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Billion Star Surveyor 'Gaia' Lifts Off
mrspoonsi writes "BBC Reports: 'Europe has launched the Gaia satellite — one of the most ambitious space missions in history. The 740m-euro (£620m) observatory lifted off from the Sinnamary complex in French Guiana at 06:12 local time (09:12 GMT). Gaia is going to map the precise positions and distances to more than a billion stars. This should give us the first realistic picture of how our Milky Way galaxy is constructed. Gaia's remarkable sensitivity will lead also to the detection of many thousands of previously unseen objects, including new planets and asteroids. Gaia will use this ultra-stable and supersensitive optical equipment to pinpoint its sample of stars with extraordinary confidence. By repeatedly viewing its targets over five years, it should get to know the brightest stars' coordinates down to an error of just seven micro-arcseconds. "This angle is equivalent to the size of a euro coin on the Moon as seen from Earth," explained Prof Alvaro Gimenez, Esa's director of science.'"
The article states it will map 1% of our Milky Way, and there are 170 billion Galaxies in the universe, so that is: 0.0000000000005% mapping of the known universe (if my figures are correct).
What is that in Metric? Wait, I mean American?
Given how long it will take to chew through Gaia data (Essentially, as someone starting out in astrophysics, this mission could define much of my working life) there won't be another powerful astrometry mission for a while.
Why are you fixated on having NASA try to one-up ESA though? NASA has its own top end science missions planned, doing other things. If you are lucky and take care of your space agency, so of them might actually fly in space.
The angle of 7 u arc sec is 3.3 x10 ^-11 radians . The distance is 4 light years x 5.87 x 10 ^12 miles per LY . Product is 775 miles resolution of the position of a star 4 Light years away. Astounding accuracy !! congrats !
This is a mission I've been watching and waiting for for a while. The original Hipparcos mission did this sort of mapping for a much smaller volume of space.
Think of this as being like how finding the precise latitude and longitude of a large number of places on earth would have been to navigators of a much earlier era. No big new ideas, but it makes navigating so much easier and precise.
This does this for astronomy and cosmology in a greatly expanded region of space.
Something some don't realize is that our measurements of distance to stars and other objects in astronomy are very indirect. We use red shift to measure it in many cases, but that's an indirect method that relies on assumptions and estimates of the Hubble constant.
We also use what are called "standard candles". These are objects we know the brightness of from the physics of the processes going on. Certain kinds of supernovae are some of the best known. But, again, like measuring the distance to the next town by how bright the streetlights are, it's indirect and can have errors from intervening dust, for example..
This will use parallax, the same method as used in surveying to find distance from the change in angle between two separated observations of a far object. It's a direct method that relies on few assumptions.
You're talking about not wasting money but then in the next breath that the U.S. has to "win at space"? Last I checked, we weren't in a cold war with Europe or anything. Just call this a win. We don't need to one-up them. I know it's a radical concept, but maybe we could all SHARE information about space.
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