Exposing PseudoAstronomy

July 22, 2015

#NewHorizons #PlutoFlyby – The Pseudoscience Flows #6: Data Download


Introduction

I know I’ve promised other parts to this series, but this one will be quick* and I want to get it out there because it feeds into a lot of varied and various conspiracies related to NASA’s New Horizons mission to the Pluto-Charon system, and I’ve even seen many misconceptions on normal science blogs / websites (not to be named): Where’s the data!?

Deep breath people: It’s coming. Slowly.

*I thought it would be quick, but it turned out to be nearly 2000 words. Oops…

The Slowness of Spacecraft Data Transfer

Every space mission – save for one very recent, experimental one – relays data via radio signal. In other words, light. The amount of power that the spacecraft can muster goes into figuring out the data rate it can sustain. Think of it a bit like this: If you have the Bat Signal, but you were using a flashlight, you’d be lucky if someone could just see the flashlight aimed up at the sky. There’s no way they could see details of a bat cut-out. But if you use a really really bright spotlight, you can see it farther, and you can even stick a detailed bat cutout over its front and you can make out that cutout.

Perhaps a bad analogy, but that’s kinda the idea here: If you have a very strong signal, then you can include a lot of detail really quickly. If you have a weak signal, then the data rate is slower. Oh– better analogy: bad wifi reception. You know you have low signal strength when it gets really slow.

Moving on, the New Horizons REX antenna does not have a huge amount of power. New Horizons launched with less plutonium for power than originally intended, and it needs power for running the spacecraft. It has so little power for the antenna that only the 70 meter dishes in NASA’s Deep Space Network (DSN) are big enough to receive the signal at Earth, which is a paltry 3 * 10-19 Watts. (Compare that with a 100 W light bulb.) To me, first off, it’s amazing that we can even receive that faint of a signal.

But once you get over that amazement, the DSN also has to be able to detect changes in that tiny signal. That’s how we get data. Like blinking your flashlight in Morse code, or putting the Bat Signal stencil up. If we have very little signal strength, we can’t change our signal very quickly, or the DSN may not be able to read it. Change more slowly, then they will.

For planning purposes, we were able to send data at 1296 bits per second. I’m old enough (sigh…) to remember dial-up modems in the 1990s. My family’s first modem was the dreaded 14.4 kbps modem which was painfully slow at pulling up AOL’s e-mail. Or Hamster Dance. But even that was over 10 times faster than New Horizons’ data rate. And, let’s convert it to real things, bytes. There are 8 bits to a byte. 1296 bits per second is only 162 bytes per second. I have a thumbdrive attached to my computer that holds 64 GB, or 64 gigabytes. It would take about 4572 hours, at the average New Horizons download rate, to fill that fairly modest thumb drive. That’s 190 days.

Keep in mind that the spacecraft is still taking data. Keep in mind that there are only 3 70m DSN dishes at the correct latitudes to see the spacecraft, ever, from Earth. Keep in mind that there are other missions out there that need the DSN to communicate with Earth. Keep in mind that 1296 is an average planning bit rate, and while the Canberra and Goldstone dishes get more like 2000 bps, Madrid tends to get less due to the elevation of the spacecraft above the horizon.

So, from the get-go, just from considering the data rate (power requirements on the spacecraft, distance to the spacecraft, and timetable of receiving stations on Earth), one should be able to see that it will take a painfully long time to get the data from the spacecraft.

While we could keep up with the data rate and did a large download a month before encounter (which is why data weren’t taken in late May), there’s no way we could get all the data during encounter very soon after it, which is why the craft flew with two 8 GB storage drives, and it filled up 60 Gb during encounter (see what I did there, switching between bit and byte?).

There’s Other Data Besides Images!

And that’s any kind of data. There aren’t just images and “pretty pictures” that many of us want. There is one B&W camera on the craft, but there’s also a color camera, two spectrometers, a dust counter, two plasma instruments, the antenna itself took data, and there’s basic spacecraft housekeeping and telemetry that says things like, “Yes, I really did fire my thrusters at this time when you wanted me to!”

Basic Download Plan

I can discuss this because the basics have been made public. It’s just not “sexy” like pretty pictures so it’s not that easily findable.

Leading up to encounter, data were prioritized as though we were going to lose the spacecraft at any time, so the most important, “Tier 1” science data were downloaded first. And, critical optical navigation images.

After encounter, the same thing happened, where compression algorithms were used on the data on-board the spacecraft and that lossy-compressed data were sent back to Earth to fulfill as many Tier 1 science goals as possible. That’s how – and why – in the last week we’ve already revolutionized what we know about Pluto. Those first high-res (0.4 km/px) images of the surface were planned out based on Hubble Space Telescope maps of the surface and the spacecraft timing and trajectory to get images that cover different brightness and color patches. (Which takes care of another, minor conspiracy that I’ve seen that claims we “knew” where to point the cameras because the Secret Space Program had leaked us information about what would be interesting.)

But now that we’re more than a week from closest approach, thoughts are turning to what to do next. Originally, a “browse” data set of all the lossy data (only the imagers and spectrometers store lossy-compressed in addition to lossless) were going to be returned first, along with the lossless data from other instruments. That would at least let us at least understand the surface at a lossy JPG quality and for the plasma folks to do their science.

But now people are discussing scrapping that and bringing down the lossless data instead, albeit many times slower because of the larger file sizes.

Planning, Fairness

But, believe it or not, planning of what’s downloaded when is made no more than a few weeks out (except for the closest approach weeks). Right now, we’re working on the late August / September load of commands and deciding what data to bring down in what order.

Each of the four science theme teams (geology geophysics & imaging (GGI), atmospheres, composition (COMP), and particles & plasma (P&P)) puts together a list of their top priorities based on what we’ve seen so far. The Pluto Encounter Planning (PEP) team then sits down and looks at how much they can bring down in what time and puts things in order. The sequencers then take that and try to make it happen in the test computers. Then we iterate. Then it gets reviewed. Extensively. Only then does it get uploaded to the spacecraft to execute.

But besides that priority list, it’s the Principle Investigator who decides how much data each science team gets. For example, while I’m on PEP (it’s what I was initially hired to do), I’ve been adopted by GGI. Wearing my GGI hat, I want images from the LORRI instrument. All the time, and only LORRI. I don’t care what the plasma instrument PEPSSI recorded. But by the same token, the P&P folks don’t care anything about images, they want to know what their instruments recorded as the craft passed through the Pluto system to see how the solar wind interacted with escaping particles from Pluto – or even if it did. (Which it did, as was released in a press conference last Friday.)

So Alan Stern has to make the decision of how to be “fair” to so many competing interests within the large – and broad – science team. So while COMP may want to have 5 DSN playback tracks in a row to bring back just one of their very large spectra data cubes, Alan has to make sure that GGI gets their images and P&P gets their data, too.

The Plan

The decision was made several months ago that after this initial batch of data – what we saw last week, what we see this week – that all of the “low speed” data will come down in August. That’s housekeeping & telemetry, that’s things like how many dark pixels are in any given LORRI image, it’s the two plasma instruments and data recorded by the antenna and dust counter, and that’s about it. After that, we get back to the imagers and spectrometers, per the balance discussed above.

And since it’s not sequenced, and it’s not public, I can’t tell you any more than that.

So we are, unfortunately, not going to see any new images for practically a month, beyond the two navigation images that should come down tomorrow and Friday.

Conspiracy!

Due to the nature of this blog, obviously this is going to fuel conspiracies: NASA’s hiding the data, NASA’s manipulating the data, NASA’s [whatevering] the data, etc.

It’s just not true.

I have known for years that these conspiracies about NASA somehow intercepting the data and manipulating it before even us naïve scientists can get our hands on it would be very difficult, but being on this mission has made me realize that it’s even more difficult to somehow support that conspiracy than I had thought.

Literally, as the data are received by the DSN – before it’s even completely downloaded – it’s on our processing servers and in the processing high-cadence pipeline. On Monday morning when we were supposed to get four new images, we were literally sitting in the GGI room hitting the refresh button and marveling over each new line of pixels that we were getting back in practically real-time. To use a religious analogy, it was every Christmas morning rolled into a one-hour marathon of hitting the refresh button.

And we were all there watching — over 20 of us. And other science team members kept coming in to look.

The idea of secretly having one or two people intercepting the data, “airbrushing” things in or out of it, and only then giving it from On High to the scientists just shows how out of touch from reality conspiracists are. (By the way, I use the term “airbrushing” here because that’s how many conspiracists still talk. Obviously, no one is physically airbrushing things anymore — and I doubt anyone younger than 30 even knows what a real airbrush is.)

To sustain the conspiracy, I can only see one of two choices: (1) Either all of us scientists are in on it, in which case it becomes ridiculously large and unsustainable and scientists suck at keeping secrets about exciting new things, or (2) somehow there’s super secret advanced tech that intercepts the spacecraft signal and at the speed of light “airbrushes” things out and retransmits it to the DSN to get into our processing pipeline. Because we know when stuff is supposed to appear on Earth. Because we write the sequence that does it.

Final Thoughts

Not that I expect this to convince any conspiracy theorist of their folly. The lack of image data for the next month, and the lossy JPG data we have now all contribute to the little anomalies that don’t immediately make sense, and the average conspiracist can easily spin into something that it’s not.

14 Comments »

  1. Way back in the late 1980’s I had a laptop computer which was equipped with a 1200 baud modem. This is similar to the data transmission rate from New Horizons. Each plain text email took several seconds to download. Nobody knew about the WWW and the really big things at the time were Bulletin Board Systems and AOL for email. NSCA Mosaic, the first web browser and the precursor to Netscape’s first web browser, wouldn’t be released until 1993. Yet way back in the late 1980’s I downloaded a CAD program called Draft Choice. It was a whopping download of approximately 460 thousand bytes which took nearly an hour to download! Now let’s consider the latest image from New Horizons which is of the newly discovered mountain range which lies near the southwestern margin of Pluto’s Tombaugh Region. This image is 1041 by 1039 pixels in size. One can see obvious JPEG image compression artifacts in the image, particularly in areas where brightly lit areas meet deeply shadowed areas. The raw (uncompressed) version of this 256 gray scale image would be 1 megabyte in size. Looking at the visible JPEG image compression artifacts, I estimate that the amount of JPEG compression used by the New Horizon spacecraft was such that only roughly 80% of the original image quality would be preserved. This might be an overestimate for how much image quality the New Horizons team chose to preserve when the New Horizons spacecraft’s on-board computers compress each raw camera image. Assuming that 80% of the original image quality was preserved by JPEG compression, then the compressed JPEG version of this image would be approximately 180 thousand bytes in size and would take 20 minutes to be transmitted by New Horizons to Earth at 1200 baud. On the other hand, the original uncompressed image would take nearly 2 hours to be transmitted by New Horizons. And this doesn’t include any additional overhead such as CRC check-bits which assure that any corruption in the received data stream can be corrected.

    I find it to be quite remarkable that this tiny spacecraft, so far from Earth and the Sun and with a very small antenna and equipped with what is now ancient computer technology, is able to send to all of humanity these strikingly amazing and beautiful images of the Pluto system. The timing of these latest images is also especially appropriate since this month marks the 46th anniversary of the first moon landing, or the first time in which a human being from our planet Earth ever set foot on another world. There are many layers of cultural significance for all of humanity in this remarkable feat. Yuri Gagarin cried with joy while he watched Neil Armstrong set foot on the moon since he realized the significance of what Apollo 11 at that moment was accomplishing. The word “remarkable” was one of Neil Armstrong’s favorite yet rarely used words. Neil only used this word to describe something which truly impressed him. I think that he would describe the images which New Horizons had returned from the furthest reaches of the planetary region of our solar system as being truly remarkable because they are.

    And to all of you conspiracy theorists out there: The first two EVA photographs which Neil Armstrong took while on the surface of the moon inherently prove that he really was on the moon. All you have to do is to translate them in Hugin and compensate for the lens focal length since one was taken with the 60mm Biogon lens set at its near focus setting, and the other was taken with the lens set at its far focus setting. And then you take these translated imaged and turn them into a 3D anaglyph which you align on the distant horizon. The result of this 3D anaglyph is that, with a calculator and measuring the horizontal displacement of every boulder, you can measure the distances to every boulder from nearby the LM to the most distant boulder field which is seen and which is located to the south of West Crater and which is over 1500 feet away from the camera. The results match with remarkable precision to the LRO images of the landing site, all the way from 12 feet from the camera to over 1500 feet from the camera. So, all you conspiracy theorists, how do you evenly illuminate a “movie set” in every direction out to a radius of at least 1500 feet using a single light source which is located 11° high in the sky? How do you do it, with the distortion effects of Earth’s atmosphere which are readily seen in telephoto lens photographs, such that absolutely no distortion effects due to heat waves are visible in ANY Apollo EVA photograph? It is impossible to build a vacuum chamber which is 3000 feet in diameter, let alone the even larger vacuum chambers which would be required to create fake “movie sets” for the later Apollo missions which traversed much larger distances across the lunar surface. Oh, I know what the answer must be. Aliens must have helped NASA do it. Or maybe the truth and fact is that, as Neil said a year before his passing, “This proves that we really did it.” He was referring to the video which I created by overlaying LRO images of the Apollo 11 landing site into Google Moon and then matching each second of the last 4 minutes of the Eagle’s descent and landing to the Eagle’s DAC footage of the first moon landing. Every single tiny boulder and crater which is seen in the LRO images precisely matches with what is seen in the Eagle’s DAC descent and landing footage from 46 years ago.

    I dislike conspiracy theorists since all of them are and to a tee, people who suffer from delusional disorder. You can’t help them since they won’t even trust a doctor or psychiatrist. I also think that Stuart, by responding to the ridiculous conspiracy claims which are put forth by conspiracy theorists, gives them credence by countering such conspiracy claims. What is the old saying? “Give them an inch and they will take a mile.” My position is that Stuart, like NASA, should take the high road by ignoring the claims which are put forth by conspiracy theorists since, by responding at all, one is giving credence to such claims by even discussing them. Yet I also see where Stuart is coming from since he, like me, can’t stand these ludicrous conspiracy theories. The moon landing conspiracies have been a thorn in the side of the Apollo astronauts who put their lives on the line in order to accomplish their missions. These are men of a caliber and of a generation which the world is likely to never see again. They were the best of the best. Integrity was everything to them, and still is. It grates at them, far more than most people know, whenever conspiracy theorists such at Bart Sibrel claim that that they are liars and that they never landed or walked on the moon. The famous video of Buzz Aldrin punching Bart Sibrel shows just how much the ludicrous moon landing conspiracy claims grate at the Apollo astronauts.

    The sad thing about humanity is how prevalent delusional disorder actually is. It may well be our downfall since delusional disorder is so prevalent that many people don’t “believe” that global warming is mostly caused by the burning of fossil fuels. I have had plenty of Bible Thumpers come knocking on my door on Sunday mornings who ask what I “believe.” It is the same old story. Delusional people who, in an effort to support their delusional beliefs, need to convince others to believe what they do. I slam the door on them every time.

    Comment by GoneToPlaid — July 22, 2015 @ 10:01 pm | Reply

    • Compression of the lossy LORRI images is 6:1.

      Comment by Stuart Robbins — July 22, 2015 @ 10:07 pm | Reply

      • Yep. My estimated compression ratio was 5.75 to 1. So it looks like the team decided on 75% image quality for the JPEG compression settings?

        Comment by GoneToPlaid — July 22, 2015 @ 10:27 pm

      • I don’t really know the exact chain of thought on what was chosen how. My understanding is that it’s hard-coded into the spacecraft which is why we can’t use smarter compression schemes that exist now, but I could be wrong. Each instrument has different compression ratios.

        Comment by Stuart Robbins — July 22, 2015 @ 10:39 pm

  2. Unfortunately, I stumbled across the Pluto truthers (I call them pluthers) shortly after the flyby. I was not amused. Honest. Ask my co-workers.

    Here we have these great scientific achievements, and their deluded minds say nope, not possible. And they’re all obviously highly educated people who put forth logical arguments. It’s fake, because REASONS!

    I do kinda wonder how many people are just trolling, though.

    I love the podcast, Stuart. Have fun analyzing your photoshopped images from “Pluto.”

    Comment by Steve — July 22, 2015 @ 10:25 pm | Reply

  3. I worked as a Sequence Integration Engineer for Galileo. Because the main antenna didn’t open all the way, our maximum data rate was 120 b/s. What’s amazing is the amount of information about Jupiter and its satellites we were able to receive.

    Comment by kmoyd — July 22, 2015 @ 11:56 pm | Reply

    • Agreed. But it’s also sad how little data came down from what was originally planned.😦

      Comment by Stuart Robbins — July 23, 2015 @ 5:06 am | Reply

      • Actually, it’ was not as bad as it seems. They had planned on sending all encounter data in real time. Fortunately, a tape recorder had been put on the spacecraft for the probe data, and they were able to use it to store the flyby data and downlink during the one or two months between satellite encounters. They also had enough time to change the telemetry format so they could select the observations to downlink.

        Comment by kmoyd — July 23, 2015 @ 10:07 am

      • It’s still pretty bad. I made this infographic a few months ago showing the amount of images of each planet in the solar system and taken by what probe, and you can very easily visibly see what the Galileo main antenna failure did to the data return. Granted, a lot was made of a sucky situation, but it was still a very sucky situation.

        Comment by Stuart Robbins — July 23, 2015 @ 11:03 am

  4. This article describes the changes made and the effect on the science.

    http://www.lpi.usra.edu/publications/newsletters/lpib/lpib76/gal76.html

    Comment by kmoyd — July 23, 2015 @ 1:55 pm | Reply

    • Way too late now of course, but I wonder if Galileo could have been spun about its axis to pop open the antenna, or at least to reduce the stiction which was preventing the antenna from fully deploying. I figure that somebody must have had this idea when the problem was discovered.

      Comment by GoneToPlaid — July 23, 2015 @ 4:25 pm | Reply

      • Engineers tried thermal-cycling the antenna, rotating the spacecraft up to its maximum spin rate of 10.5 rpm, and “hammering” the antenna deployment motor — turning it on and off repeatedly — over 13,000 times, but all attempts failed to open the high-gain antenna.

        Comment by kmoyd — July 23, 2015 @ 7:29 pm

      • I figured that you all tried all of these things and them some. Wow. You guys really did try everything under the sun in hopes of getting the antenna to fully deploy. At least it is was an extremely good learning experience for future missions. Like NASA did for the Apollo missions, red tag anything which is mission critical for the overall success. The only difference in the manned Apollo missions was that red tags also implied the potential loss of life as well as end of mission. Still, it is really neat to see that the Galileo Team tried everything which they could think of to un-stick the antenna. This should have been communicated in press releases at the time since the public was under the impression that the force required to open the antenna was less force than what it took to lift a piece of paper, and that nothing was tried to resolve the problem. I, and I assume that the general public as well, assumed that the antenna design simply didn’t have a strong enough motor to deploy the antenna. I see now that this is a misconception of the overall situation. What was mostly glossed over was the fact that Galileo sat in storage for way too long, due to budget constraints, before Galileo was launched. The antenna would have deployed just fine as originally designed and if Galileo hadn’t been mothballed for a few years such that the antenna lubricants dried up. It seems to me that all future missions, in terms of engineering, should factor in the potential “mothball” scenario which politicians might unexpectedly introduce. In my personal opinion, there are very few politicians who can see much further than the end of their nose, or at least no further out than their next re-election. SLS is designed to return to the moon since all proposals over many decades require setting up a lunar base before going to Mars. At least NASA this time got it right by selling SLS to politicians as a launch vehicle for Mars, instead of telling politicians that SLS first and foremost is designed to establish manned lunar bases for the testing of the equipment and technology which is required to actually send humans to Mars. And then SLS can be used to launch the components of a vehicle which has the proven systems to actually send humans to Mars. Sorry for the bit of a rant. But as soon as the specs for the SLS became public, I realized that NASA fully intended to return to the moon before proceeding to Mars. Any alternative is absurd in terms of risk to human life for a manned mission to Mars.

        Comment by GoneToPlaid — July 23, 2015 @ 8:37 pm

  5. I think there was some publicity about the hammering. I believe the main layover for Galileo was the Shuttle shutdown after the Challenger accident. There was also an extra round trip between JPL and the Cape.

    Comment by kmoyd — July 24, 2015 @ 12:37 am | Reply


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