Gaia will map a billion stars

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

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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Eagle Eye Observatory

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.

the work is moving along

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.

ops: Sorry, but I cannot resist.

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

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"I've never heard of such a brutal and shocking injustice that I cared so little about!" - Zapp Brannigan (Futurama)

"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.

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...)

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.

Right. To be specific, Gaia will have an accuracy of about 10 microarcseconds, about two orders of magnitude better than the USNO and Hipparcos!

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.

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.

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.

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.

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!

Biggest space camera will map Milky Way

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Everything I need to know I learned through Googling.

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.