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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?
Next step: Galaxia
Just slightly smaller than an American Quarter, not enough difference to affect this comparrison.
On a Five Year Mission, no less. Quick, establish the United Earth Space Probe Agency immediately so the Americans can claim to be involved while they contribute nothing.
It seems even the definition of star isn't always clear
I fervently hope that Nasa will get enough fund to construct a much powerful equipment than Gaia and sent it to space to help us understand the universe better.
I fervently hope that the American government will stop wasting money on all the wasteful and counter-productive pork-barrel programs and put the money into GOOD USE and help put America in the lead again in the Space Frontier.
2013 is drawing to a close. Will 2014 be a better beginning for the United States of America ?
Muchas Gracias, Señor Edward Snowden !
...is whether it can detect Apollo 11 mission stuff on the moon. That would shut a few mouths. The Hubble telescope lacks sufficient resolution in the visible light range.
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 !
That's the uncertainty in the sideway position only.
sideway uncertainty = (3.3 x10^-11) * (4 LY) = 775 miles
Most of the error in the position of a star is in the depth direction. That error is given by a different formula:
depth uncertainty = (3.3 x10^-11) * (4 LY)^2 / (2 AU) = 98,150,000 miles
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.
1.01 billion dollars.
Gaia is the first God, the God of all Gods and a women.
http://en.wikipedia.org/wiki/Gaia_(mythology)