7 April 2010
We've come a long way
Posted by Ryan Anderson
Yesterday our Mars Journal Club met to talk about a book chapter from 1990 about geologic mapping on other planets. It was really useful and informative, but what really struck me was how much things have changed since then. When the chapter was written, the best images of Mars were the Viking orbiter maps. There were also a lot of lunar examples in the chapter along the lines of: “Clearly seen in figure 7, the ejecta from Copernicus overlies the lunar highlands and mare.” But the image where this was suppsed to be “clearly seen” was a grainy, low resolution image that we all had a hard time interpreting.
These days we are spoiled rotten with the quality of data for both the moon and Mars. When I do a geologic map, my “low resolution basemap” is made of CTX images at 6 meters per pixel! Or if that coverage is incomplete, maybe I’ll use THEMIS infrared coverage at a crude 100 meters per pixel. Looking back at maps of the planet that were done using data measured in kilometers per pixel, I’m a little jealous because the people using that first data got to map everything in detail for the first time. But it also sort of boggles my mind that they were able to draw anything but the broadest conclusions from the available data. Those maps form the foundation for modern Mars work, but they must also have gone into the project knowing full well that many of their interpretations were probably wrong.
A geologic map of eastern Valles Marineris, based on Viking data.
I found it especially interesting that the chapter that we read gave detailed instructions about how to draw a geologic map that a drafter would be able to make into a publishable final product. The chapter discussed sketching the map (by hand) on a medium such as mylar that wouldn’t change size day-to-day between mapping sessions, and the consideration that dashed lines were more time consuming and expensive for the drafters to draw. All of this seems so quaint and archaic compared to modern computer programs that can do mapping on the screen in incredible detail. And yet, it also forced early mappers to be incredibly careful and systematic.
The amazing thing is that it doesn’t seem like 1990 was all that long ago! And yet we have gone from hand-drawn maps of the crudest features on the martian surface to digitized maps of amazingly high resolution, using images in which we can count individual boulders. Not to mention all the other supporting datasets that are now available from the orbiters and multiple rovers and landers.
It just reminds me that we’ve come a long way, but we still have a long way to go. And that, in turn, reminds me of the cheesy theme song to Star Trek Enterprise. It has indeed been a long road…
http://www.youtube.com/watch?v=qt_GIBTUk9Y
I remember visiting a computer mapping room (?Dept.) at the University in 1978 and the complaint was that they jsut could not store that much graphical data because the files were large. No Graphical user interface like Windows. We used DOS> These guys were being held back on their work just because of storage issues. You probably have more power and storage on your laptop computer than whole Univeristy depts. did.
The funny thing is, the data we’re working with has grown too, so I still run into files too large to work with and/or store.
“it also forced early mappers to be incredibly careful and systematic”
How true that is! Modern mapping techniques all everuything to be digital from data capture inthe field to the final product. And yet that final product is often inferior because not enough thought has gone into the presentation. Too many units and too much detail for the scale at which the map is used is a common failing. Bore map layout, bad colour combinations, poorly chosen symbols are common problems, as is failure to match adjacent map sheets. Another problem is the difficulty to map features that don’t fit the preconceived nottation. then there is the fact that the csoftware is designed by computer people, not geologists.