Exposing PseudoAstronomy

October 5, 2011

Playing Hide-and-Seek with the Apollo Landers


This post is less about “pseudoastronomy” and more about what you (or anyone) with an internet connection can do with the amazing pictures taken by NASA’s Lunar Reconnaissance Orbiter. Though I suppose it’s also related to the Apollo Moon hoax in that we finally have a camera in orbit that’s capable of seeing the Apollo landers.

The Instrument

The Lunar Reconnaissance Orbiter (LRO) spacecraft has been in orbit of the moon for nearly three years. It has a suite of instruments onboard, though the one we want for this exercise is called the Lunar Reconnaissance Orbiter Camera (LROC). This camera actually has two “lenses” on it — a wide-angle camera (WAC) and a narrow-angle camera (NAC).

The spacecraft is in an orbit that, with the field of view of the cameras, allows WAC images to have a pixel scale of 100 meters, and the NAC has a pixel scale of about 50 cm (0.5 meters, or about 20 inches). And that’s just cool.

So we’re using LRO’s LROC’s NAC. Lots of a.c.r.o.n.y.m.s. Each NAC image is about 2.5 km wide and generally about 50 km long – a tiny fraction of the surface of the moon.

What to Do

You could use the LROC image search feature and find the Apollo landing coordinates from Wikipedia or some other source, put them into the search, and go searching for the Apollo sites that way.

You could cheat a bit and use this website’s list of NAC images with the Apollo landing sites in them (that’s what I did). Then you can use the LROC image search and search for that exact image and click on it. Or, you can directly go to the URL http://wms.lroc.asu.edu/lroc/view_lroc/LRO-L-LROC-2-EDR-V1.0/M113853974RE and replace that last string of letters and numbers (M113853974RE in the case here, which is for the Apollo 16 landing site) with the image ID.

Then, search! You can use the Flash-based tool that the LROC team has set up on that page to zoom in and out and search for the landing site, or you can download a TIFF image (generally around 20-50 MB) from the link towards the top (“Download CDR PTIF”). Sometimes using the information and image on the site with the list helps you to find it more easily.

But while you’re searching, you’ll find a lot of other interesting features. You could find the Apollo 17 “Challenger” descent stage along with the astronaut tracks (story about that on the LROC site here). And if you end up liking treasure-hunting on the moon, you may find Moon Zoo a citizen science project, of interest.

When identifying the NAC images to look through, one thing to pay attention to is the “incidence angle” or “solar altitude” which tells you what the shadows are going to be like. You may think that it’s best to see these when the sun is directly overhead (solar altitude is 90°, or incidence angle is 0°). But, this isn’t actually the case, You want longer shadows so that the features are easier to see. Incidence angles closer to 60-80° or so are generally best (solar altitude 10-30°).

But don’t take my word for it — try looking at the same landing site under an 80° incidence versus a 10° incidence angle. While the craters are much harder to see and the landing sites look more like brightness features rather than “3-D” because of the lack of shadows, you’ll see things like bright crater ejecta and dark crater ejecta that the lower sun angles made invisible!

Final Thoughts

Maybe it’s just me, but I actually find this kind of thing fun (I spent an hour looking for Apollo 15 last night in 5 different lighting conditions). It also gives you a nice perspective on the relative sizes of things — not necessarily that the Apollo hardware was “small,” but really how BIG the moon is, and how much we have left to explore.

If the solar system were reduced in size such that the sun were a grapefruit (about 10 cm), Earth would be located about 11 meters away. Humans have traveled a mere 2.8 cm, or about 1 inch, into the solar system.

I also find it absolutely amazing that in this day and age, there are still people out there who don’t think we ever landed people on the moon.

P.S. Please remember my comments policy. I consider anything related to UFOs to be off-topic for this post.


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