & Jupiter.
  3. Lowbacca_1977 Force Ghost

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    Alright, the criticisms surrounding this story are all the more appropriate as we left off with what "earth-like" means....

    Kepler just announced last month (I've been busy, so this takes some time to get going) that they've got 706 new planetary candidates, of which over 100 are planetary candidates that would be earth-sized.

    Here's two links from Space.com, the initial announcement and a second that addresses the claim of over 100 earth-like planets.

    Something that the initial link says that's simply wrong is that they they set up the idea that all 706 could be planets by saying "If all 706 of these objects pass the stringent follow-up tests to determine if they are actually planets, and not false alarms, they could nearly triple the current number of known extrasolar planets" however at least some of these, WILL be things that look like planets but aren't. There are phenomena that in terms of periodic dipping look like a planet, but aren't. This is why one of the things that will be done to confirm this is going to be to use radial velocity measurements to calculate out masses of these planets. If you get a very high number, it can be a small star, instead, that is orbiting and only a part of it moves in front of the larger star, so you're only seeing a dip from a fraction of the orbiting star's actual size. Now, the question is how good is the KEPLER team at filtering out false positives when they compiled their candidate list. They're claiming that so far it's something like 50%, which would mean that we're looking at 300-400 new planets here, although that strikes me as very optimistic and I'll believe it when I see it.

    The other thing I'd note here is that the reference to earth-like planets, while it's drawn a lot of criticism, is something that is understandable since the claim came from a conference, and in the setting of people that are all within the field, referring to 100 earth-like planets in conjunction with the data represents a statement more about composition and size than about orbits or environmental characteristics, and so it's more people not understanding the original source than anyone being wrong or making broader statements than the evidence allows. One noteworthy thing with this, though, is that unlike all previous studies, that have found that most objects are larger than Jupiter (due to a selection bias that has been addressed in here, I believe) the Kepler mission's candidate list finds that most common are planets with smaller sizes, and the larger ones are rarer, which is what we'd expect but haven't had the ability to find the smaller ones to see if the data would validate that claim. That does greatly lend support, if we see that hold up as we try to confirm that these candidates are planets, to the idea that earth-sized planets are equally common out there and that we've just not had the technological ability to see them until now.
    The paper that has this info can be found here.
  4. VadersLaMent Chosen One

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    Found this interesting

    I would be curious as to when it was all knocked around. It could have been anything from an accreation disk that got chaotic to an object passing through at any point. I wonder how quickly we could build a massive fleet of space habitats and get as much of the population off the Earth as possible if we saw a black hole coming our way.
  5. Ghost Chosen One

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    What about Venus?

    And didn't they discover a couple years ago that, despite decades of thinking otherwise, Mercury actually does have some geoactivity and atmosphere?

    http://www.nasa.gov/mission_pages/messenger/multimedia/release_telecon_20090430.html

  6. Mr44 VIP

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    Venus is an excellent example.

    Mercury though, I'm not sure. I believe it was the Mariner 10 probe that first detected Mercury's faint magnetic field. Mercury's magnetic field is actually stronger than Mars's, and is powerful enough to contain a thin layer of gas. But I don't think it is considered to be an "atmosphere" in the accepted definition of the term. For example, Mercury's atmosphere has the same pressure at its surface that Earth's does at 1,000Km of altitude. Earth's surface atmosphere is a million times more dense than Mercury's. That's not strong enough to act as a radiation filter like normal atmospheres do. As such, no radiation is blocked on Mercury's light side, and also, no heat is held on Mercury's dark side.

    But Mercury's thin layer would be a start for possible terraforming. Since a day on Mercury lasts 6 Earth months, artificial heat could be generated on the dark half. You'd just have to have radiation shielding in place when it swings around and faces the sun for the next 6 months. (or set up some sort of relay and work on each half as it turns away from the sun.)
  7. Mr44 VIP

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    So, the latest issue (Oct) of Sky and Telescope magazine has a decent feature on the search for "super-Earths." It's more of a general overview-it covers the Kepler and Corot probes, and mentions the upcoming Webb Space Telescope.

    Gliese-1214b, while it's much too hot with a surface temperature of 400 degrees, has all the materials to be a near-Earth, or almost habitable planet. There's a good possibility that it's a "waterworld," comprised of an iron and silicate core, surrounded by high pressure ice, liquid water, and constantly vaporized water atmosphere. Kevin Costner would be proud.
  8. Alpha-Red Force Ghost

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    But Mercury's thin layer would be a start for possible terraforming. Since a day on Mercury lasts 6 Earth months, artificial heat could be generated on the dark half. You'd just have to have radiation shielding in place when it swings around and faces the sun for the next 6 months. (or set up some sort of relay and work on each half as it turns away from the sun.)

    What's the point of terraforming if the stuff you're growing is just going to get fried with every rotation of the planet? You'd have to shield the a HUGE chunk of the planet's surface if you want to get any meaningful ecosystem up and going, and even then the shielding would have to be constantly maintained.
  9. SithLordDarthRichie London CR

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    Venus is far too hot to be sufficiently managed. The atmosphere is so dense the surface temperature is 460celsius. Even the most advanced spacesuits probably couldn't protect for very long in that kind of heat. How can you terraform when even colonisation would be pretty darn hard?

    Mercury is a death ball, it rains fire there and when the Sun expands it will be the first to go. One renegade Solar Flare onto the planet and any inhabitants are barbecued.

    Jupiter & Saturn moons are the best bet within the Solar System.

    Recently dicoveries by Keplar of Saturn-sized worlds as well as a third much smaller world holds out hope of finding a planet to match the conditions of our own.
  10. Lowbacca_1977 Force Ghost

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    Heh, GJ-1214b is arguably my best data set from the spring in Texas... when that finally gets published or is offically not going to be too useful, may share that.

    And I'd point out that Jupiter's moons may run afoul of it's magnetic field. I can't recall offhand what range that's a problem for, but it would be a concern.
  11. SithLordDarthRichie London CR

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    Indeed it would. Io suffers greatly as the closest moon to Jupiter. In fact it is believed by some that its continuous geological activity considering its small size may be caused by Jupiter's gravitational impact upon it.

  12. Lowbacca_1977 Force Ghost

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    Well, I've read that fairly noncontroversially presented, but that's the gravitational field. The magnetic field is a different set of problems that, due to Jupiter's composition, I've read some things that say that anywhere within a certain distance of Jupiter would be inhospitable simply because of the radiation.
  13. Mr44 VIP

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    What's the point of terraforming if the stuff you're growing is just going to get fried with every rotation of the planet? You'd have to shield the a HUGE chunk of the planet's surface if you want to get any meaningful ecosystem up and going, and even then the shielding would have to be constantly maintained.

    Mercury is a death ball, it rains fire there and when the Sun expands it will be the first to go. One renegade Solar Flare onto the planet and any inhabitants are barbecued.

    Because there are different goals and methods of terraforming. The goal would be to get the atmosphere down to a habitable level, where lead doesn't melt in Mercury's "afternoon." Getting the temperature down from 427C to 180C isn't much of a hypothetical challenge. We're talking about millimeter thick shield of gold alloy, (which would protect against heat and solar radiation) or mylar (which is cheap, but mostly protects against heat) Sure, you're not going to have lush fields of fresh tomatoes on Mercury, but you could certainly have domed gardens where plants grow and people live quite comfortably. Colonists would mine the vast fields of nickel, iron, magnesium, or other rare elements. A bio-engineered strain of algae would give Mercury a pseudo-atmosphere, or unlock the surface atmosphere Mercury already has, and you wouldn't have to rely that much on shielding.

    Venus is far too hot to be sufficiently managed. The atmosphere is so dense the surface temperature is 460celsius. Even the most advanced spacesuits probably couldn't protect for very long in that kind of heat. How can you terraform when even colonization would be pretty darn hard?

    Because the atmosphere would filter this out and reverse Venus's greenhouse effect. Out of all the terraforming proposals, Venus is the most workable. After a couple hundred of years, Venus's atmosphere would be almost Earth-like, and you wouldn't need a space suit.

    Of course, all the various proposals are hypothetical, but you guys seem to limit yourselves to looking at how these examples are, not what they could become.
  14. Lowbacca_1977 Force Ghost

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    I'm not sure I follow on Mercury. How would adding atmosphere, which would increase the greenhouse effect and warm the planet, lead to a cooler planet?
  15. VadersLaMent Chosen One

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    Do you guys mean Venus? Mercury is far to close and you sound like you are talking about Venus.
  16. SithLordDarthRichie London CR

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    If Earth was as close to the Sun as Mercury is, its atmospheric shielding wouldn't do much good. The atmosphere would probably get burnt away by the heat. And what good is having fancy greenhouses on the surface going to be if fireballs from the Sun's surface would most likely destroy them anyway?
    Mercury is a bad idea, for the long-term future of mankind picking the planet first to go when the Sun gets old and swells won't work out very well.

    Venus is much like Earth in size, but how does one disperse dense cloud by adding greenhouse gases and making the atmosphere thicker? The Greenhouse Effect here is warming the planet by making the atmosphere thicker so that heat gets locked in. Venus is an extreme version of this therefore adding to it will make it worse.

    THe thing that is being overlooked with all this terraforming idea is still geological activity. Venus and Mars used to have atmospheres long ago, but once the heart of the planet ceased to be active they died and the atmospheres went away or were intensified too far.
    Without a lving world to naturally sustain it's own atmosphere, any new one made artificially will only fade away.

    They only living worlds other than Earth now are moons of Saturn or Jupiter so they should be a focus.
  17. Mr44 VIP

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    Mercury and Venus are two different ideas. Atmospheres in general filter out solar radiation, and even out temperature extremes.

    Mercury already has an atmosphere, it's just trapped down at its surface. Mercury's atmosphere is just about reversed in relation to Earth. Stabilize the Nitrogen and Oxygen, and Mercury's surface temperature would drop considerably. Mercury also has a relatively strong magnetic field, which makes it more attractive to terraform than say, Mars (from a magnetic standpoint.) There are already proposals to set up bases on Mercury, so it's not outside of the impossible. In fact, the Messenger probe is going to descend into Mercury's atmosphere in about 6 months.

    Solar radiation is the easiest to protect against. And there are common materials that protect against heat well past the Mercury threshold in existence right now. The solar shielding is also comparatively inexpensive. Working in tandem with an atmosphere, one wouldn't have to shield the entire planet, only certain sections. If you get really advanced, you could used the parallax effect and set up a shield approximately 1/3 of the distance between Mercury and the sun at the point where the planet's orbit is closest. (approximately 19,300,000Km away from Mercury's surface)

    The proposal for Venus is perhaps the most inexpensive, and has the greatest theoretical chance for success. It uses blue-green algae to gobble up the carbon dioxide and convert it into oxygen, which actually reverses the out-of-control greenhouse effect on Venus. Your assessment of the greenhouse effect isn't exactly accurate, Richie. It's the type of gases in the atmosphere that impact the effect.

  18. SithLordDarthRichie London CR

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    Exactly how does algae survive on a surface as hostile as Venus' is? If life could survive there, wouldn't it be doing so already?

    And I think you'll find Al Gore agrees with me about the Greenhouse Effect.
  19. Mr44 VIP

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    The algae already exists. It was first proposed back in 1961 at NASA's Jet Propulsion Laboratory and bio-engineered shortly after. Algae wouldn't just sit at the surface, it would be a self replicating process. Algae seeded in the upper atmosphere would transform enough carbon dioxide into oxygen that the next level would then float down and engage in the same process and so on and so on.. The surface would be the last stop, not the first, but that's after the temperature on Venus was vastly reduced from its 450C core temp.

    Now, these things are all hypothetical, but I don't think your dismissal is warranted. New information about Venus indicates that its atmosphere is more dense than originally thought, so a "solar shade" proposal similar to the one mentioned for Mercury has also been proposed to work in tandem with the algae. You have to keep in mind, although their area is quite massive, concepts like solar shades and algae seeding are really, really inexpensive and workable with technology that exists right now.
  20. Lowbacca_1977 Force Ghost

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    This is the part I question. You later mention putting a shield to block a large portion of the sunlight, that could work, but the atmosphere alone as you've suggested as well, I don't see how you justify that as feasible.

    To look at surface temperatures, one can calculate out the temperature of a planet's surface based off of the size and temperature of a star, the distance to the planet, and the albedo as well as how much energy the atmosphere absorbs. The calculations for the earth can be found here. The albedo for Mercury is, the most accurate I find, .1 because of the material it's made up of. (Comparison, earth's is .31). Since we're terraforming, I'm going to presume that we'd have the same atmospheric absorption as we have on Earth, which is .26 (and realistically, I don't think you could maintain that much atmosphere that close to the sun on a smaller mass, but this is benefit of the doubt). Plugging the albedo and the generous atmospheric absorption finds that the temperature on Mercury would be 436 Kelvin, which is still over 300 Fahrenheit. You'd need some drastic changes that I simply don't see how you can support by trying to tweak the atmosphere and only that.
  21. Mr44 VIP

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    Ah, but Earth-like isn't a goal. I'd have to go find the original proposal, but each section of the process works with each other. The goal is to stabilize Mercury's temperature. Ultimately, a final range of about 180-200 degress, or about82-87C is possible, even accounting for its position near the Sun.

    You'd first have to erect some sort of artificial solar shielding. With suitable technology, put up a parallax-based envelope between the Sun and the planet, which would be pretty cheap, or simply use direct panels, which would be more expensive. This would filter out a great deal of solar radiation to get things started.

    Next, you have to expand the atmosphere to neutralize the temperature swings. Remember, Mercury experiences a tremendous range of temperature. Only the sunward side is hot. The dark side of Mercury falls to 300 degrees below zero(-183C). An atmosphere on Mercury would filter out more of the Sun's rays. Mercury's ozone layer would block 90% of solar radiation, the level of which would still be above Earth's, but infinitely less than a non-ozone Mercury. But more importantly, it would disperse the heat reflected from the ground across the planet and even out the days and nights.

    "Miners" on Mercury would most certainly have to wear filter suits when walking around, but that's more to protect from the tissue damaging ultraviolet radiation. The suits themselves would be no more cumbersome than flight suits that currently exist. Finally, you'd need domed dwellings, but the domes would work with the above processes. Silicate-based glass, such as zincs or titaniums, can block UV radiation to almost 100% efficiency. It's handy, because Mercury is made out of silicates, so the planet itself provides the materials.
  22. Lowbacca_1977 Force Ghost

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    And I'd point out that the numbers I provided had energy absorbed by the atmosphere already taken into effect and at temperatures in excess of 300 Fahrenheit, and I still don't see how one is saying that one would be able to sustain the levels of atmosphere being discussed, as we're looking at issues with solar wind, temperature, and mass.

    Aside, parallax-based envelope means what exactly? I'm not sure I follow how it is using the word parallax in that context.
  23. Mr44 VIP

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    Well, I think one of the issues is that you're examining the topic from a standpoint of it actually existing, instead of from the standpoint of it being possible, but hypothetical. NASA's Goddard Space Center has all of the available data to date from the already mentioned MESSENGER probe.

    One of the fascinating things that Goddard has is data that actually shows that Mercury's thin exosphere replenishes itself. It almost mirrors an active planet, despite being in such proximity to the Sun. It has something to do with Mercury's proportionately strong internal magnetic field.

    Could Mercury's "exosphere" be expanded into a full atmosphere? It's possible, but since it's never been actually attempted, it's conceptual. The extent of the external shielding would also impact your figures, which from what I can tell, just accounts for Mercury's atmosphere by itself.

    To answer your other question-In general, a parallax-based shield uses the vast distance between objects overcome the massive areas that are otherwise needed. Have you ever held up your hand while looking up at the Sun, and have the entire ball blocked by your fingers? Your hand isn't bigger than the Sun, it's just so far away. If anyone is a "Kids in the Hall" fan, the concept is also represented by the "I'm crushing your head" skit.

    At Mercury's closest point, it's 46 million Km away from the Sun. (It's farthest point is 70 million Km away) You put a shield up at a fixed distance, (say 19.7 million Km) either in geostationary orbit, or at a fixed location, and it will actually completely cover the "target," and block out the radiation that is emitted by the Sun, and require much less overall area to do so.
  24. Lowbacca_1977 Force Ghost

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    Well, the reason I asked, though, is that's not what parallax is, parallax has to deal with how an object's apparent position changes with different lines of sight, which didn't seem tied to what it was being suggested it would do.

    As far as positioning, the orbits you mention wouldn't be suitable, the spot you'd be wanting is Lagrangian point L1 in terms of being constant at blocking, although you'd be restricted on just what distance the shielding would have to be at.


    And my issue isn't with it being hypothetical, but with it, at least as addressed, skipping some key questions, imo. Once you introduce the shielding, then it becomes more manageable as you can reduce the amount of energy reaching the planet, but from a physics standpoint atmospheric controls alone don't seem to be able to have the control needed to get Mercury close to habitable, although there could be factors I'm missing as I don't deal in planetary atmospheres.
  25. Mr44 VIP

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    Well, I didn't come up with the term parallax shielding, so it might have had an original meaning? I'd guess that the 2 bodies "viewing" the shield would be the Sun and the other planet against the stars? Or maybe the "parallax" is physically represented by the overlaping of the actual scales that make up the shield? I don't know.

    Paul Birch, writer and British Planetary Society member, calls them "sunshades," but they're basically the same thing:

    CLICK HERE and he even mentions some other mechanical methods of terraforming that haven't even been touched on yet in this thread. He gets major bonus points for the Hitchhiker's Guide to the Galaxy reference in the title contained in the link.