Exposing PseudoAstronomy

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

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December 16, 2014

Podcast Episode 122: Comet 67P/Churyumov-Gerasimenko and Rosetta Conspiracies


Conspiracies of
Comet 67P …
Few, but they are weird.

A timely and listener-requested episode! What’s not to love!? In the episode I talk about several of the conspiracies I’ve seen surrounding the Rosetta mission and Comet 67P. From artificiality (Hoagland makes a guest appearance) to singing so as to raise our consciousness to angelic levels when 2012 failed, I spend nearly a half hour going through 2 to 4 claims (depending on how you count them) that have been making the rounds. I also get to touch on image analysis.

There is also one New News segment this episode, and it refers to the death of the Venus Express mission around (oddly enough) Venus. The news relates to the episodes on uncertainty. Not sure what the connection is? Listen to the episode! The episode also comes in at just over 30 minutes, my target length.

April 10, 2014

Alien Lights or Cosmic Rays on Mars


Introduction

I was not going to talk about this because I didn’t think I had much to add. And I thought it was stupid. And, I’ve had run-ins with UFO Sightings Daily before (well, one).

But, people keep talking about it, so it at least deserves a mention here.

Origin Story

Everybody likes a good origin story. Wolverine made quite a lot of money.

The timeline, so far as I can tell, is that UFO Sightings Daily “discovered,” on April 6, 2014, and then posted, on April 7, 2014, the following:

Light on Mars in Curiosity Image (from UFO Sightings Daily)

Light on Mars in Curiosity Image (from UFO Sightings Daily)

An artificial light source was seen this week in this NASA photo which shows light shining upward from…the ground. This light was discovered by Streetcap1 of Youtube. This could indicate there is intelligent life below the ground and they use light as we do. This is not a glare from the sun, nor is it an artifact of the photo process. Look closely at the bottom of the light. It has a very flat surface giving us 100% indiction that it is from the surface. Sure NASA could go and investigate it, but hey, they are not on Mars to discovery life, but there to stall its discovery. SCW

Houston Chronicle Posts

It would’ve been relegated to everything else of random bright spots in images except that the Houston Chronicle‘s reporter Carol Christian decided to write a story about it.

And then two people posted to my podcast’s Facebook page (thanks Linda and Maryann). And Doubtful News picked it up, as did Phil Plait.

What Is It?

It’s a cosmic ray. >99% chance. Here’s what happens: High-energy particles constantly stream throughout the universe. We’ve been detecting them for decades, and their energy varies considerably.

Electronic imagers typically work when a photon – a bit of light – kicks up an electron within a pixel. Those electrons are counted after the exposure is done, and that’s how you get your image.

When high-energy particles randomly stream into a detector, they are higher-energy than the photons we’re usually trying to collect, and they appear as bright streaks. Digital cameras that you use for normal photography have algorithms to remove those as known noise sources, so you typically never see them. We also see them more rarely on Earth because many are blocked by the atmosphere.

Those of us who use research-quality cameras on telescopes, however, see them all the time. In fact, Phil said the exact same thing: “I’ve worked with astronomical cameras for many, many years, and we see little blips like this all the time.” (It’s nice when we agree.)

Right now, some of my research is focusing on using images from the Cassini spacecraft in orbit of Saturn, studying some of Saturn’s moons.

Rhea from Cassini (W1594713967_1)

Rhea from Cassini (W1594713967_1)

Here is one image of Rhea, taken by the ISS camera. It’s a raw image, about as original as you can get with respect to almost no processing has taken place. And look at all those stray bits of light! Pretty much every single one of them, including the two long streaks, and including the dots, are cosmic rays.

More evidence? Courtesy of Phil Plait, we have an animation:

Light, No Light (Phil Plait)

What’s nice is that this is from Curiosity’s NAVCAM, which has a pair of cameras. From the right camera, we have the bright spot. From the left camera, we don’t. The reason that you’re seeing a small shift in position is due to parallax between the two cameras (by design, since this helps tell distance). (FYI, Mike Bara, who addressed this just a half hour ago on Coast to Coast AM, claimed that the cosmic ray was the least likely explanation, and while he posts the parallax GIF on his website, he said he refused to name the source because “I dislike him [Phil Plait] intensely.” Despite showing a another image that Phil linked to, so clearly he read Phil’s blog. Mike’s seemingly only explanation for why it was not a cosmic ray is that he said it didn’t look like other cosmic rays people are pointing to. That’s like me saying that a rose is not a plant because all the examples of plants you’re showing me are trees. It’s a class of object, every cosmic ray on a detector looks a little different, especially when you have blooming factored in (see the next section).)

Why a Rectangle?

Either the cosmic ray hit at an angle, so we see it as a streak (see above example ISS image), or, as is also common with CCD images, when an individual pixel collects too much light, it tends to overflow, and spill over into neighboring pixels, almost always along columns. We call this “blooming.”

But Wasn’t It Seen In a Second Image in the Same Spot a Day Later?

Mike made this claim, and I saw it from a commenter on Phil’s blog. Thus far, no one has actually posted or linked to such a second image that I can find. If anyone has seen this claimed image, please let me know. And by “please let me know,” I mean providing the NASA image ID so I can find it. I know that Mike put an “Enhancement of April 3rd image” on his blog, but it’s useless for proving anything without the ID it came from.

Anything Else?

Maybe? This post might be slightly premature, and it’s a bit stream-of-consciousness, but I wanted to get it up before bed. The station on which I was listening to Mike on C2C decided to cut out the second half hour because of some crash somewhere, something about people dying, breaking news, etc. When I get the full audio, I may add to this, but it sounded like George was taking the interview in a separate direction after the bottom-of-the-hour break, though a caller may have brought it back up.

Let’s be clear about a few things, though:

1. The object is seen in one camera, not in another, despite the two cameras taking an image at the same time of the same spot.

2. There is a claim that it showed up in another image a day later, but so far as I can tell, this is just a claim and no one has pointed to that image. If it exists, I’d like to see it and I’ll re-examine my curt analysis.

3. We see similar artifacts in other Mars images, and we see them all the time in space-based cameras, and we see them generally in all electronic cameras (at least those that don’t get rid of them for us).

4. The story comes from UFO Sightings Daily and only became mainstream because a reporter at a somewhat mainstream paper picked it up.

So, what could it be? Aliens? Architecture that glints just right so it’s only in one camera of two that are right next to each other imaging something a few miles away? An impact flash from a crater forming? A dust devil reflecting the light just right? Lens flare?

Or a cosmic ray? I don’t think any of those previous explanations are likely, I think this is most likely.

Bara, as with other UFO / aliens protagonists, say that Curiosity should live up to its name and drive over there and investigate. Yup, take days, power, money (gotta pay the ground crew), and investigate what is very likely to be a high-energy particle that made it through the atmosphere and onto a camera’s CCD.

What do you think?

Edited to Add (10 hrs later): Per Phil’s latest blog post: “Except not really. Another expert on Mars hardware said it may have actually been a “light leak”, a bit of sunlight that somehow got into the camera through a hole, or crack, or seam somewhere in the hardware. He also says it may be a sharp reflection of sunlight off a glinty rock. Those are certainly plausible, though right now we don’t have enough evidence to say for sure which of these explanations may or may not be the right one.” Yup, another possibility. As is a defect in the camera sensor itself (see discussion in the comments to this blog post).

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