Chandrayaan-2 Found By Citizen Scientist; Reminds Us Of Pluto Discovery

What does Pluto — not the dog, but the non-Planet — have in common with the Vikram lunar lander launched by India? Both were found by making very tiny comparisons to photographs. You’d think landing something on the moon would be old hat by now, but it turns out only three countries have managed to do it. The Chandrayaan-2 mission would have made India the fourth country. But two miles above the surface, the craft left its planned trajectory and went radio silent.

India claimed it knew where the lander crashed but never revealed any pictures or actual coordinates. NASA’s Lunar Reconnaissance Orbiter took pictures several times of the landing area but didn’t see the expected scar like the one left by the doomed Israeli lander when it crashed in April. A lot of people started looking at the NASA pictures and one Indian computer programmer and mechanical engineer, Shanmuga Subramanian, seems to have been successful.

According to Shanmuga and NASA, he looked at the last known position and velocity and used it to estimate where there might be debris. A white speck about a kilometer away from the proposed landing site wasn’t there on earlier images of the same area. NASA received the report of the suspected finding and confirmed it along with finding a spray of debris.

Is It or Isn’t It?

According to NASA, the camera resolution is about 1.3 meters per pixel and the largest debris is about two square pixels. The Indian Space Research Organization (ISRO) claims they already knew where the lander crashed. On the other hand, a senior ISRO official has cast doubt on the NASA images, although he points out he is stating his personal views. Still, you’d presume if they know where it is, they would know for sure if the NASA analysis is correct or not.

See For Yourself

NASA has a great before and after image that shows the difference very clearly. You can see it below:

Pluto in a Blink

This couldn’t help but remind me of how Pluto was discovered using a machine called a blink comparator. This machine dates back to 1904 and — like many things — has been superseded by modern technology. In 1930, scientists knew there was something pulling the orbits of the planets but they didn’t know where it was.

The blink comparator helps you find something that moves by showing you two photographic plates in quick succession. Anything in the same spot on both plates appears stationary. Anything moving in the frame will stand out as it appears to jump from one spot to another.

In 1906, Percival Lowell started searching for “Planet X” in earnest. He died ten years later never knowing that he had photographed Pluto twice in 1915 but failed to notice it. Retrospectively, there were at least 14 other photographs of the quasi-planet that no one noticed at the time, going back to 1909.

In 1929 — after a lot of legal battles between the Lowell Observatory and Lowell’s widow, the search resumed with Clyde Tombaugh given the task as something suitable for a young astronomer. Tombaugh took pictures of the night sky in pairs and used a blink comparator to see if anything moved. He had a 13″ telescope — respectable, but not huge by today’s standards.

The discovery came out in March of 1930. Did you know that since then Pluto still hasn’t made it all the way around the sun? A year on Pluto is nearly 250 Earth years long. You can see more about the comparator at the Lowell Observatory in the video below.

Modern Science

While Tombaugh wasn’t technically a citizen scientist, we have access to tools he couldn’t dream of. While blink comparators are a thing of the past, we have a whole arsenal of digital imaging tools along with large numbers of images from ground-, space-, and vehicle-based telescopes and cameras. We applaud Shanmuga Subramanian for making use of these tools so successfully.

You can even do observations with a crowd if you like. You can also use some pretty big scopes online. Meanwhile, good luck to ISRO with their third mission, coming soon.

40 thoughts on “Chandrayaan-2 Found By Citizen Scientist; Reminds Us Of Pluto Discovery

    1. It’s not just you.

      In the center of the image, there’s an area that gets lighter in the ‘after’ picture, which I’m guessing is disturbed dust. In that area, pretty close to the center of the whole image, there’s a triangle that gets darker rather than lighter. I’m guessing (again) that this is the impact location.

      But I have very little confidence in these guesses. If someone sees more profound changes elsewhere, please share details.

      There’s also a diagonal line in the ‘after’ image, which I’m guessing (yet again) that’s an artifact of the data, not the moon. Otherwise some part of the lander must have rolled quite a distance after impact, and that seems extremely unlikely. :-)

    2. I can’t really see anything remotely conclusive. All these craters were created by impacts into the dust, although with much higher velocities. One would expect to see some obvious sharply defined shading from the impact. Like maybe new craters?

    3. It’s pretty useful to pull that gif into Photoshop (or whatever other image manipulation software that isn’t made by a terrible company like Adobe) and put the “before” image on top of the other one and set its blending mode to difference. Pretty clearly highlights the little dent on the side of a crater where it landed, plus it makes the cloud of ejecta that dusted the landscape beyond very clear. You can easily see the direction the impact came from. You can kind of see the ejecta on the blink animation but it’s incredibly well-defined with difference mode.

  1. What the Hell was IRSO thinking keeping their latest litho-breaking hunk of junks fate secret? Of course somebody is going to find it. Just be open and honest or get out of the space business.

    1. I doubt they have found the pieces with their orbiter yet. They are pretty much only visible when contrasted with the previous maps, and they hadn’t the time to collect the information before landing. Even if they collected images from the crash site after the incident it would be pretty much impossible to find the debris without a base map, and using the LRO maps as a base would still make the job quite hard due to the difference in their instruments.

      1. ISRO made claims about the lander just being in an odd orientation earlier instead on simply announcing that the thing hit the surface at 300kph. So either their telemetry was shit or they simply lied. Combined with that nice anti satellite exercise they pulled earlier this year, India clearly is not a wanted and honest player in these things.

          1. What makes it worst is the fact that they are doing it right now !

            I’m not a fan of the USA in many areas, but at least they are trying to clean their act up in some areas despite their natural tendencies and more then occasional partial relapsing into insanity.

            It simply is a non argument to grand India permission to shit in the galactic Ganges rivers because hindsight apparently is blind.

            If it is allowed to have Pakistan, China or India fight out their petty third world shit-hole bitch-fights in LEO, then all you will have left is the worthless smugness of treating idiots like equals… Space will be unobtainable for a couple of centuries,but at last your skewed morals stand.. Good thing!.

          2. 20 bucks say we still have ’em. We don’t take pieces off the playing field. Just got better at hiding it. When have we ever followed an international accord?

          3. “20 bucks say we still have ’em. We don’t take pieces off the playing field. Just got better at hiding it. When have we ever followed an international accord?”

            I’m sure the USA still has anti-satellite capability, just as it still has the ability to nuke the world ten times over. Lucky for us, the USA also is addicted to its space toys. It simply can not afford losing access to space for both military and economic reasons.

            That is a situation and mindset that I do not think really exists anywhere else.

          4. qwert wrote:
            “When have we ever followed an international accord?”

            I’m sure I’ve followed Japanese built Honda Accords in the USA,
            that would be following an international Accord.

    1. -1
      Try not to anthropomorphize taxonomy. Who is crying about Ceres anymore? All the people who went to school and were taught that was a planet died off, so nobody gets nostalgic about it anymore. It’s a useful distinction to keep the definition of planet nice and neat, and not have a couple grandfathered-in exceptions.

  2. Pluto is NOT a “non-planet.” Please stop blindly reporting one side of an ongoing debate as fact when that is far from the case. Just four percent of the IAU voted on the controversial demotion of Pluto, and most were not planetary scientists but other types of astronomers. Their decision was immediately opposed by an equal number of planetary scientists in a formal petition. These planetary scientists instead support the geophysical planet definition, according to which any non-self-luminous spheroidal body orbiting a star, orbiting another planet, or free floating in space is classed as a planet. If an object is large enough and massive enough to be rounded by its own gravity, according to this definition, it is a planet. Dwarf planets are simply a subclass of planets, as intended by the scientist who coined that term back in 1991, Alan Stern. Significantly, the New Horizons mission revealed Pluto to have complex geological processes seen elsewhere in the solar system only on Earth and Mars.

    1. That would make our moon, the Moon, a planet. As well as hundreds of other objects. One of the lamest arguments for planet status of Pluto was “that it will confuse kids who learn there are nine planets”. Good luck learning all those new planets…

      Teacher , “so then there is planet Moon”…
      Kid “wait, the Moon is a planet?”
      Teacher “yup”
      Kid “so why is called THE Moon?”
      Teacher, “well, astronomers decided to reclassify hundreds of moons as planets. So officially it is Planet Moon”.
      Kid, “ok, but the Earth still has a moon.”
      Teacher “No the Moon is a now a planet in the binary planet Earth-Moon system. Earth has no moons”
      Kids “but it’s called the Moon…”
      Teacher “Anyway, we’ve got another 100 planets to learn today, we need to move on”.

      1. An ant is still an insect, I don’t care much whether pluto is a planet or not it doesn’t really affect our daily life. And considering how hard it is to name different types of cyclepaths I do not think we are going to put Pluto in it’s final category any times soon, I mean what is a “bicycle super highway” look like an ordinary cyclepath to me.

      2. I have witnessed few similar discussions. One of them was like this:

        – There is this star called Sun.
        – Since when Sun is a star?
        – It always was.
        – So why is it called the Sun?
        – That is the name of that star. If it’s not star what you think it is?
        – A Sun! THE Sun is A sun.

        Discussion between teacher and kid would probably looked like this:

        – There is this planet Moon.
        – wait – Moon is a planet?
        – Yes.
        – So why it’s called THE moon.
        – Because that particular planet is orbiting our planet. Anyway we used to call it like this in the past and decided not to change it – otherwise you would have to correct all romantic stories.

        But I am not in position to discuss on what is a planet and what is a moon or could planet be a moon? I am just sure that there are more confusing things.

        By the way – that discussion on sun had very funny ending:

        – Sun is a sun. Star is a star. Calling Sun a starr is like calling tomato a friut.

    2. Let it go already, jeez. Where is the fanboy club for Chariklo, Ceres, Sedna, Eris, etc etc etc… in 300 years, once we’ve discovered 30,000 more Plutinos, what use will it be to have an asterisk in the definition of planet with a long, lengthy explanation of why this certain one is an exception just for emotional reasons?

  3. I appreciate the commentors that pointed out the diagonal lines. I missed them at first. The long one that runs the entire height of the frame has to be an image processing artifact, e.g. maybe the L/R halves of the after image were stitched together from two separate ones.

    What struck me immediately though is that the darker areas outside of the supposed debris area are themselves darker in the after image. This suggests three possibilities to me: 1. the angle relative to the sun is different in the after image; 2. an auto-leveling or white balance function was applied to keep overall luminosity roughly even between the two images; 3. the after image was otherwise manipulated for indiscernible reasons, e.g. an effect of the gif creation process?

    These are just my own guesses, e.g. #1 might justify the use of #2. What seems logical to me either way is that the brighter area in the after image should appear even brighter if the darker areas were balanced across both images. I haven’t looked at the original images yet to test my theory, but hope to find the time to do so.

    1. Forgot to mention as well that if my #1 was true, incident angle may also cause the brightening effect observed in the regolith. If true, then it makes sense that my #2 suggestion may have been used to reduce the impact of that natural lighting, and thus, exposure difference; in order to produce an easier blink detection effect.

      The dark line, if not an image processing artifact is in my opinion the best candidate for the crash site. I am guessing that estimated crash velocity vs. last known position vs. estimated regolith density for that region could produce a rough estimate of how long a streak would be left by a “slow” moving spacecraft approaching the surface at a shallow angle, compared to the much higher speeds and angles associated with meteor impact craters.

      Again, just my uninformed opinion.

      1. It’s been a long time for me since I’ve done graphics, but there’s some basic principles of image manipulation that wouldn’t even require a blink comparison. Just superimpose the two images and you can have differences show up as bright colors using certain filters. Hell, why not just have the entire historical library of moon surface images continuously being cross-referenced for differences every time a newer sweep of the surface is taken by this LILO deal or whatever the hell it’s called.

        Also, and more controversially, I find it hard to believe the ratio of high/low technology that is employed with NASA in general. Really, we have cellphones that have high definition live streaming video manipulation technology that wasn’t available on computers 10 years ago but NASA is streaming only black and white lo-res images of the moon from very close to the surface? And on the same token, we could send live audio/video (albeit even poorer quality) in the hands of human beings on the surface 50 years ago, but today we are trying to find a crashed vehicle on the surface with blinky pictures???

  4. I really like this hack, and the cool history lesson — and I’ve used methods similar to the blink comparator before to check out the differences between two versions of an image (comparing artifacts and such). But I read the linked Wikipedia page and read “image differencing algorithms detect moving objects more effectively than human eyes can” — so I wondered what that could tell us with simple tools and not much time spent.

    My favorite image processing suite is still ImageMagick, though it’s more than I can keep in my head these days — the Examples page at has how to run comparisons between two images, under the heading “Image Comparing”.

    I haven’t bothered to work with anything prior to the given GIF, and I cropped out (very roughly) the labels on the two frames so those wouldn’t swamp the comparison — a crop value of 885×885+50+40. After that, I used the given methods of pixel-based image comparison pretty exactly from the examples page.

    The first is a simple pixel-based comparison using a fuzz factor of 5% to mask noise: . The command line was:

    compare -metric AE -fuzz 5% vikram_impact_001c.png vikram_impact_002c.png -compose Src vikram_impact_c_diff.png

    The second is a difference composition, subsequently auto-leveled:

    composite vikram_impact_001c.png vikram_impact_002c.png -compose difference vikram_impact_c_diff_comp.png

    convert vikram_impact_c_diff_comp.png -auto-level vikram_impact_c_diff_comp_al.png

    (There are further examples in the composite section, but they all boil down to more or less the same image, give or take some brightness.)

    With both, you can see much more clearly the right-to-left diagonal lines previous posters mentioned — I agree that those are probably artifacts, if only because there are three of them running parallel to each other. There’s also still a fair bit of difference from shadow angles. But it does look as if the diagonal running the other way in the bottom third (and between the leftmost artifact diagonals) is a real feature — and it points to a large amount of change right in the center of the frame. It does seem convincing as an angled impact and a debris field.

  5. The “thing” that Indians used to reach the Moon took four months to arrive there. It orbited Earth a number of times, each time receiving a gravitational assist to translate to a longer orbit until they obtained Lunar orbit insertion.
    There were no injection of sort, because there were no orbital engine! Cheap as chips, and I believe in all that travel the on board electronics and batteries were well cooked by radiations. Too cheap to work, IMHO…

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