Neat Animation of Moon’s North Pole with LASER Altimetry – And Artifacts

I’ll be attending a µSymposium before the Lunar and Planetary Science Conference this coming weekend, and I just got a reminder e-mail today. Included in that e-mail was a link to an animation that shows Shackleton crater, a crater that is ON the moon’s north pole. As such, its interior is in permanent shadow.

BUT!! The Lunar Orbiter Laser Altimeter instrument (LOLA) on the Lunar Reconnaissance Orbiter (LRO) has plenty of data that allow it to be viewed: Click Me!.

I find this very neat — until the last decade, we could never see stuff in permanent shadow because we didn’t have the instrumentation. LOLA and LROC have allowed us to do that. And there are thousands of craters in permanent shadow on the moon that may hide water (which is what I’ll be presenting at the µSymposium).

For reference, the north pole of the moon is just about smack dab at the 10:30 position on the large crater’s rim. Just inside the rim, along a line from that small crater just outside the rim to the center of the crater.

But for pseudoscience, you may also notice that there are some artifacts in the data. There are radial streaks from the center of the frame (usually). There’s a prominent one diagonally from upper right to lower left on the upper wall of Shackleton itself. Others are more prominent towards the edges of the animation.

These are not lunar roads nor subways nor trollies nor anything else made by an ancient civilization. They are artifacts in the data itself. LOLA is very well calibrated, and the “average” (root-mean-square) uncertainty is under 5 meters in elevation data. But some tracks (orbits) are a bit off. And since LOLA is fundamentally measuring the time it takes light to bounce off the surface from a laser beam from the craft, it needs to know exactly where the craft was to get an accurate surface elevation.

And some are off by a bit. These manifest in this kind of product as ridges or troughs that are perfectly in a straight line, along the line of the orbital track. It’s something that scientists who use these data see and ignore because we know exactly what they are. But pseudoscientists will look at line artifacts like this, or at image seems in a mosaic, and claim things like they are artificial tram lines.

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Some Real Science: Lots of Grunt Work, Moon Craters

Over the last few days, I’ve been hunkering down due to the deadline for abstract submission to the premier planetary science conference, the Lunar and Planetary Science Conference. It’s held annually in March in Houston, TX. Everyone is allowed to submit up to two first-author abstracts, and I have, for the last couple years, done two. This year’s not an exception. I’ll post about my New Horizons -related one later.

This post is about my abstract entitled, “Developing a Global Lunar Crater Database, Complete for Craters ≥1 km.” Because the file sizes have to be <1 MB, the figures are low resolution.

There are many, many different purposes to conferences, though the primary is “communication with colleagues.” Within that are many different things, like talking about your research and getting ideas. Another is to be able to show colleagues what you are doing so that, if your name happens to come in, say, a grant application, they might just recognize it.

For LPSC this year, my non-New Horizons abstract is in that category. I’m setting myself up for writing a grant later this year to build a lunar crater catalog that contains a lot of information about roughly 1 million craters on the moon. It’s been rejected for a couple years, and one of the underlying reasons is that I don’t know how many craters there are, therefore I can’t give a good, accurate work effort estimate to do all the information-gathering about each crater.

This abstract is meant to answer part of that. I’ve been leveraging bits and pieces of funding from different sources over the last year to do the initial mapping part — identifying the craters and locating them and measuring their diameters. For this abstract, I’ve roughly 28% of the moon done. For the March conference, I’m hoping to be closer to 50%, and by the time the grants are due this autumn, 100% so I know how many craters I have to do more stuff with.

Two more things I want to talk about in this slightly longer post. First is grunt work. Science is not easy. Science is rarely glamorous. Science is sitting down and 99% of what you do no one will ever know about because it’s only the results – not that big data-gathering process – that form the bulk of your paper. Methods sections are usually <25% of a paper because relatively few people care about that in comparison with your results.

And trust me, sitting down and drawing circles for hundreds of hours on end is NOT glamorous. But the results are cool.

Second is why we care – why are the results "cool." One reason is that it just looks cool — seeing all those dots that indicate a crater, and seeing all the patterns that emerge tell us a lot about the different history of those areas of the moon. The main one is ages (more craters = older). But we can also do things like better understand what's hit the moon in the past, and hence what is likely to hit Earth in the future. We can study different materials even, which is why the second figure is devoted to permanently shadowed regions where there might be water (areas that never see the sun act as cold traps for water molecules).

Anyway, this is turning out longer than I wanted, so to wrap it up … that's one thing that has been occupying a lot of my time over the last few days. One down, one to go.