This has been over two months in the making: I’m finally releasing my first infographic. It’s entitled, “Planets and Major Moons: Distribution of Non-Lander Spacecraft Photos Since 1970.” (Suitable for printing on A-size paper with a bit of top and bottom margin to spare.) The purpose is to show the number of images taken by different space probes of the planets (and major satellites), the percentage of the total images that were for each body, and for each body, the percentage taken by each different spacecraft.
PDF Version of Spacecraft Imagery Infographic (3.5 MB)
PNG Version of Spacecraft Imagery Infographic (4.7 MB)
Number of Images of Planets Taken by Spacecraft Infographic
I’ve been wanting to create infographics for awhile. Really good ones are few and far between, especially for astronomy, but the good ones are often amazing works of art. I don’t pretend that this is an amazing work of art, but hopefully it’s not ugly.
To me, the key is to have a lot of information crammed into a small space in an easy-to-understand way that you don’t have to be an expert to interpret. In my work, I deal a lot with multi-dimensional datasets and so already I have to come up with ways of displaying a lot of information in as few figures as possible and yet still make them readable.
An idea that I came up with is based on the claim that “NASA hides all its pictures!” (This is often, hypocritically, almost immediately followed up with NASA spacecraft imagery showing claimed UFOs and other pseudoscientific claims.)
And so, I wanted to investigate this: How many images really have been taken and are available publicly, for free, on the internet? After several days of research, I had the results, and I assembled them into the above infographic.
I was surprised by some of the numbers and I was not surprised by others. One thing that did not surprise me was that the outer planets have very few photographs (relatively speaking) of them, while most imagery has focused on Mars and the Moon (fully 86%).
But, I was not prepared for how very few photographs were taken by our early probes to the outer solar system. Pioneers 10 and 11 were the first craft to venture out, and yet, because of the (now) archaic method of imaging and slow bandwidth, they collectively took a mere 72 images of both Jupiter and Saturn. Compare that with the ongoing Lunar Reconnaissance Orbiter around the moon, which has publicly released over 1.1 million images.
You can also see the marked effect of the Galileo high-gain antenna failure: Only 7.4% of the photos we have of Jupiter were taken by Galileo, despite it being an orbiter in the 1990s. Compare that with the Cassini orbiter of Saturn, which has returned nearly 50 times as many images, despite no dramatic change in technology between the two craft. This means that only 0.4% of our images of planets and moons are of Jupiter, while 1.9% are of Saturn.
You can also see the marked success of modern spacecraft and the huge volumes of images that (I repeat) are publicly available. The pie slices in the infographic are color-coded by approximate spacecraft operation era. Well over 90% of all images were taken after 1995, and the current suite of the latest NASA spacecraft (MESSENGER around Mercury, Lunar Reconnaissance Orbiter around the Moon, and Mars Reconnaissance Orbiter around Mars) account for a sizable fraction of the returned data for that body — especially MESSENGER, which accounts for 98.1% of all Mercury images.
What was I most surprised by? The Clementine mission to the moon. It returned and has publicly archived just shy of 1.5 million images of the lunar surface. I expected the Lunar Reconnaissance Orbiter to have surpassed that. And, it still may, as it continues to operate and return data. We shall see.
Why the Conspiracy Theorists Are Wrong
As I said, one of the primary reasons I made this was to investigate the claim by conspiracy theorists that these space agencies hide photographs. The blame rests almost entirely on NASA by most conspiracists’ accounts. This infographic proves them wrong in two significant ways.
First, at least for the Moon, Mars, and Venus, sizable numbers of images have been taken by and publicly released by non-NASA sources. I specifically have data from the European Space Agency (SMART-1, Venus Express, and Mars Express), and Japanese Space Agency (SELENE / Kaguya). While both the Indian and Chinese space agencies have also sent spacecraft to the moon and Mars (Mars for the Indians with the recently-in-orbit “MOM” craft), and Russia has sent craft to Venus, Moon, and Mars, I could not find the public repositories – if they exist – for these missions. Therefore, I could not include them. But, a lack of those two does not affect the overall point, that non-NASA agencies have released photos of these bodies.
Second, as I’ve repeated throughout this post, these are the publicly released images. Not private. Public. To public archives. In the bottom-left corner, I have the sources for all of these numbers. (Please note that they were compiled in late October and may have increased a bit for ongoing missions — I’ll update periodically, as necessary.)
The total number of lunar images? About 3 million.
Mars? Around 1.6 million. Venus? Over 350,000. Mercury? Over 210,000.
It’s hard to claim that NASA hides lots of images when these numbers are staring you in the face.
What Conspiracists Could Still Claim
I think the only “out” at this point, given this information (and if they acknowledge this information), is for conspiracists to claim that NASA and other space agencies simply obfuscate the “interesting” stuff. I suppose that’s possible, though they’d need armies of people to do it on the millions of returned images. And they apparently do a pretty bad job considering all the images that conspiracists post, claiming that features within them are of alien-origin.
It’s amazing how the “powers that be” are so powerful, and yet so sloppy. Apparently.
What This Infographic Does Not Show
I had to decide to clip a lot of information. We’ve imaged a lot of asteroids and a lot of comets. Those are out. We have had landers on the three closest bodies (Moon, Mars, Venus). Those images were not included.
Also, I focused on visible-light images, mostly. There are some instruments that take more UV images, or far-IR images, or various other wavelengths, but this infographic focused on the visible or near-visible light camera data.
Pretty much the only exception to this is for the Magellan mission at Venus, which took radar swaths of the planet to “image” the surface. I included this because, in early test audiences, I did not have Venus at all, and they requested it. Then, I did not include Magellan, but the test audiences wondered what happened to it. Describing why that data was not present made things wordy and more cluttered, so I, in the end, simply included it and put a footnote explaining the Magellan data.
This also fails to show the volume of data as measured by or approximated by (for the older craft) pixel count. If I were doing this by amount of pixels returned, the Moon and Mars would be far larger in comparison, and the Lunar Reconnaissance Orbiter and Mars Reconnaissance Orbiter would be much larger fractions of their respective bodies.
I’m releasing this under the Creative Commons license with attribution required, non-commercial distribution, and no derivative works (please see the CC stamp at the bottom of the infographic). This is so that I can at least have some semblance of version control (see release date at lower right).
I hope you find it useful and interesting. And at least somewhat purdy. If you like it, share it.