Digitizing 100 Years of Astronomical Data 115
Maximum Prophet writes to mention that a collection of glass plates containing astronomical information from the late 19th century through the mid-1980s is being considered for digitization. "The accumulated result weighs heavily on its keepers on Observatory Hill, just up Garden Street from Harvard Square: more than half a million images constituting humanity's only record of a century's worth of sky. 'Besides being 25 percent of the world's total of astronomical photographic plates, this is the only collection that covers both hemispheres,' said Alison Doane, curator of a glass database occupying three floors, two of them subterranean, connected by corkscrew stairs. It weighs 165 tons and contains more than a petabyte of data. The scary thing is that there is no backup." I'm sure that anyone with a spare $5 million or so would be welcomed with open arms.
InfiniBytes (Score:5, Informative)
Glass photographic plates, especially from silver emulsion, are analog at extremely fine granularity. Effectively molecular, depending on how flat the glass surface was settled from its molten liquid state. The features of its silver oxide crystals, laid in place by individual photons arriving from vastly distant stars, could be meaningful at less than a nanometer. Especially when measuring extremely subtle influences, like the gravity from one distant star bending the light of another distant star, measured across a century in which those stars lost gravitational mass, for comparison.
There is a practically infinite amount of data on each of those plates, limited by our precision in measuring them. It's a smaller degree of infinity than that of the sky. But the original infinite sky is lost. While the plates' lesser infinities are impossible to replace, and all we'll get to use to look back across all the billions of years we saw in a long century of them.
Re:This sounds like a job for Google (Score:3, Informative)
Re:Why does it have to cost so much? (Score:5, Informative)
> It took 2 years and way WAY WAY less than $5,000,000 to do it
500,000 plates. Over 2 years, assuming 50 wks/yr means just 5000 plates need be scanned per week. 1000 plates per day. 125 plates per hour. And this is large, fragile glass with really high data density, so you have to be a) careful in handling and b) use slow high-res scanning.
Let's take a guess that it takes only 10 minutes per plate (to fetch, tag, load, scan, and return). So we need only 20 people to scan 125 plates/hour.
Well, assume 20 scanning people and 1 IT guy handling the sysadmin work for the petabyte storage. Also one scientist/manager. Take a low intern/grad student $35k, 1 sysadmin at $65k, 1 PM/sci at $85K. All x2.5 for overhead, for 2 years. That's $4.25 mil in salaries.
There's also buying a redundant petabyte and all the necessary gear. I'm amazed they figure $5mil can do it.
Re:Glass plates will outlive the digital"backup" (Score:4, Informative)
So what? Copy the digital version onto a second set of disks when it comes close to expiring.
Lossless copying means that given a little bit of maintenance, expiration of digital media is a nonissue.Re:data/mass ratio (Score:4, Informative)
165 short tons = 149,685,482 grams
1e15 / 149,685,482 = 6,680,674 bytes per gram
A quick check of amazon turns up a 1TB drive which weights 2.4 pounds.
That's 1,089 grams which is 918,592,757 bytes per gram.
Unless I've messed up my math, it looks like hard drives store 137 times more information per gram. That's not as large a multiple as I had imagined though. The whole thing should still be between 1 and 2 tons when put on hard drives.
Harvard can handle the burden (Score:5, Informative)
This:
Harvard University's endowment, valued at $25.9 billion at the end of FY 2005, is a collection of more than 10,800 separate funds established over the years to provide scholarships; to maintain libraries, museums, and other collections; to support teaching and research activities; and to provide ongoing support for a wide variety of other activities. The great majority of these funds carry some type of restriction.
I think they can scare up the change.
Re:InfiniBytes (Score:3, Informative)
If the astronomers who recorded these plates weren't anal, then astronomy wouldn't be advanced enough by now for you to enjoy it as an amateur.
Re:Harvard can handle the burden (Score:2, Informative)
More than just a flat scan (Score:4, Informative)
There is more to this than simply scanning a flat image. The emulsion on these plates is a three dimensional medium, and different data can be extracted depending on your focal depth into the the emulsion. I believe David Malin did much pioneering work on this kind of thing, including the use of different layers for unsharp masking.
There will be information in the plates that is not yet part of human knowledge, and a simple scan of one focal plane is not going to get it all.
Certainly it is worth taking backup images of these plates in any way we know how, but we should remain aware that, as of today, no technology exists that will make exact duplicates of them, so great care should always be taken to preserve the originals.
Re:Why does it have to cost so much? (Score:2, Informative)
You need specialized scanning machines for astronomy. Office equipment doesn't do the job.
My colleagues in the UK had such a scanner. It was ~7 tonnes of metal, glass and electronics (heavy so as to be very stable), lived in its own building and needed several clever people to keep it running. Building one of these (or cloning one you already have so as to work faster) could cost a big chunk of the $5M.
The scanner I knew took ~ 30 minutes to scan a plate. For the harvard collection, choose between one scanner (which they may not have; otherwise why did they wait until now to start the project?) and a long project with big sallary bill, or multiple scanners, at extra capital cost, and less money for people.
Re:Luckily glass isn't a liquid.... (Score:3, Informative)