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Thread: Gaia will map a billion stars

  1. #1
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    Gaia will map a billion stars

    Gaia will map a billion stars

    The European Space Agency is working an ambitious new space observatory that will be capable of precisely mapping a billion stars in our galaxy. Called Gaia, the spacecraft will launch in 2010 and observe the sky for a period of five years. Astronomers will compile this detail into a 3D map of a billion stars, including their position, motion and even composition. With such a comprehensive map of the sky, Gaia will turn up all kinds of new objects, and give astronomers plenty of future targets to study with more sensitive instruments.
    Everything I need to know I learned through Googling.

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    What a great idea for a mission , 3-d mappings of millions of stars
    hope it goes well

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    Interesting. I wonder how they are going to compute the parallax needed to define an accurate 3d model? Compare images in January to images from June?

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    Quote Originally Posted by skrap1r0n
    Interesting. I wonder how they are going to compute the parallax needed to define an accurate 3d model? Compare images in January to images from June?
    I agree, some modeling techniques will have to be utilized. The issue of non-radial motion and earth referenced real time position requires some presuppositions. More than likely a non-radial expansion utilizing red-shift for distance traveled, speed and acceleration. But even more detail will be needed to calculate say a 1 billion ly galaxy, where is it now? GR and SR would say it doesn't matter because the speed of light and gravity are the same and so for any practical or physics related issue this is all that matters because what we see now is how we are affected now. I think this is a terrible mistake and does not allow us to understand or explore any Gross geometric dynamics that the Universe may or may not display.

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    the work is moving along


    2005-01-10 PWG recommendations for Gaia filter systems
    Following extensive studies the Photometry Working Group has recommended baseline filter systems for Gaia's Broad-Band and Medium-Band Photometry systems. The C1B system (5 filters, two of which share a CCD strip) has been adopted for BBP; the C1M system (8 blue bands, 6 red bands) has been adopted for MBP. Further details are available from the Photometry Working Group web site under PS optimization.
    http://gaia.am.ub.es/PWG/index.html

    will provide unprecedented positional and radial velocity measurements with the accuracies needed to produce a stereoscopic and kinematic census of about one billion stars in our Galaxy. Estimates suggest that Gaia will detect between 10 000 and 50 000 planets beyond our Solar System. It will do this by watching out for tiny movements in the star's position.

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    ops: Sorry, but I cannot resist.

    Doctor Evil: "Gaia will map a BILLION stars! Mwahahahahaha!"

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    "with this new satellite we will map ONE MILLION stars! MWAHAHAHAHA!!!"

    "uhm, one million stars ain't that much, sir"

    "ok with this new satellite we will map ONE BILLION stars! MWAHAAAHAHAHAHAHA!!!"


    On topic, how do they get the 3D position of far away stars correct? Because I heard stories of people being unable to say whether very distant stars were forming groups or were far away from each other (I don't know anymore, something concerning binary systems, or exoplanets, it slipped my mind). I thought it was said after the Hubble image of those very old galaxies some months ago too. The bottom line was that they appeared to be standing next to each other, but as they couldn't see perspective, it was difficult to tell their actual distance (really next to each other, or one much further "behind" the other) (with redshift measurements or something they didn't seem to come out). Can you help me out, cause it are all loose bits in my mind now

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    Where is this spacecraft going? Is it going to be in Solar orbit ? If it is far enough away, then the large baseline between Earth and the spacecraft might permit accurate direct distance measurements. I'm guessing that maybe 1000ly would be the limit for this type of measurement, but I could be off by an order of magnitude.

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    Quote Originally Posted by jfribrg
    Where is this spacecraft going? Is it going to be in Solar orbit ? If it is far enough away, then the large baseline between Earth and the spacecraft might permit accurate direct distance measurements. I'm guessing that maybe 1000ly would be the limit for this type of measurement, but I could be off by an order of magnitude.
    Gaia will observe at the L2 point which is located directly behind the Earth as seen from the Sun. The baseline is as usual, the diameter of Earth's orbit. It's just that the spacecraft is extremely accurate.

    Personally, I think this is the most interesting mission in near future: Is there any field of astronomy that is not affected by Gaia? (And what really bothers me, Gaia was postponed because of the BepiColombo Mercury probe. Not that I don't care Mercury, but 50,000 potential accurately measured new planets versus one...)

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    Determining the 3-D position of stars is really not difficult, if you have the right equipment. All you need to know are:

    1.) The star's distance (determined from parallax).
    2.) The star's radial velocity (determined with spectroscopy).
    3.) The star's transverse velocity (determined using proper motion and distance).

    GAIA will directly or indirectly provide all of these measurements.

    It's distance estimates limit will be considerably greater than 1,000 ly. With a measuring accuracy of about 4 microarcseconds, it should be able to determine the distance to stars with 1% accuracy out to 2500 pc, or almost 8200 l.y. The 10% accuracy distance would be ten times farther, or 25 kpc.

    I myself and looking forward to GAIA, as well as its American equivalent, SIM. I literally think that if they get off the ground, that there will be two eras in astronomy: the Pre-SIM/GAIA era, and the Post-SIM/GAIA one.

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    Quote Originally Posted by Kullat Nunu
    Gaia will observe at the L2 point which is located directly behind the Earth as seen from the Sun. The baseline is as usual, the diameter of Earth's orbit. It's just that the spacecraft is extremely accurate.
    Right. To be specific, Gaia will have an accuracy of about 10 microarcseconds, about two orders of magnitude better than the USNO and Hipparcos!

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    Quote Originally Posted by Kullat Nunu
    Quote Originally Posted by jfribrg
    Where is this spacecraft going? Is it going to be in Solar orbit ? If it is far enough away, then the large baseline between Earth and the spacecraft might permit accurate direct distance measurements. I'm guessing that maybe 1000ly would be the limit for this type of measurement, but I could be off by an order of magnitude.
    Gaia will observe at the L2 point which is located directly behind the Earth as seen from the Sun. The baseline is as usual, the diameter of Earth's orbit. It's just that the spacecraft is extremely accurate.

    Personally, I think this is the most interesting mission in near future: Is there any field of astronomy that is not affected by Gaia? (And what really bothers me, Gaia was postponed because of the BepiColombo Mercury probe. Not that I don't care Mercury, but 50,000 potential accurately measured new planets versus one...)

    2005-01-15 Call for 'Letters of Intent' issued for Gaia data processing
    ESA has issued a call for Letters of Intent to participate in the the data processing segment of the Gaia mission
    The European Space Agency will need help interpretating data from its ambitious Gaia mission. Now's the time to register interest
    ESA is facing a challenge. The 450m programme will beam back vast quantities of data to Earth, which will have to be turned into constellations and alien worlds using computer programs. Gaia will map a Billion stars and will provide unprecedented positional and radial velocity measurements with the accuracies needed to produce a stereoscopic and kinematic census of about one billion stars in our Galaxy. Estimates suggest that Gaia will detect between 10 000 and 50 000 planets beyond our Solar System. ESA is looking for number crunchers to lend them a hand and wants computer whizzes to submit "letters of interest" in joining the project. A more detailed announcement of opportunities will be made by ESA to the scientific community about five years before launch.


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    This is what the scientists say on Gaia
    you can check up info from the links already posted and the esa website
    GAIA will be a 3,000-kg astrometric observatory, scheduled for launch on an Ariane 5 in 2011 (no later than 2012). GAIA will study the composition, formation and evolution of the Galaxy by mapping 1 billion stars. GAIA is planned for operation in a Lissajous-type, eclipse free orbit, around the L2 point of the Sun-Earth system. (L2 is 1.5 million km from the Earth.) An operational lifetime of 5 years is planned. ESA will take a 50% participation role in NASA's LISA mission, which is scheduled for launch in 2009 atop a Delta 2 7925H (or equivalent) vehicle, to study gravity waves. The Laser Interferometer Space Antenna (LISA) consists of three spacecraft flying 5 million km apart in the shape of an equilateral triangle.

    Through its five-year sky scanning, Gaia will compile an unprecedented census of our Solar System, our Galaxy, and beyond: it will detect new Solar System objects including near-Earth asteroids, tens of thousands of extra-solar planets, hundreds of millions of variable and binary stars, and hundreds of thousands of supernovae.

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    I hope they look for proper motion in quasars. Hipparcos could not measure objects that dim.

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    Quote Originally Posted by John Kierein
    I hope they look for proper motion in quasars. Hipparcos could not measure objects that dim.
    Why? Quasars are *way* too distant to have detectable proper motions.

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    Quote Originally Posted by Kullat Nunu
    Why? Quasars are *way* too distant to have detectable proper motions.
    John thinks otherwise. So, actually, I hope they try to measure proper motion of quasars, too. I think they are at great distances, and that the redshifts we see are cosmological. If one were to show that quasars show no proper motion*, that would be pretty clear evidence that they are not close by.

    And hey, I'm always willing to be proven wrong by observation. If they really are close by, as some non-mainstream folks claim, observing proper motion would actually be the sort of evidence that would be necessary to really support such a claim well.

    * Or only that expected, given typical galactic peculiar velocities along with the distances we think they're at. I don't think even Gaia has that kind of resolution, but someday we might build something that could measure even that small of a proper motion.

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    Quote Originally Posted by Grey
    And hey, I'm always willing to be proven wrong by observation. If they really are close by, as some non-mainstream folks claim, observing proper motion would actually be the sort of evidence that would be necessary to really support such a claim well.
    Well, quasars would have to be very close cosmologically speaking, within our Local Group, to have measurable proper motions.

    MAXIM X-ray interferometry mission, if it ever realizes, should be precise enough to detect parallaxes of stars to the distance of Virgo Cluster 60 million light years away!

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    Biggest space camera will map Milky Way

    Gaia, a European mission with the ambitious goal of mapping a billion stars and thousands of strange, new worlds, is set to use the biggest digital camera ever flown on a spacecraft.

    The mission is scheduled to launch in 2011, though the European Space Agency has yet to choose which of two companies will build the spacecraft itself. But on 9 June, the agency signed a 9.6 million ($17.3 million) contract with UK electronics company e2v Technologies to start making the camera sensors for Gaia.

    The deal shows how critical the imaging system is to the mission. "We will be trying to track the motion of a billion stars at once. It has to be right," says ESA's science director David Southwood.

    And the 1.5-gigapixel camera seems up to the task. Called Astro, its sensitivity dwarfs the Hubble Space Telescope's 16-megapixel main camera and even NASA's planned extrasolar planet finder, Kepler, which will boast an 84-megapixel array.
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    Gaia CCD, Gaia originally stood for Global Astrometric Interferometer for Astrophysics. As the project evolved, it became clear there would be more to Gaia than just interferometry. Gaia is to create the largest and most precise three dimensional chart of our Galaxy by providing unprecedented positional and radial velocity measurements for about one billion stars in our Galaxy and throughout the Local Group.

    http://www.esa.int/esaSC/SEMC7L1DU8E_index_0.html
    http://www.sharecast.com/cgi-bin/sha...tory_id=492947
    http://sci.esa.int/science-e/www/obj...objectid=37532

    Gaia will be placed in an orbit around the Sun, at a distance of 1.5 million kilometres further out than Earth. This special location, known as L2, will keep pace with the orbit of the Earth. Gaia's goal is to perform the largest census of our Galaxy and build a highly accurate 3D map. The satellite will determine the position, colour and true motion of one thousand million stars and over 100,000 objects in our Solar System. Gaia will also identify as many as 10,000 planets around other stars. To accomplish this ambitious task, Gaia requires the largest focal plane of charged couple devices (CCDs) ever built for space application. Gaia's measurements will be so accurate that if it were on the Moon, it could measure the thumbnails of a person on Earth.

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    Quote Originally Posted by Manchurian Taikonaut
    Gaia's measurements will be so accurate that if it were on the Moon, it could measure the thumbnails of a person on Earth.
    Whoa.

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    Quote Originally Posted by Manchurian Taikonaut
    Gaia will be placed in an orbit around the Sun, at a distance of 1.5 million kilometres further out than Earth. This special location, known as L2, will keep pace with the orbit of the Earth.
    WMAP is there already, and the James Webb Space Telescope will be going there as well. Going to get crowded!
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    Quote Originally Posted by ToSeek
    Going to get crowded!
    Solar and Heliospheric Observatory (SOHO), remains at the L1 point
    It is thought that we are unlikely to find any recent use for the L3 point since it remains hidden behind the Sun at all times. Recently, the DIRBE instrument on the COBE satellite confirmed earlier IRAS observations of a dust ring following the Earth's orbit around the Sun. The existence of this ring is closely related to the Trojan points. DSCOVR the Deep Space Climate Observatory previously known as Triana, will ba an Earth observing mission to travel to Lagrange-1 the neutral gravity point between the Sun and the Earth.

    Others who have gone or were going for that Lagrange-2 area

    Herschel a mission from the Euros largest space telescope will collect long-wavelength infrared radiation from most distant objects in the Universe

    Lagrange point is feasible for the TPF mission - NASA's Terrestrial planet Finder Coronagraph

    XEUS is a follow-on to ESA's highly successful XMM-Newton designed to search for the first massive black holes that formed in the Universe

    NASA's Genesis mission mapped some possible flight paths among the Lagrange points

    European Planck will collect the most ancient radiation in the Universe, known as the cosmic microwave background.

    NASA Kepler Mission has looked at the L2 for planet hunting so it could be another

    Darwin is an ESA flotilla of four spacecraft that will search for Earth-like planets



    Even with all these other missions coming up Gaia still looks to be one of the most exciting, a mission compiling the most precise map of one thousand million stars in our Galaxy. And after doing all this great work they will discover even more by using Gaia inofrmation to look at all the objects in Space and plot them all in a giant three-dimensional computerised model that shows not only their current position, but their direction of motion, colour and even their composition. Every day it will discover, on average, about 100 new asteroids in the Solar System, 30 new stars possessing planets, 50 new stars exploding in other galaxies, and 300 new distant quasars, which are powered by giant black holes. There are Asteroids which are difficult to see from Earth, monitoring these unseen but potentially hazardous asteroids could be important. Gaia is able to view the 'blind spot' found between the Sun and Earth's orbit. From Earth, we can only observe this area during the daytime one group known as the Atens could be a threat and it weaves between the Sun and Earth's orbit.

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    How about sending one or two space telescopes into orbit around one of the gas giants? The larger area would allow for better parallax. With two telecopes they could do VLBI with a baseline of dozens of AUs. Of course, the sun is dim out there so that might be a problem maintaining proper temperature and power.

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    Gaia and the Sunshield demo

    http://sci.esa.int/science-e/www/obj...objectid=37831

    GAIA will detect objects at about magnitude 20
    Gaia, the ultimate galaxy mapper

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    Quote Originally Posted by Jpax2003
    How about sending one or two space telescopes into orbit around one of the gas giants? The larger area would allow for better parallax.
    Why stop at a gas giant? Why not make several RTG powered Gaia-like probes with big communication dishes, and send them into faster-than Voyager escape trajectories in very different directions? You could have a factor of 100 improvement in parallax in ten years, and even more later.

    This could give you direct parallax measurements to any bright star in the galaxy, most of the globular clusters around the galaxy, and to the bright stars in the Magellenic Clouds.
    Forming opinions as we speak

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    When measuring the distance of stars using parallax, how do they compensate for the motion of the stars as well as the effects of gravity on the light?

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    Quote Originally Posted by Utwo
    When measuring the distance of stars using parallax, how do they compensate for the motion of the stars as well as the effects of gravity on the light?

    I don't think they need to because only close stars are measured this way

    parallax for nearby stars is quiet accurate, but the margin of error increases at larger distances
    I think distances were limited to 250 pc
    The Hipparcos craft also measured proper motions of stars.

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    The amount of data that will be produced by this craft will be indredible. It will have to be measured in the gigabytes per day, but I suppose thats comparable to the Hubble.

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    If you click on the link in the OP, then the ESA PR, you will find a wealth of material about this mission.

    This PDF contains a summary of the expected accuracy for parallax, position, and proper motion. At its best (bright red stars), Gaia will measure distance (from parallax) out to ~100,000 parsecs; for stars ~10,000 pc away, with a Vmag of ~<15, Gaia will measure their distances accurate to ~10-20%.

    The effects of 'gravity on light' will be calculated, using accurate data on the spacecraft's position, the mass of the Earth, etc.

    Gaia aims to measure the proper motion of the stars it observes. It will make ~90 observations of each of the ~1 billion stars, over its 5 year lifetime.

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    Quote Originally Posted by Manchurian Taikonaut
    ...Gaia will also identify as many as 10,000 planets around other stars...
    Gaia accomplishes a lot of different tasks in one package. That's really amazing. With regard to detecting "as many as 10,000 planets around other stars..." this seems like a long term project since star wobble over time would have to be the main factor for detection. I wonder if the programming linked to Gaia would also be capable of refining detection to include estimated sizes of planets.

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