Exposing PseudoAstronomy

January 27, 2016

Scientific Fields Are Never Solitary, in a Vacuum


One of the more annoying claims made by pseudoscientists is that because scientists are so specialized these days, that they cannot “see the forest for the trees” as the metaphor goes. But they, as outsiders, totally can and therefore show that all of science is wrong. Or something like that.

It is true that sub-sub-sub-sub-sub-…-sub fields do exist, and these days that’s a manifestation of really how far we’ve come in science. Back in the day (say, 400 years ago), we knew comparatively so little that someone could study for a few years and get a good understanding of the state of human scientific knowledge. These days, you need an advanced degree to understand a sub-field of science, such as physics:optics, or psychology:adolescent (the colon indicating the sub-field).

If you want to work in a field, you pretty much must specialize, otherwise you will never be out of school because you won’t know enough about that broader topic.

But we always have to incorporate other fields of study, even if we don’t realize we’re doing it. I’ve tried to point out in my podcast and blog how tugging at one string by a pseudoscientist unravels so many other strings in unrelated subjects that it completely disproves their point about being able to have a broad knowledge base from which to draw new connections.

But that’s a long-winded way to get to why I’m even talking about this. I’m home right now for a period of 10 days, between travel, and I’m using the time to convene a working group. A working group is sort of like a mini-workshop. Where a workshop, in science, tends to be a specialized conference convened where people give presentations meant more to explore a topic rather than to brag about their latest research.

Last May, I convened a workshop entitled, “Workshop on Issues in Crater Studies and the Dating of Planetary Surfaces.” Succinctly, it was intended as a step back from the minutia we deal with to look at the original problems we were trying to solve, how we tried to 50 years ago, why we did it the way we did then, and what we’re trying to do now with craters and what outstanding problems we still have. I was able to bring in several founders of the field (since it really got going in the 1950s and 60s), and we addressed a wide range of issues.

Among those was statistics. We’re doing statistics the way we did it in the 1970s, before we had computers and when people had to draw graphs in papers by hand. We realized that the field of statistics has changed considerably and the way we were doing things and are doing things is not necessarily completely correct, nor is it necessarily the best way.

So, I also had money to bring in three statisticians to the workshop to learn.

And this week, since five of us crater people who work in the Boulder area were at the workshop and are interested in bringing in this completely unrelated (but related) field of statistics into planetary geophysics, we’re holding a working group. The five of us, one of the statisticians who is local, and one of the statisticians who I flew in from Los Alamos.

And it’s fascinating. If nothing else (because I’m sure no one reading this cares about statistics of crater populations), I find it fascinating to watch the interaction between the statisticians and the planetary scientists. We know some of our issues, and we are completely steeped in our language to describe it. They know stats, and they are constantly bringing in similar problems in other fields that are solved certain ways to see if it can apply. It’s taken a year to almost get on the same page just with what we mean when we talk about different graphs.

And they sometimes come up with potential solutions, but then we say “no” because it completely misrepresents the physical situation.

Today, after working all morning and being brought back up to speed yesterday, one of the surprising things that we (planetary scientists) had to grasp was that we may need to start thinking about craters – at least the population of craters, the ensemble – in a completely different way: Rather than discrete objects which we observe (with a definite location and size), think of them as a probability, where each observation is actually a distribution (albeit narrow). If we can do that, then we can bring in a huge field of well established statistics to deal with some of our fundamental problems with how we work with craters. Like simple things … like how we really should be assigning uncertainty to our measurements and results.

And throughout this, there was the constant nagging question in the back of my head of how we’re going to convince the entire field that this is the proper way to go — if it’s the proper way to go. Fortunately in our working group we have one of the founders of the field, so if we can convince him, we can figure out how to write up the paper to convince others.

This is a long post … and it’s a lot of stream of consciousness. From it though, I want you to get a few things:

  1. Even in highly specialized disciplines, they must always be informed by and incorporate other disciplines, even in completely different fields (astronomy/geology:planetary-gephysics:surface-processes:impact-craters:crater-populations … meet mathematics:statistics:[huge list of stuff they’re bringing in]).
  2. Sometimes, to update a field of study and bring it in line with what’s known in others, you have to think of the problem in a completely new way, but one that remains informed by its roots and always in what we’re really trying to understand (as in, they can model whatever, but we constrain them by keeping it physically meaningful and realistic).
  3. There’s always inertia in a field of study, but there are always ways to bring about change if that change gets you to a more correct methodology or answer.

This post is also my way of updating you all on what I’ve been doing, partially, work-wise for the past few days and why the podcast still hasn’t come out with a new episode in over a month.

January 10, 2016

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.

December 13, 2015

Podcast Episode 143: Round-Table Discussion with New Horizons Early Career Scientists


A round-table talk
‘Tween seven New Horizons
Scientists … ’bout stuff!

The missing episode!!! And the interview I’ve been promising for months between myself and six other early career scientists is finally posted. It took only 5% the time of New Horizons to reach Pluto, this podcast from the time it was recorded to the time it’s being posted. It also “only” took 6 hours to edit. Why? Because of needing to cut some things out, someone constantly knocking the table (I know who you are …), legitimate outtakes, and severe noise level differences.

Excuses aside, I’m glad that this is finally up, and I enjoyed actually listening to it (4x through during editing). It brought back memories from July and I think it gives insight into how us “grunts” or “minions” or, perhaps just “early career scientists” viewed the mission and what we did during that month of hectic excitement.

There are no other segments in this podcast episode, for the interview / round-table itself is 59 minutes 59.5 seconds. If you stay after the end music and how you can get in touch with the show / me, there is roughly 3.3 additional minutes of outtakes. These are not always rated G.

I hope that you enjoy this episode.

October 1, 2015

A New Interview and New Movie from New Horizons Data


Quick post before I get back to work (next podcast episode hopefully out this weekend).

First up, I was interviewed live for about 100 minutes on this past Sunday on David Livingston’s “The Space Show.” We spent the first half talking about my research (impact craters) and the second half about the education & public outreach that I do. Since it was live, and a call-in show, there was one call and many e-mailed questions that I responded to. There’s also an associated blog, so you can comment on the interview there if you wish.

Second, NASA has put out a press release about Charon (Pluto’s largest companion). There is a flyover animation of some of its many varied features, and I was the one who made the animation.

We have images of some areas of Charon from two different vantage points, as New Horizons flew by the body, and so we have a very, very early digital terrain / elevation model (DTM). I was able to use this in a non-exaggerated view of what it would be like to fly low through its massive canyon.

It looks a bit like an early 3D video game because of the somewhat low resolution, but I think it’s still pretty neat, and we should get better quality over the next few months as we better understand the surface and camera models.

August 20, 2015

Podcast Episode 138: New Horizons Pluto Encounter Conspiracies, Part 1


New Horizons’ pass
Through the Pluto system: Lots
Of crazy ensued.

FINALLY! It’s out! Only 3 weeks overdue! The “August 1” episode is about the New Horizons mission to Pluto and some of the conspiracies and pseudoscience and bad media reporting related to it.

To be fair, all of these I have written about in my 11-part series. However, I know some people never read blogs and only listen to podcasts, and vice versa. So, I’m double-dipping. I don’t care. :)

And it’s late at night, so I’ll close this brief post out by saying that I was recently interviewed on Steve Warner’s “Dark City” podcast, which you can directly listen to at this link. If you liked it, make sure you tell Steve by contacting him through his website.

August 17, 2015

#NewHorizons #PlutoFlyby – The Pseudoscience Flows #11 — Geometry Proves Aliens


This is the last planned post in this series of posts of pseudoscience related to the New Horizons Pluto flyby, until at least we get more images in a few weeks. This is also hopefully the last post that uses Richard Hoagland’s statements as an example of a style of claims made about New Horizons -related pseudoscience, at least for awhile. This particular one is NOT unique to claims that Mr. Hoagland has made about New Horizons and what the images show about the surface of Pluto and Charon; rather, he has made this particular claim about practically every solid body in the solar system: Geometry = artificial.

Let’s start looking at this claim as Richard makes it, for on its surface, it seems like it might make sense. Richard, whenever bringing this up, does not claim credit for it. Rather, he says that this comes from Carl Sagan (argument from authority), that when some of the first satellite photos of Earth were returned, Carl searched for any signs of intelligent life, and the only thing he could find was a dark logging road in Canada in contrast against white snow. That it was long and linear.

Hence came the maxim: Intelligence will reveal itself on a planetary surface by creating geometry. I have paraphrased it slightly, but unfortunately I don’t have the audio in front of me so I can’t state it exactly. But really, that’s the claim: If you see regular, repeating geometry, it requires life.

Now again, on its surface, this makes sense. People certainly make geometric patterns (it’s easier to drive on a straight road, for example, and we like to make square or angular buildings). We see nice geometric patterns in the animal and plant kingdom, too, including seemingly complex patterns such as spirals and the Fibonacci Sequence (which turns out to be an optimal pattern for leaves to get sunlight, and you see it (for example) in the patterns of seeds on a sunflower).

Life can and often does certainly create geometric patterns.

But so does non-life. The Grand Canyon is an excellent example of a fractal — an incredibly complex geometric shape. As do clouds, snowflakes, mountains, river deltas, and waterfalls. Valleys have a characteristic size given the environment, creating patterns of undulating waves. Sand dunes also have a characteristic wavelength and create undulating patterns. Individual mountains have nice, regular geometric shapes within the fractal pattern mentioned above. And so on.

In my particular field of study, we can look at impact craters. These are typically circles. Or ellipses. On Mars, there’s a certain type of crater that produces ejecta that looks like petals on a flower with nice broad, sinuous, regular perimeters. We also get craters forming all in a row, either from the impact or breaking up into a string of objects or ejecta from the crater itself producing them. These can have very regular, V-shaped ridges between them formed by overlapping ejecta curtains during formation. There’s also the famous “Meteor Crater” in Arizona which is practically a square: This was made by pre-existing faults that controlled the shape as the crater was formed, and we see these elsewhere, too. In fact, I was just in Arizona for a conference and you see plenty of flat-topped mesas which sharp, angular edges that form the drop-off of a cliff, controlled by veins of material with slightly different strengths.

These are all very regular “geometries.”

You do not need life to create “geometry.”

In fact, this kind of claim is so common in many fields of pseudoscience that it has a basic logical fallacy to describe it: The Single Cause Fallacy.

From its name and this blog post so far, you can probably guess what that is, but I’ll elaborate. It tends to go in this form:

  1. Item A can be caused by Thing B.
  2. I observe Item A.
  3. Therefore, Thing B was the cause.

This ignores the obvious: Many other things could be the cause of Item A, I just assumed that it was Thing B for whatever reason.

In this particular case, Richard and other people observe something that they have classified into the nebulous and ill-defined term “geometry.” And because life can give rise to geometric patterns, they conclude life made this “geometry.”

As opposed to a natural process that we see not only at home on Earth, with myriad examples, but all over the solar system, as well.

As opposed also to – in some cases that he and others have claimed – what really could be an intelligent cause: computer compression artifacts and/or electronic noise (think speaker static) in the camera detector.

My bet for some of the stuff shown across the internet is in that last category. My bet for all the rest is in that first category, that it’s simple, basic, geologic (and other natural) processes that can easily create regular geometric patterns.

While Richard is fond of quoting Carl Sagan when it helps him, he needs to remember other things that Carl also said: Extraordinary claims require extraordinary evidence. Pictures of features that could very easily be described by known, does-not-require-intelligence-to-explain-them phenomena do not qualify as that extraordinary evidence.

August 16, 2015

#NewHorizons #PlutoFlyby – The Pseudoscience Flows #9 — Young-Earth Creationist Take, Part 2


Terry Hurlbut Advocating Walter Brown’s Hydroplate Nonsense

In my Part 1 of this lengthy series of probably 11 posts, I talked about the machinations of Terry Hurlbut, one of the primary editors of Conservapedia and (I think) the founder of the incredibly ad-rich Conservative News and Views website that espouses über-right wing ideals and young-Earth creationism. He said that Pluto is red therefore it’s rusty therefore it formed from material ejected from Earth during Noah’s Flood.

In a follow-up post, Terry followed the same protocol as before, grabbing onto one tiny finding, saying it’s impossible to explain with modern science, therefore Pluto was launched from Earth during the Flood.

In this case, the finding was carbon monoxide (CO) ice, found in the “heart” area now informally known as Tombaugh Regio. Terry explains this by saying that during the Flood, Pluto and Charon formed by material ejected from Earth, which heated as they contracted, burning the plant matter that was also ejected. The gases released from the burning plants included CO, which fell as “rain” onto the surface of Pluto in what he claims is a basin that is now Tombaugh Regio.

Okay, I know I try to avoid ad hominem attacks on this blog, but I had to fight my brain to type that last paragraph. It’s so ridiculous, that unless one actually is familiar with Terry’s writings on his own sites and elsewhere, one would think it’s a really bad Poe or Onion article.

Terry tries to emphasize in his article that neither NASA, SwRI, nor JHU/APL (the three institutions involved in the mission) have tried to explain the CO ice. Therefore, we don’t know now and therefore Terry’s idea is the only one out there.

The thing is, we don’t have all the data taken yet. The data we do have is lossy-compressed. And scientists by their nature are very cautious about publishing hypotheses about something without doing a lot of tests of those hypotheses. AND within the mission itself, there’s the situation that it’s better to put out obvious findings now and save the possible interpretations later once we have more time to look at the better data and talk with more people and amongst ourselves.

Put in that context, it’s perfectly reasonable to expect that NASA would put out the press release about unambiguous findings of concentrations in one area of Pluto of CO (as in we found it, it’s in ice form, and it’s concentrated in one particular area) and have that be the press release, rather than add unnecessarily to it several possible models to explain it but “more data are needed, stay tuned several months until we get that data to test it.” That’s kinda a downer to close out a press release.

Institute for Creation Research Advocating Pluto’s a Comet

In a perhaps more mainstream young-Earth creationist venue, the Institute for Creation Research also has a take on the New Horizons mission. Jake Hebert wrote their article, “New Horizons, Pluto, and the Age of the Solar System.” It is a fascinating read if one looks at it from the standpoint of starting with one topic and twisting it into something completely different to argue against in a no less wrong way than most other creationist writings.

Here’s the train of thought:

  1. New Horizons went to Pluto.
  2. Secular scientists are going to tell a materialistic story without a deity about it but aren’t saying that so’s to avoid offending the taxpayer.
  3. That means we don’t understand how the solar system formed.
  4. New Horizons will yield information about Kuiper Belt Objects.
  5. These are comets.
  6. Insert everything that creationists have written about comets over the years that they think shows comets prove the universe (or at least the solar system) is less than 6000 years old.

Not only is it a strawman argument on their part, but by equating Pluto with comets means not only that everything THEY have written about comets over the years applies, but also everything that scientists – such as myself – have also written that thoroughly debunks their arguments applies.

For a taste of these, I refer you to my blog (post 1, post 2, or post 3) and/or my podcast (episode 3). Rehashing all those ideas here is gratuitous and a waste of space. And, there’s a reason why those are some of my earliest blog post and earliest podcast episode: They’re simple to debunk.

Answers in Genesis Telling You Half-, Leading Truths

Finally, another of the Big Three creationist institutions is Ken Ham’s Answers in Genesis. Danny Faulkner wrote their article on New Horizons, “Pluto’s Surface Is Young!”

Sigh.

Here is the first argument that Danny is making: Pluto has relatively few craters, therefore it must be young:

[S]cientists have found far fewer craters than they expected. […] Being far from the sun, Pluto ought to be very cold and hence not have experienced recent volcanism. Any primordial heat would have long ago dissipated, if the solar system were 4.5 billion years old. [… T]here ought not to be any significant geological activity sufficient to remove craters on Pluto’s surface. Compounding this problem for a 4.5-billion-year age for the solar system is the fact that Pluto is located in a particularly crowded part of the solar system. […] Therefore, Pluto ought to be undergoing impacts today at a higher rate than most other objects in other portions of the solar system. Planetary scientists who are committed to belief in a 4.5-billion-year-old solar system are at a complete loss to explain the lack of craters on Pluto.

Part of this is exactly the same argument (at least in part) that I debunked here, in my post about Venus, several years ago: “Venus and the Battle of Uniformitarianism (A Creationist Argument).”

First, Pluto does not have ZERO craters. It has many; it’s just Tombaugh Regio that has no unambiguous craters in the region that we’ve seen with the lossy JPG artifacting covering it. That means it likely has no craters >10 km in diameter, meaning it could still have plenty that are smaller.

Second, the whole way we get our crater chronology starts from the moon (which Danny acknowledges, and he actually gives a reasonable overview of the subject). We do see heavily cratered areas of Pluto. So if we see some areas that have a huge number of craters relative to other areas, it just means that the one with few craters (or maybe none) is much younger. How much younger, though? If Danny wants to say that the heavily cratered areas are 6000 years old, does that mean that the “heart” region of Pluto was created yesterday? Again — see the Venus blog post.

To bypass some more of the quote and get to the last statement, this is common among creationists: God of the Gaps. Set up a scenario and say someone can’t explain something and then say GodDidIt. Except, we have plenty of ideas of why there may be no craters over some parts. One of the main ones has to do with the second argument (in three paragraphs): The atmosphere. It’s tiny, but it cycles. Pluto is tilted almost like Uranus, except more. So for 124 years we have one pole facing the sun, and for 124 years the other. During this time, it’s likely that the ices on the surface near the sunward pole sublimate (turn from solid to gas) and some get deposited on the pole that’s in night. This gives you a “surface” that is literally no more than a hundred years old.

In fact, going into this, I was warned that several models predicted that there may be very few craters on Pluto simply because of this process, of not only ices being deposited as many, many layers of frost, but also because when they sublimate, they are removing that surface that had been cratered! So some predictions going in were that Pluto may have a few very large, shallow craters, but nothing else. Obviously that’s not the case, Pluto is more interesting, but to say that we “are at a complete loss to explain the lack [not!] of craters on Pluto” is bullocks.

Here is the second argument that Danny made: Pluto is outgassing nitrogen, and therefore it’s young because it is a body of finite size and because there should be some activity that releases the nitrogen.

Yes, Pluto was found to be outgassing molecular nitrogen gas. Though “outgassing” is the wrong word here — perhaps an honest mistake, but it’s wrong nonetheless. It’s that nitrogen gas is escaping from the surface, not being outgassed from below the surface (that we know of). So this is a classic creationist argument: Take the current rate for something, multiply it by 4.5 billion years, and claim it’s impossible. They do that with Earth’s moon. But in this case, Danny didn’t even do that simple math, even if it is wrong (the current rate may not be what it was in the past). 500 tons per hour means very roughly 2*1019 kg over 4.5 billion years. Pluto is 1.3*1022 kg. That means it would have lost a mere 0.15% of its mass due to nitrogen escaping over 4.5 billion years if the current rate has been the rate for 4.5 billion years.

Not a problem.

The third argument has to do with the very tall, 3.3 km high mountains observed on Pluto, where Danny argues that if Pluto is warm enough to have geologic activity to account for those first two things, it can’t be cold enough to support ice mountains.

The mountains are interesting. I don’t even remember if there are solid ideas yet in the team as to how they may have formed, but this is yet another example where scientists look for something to explain an observation, and creationists leap to GodDidIt. Regardless, though, both of the prior two arguments can be explained at least in part by atmospheric processes rather than geologic, therefore this is moot.

Finally, he argues that Charon has fewer craters than expected, and a large chasm, therefore it’s young, too.

Problem if we take this approach: How can Charon be older than Pluto? If we’re using the metric of craters (and incorrectly per the standard young-Earth creationist), and Charon has more than Pluto, then Pluto is even younger than 6000 years old, right? What is he trying to say here, that Pluto formed a few minutes before Clyde Tombaugh discovered it?

I’m also not quite sure where he’s getting that Charon has fewer craters than expected. I don’t remember this being discussed, but it’s possible I missed it. A lot of the issue for Charon (and Pluto, for that matter) is our ability to identify craters in these images. Most imaging is with the sun almost directly overhead. Meaning we can’t pick out craters very easily. Especially when all we have is lossy, JPG-compressed images. Think of photographing the full moon of Earth and then compressing it to 100 kb to send to your grandmother who’s running Windows 95 with a 56k modem. Not easy.

Charon probably has more craters than Pluto (no atmosphere). But our ability to find them right now is significantly hindered. That in mind, I’ve already identified a few hundred. Same on Pluto.

July 23, 2015

#NewHorizons #PlutoFlyby – The Pseudoscience Flows #7: Very Few Craters ‘Cause of Pluto’s Orbit


I swear this time, a very quick post. As with the last one, I’ve seen this claim not only on science forums but also pseudoscience forums and radio. The form goes like this: Pluto has surprisingly few craters because its orbit is inclined 17° relative to the plane of the solar system, where most impactors would be.

I’ve said it before (especially with respect to global warming deniers), and I’ll say it again here: Scientists, in general, are not stupid.

We take that into account. We also take the very low impact speeds into account. And the expected porosity of impactors. And potentially different impactor populations. In fact, Sarah Greenstreet’s thesis work was just published a few months ago, “Impact and cratering rates on Pluto,” that explicitly models a s— -load of different possible impactor populations and therefore possible crater populations, explicitly integrating the orbit of Pluto through time that – ¡gasp! – takes into account its orbital inclination. As an aside, I don’t know what “blogs” Richard Hoagland happens to be reading, but I can guarantee that scientists involved on the mission science team are not assuming that the impact rate and type at Pluto are the same for the inner solar system.

And besides that, it’s not entirely “surprising” that it has so few craters. This was predicted at least over a year ago to be a consequence of sublimating and refreezing of the atmosphere. What is surprising is the relatively few craters on Charon, though the one decent pixel scale image with favorable sun for mapping craters that we have so far does show many dozen.

Scientists unfortunately often forget that they know lots of stuff that other people don’t know, and things are taken for granted. I think, unfortunately, that when people have remarked about the “surprisingly few” craters observed on Pluto, that is taking into account Pluto’s orbital characteristics. It’s implicit, because it’s a “duh” point for those who tend to talk about it, and they forget to mention that this is implicit.

July 21, 2015

#NewHorizons #PlutoFlyby – The Pseudoscience Flows #5 — My Own Error


I’m going to shift a bit here, though the next two posts on this topic are already planned (though Sharon over at Doubtful News just pre-empted me tonight on the Crrow777 stuff that’s hit Newsweek). Instead of discussing pseudoscience that I’ve seen elsewhere, I’m going to discuss my own. Not pseudoscience, per se, but where science can go wrong when you have little sleep and are under extreme pressure to do things quickly.

But before I get specifically to this, I want to emphasize: News reports that there are “no craters on Pluto” are wrong. There are clearly impact craters. It’s that there are no unambiguously yet observed impact craters on Sputnik Planum. That out of the way:

I made a boo-boo. But, science is ultimately self-correcting because if it’s wrong, then when people try to duplicate it, they will get different results …

I generally study impact craters (among other things). One of my primary science areas of research for the Pluto-Charon system is to understand their crater populations to tease out what the impacts are like out there 40AU from home and what the geologic history of the bodies are. To do that, you have to map craters. I’m going to be focusing on that in the coming months (and currently) and I’m also going to be focusing on how our mapping changes as we start to get lossless data and higher pixel-scale data (not higher “resolution,” for “resolution” means number of pixels, while “pixel scale” refers to the length per pixel). This latter focus has been something I’ve been publishing on in the last year.

As I’ve mentioned before on this blog, images right now are being sent down lossy compressed. Meaning they are full of JPEG artifacts that wash out a lot of small features … like impact craters. So when mapping, I’m assigning a subjective confidence level that indicates how certain I am that a feature is a crater or not. Since we have repeat imagery, already, I’m going over each area multiple times, blindly, with the different images.

One area that’s hit the news is Sputnik Planum, on the “left” side of the bright albedo feature Tombaugh Regio. It’s bright, and it’s young, and we know it’s relatively young because it has no unambiguous impact craters in the images that we have so far. I’m very careful with that phrasing: unambiguous impact craters in the images that we have so far.

Except, I thought I found one. A rather large one. But I didn’t.

When I initially mapped it in the image that came down a week ago (the full-frame image that was unveiled the morning of the encounter), I gave it a confidence level of 4 out of 5. We had the lossy-compressed JPEG version of the image, and after we had attempted to remove some of the JPEG artifacts through Fourier Transform truncation and then deconvolved it with the point-spread function of the camera (the camera inherently blurs things a teeny bit), it looked like a crater, and I was pretty certain it was a crater. Since it was many pixels wide and the image had a pixel scale of 3.8 km/px, that is a significantly sized crater, at least 30 km in diameter.

Except, it wasn’t. We have since gotten a mosaic at 2.2 km/px of the planet, and we have gotten higher pixel scale images at 400 m/px that have not yet been released. In none of these is that very large, very obvious crater present.

What happened?

We made a tiny artifact bigger by image processing. It was a simple cosmic ray hit.

Here’s what happened:

  1. Cosmic ray hit the detector, meaning there was a very bright pixel with a lot of electrons in it.
  2. This detector has the annoying property that if you have a bright spot, a dark streak forms behind it. You can see this in all of the over-exposed hazards search images. So the bright pixel now had a dark streak behind it.
  3. This was lossy JPG compressed on the spacecraft by a severe amount. Heavy JPG compression can make things “ring” because it represents the data as a series of cosine waves.
  4. One of our basic image processors took that image and first deconvolved it, sharpening the ringing JPEG noise.
  5. He then looked at the image in frequency space and made a series of clips that when brought back into spatial space (what we’re used to) will dampen a lot of the obvious JPG blockiness and make for an image that is more aesthetic and helps to make out a lot more features because you don’t have the 8×8 grid of JPG blocks dominating.

This is perfectly reasonable to do, and so long as you understand the kinds of artifacts that it can introduce and don’t over-interpret it, you’re fine.

Unfortunately, it makes this particular kind of cosmic ray hit on this particular detector look like a very clear, very obvious impact crater. Despite my best efforts at not over-interpreting early images that clearly showed artifacts from the image processing, I over-interpreted this feature.

Fortunately, it never made it into a press release or a paper (though I will be talking about it in a paper I’ll be writing as a cautionary tale), but when doing stuff like this, I’m always reminded of how (and this is going to sound arrogant) I’m different from a pseudoscientist, and how working on skepticism for the past (nearly) decade has helped me to become a better scientist. Someone like Richard Hoagland, Mike Bara, Keith Laney, or the guy I talked about in the last blog post probably would not hesitate to make a big deal out of these kinds of features.

To be blunt, I’m a crater expert. I am considered to be an expert in mapping impact craters due to my experience at mapping over 1 million impact craters across 7 solar system bodies (so far). Yet, I made this significant mistake. What separates me from the pseudoscientist, though, is that when I was presenting this to people, I said that this looks very much like a certain crater, but we need to wait to see the uncompressed version of the image, and we need to wait for the higher-resolution maps before saying it’s certain. And if it isn’t, “it will be very interesting to figure out why it isn’t a crater.” I specifically said that in a team meeting on Sunday.

Many things right now are provisional simply because of the very lossy image compression. Features like craters are particularly difficult to tease out, unless they are very large and very obvious (as are many). Contrast that with the people trumpeting “geometric structures” on Pluto and Charon in these images. Of course there are “geometric structures” that were “artificially created” … all in the lossy JPG compression algorithm! I keep thinking I’m repeating myself with this — and I am — but people still keep making this claim.

But, I’m perfectly willing to be corrected. In fact, I have now written 1000 words about how and why I was wrong, and the exact reasons and process that led me to that erroneous conclusion: Based on better data, I can re-examine things and see what went on and if it’s real. Contrast that with what I listened to earlier today which was a discussion between Richard Hoagland, Keith Laney, and the host of Skywatchers Radio. This quote involves all three men, talking about the Norgay Montes image released last week, and where one stops and the other starts doesn’t really matter, for all three were complicit in this train of thought:

“Look around in that image. You will be amazed. The more you look, the more you’ll see. It’s pretty incredible. Blow the image up as much as possible and look at every little part of that image. There’s so much artificial stuff in there! Again, as denoted by the geometry.”

QED

April 23, 2015

How Do We Know How Old Stuff Is on the Moon?


Introduction

While this movie is branded under “Exposing PseudoAstronomy” for legal reasons, it has less to do with popular misconceptions/conspiracies/hoaxes and more to do with real science. This is my third more modern, lots of CGI movie, and my second to explain a research paper that I wrote.

In the movie, I go through how the lunar crater chronology is the fundamental basis for how we estimate the ages of surface events across the solar system. I also explain how my work affects the lunar crater chronology and what can be done to better constrain it.

I’m still waiting for a young-Earth creationist to claim that because of a factor of 2 uncertainty, 4.5 billion becomes 6.019 thousand.

I also wrote a blog post about this for The Planetary Society. Because it was posted there over two weeks ago, I think it’s fair game to repost here. You can click on any of the images for larger versions, and all of them are screenshots from the YouTube movie.

Planetary Society Blog Post

Three years ago, I started a project to replicate work done by various groups in the 1970s and 1980s. When the project was completed, the result implied that much of what we think we know about when events happened in the solar system were wrong, needing to be shifted by up to 1 billion years. I presented this in a talk at the recent Lunar and Planetary Science Conference at 8:30 AM, when most people were learning about the latest results from Ceres.

The project started simply enough: I downloaded some of the amazing images taken by NASA’s Lunar Reconnaissance Orbiter’s Wide-Angle Camera (WAC) that showed the Apollo and Luna landing sites. Then, I identified and measured the craters (my dissertation work included creating a massive global crater database of Mars, numbering about 640,000 craters).

The reason to do this is that craters are the only proxy we have for ages on solid surfaces in the solar system. We can determine the relative age of one surface to another (is it older or younger?) by looking at which has more craters: The surface with more craters will be older because, when you assume that craters will form randomly across the body, then the surface with more craters has had more time to accumulate them.

How to Use Craters to Understand Ages

Basic principle behind this work. (Background image © NASA/ASU; composite © S.J. Robbins.)

If we want to use craters for an absolute timeline – as in, actually put numbers on it – then we need some way to tie it to real ages. This was made possible only by the United States’ Apollo and the USSR’s Luna missions that returned rocks from the moon that could be radiometrically dated in labs on Earth.

With these radiometric ages, we then identify the craters on the surface those rocks were gathered and say that a surface with that many craters per unit area is that old.

That’s the lunar crater chronology: The spatial density of craters larger than a standard size versus radiometric age (we use 1 km as that standard size). This crater chronology is then scaled and used as a basis for the chronology across the rest of the solar system. When you hear someone say that something on the surface of Mars is X number of years old, chances are that’s based on the lunar samples from the 1960s and 70s and the crater counting done 40 years ago.

Apollo 15 Landing Site

Example landing site area, Apollo 15 (yellow star). Blue outlined areas indicate regions on which craters were identified, blue shaded areas were removed because they are a different type of impact crater, and blue circles are the craters mapped and measured. (Background image © NASA/ASU; data and composite © S.J. Robbins.)

And, that’s where my project came in. While the rock samples have continued to be analyzed over the decades, the craters were not. It’s easy to assume that the researchers back then did a great job, but by the same token, science is about replication and re-testing and we have developed new ways of doing things in the crater community since the Apollo era. A simple example is that the crater chronology requires a spatial density, and therefore you need to know the area of the surface on which you have identified craters. Over the past 40 years, we have better understood the shape of the moon and now have computers to allow for much more precise area calculations. This can result in changes by 10s of percent in some cases.

When I had finished my reanalysis, my results differed for many of the landing sites, in some cases by a factor of 2 from what the standard is in the field. I was surprised. I checked my work and couldn’t find any mistakes. So, I combed through the literature and looked to see what other people had published. I ended up finding a range of values, and only in one case was my result at the extreme low or high of all the published results. I showed my work to colleagues and none of them could find any issue with it. So, eventually I published it, early last year.

The Lunar Crater Chronologies

The new (blue) and old (red) chronologies and the data used to fit the model. The vertical axis shows the spatial density of impact craters larger than or equal to 1 km in diameter, and the horizontal axis shows the age of the surface from radiometric dating of collected rock samples. (© S.J. Robbins)

When I fit my crater data to the radiometric ages, my fit function showed a difference with the standard that has been used for three decades: Surfaces assigned a model age of about 3.5 to 3.7 billion years under the old chronology were older, by up to 200 million years. And, surfaces younger than about 3.4 billion years under the old chronology are younger, by up to about 1 billion years.

Differences Between the Lunar Crater Chronologies

The new and old chronologies in blue and red (top), and the difference between them in terms of model surface age. (© S.J. Robbins)

There are a lot of implications for this. One is that volcanism on the terrestrial planets may have extended to more recent times. This would imply that the planets’ cores stayed warmer longer. Another implication is that the large reservoirs of water thought to exist around 3 billion years ago may have existed for another 500 million years, with implications then for favorable environments for life.

But, something that I added near the end of my LPSC talk was the question, “Am I right?” The answer is an unsatisfying, “I don’t know.” I of course would not have published it if I thought I was wrong. But by the same token, this type of science is not about one person being right and another being wrong. It’s about developing a model to fit the data and for that model to be successively improved as it gets incrementally closer to explaining reality.

And, there are ways to improve the lunar chronology. One that I’m a big advocate of is more lunar exploration: We need more data, more samples gathered from known locations on the moon’s surface. We can then date those samples – either in situ or in labs on Earth – and along with crater measurements add more tie points to the lunar crater chronology function. Right now, there is a glaring gap in the sample collection, one that spans 2 to 3 billion years of lunar history. A single point in there could help differentiate between my model and the classic model. And more data would be even better.

Until we land robotic missions to send back samples from other planets or that can date samples there, the moon is still our key to ages across the solar system.

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