They're not just snapshots, they're data
Posted by Emily Lakdawalla
26-06-2007 11:23 CDT
I've just put together the beginning of a new section on our website on space imaging data. We all love the beautiful images that are returned to Earth by our robotic spacecraft (well, at least I love them). But these images are much more than holiday snaps; each image contains hundreds or thousands of pixels, and each one of those pixels is a number; every number in every pixel represents a data point returned by the mission, a measurement of the amount of light reflected (or emitted) by a particular object in a particular spot in space.
Spacecraft return a lot of this data. A lot. Only a tiny fraction of it ever appears in print, because it takes a great deal of work to take an image from a raw data product to a beautiful, publication-worthy photo. Science teams tend to pick some of the best pictures, put their best work in to them, and then use the same pictures over and over in their presentations and publications. They use the other images in their research -- that's what the images were taken for -- but only a tiny subset of these ever gets shown to the world.
But the data hasn't been lost to the world; it's out there, waiting for anyone with the time, interest, and expertise to find it, download it, manipulate it, and make new images that few people in the world have seen. I know that lots of you have the time and interest but perhaps not the necessary expertise. So I'm putting this new section together in the hopes that I can help more of you reach the 95% of image data that only a few people have ever seen.The new section is on Space Imaging, and there's a few pages up for starters. There is a summary of the sources of planetary mission image data, like the Planetary Data System and all its Nodes, and the Planetary Science Archive. Eventually that page will also contain a list of where to find specific mission data; right now there's just a few scattered missions listed there. There is also an explanation of commonly used planetary image formats, such as VICAR and PDS, and what "raw" means. There's a summary of free software and tools that are available to access and retrieve this unusually formatted data. And there are tutorials demonstrating some of the most commonly used image processing techniques -- actually only one technique so far, but I now have the tutorial for making color images in Photoshop Elements in addition to regular Photoshop, thanks to Eric Hartwell for sending the modified instructions and screen caps.
I had a lot of help in assembling this material from Bill Green, who worked at JPL's Image Processing Laboratory through many missions over many years.
As part of this new section I've now posted the entire data set on the rings and moons from the Voyager encounter with the Saturn system in PNG format. This data comes from the Rings Node's ongoing project to calibrate and correct the Voyager images, and it is much more pleasant to work with than the original raw data. (For an explanation on what "Rings Node" means, read the new page on where to find the data.
Go play around with the data, and have fun! One thing in particular that is begging to be done is for someone to have a go at re-creating the Voyager multispectral movie of spokes moving around the B ring...all the images are there, on the rings page, just waiting to be used...
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