Digitizing 100 Years of Astronomical Data

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.

Comments

Glass plates will outlive the digital"backup"

[gatkinso]

now there is some irony.

Re:Glass plates will outlive the digital"backup"

[WhatHappenedToTanith]

Are you sure about the stability of glass plates? I hear a lot of people have real trouble with windows stability! Sorry, I'll go now....

Re:Glass plates will outlive the digital"backup"

[KokorHekkus]

now there is some irony.

But currently they also makes them vulnerable to a single point of failure (as indirectly pointed out in the article). If you have some data that has any real value for you then having only one copy (or only one storage facility) isn't any real protection whatever method you use. In this case we have data that would be readily accepted for backup by organisations all around the globe and barring a worldwide upheaval the safety of the data would be much better than any single glassplate could offer.

Of course the ideal would be if we could develop a cheap digital permanent storage that had guaranteed physical longevity, say several millenia. That combination would allow easy dissemination of the data and safety by using a multiplicty of sources.

Re:Glass plates will outlive the digital"backup"

[Cecil]

Ever tried to maintain archival backups for a petabyte-worth of data?

Yes, as a matter of fact. Definitely a lot of work is involved, but do you believe that you wouldn't need a team of document managers, millions of dollars worth of floor space, and expensive climate controlled facilities for archival of microfiche? You most certainly do. It's a lot of data. Period. No matter what you try to do with it, it's a lot of data. It's going to require a lot of resources. That's just a fact of life.

Anyway, noone in their right mind would choose microfiche for that type of data. If you're only storing plain text pages it's adequate (though I still don't think it would be the "right way to do it" in this day and age), but for photographic plates? Not going to work.

Microfiche is vastly overrated, in my opinion. My current project involves taking 2 floors worth of 30-50 year old microfiche and scanning it, OCRing it, and PDFing it. Yes it certainly does age. Quite poorly, in fact. The quality is absolutely terrible compared to the paper versions, some of it is stuck together, and indexing and cataloging it is a nightmare all of its own.

Yes, there are challenges in the digital world too, but most are easily surmountable given a little bit of common sense in understanding that digital is not magic. It doesn't mean you can "fire and forget". The documents will still require maintenance, cataloging, protection and monitoring. Format obsolescence is very nearly a nonissue, it is blown way out of proportion. That's where the "maintenance" comes in. The key benefit of digital is that you can and should losslessly upgrade your format whenever obsolescence is becoming a concern. Formats do not disappear overnight and suddenly everyone forgets what to do with them, you have plenty of time to make your transition if you're paying attention (which you must be: again, digital is not magic).

Google

[blhack]

I'm sure that a company like google would be MORE than willing to fund a project archiving these. The positive press, proliferation of their intended "do no evil/good guy/just another bunch of geeks" image, having their name on a major scientific project would easily be worth the investment.

InfiniBytes

[Doc Ruby]

contains more than a petabyte of data

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:InfiniBytes

[modecx]

here is a practically infinite amount of data on each of those plates, limited by our precision in measuring them.

And limited by the lenses/mirrors, and limited by atmospheric effects, and inconsistencies in the glass, and the silver, and, and....

I can't testify to the quality of the glass negatives, but I can testify to the fact that as much as people like to believe, even the best modern analog capture sources aren't anywhere near practically infinite, even in the best laboratory conditions.

sounds familar

[Anonymous Coward]

anyone with a spare $5 million or so would be welcomed with open arms

That's what she said!

Re:Why does it have to cost so much?

[ghostlibrary]

> I spearheaded a "digital backup" of around 90 filing cabinets of papers ...
> 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.

Harvard can handle the burden

[tchdab1]

From here: http://www.hno.harvard.edu/guide/finance/index.htm l,

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:Would Google archive it, perhaps?

[networkBoy]

Google Universe (beta)
Searchable in Lat/Lon/time/intensity
that would be awesome...

A great idea.

[niktemadur]

If they manage to standarize a century of these plates, it would significantly extend the time range of data to digitally extrapolate and detect objects previously missed. Just to speak of mapping our own cosmic backyard, a significant amount of slow moving, previously undetected Kuiper Belt Objects, for example, would more easily pop into view. Surely a bunch of comets, too.

Clyde Tombaugh captured Pluto several times during his three decades long hunt for the elusive Planet X, but failed to put the pieces together. If he had had digital technology, he would have shaved off at least a decade of effort. So imagine all the extremely useful raw data still stored in those plates.

More than just a flat scan

[CraterGlass]

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.