Heroic data recovery story: 40-year old lunar orbital data

Thanks to Andrew Treloar for the heads up on a wonderful data recovery story. Andrew’s link was to a Slashdot article; there’s not a lot of information there. After a bit of searching around, I found a longer version of the story from last November at CollectSpace, and an interesting discussion on WattsUpWithThat (dated 1 April, which is why I emphasised the November date!).

Roughly the story is that NASA has been sitting on a collection of some 1500 2” analogue tapes which captured high resolution images taken by the Lunar Orbiter mission in 1964 that preceded the Moon landings. The aim of this program was to identify sites for the landings. Although NASA only used low resolution versions of the images (including the famous “Earth Rise” image, see Wikipedia article), the high resolution images were recorded onto the tapes by special Ampex FR-900 instrumentation recorders. Many years later, the archivist concerned refused to throw the tapes out. And eventually even found 3 non-functioning drives, which she stored in her garage, until news of the story leaked out to some interested people, including at least one retired Ampex engineer. Since then, with a little funding from NASA, and some space in an old McDonalds at NASA Ames, they have been attempting to refurbish the drives, and have managed to get at least two images off the tapes. If they can find more manuals and parts, they hope eventually to read all the tapes.

There’s lots that is interesting here. I particularly liked the response to this question from a reader: “What’s being done about the tape itself? You can’t just pull it out of the tins and thread it up.” Dennis Wingo, the main engineer involved replied:

“You know, amazingly enough that is exactly what we do. I am continually amazed that this works as I used to run a TV studio in LA where we could not do that even 20 years ago, but we have had an amazingly small number of tapes that even produce head clogs. We have run some tapes as many as 20-30 times in doing testing. Absolutely amazing to us.

I heard a story, that seems plausable but not sure about it really. It turns out that in 1975 all of the vendors changed the formula for the adhesive that holds the iron particles to the tape back. The new formulation had problems with moisture and over time degraded significantly.

However, the tape before 1975 that did not have this problem was made with a different mixture that included WHALE OIL, I kid you not. I don’t know if this is true […].”

One commenter had a major set of suggestions on how to deal with the stream if all they had was the analogue signal. Dennis responded, in part:

“We are using PCIe digitizers on a Mac Pro workstation to capture our data so we are able to get high data rate captures up to 180 megasamples per second.

We can do a lot with that but we would have to do a LOT of digital post processing including doing the demodulation in the digital domain, which is NOT going to be easy. Much easier to do in hardware, especially since we have spent the money doing so.”

Hey, that'se a hardware engineer talking! I guess it means he’s optimistic to be able to make and keep the drives alive long enough to digitise the entire set, rather than trying any more radical software solutions.

Data recovery from > 40 years ago, anyone? It is heroic, but let’s not be frightened!

Obsolete drives; sideways thinking?

I’ve been trying to write this post for ages, but the draft never seemed right, so this is starting all over again, blank sheet.

Many people have a bunch of stuff on media for which it’s hard to find a working drive, whether disk or tape, or punched card or paper tape, or… A feature of the response to my “12 files for Christmas” post was that those who responded have their interesting stuff locked away on such media. There may be other challenges to reading it, but the first is getting the content off the media.

We tend to go all gloom and doom about this. I’ve got stuff on Iomega Jaz cassettes from an earlier Mac, so without a Jaz drive I can’t read it. Might as well chuck it in a bin? Folks have stuff on early Mac 3.5” drives, or Amiga drives, neither of which can be easily read on current systems. And 5.25” or 8” drives are even scarcer in working condition.

Is the only answer to find a working drive on a working computer of the day, the "technology preservation" approach? I remember an ancient engineer scolding me years ago for failure of the imagination, on the subject of disappearing 7-track magnetic tape drives. “Young man” he gruffed, “if you really care about this stuff, lay the tape on your kitchen table, cover it with paper, scatter iron filings across the top, give it a tap, and read the bits off with a magnifying glass!” He didn’t mention that I had to know the relationship between domains and bits, the parity and other features of character encodings, the block structure of the tapes etc; in those days we knew that stuff!

Now I’ve done the maths, and this is NOT feasible with a 3.5”, 2 MByte floppy disk (the iron filings are too big)! It might just be feasible with some of the 8” floppy formats. Different technological approaches (not iron filings, but some other means of making magnetic domains visible, if such means exist) might be feasible for higher densities. In any such case, you would end up with an image of the bits on the disk, in concentric tracks. From here, you have a computational task, or a series of such tasks: identify the tracks, separate into sectors, decode into bytes or characters, decode into directories and file structures, process into files, and now you have something to operate on! Yes, it’s tough to do all that, but you would be able to combine lots of contributions together to do it.

Now, I’m NOT saying that’s the best approach. I AM saying, 8” drives were advanced technology when introduced more than 20 years ago. The requirements for a production 8” drive included high read/write performance (for the time). The requirements now have changed. Performance isn't the issue; scraping every last reliable bit off that drive is!

Today, more than 20 years later, storage engineers in their clean-room high tech environments can build amazingly high performance production drives with previously inconceivable capacities and speeds. But what could you do today with a Masters-level Electronic Engineering lab, some bright students, a few hundred dollars, these ancient media formats, and a much-reduced performance requirement? I don’t care if it takes 10 minutes to read my disk, as long as I can do it!

Is this important? These disks have been stashed away for 20 years, who cares what’s on them? Well, in many cases no-one does. But just think who was using those early drives, and what for. They certainly include authors, poets, scientists, scholars, politicians, philosophers… and many of those people, if not in the first flush of youth then, are moving towards retirement now. Some of these will be candidates for approaches from libraries and archives interested in their “papers”. Previously this meant boxes of paper, photos, diaries etc. Now it includes old media, dropped in the box years ago. Who knows what treasures they may contain? (See the Digital Lives project for examples.)

So, I think there is or will be an emerging interest in these obsolete media and their contents. And at the same time, I think (hope) it would represent an interesting challenge to set students. Perhaps not quite in the same class as building a car to drive across the country on solar power, or robots to play football, but interesting in its own different way.

One of those combined Computing Science and Electronic Engineering schools would be perfect. Would a prize help? Maybe this could factor in something like the Digital Preservation Awards one year? A new kind of Digital Preservation Challenge?

Old and not so old peripherals needed

The DCC has started to get a number of help-desk queries from people who want to know how to read information from obsolete media, and therefore want to find someone with a working example of the appropriate peripheral. These days, this can be as simple as finding a working 3.5 inch diskette drive (I'm not sure there is one on this entire floor!). We have also been asked to report the whereabouts of 5.25 inch diskettes, 80-column punched card readers, open reel magnetic tape drives and Jaz and other "high capacity" portable media drives. I have a bunch of Jaz media myself, although I think (!) that everything important is now on my hard drive AND backed up. It can be surprisingly hard to find the answer to such questions.

In 1999 the eLib Programme commissioned a study that resulted in a useful report: ROSS, S. & GOW, A. (1999) Digital Archaeology: Rescuing Neglected and Damaged Data Resources. Appendix 3 of that report lists then current data recovery companies, some of which are still in operation (perhaps it would be useful for JISC to commission someone to update this report?). These companies would certainly be one place to start, albeit an expensive one (as they are aimed at the corporate disaster recovery market).

Perhaps institutions should have a considered strategy for continued access to the more common examples. As staff retire and remember possible valuable content amongst their pile of obsolete media, it would be valuable to have a simple means at least to check them...

Does anyone know of any register of the less common such peripherals available within the public sector, preferably available for external use at a reasonable fee?

As a starter for 10, I believe there is a 80-column punched card reader at the UK Data Archive...