Space Junk And Visual Lies
October 14, 2009
A little while back, due to a collision between a dead Russian military satellite and a US commercial satellite, there was some noise about space junk because of the potential danger it posed to the International Space Stations and the Shuttle. The image that of space junk that became the icon of the problem is this image (click to enlarge):
I hate this image. Passionately.
The reason I hate this image is because it is probably the biggest visual lie I’ve ever seen. In his book The Visual Display of Quantitative Information, Edward Tufte has a concept called the “Lie Factor”. The “Lie Factor” judges the extent to which the data and the visual are out of sync.
Nothing could be more out of sync with reality than this image. While it imagines the appropriate number of objects circling the earth, it completely misrepresents the scale of those objects.
Space is unimaginably huge. While there are thousands of objects circling the earth, they range in size from a volleyball to a small school bus. If you do the calculations, the objects in this image range in size from Delaware to Tennessee.
Math Time! (skip if you don’t care)
In this image the diameter of the earth is about 1950 pixels. The real diameter of the earth is about 8000 miles. That means that every pixel is a shade over 4 miles.
The smallest piece of space junk in this image is about 10 pixels wide and 18 pixels tall and the largest one is about 24 pixels wide and 104 pixels tall. That gives the small objects an area of about 3000 square miles (about 30% larger than Delaware) and the large ones an area of 41,000 square miles (a shade smaller than Tennessee).
End of Math Time
To give an example of this exaggeration, let’s look at Angelina Jolie. (How’s that for a non sequitur?) Jolie has a freckle (beauty mark, mole, whatever) above her right eye.
Let’s say we’re concerned about people getting skin cancer, so we want to make a shocking graphic that we hope will help people remember to monitor skin markings for signs of melanoma. If we lied visually as much as the space junk photo, we would change a picture of Angelina Jolie from:
Imagine the Photoshop is done a shade better than I can do. The intention to do good and get people to realize the severity of melanoma is all well and good, but it doesn’t justify lying to people.
Granted, the space junk image holds the disclaimer that it is “an artists impression”. But that isn’t how people read these kinds of things and anyone who believes otherwise is, quite frankly, lying to themselves about the realities of human perception and belief. People see these images and they expect that they match reality in some way. Do a search for “space junk” to find out how many otherwise intelligent people have accepted this image as reality without a breath to admit how inaccurate it is.
This is not to say space junk isn’t a problem. I would have “solved” the problem of visual representation by portraying the space junk as a dot. A single pixel that can clearly indicate position instead of pretending to be a representation of size. Then, I would explain that, even though these objects are very tiny compared to the size of the space they’re in, this junk moves at thousands of miles an hour… making very small objects insanely dangerous.
You could effectively compare it to shooting a bullet into the air. A tiny piece of metal in a huge space can be really dangerous. People get that. There is no reason to portray the bullet as a 747.
I’m worried that even scientific people either didn’t recognize this problem or didn’t feel the need to speak up about it. Even people experienced in infographics didn’t say anything (see here, and here). (Side Note: I take particular pleasure is smacking down Wired magazine for putting up this graphic without even mentioning that it is an “artist rendering”. As a whole, they tend to be smug and irritating in the extent to which they dismiss anyone without technical or scientific expertise. Here they reveal that they are just as susceptible to junk science as the average Joe.)
There is an extent to which many people in scientific and technical journalism are content to give people the appropriate impression (“Space junk is a dangerous problem”) without providing them with the appropriate information. Or, to put the problem simply, they think the end justifies the means.
I take the view that truth in data is the highest importance. I’m frustrated in how lonely it is out here on my high ground.