Huge Camera to Observe Dark Energy
Written by Nancy Atkinson
Discovering the universe is accelerating and not slowing down made it obvious to astronomers there’s a lot we don’t know about the universe; namely, a big chunk of it is missing from our visible observations. Astronomers determined roughly 4% of the universe is made up of ordinary matter and 22% of Dark Matter (inferred from gravitational affects on visible matter), leaving 74% unaccounted for. Dark energy, while still hypothetical, is what is believed to keep the pedal to the metal, so to speak, on the universe’s expansion. But an international group of astronomers believes that dark energy should be detectable, and they are constructing a huge camera, designed to look for it. The camera will consist of five massive lenses, with the largest at one meter in diameter, making it one of the biggest lenses in the world. A milestone was reached in the construction of this camera, as the pieces of glass for these unique lenses, seen in the image here, are ready to be shaped and polished into their final form.
The Dark Energy Survey (DES) camera will map 300 million galaxies using the Blanco 4-meter telescope - a large telescope with new advanced optics at Chile’s Cerro Tololo Inter-American Observatory. This instrument will consist of an extremely red sensitive 500 Megapixel camera, with a 1 meter diameter, 2.2 degree field of view prime focus corrector, and a data acquisition system fast enough to take images in 17 seconds.
Creating this huge map of the galaxy will enable astronomers to measure the dark energy far more precisely than current observations. Professor Ofer Lahav, who leads the United Kingdom DES Consortium said, "Dark Energy is one of the biggest puzzles in the whole of Physics, going back to a concept proposed by Einstein 90 years ago. The DES observations will tell us if Einstein was right or if we need a major shift in our understanding of the universe.”
The glass for the five lenses was manufactured in the US. In France the lenses will be polished to a smoothness level of one millionth of a centimeter.
After, polishing, the lenses will be sent to the telescope in Chile. Observations are scheduled to begin in 2011, continuing until 2016.
The team’s goals are to extract cosmological information on dark energy from counting galaxy clusters and the spatial distribution of clusters, and measuring the redshift of galaxies and supernovae.
The Science and Technology Facilities Council (STFC) is providing support for the Dark Energy Survey (DES) collaboration, which involves over 100 scientists from the US, UK, Spain and Brazil.
Orignal news sources: Science and Technology Facilities Council, Dark Energy Survey
Filed under: Dark Energy
June 25th, 2008 at 3:55 am
My reply to this article is that research should be a high priority for Science in these United States. I am a Math Professor and I think the students of today need a future they can look forward to.
June 25th, 2008 at 4:35 am
Nice to see the UK is still putting some efforts into research, but still below par compared to our European neighbours. For subjects like this, international collaborations are vital and need to be funded at a much higher level.
Nancy: it's 'gravitational effects', not 'affects'
June 25th, 2008 at 4:46 am
Quite apart from the important and interesting science to be taken from projects like these, maufacturing and engineering challenges at a whole new level have to be met., and solutions found.
These are important spin-offs which may bring benifits in other areas
June 25th, 2008 at 6:23 am
I was thinking the same thing.. I don't know if it will be successful in proving, understanding or debunking the current theory of dark energy (hopefully something will come of it) but the spin-offs could be useful.
June 25th, 2008 at 7:19 am
Looks like great fun, I love huge lenses.
You know… the size limit on glass lenses found on earth (About 40 inches) doesn't exist if they are created in space. Perhaps some day it will be possible to bring a bag of sand up to space and grind it into a huge lens.
June 25th, 2008 at 9:00 am
I don't understand. For a long time telescope makers have favored mirrors over lenses. What advantages does this big lens have over an equivalent mirror?
June 25th, 2008 at 12:35 pm
The problems with refractors are 1) chromatic aberration, and 2) over a certain size, the lens can't support it's own weight. A refractor in space can be bigger, but you still have chromatic aberration.
But this isn't a refractor. It's a camera.
"The cage containing the system mounts at the prime focus of the Blanco 4-meter telescope at CTIO, a southern hemisphere NOAO telescope." This is a reflecting telescope. So, one might think of this as an eyepiece for a big CCD. Maybe it lies flat, and therefore doesn't have to support it's own weight. The second of the two links has an image of the camera. It's unlabeled, and i can't make much from it, like where the lens or CCD goes.
My point and shoot camera has a smaller detector than 500 megapixels. But, it can take pictures faster than 17 seconds, without having to wait to 2011. There are always trade offs.
Maybe some small university could take delivery and make use of their older camera.
June 25th, 2008 at 1:22 pm
How can they be sure what physicists will be observing is dark energy? If the understanding of time and space is in fact incorrect then mapping galaxies and galactic redshifts will not prove anything other than noting that in the distant past galaxies were moving away from us at a faster rate due to the time it takes for their light to reach us. As for cosmological redshift, well that supposition is only right if physicists do really understand space and time.
June 25th, 2008 at 3:34 pm
Can't they just leave the lens cap on ?
June 25th, 2008 at 3:45 pm
Yeah exactly.. Or better yet, put it a couple of kilometers underground so it can look for WIMPS.. Oh wait.. That's dark 'matter', I think..
Sorry.. Just messing around..
June 26th, 2008 at 12:53 am
This sounds like a fun experiment.
Ian/Nancy, can you please keep us up to date on how this is progressing?
July 9th, 2008 at 11:50 pm
Should a black hole effect dark matter ? How about a star ? Is there a barrier like the opposite of gravity preventing this merge? Could gravity be actually dark matter flowing through us and into us and into the earth (all objects) all to keep us in existence ?
How about before the big bang there was dark matter then the bang that forces the weight of the black matter out into the depths of space and we appear (our visible world) then as this dark matter is expanding it is also expanding our universe like a suction so now we are in the vacuum of space .now here is where it gets tricky now the black matter is drawn back into our universe and its inrush is what is the force pushing us apart even faster because there is only so much room for black matter to exist in and we are being forced out of its way ( accelerated expansion of our universe)!