Emily LakdawallaApr 29, 2015

New Horizons sees surface features on Pluto, begins raw image release

Today the New Horizons team released a new animation of images taken on approach to Pluto. The animation clearly shows how Pluto wobbles around the Pluto-Charon barycenter. It also shows something more exciting to the scientists: variations in brightness across the surface of Pluto.

New Horizons sees surface features on Pluto for the first time
New Horizons sees surface features on Pluto for the first time This animation contains 13 images taken over the course of one Pluto rotation between April 12 and April 18, 2015. During this period, New Horizons was roughly 110 million kilometers from Pluto. Stacking and deconvolution has been used to increase the resolution of the images over the raw data, revealing Pluto's spotty surface. The brightness variations make Pluto appear lumpy, but it is actually round. NASA / JHUAPL / SwRI

We knew those variations existed, but they didn't expect to see them so early in New Horizons' approach, according to project scientist Hal Weaver. He said at a press briefing today that they didn't expect to see the surface variations for another month. They were made visible thanks to a process of stacking multiple photos taken one after another, and deconvolving the result. Hal said that the astronomy community's deconvolution algorithms were developed after Hubble was launched with its initially blurry vision -- so the Hubble problem has had a silver lining for the New Horizons mission!

The most common question I've been asked about this image today is: Is Pluto lumpy? The answer is no; Pluto is round. It appears lumpy because of those very brightness variations that the scientists are so excited about. Wherever a bright spot is near the edge of the disk, it looks like an upward lump; wherever a dark spot is near the edge, it looks like a downward lump. The variations in surface brightness are probably going to make it very hard to figure out what kind of topography Pluto actually has until we're quite close to it. In the meantime, they make animations of Pluto very interesting!

The other big announcement today is that the New Horizons team has begun sharing their raw images on the Web! Unlike with the Jupiter flyby, where they shared lossless PNG-formatted data, they are putting the Pluto images out in lossy JPEG format, which reduces their quality. While of course I'd love to have PNGs, lossy JPEG format is a tradeoff I'm certainly willing to accept in exchange for rapid access to images that help me to follow the mission! They say that images will generally appear on the raw images website within 48 hours of their receipt.

I've spent some time on the raw images website this afternoon, and thought I'd give you a tour of the kinds of images you'll find there.

First of all, I can decode the filenames for you. The filename convention is:

lor_NNNNNNNNNN_MMMMM_sci_P.jpg

Where

  • "lor" tells you that it's a LORRI image
  • NNNNNNNNNN is the mission elapsed time in seconds
  • MMMMM is an "ApID", a hexadecimal code that contains information about the observation (see table below)
  • "sci" tells you that the data has been lightly processed from the raw engineering data (it is "Level 2" rather than "Level 1" data)
  • P is the version number (there may be multiple versions of images; it looks like the raw page links only to the latest-version one for each observation)

Here is a lookup table for the ApIDs:

APIDC&DH sidebinning modecompression type
0x63011x1lossless
0x63111x1packetized
0x63211x1lossy
0x63314x4lossless
0x63414x4packetized
0x63514x4lossy
0x63621x1lossless
0x63721x1packetized
0x63821x1lossy
0x63924x4lossless
0x63A24x4packetized
0x63B24x4lossy


So far, all of the available data appears to have ApIDs of 0x630 or 0x633. That tells you that only the Side 1 computer has been used (presumably Side 2 will only get used if something bad happens). It also tells you that all these images have been transmitted to Earth losslessly. That will continue to be true for all of these early images because they are being used for optical navigation and the New Horizons navigators need every scrap of precision they can eke out of the data. We'll begin seeing lossy data closer to encounter. The main difference between 0x630 data and 0x633 data is that the 0x633 images have been binned 4x4 before transmission to Earth. That means that the images are only 256 pixels square. As I explained in an earlier blog post, this binning is necessary to allow LORRI to be able to take the long exposures needed pick out the faint light from Pluto's smaller moons Nix and Hydra from very far away without smearing the images.

Here's an example 0x630 image. These images are usually taken with relatively short exposures, so you can pretty much only see Pluto and Charon. Few or no background stars are visible. This image had an exposure time of 0.1 second.

Raw New Horizons LORRI image: 0x630, 1x1 binned, losslessly transmitted
Raw New Horizons LORRI image: 0x630, 1x1 binned, losslessly transmitted Keep in mind that although the images were transmitted to Earth losslessly, they have been converted to JPEG format before being posted on the Web, so the images you can download rapidly are lossy-compressed. Lossless data will be available through the Small Bodies Node of the Planetary Data System 9 to 12 months after receipt from the spacecraft. NASA / JHUAPL / SwRI

Here's an example 0x633 image. These are taken with much, much longer exposures in order to reveal the faint moons. Lots of background stars are visible; astrometry.net readily identifies the star field. (Thanks to some friends on Twitter for reminding me about astrometry.net!) The long exposures cause pixel bleeding from the relatively bright Pluto and Charon, which appear as jagged spears of white pixels trailing to the right. This one is a 10-second exposure.

Raw New Horizons LORRI image: 0x633, 4x4 binned, losslessly transmitted
Raw New Horizons LORRI image: 0x633, 4x4 binned, losslessly transmitted NASA / JHUAPL / SwRI

I downloaded a bunch of these pictures and tried stacking them to reduce artifacts and aligning them to reduce the visual confusion of dancing stars in the hopes that I could spot Nix and Hydra, but I don't know that it was effective:

There are a few weird-looking photos on the raw images page. Some of them, like this one, are very light-colored with a vertical stripe down the center. If you look within the vertical stripe, you'll see Pluto and Charon. The website helpfully explains what is going on in these images:

Sometimes only partial images are downlinked in order to reduce downlink data volume using a process called "windowing". The region of interest, also called the "window", is captured from the LORRI detector and the rest of the image is not even downlinked. However, the subsequent ground processing populates the missing regions with zeroes and then subtracts the bias level, which produces negative numbers in the final calibrated image. This combination of negative numbers in the "Blank Region" and "Real Data" in the windowed region, and the automatic intensity scaling used to produce the JPEG image (which ranges from the minimum to maximum values in the image), produces a banded structure in the JPEGs. A similar effect also applies to images for which data have been "lost" (e.g., data dropouts at the Deep Space Network).

Sometimes data are lost during the transfer from the New Horizons spacecraft to the Mission Operations Center at APL (e.g., bad weather at one of the DSN sites can sometimes cause data dropouts). When these dropouts occur, the subsequent processing of the images is affected and some of the missing pixels are assigned incorrect intensity values. Furthermore, these incorrect intensity values can adversely affect the automatic scaling used to produce these figures, with most of the field appearing to be white and the missing pixels set to black. If an image "corrupted" in this way is considered "critical", the Mission Operations Center may request a re-transmission of the data from the spacecraft. But if the loss of the image doesn't significantly impact ongoing operations or science analysis, we will not try to re-transmit the image from the spacecraft.

The following table shows when you can expect New Horizons to be taking optical navigation images like the ones available on the raw images website so far. I posted this once before; thanks very much to Kim Ennico for getting this information to me! There are two periods during Pluto approach when New Horizons is not taking new images, but is instead focusing on transmitting data to Earth. We're in the middle of the first one of those (April 19 to May 8), and there will be another gap May 15-27. But those gaps are when the lion's share of the data arrives on Earth. So stay tuned to the raw images website for more and more data!

Date/time
(UTC)
Range
(Mkm)
Targets4x4
binned?
Resolution
(km/pix)
2015 Jan 25 02:01203Pluto and Charon 1015
2015 Jan 25 02:06203Pluto, Charon, Nix & Hydrayes4059
2015 Jan 25 14:01202Pluto and Charon 1012
2015 Jan 26 01:57202Pluto and Charon 1009
2015 Jan 26 13:57201Pluto and Charon 1006
2015 Jan 27 01:53201Pluto and Charon 1003
2015 Jan 27 01:58201Pluto, Charon, Nix & Hydrayes4012
2015 Jan 27 13:53200Pluto and Charon 1000
2015 Jan 28 01:49199Pluto and Charon 997
2015 Jan 28 13:49199Pluto and Charon 994
2015 Jan 29 01:45198Pluto and Charon 991
2015 Jan 29 13:45198Pluto and Charon 988
2015 Jan 30 01:41197Pluto and Charon 985
2015 Jan 30 01:49197Pluto, Charon, Nix & Hydrayes3941
2015 Jan 30 13:41196Pluto and Charon 982
2015 Jan 31 01:37196Pluto and Charon 979
2015 Jan 31 01:42196Pluto, Charon, Nix & Hydrayes3917
2015 Jan 31 13:37195Pluto and Charon 976
2015 Feb 01 01:33195Pluto and Charon 973
2015 Feb 02 01:25193Pluto, Charon, Nix & Hydrayes3869
2015 Feb 04 01:17191Pluto, Charon, Nix & Hydrayes3822
2015 Feb 06 01:09189Pluto, Charon, Nix & Hydrayes3774
2015 Feb 08 15:00186Pluto, Charon, Nix & Hydrayes3713
2015 Feb 10 18:00183Pluto, Charon, Nix & Hydrayes3662
2015 Feb 12 00:45182Pluto, Charon, Nix & Hydrayes3632
2015 Feb 15 01:37178Pluto, Charon, Nix & Hydrayes3560
2015 Feb 16 20:00176Pluto, Charon, Nix & Hydrayes3517
2015 Feb 18 20:00173Pluto, Charon, Nix & Hydrayes3470
2015 Feb 20 00:13172Pluto, Charon, Nix & Hydrayes3442
2015 Feb 22 20:00169Pluto, Charon, Nix & Hydrayes3374
2015 Feb 23 20:00168Pluto, Charon, Nix & Hydrayes3351
2015 Feb 26 08:00165Pluto, Charon, Nix & Hydrayes3291
2015 Feb 27 23:41163Pluto, Charon, Nix & Hydrayes3252
2015 Mar 01 23:33160Pluto, Charon, Nix & Hydrayes3204
2015 Mar 03 12:00158Pluto, Charon, Nix & Hydrayes3168
2015 Mar 05 00:30157Pluto, Charon, Nix & Hydrayes3132
2015 Apr 05 07:48119Pluto, Charon, Nix & Hydrayes2386
2015 Apr 07 05:44117Pluto, Charon, Nix & Hydrayes2340
2015 Apr 08 06:00116Pluto, Charon, Nix & Hydrayes2316
2015 Apr 11 18:00112Pluto, Charon, Nix & Hydrayes2233
2015 Apr 12 03:47111Pluto and Charon 556
2015 Apr 12 03:55111Pluto, Charon, Nix & Hydrayes2223
2015 Apr 12 21:45110Pluto and Charon 551
2015 Apr 13 04:16110Pluto and Charon 550
2015 Apr 13 22:02109Pluto and Charon 545
2015 Apr 14 09:32108Pluto and Charon 542
2015 Apr 14 21:37108Pluto and Charon 539
2015 Apr 15 04:08108Pluto and Charon 538
2015 Apr 15 04:16108Pluto, Charon, Nix & Hydrayes2151
2015 Apr 15 21:54107Pluto and Charon 533
2015 Apr 16 09:24106Pluto and Charon 531
2015 Apr 16 21:29106Pluto and Charon 528
2015 Apr 17 04:00105Pluto and Charon 526
2015 Apr 17 21:46104Pluto and Charon 522
2015 Apr 17 21:48104Pluto, Charon, Nix & Hydrayes2086
2015 Apr 18 09:16104Pluto and Charon 519
2015 Apr 18 21:21103Pluto and Charon 516
2015 Apr 19 03:52103Pluto and Charon 514
2015 Apr 19 04:00103Pluto, Charon, Nix & Hydrayes2056
2015 Apr 21 14:00100Pluto, Charon, Nix & Hydrayes1999
2015 Apr 22 09:2099.0Pluto, Charon, Nix & Hydrayes1980
2015 Apr 25 02:3395.7Pluto, Charon, Nix & Hydrayes1915
2015 Apr 27 02:2593.4Pluto, Charon, Nix & Hydrayes1867
2015 Apr 29 02:1791.0Pluto, Charon, Nix & Hydrayes1820
2015 May 01 02:0988.6Pluto, Charon, Nix & Hydrayes1772
2015 May 02 14:0086.8Pluto, Charon, Nix & Hydrayes1737
2015 May 05 01:5383.9Pluto, Charon, Nix & Hydrayes1677
2015 May 06 21:0081.7Pluto, Charon, Nix & Hydrayes1634
2015 May 09 03:3679.0Pluto, Charon, Nix & Hydrayes1580
2015 May 11 01:0076.8Pluto, Charon, Nix & Hydrayes1535
2015 May 13 03:2074.3Pluto, Charon, Nix & Hydrayes1485
2015 May 14 02:0073.1Pluto, Charon, Nix & Hydrayes1463
2015 May 28 06:0056.3Pluto, Charon, Nix & Hydra 281
2015 May 28 09:4556.1Pluto, Charon, Nix & Hydrayes1122
2015 May 29 01:3555.3Pluto, Charon, Nix & Hydra 276
2015 May 29 01:4555.3Pluto, Charon, Nix & Hydrayes1106
2015 May 30 06:0053.9Pluto, Charon, Nix & Hydra 269
2015 May 30 06:0053.9Pluto, Charon, Nix & Hydrayes1078
2015 May 31 01:1052.9Pluto, Charon, Nix & Hydra 265
2015 May 31 01:1052.9Pluto, Charon, Nix & Hydrayes1059
2015 Jun 01 05:4551.5Pluto, Charon, Nix & Hydra 258
2015 Jun 01 05:4551.5Pluto, Charon, Nix & Hydrayes1030
2015 Jun 02 01:1050.5Pluto, Charon, Nix & Hydra 253
2015 Jun 02 01:1050.5Pluto, Charon, Nix & Hydrayes1011
2015 Jun 03 05:4549.2Pluto, Charon, Nix & Hydra 983
2015 Jun 03 05:0049.1Pluto, Charon, Nix & Hydrayes246
2015 Jun 03 18:5048.5Pluto, Charon, Nix & Hydra 242
2015 Jun 03 18:5048.5Pluto, Charon, Nix & Hydrayes970
2015 Jun 05 05:5046.7Pluto, Charon, Nix & Hydra 234
2015 Jun 05 05:5046.7Pluto, Charon, Nix & Hydrayes935
2015 Jun 06 01:1545.8Pluto, Charon, Nix & Hydra 229
2015 Jun 06 01:1545.8Pluto, Charon, Nix & Hydrayes916
2015 Jun 07 05:1544.4Pluto, Charon, Nix & Hydra 222
2015 Jun 07 05:1544.4Pluto, Charon, Nix & Hydrayes888
2015 Jun 08 01:1043.4Pluto, Charon, Nix & Hydra 217
2015 Jun 08 01:1043.4Pluto, Charon, Nix & Hydrayes868
2015 Jun 09 05:0042.0Pluto, Charon, Nix & Hydra 210
2015 Jun 09 05:0042.0Pluto, Charon, Nix & Hydrayes840
2015 Jun 10 01:0041.0Pluto, Charon, Nix & Hydra 205
2015 Jun 10 01:0041.0Pluto, Charon, Nix & Hydrayes821
2015 Jun 11 05:0039.6Pluto, Charon, Nix & Hydra 198
2015 Jun 11 05:0039.6Pluto, Charon, Nix & Hydrayes793
2015 Jun 12 01:0038.6Pluto, Charon, Nix & Hydra 193
2015 Jun 12 01:0038.6Pluto, Charon, Nix & Hydrayes773
2015 Jun 13 05:0037.3Pluto, Charon, Nix & Hydra 186
2015 Jun 13 05:0037.3Pluto, Charon, Nix & Hydrayes745
2015 Jun 13 16:2036.7Pluto, Charon, Nix & Hydra 183
2015 Jun 13 16:2036.7Pluto, Charon, Nix & Hydrayes734
2015 Jun 15 05:2934.9Pluto, Charon, Nix & Hydra 174
2015 Jun 15 05:2934.9Pluto, Charon, Nix & Hydrayes697
2015 Jun 16 00:5933.9Pluto, Charon, Nix & Hydra 169
2015 Jun 16 00:5933.9Pluto, Charon, Nix & Hydrayes678
2015 Jun 17 05:1332.5Pluto, Charon, Nix & Hydra 162
2015 Jun 17 05:1332.5Pluto, Charon, Nix & Hydrayes650
2015 Jun 18 00:3631.5Pluto, Charon, Nix & Hydra 158
2015 Jun 18 00:3631.5Pluto, Charon, Nix & Hydrayes630
2015 Jun 19 05:0530.1Hydra, Image Pluto & Charon 151
2015 Jun 19 05:0530.1Hydra, Image Nixyes601
2015 Jun 20 00:2829.1Pluto & Charon, Image Hydra 146
2015 Jun 20 00:2829.1Hydra, Image Nixyes582
2015 Jun 21 04:5727.7Hydra, Image Pluto & Charon 139
2015 Jun 21 04:5727.7Hydra, Image Nixyes554
2015 Jun 22 00:2026.8Pluto & Charon, Image Hydra 134
2015 Jun 22 00:2026.7Hydra, Image Nixyes535
2015 Jun 23 04:4925.4Hydra, Image Pluto & Charon 127
2015 Jun 23 04:4925.3Hydra, Image Nixyes507
2015 Jun 23 23:3424.4Pluto & Charon 122
2015 Jun 23 23:4024.4Hydra 122
2015 Jun 25 05:3722.9Hydra 115
2015 Jun 25 05:4322.9Pluto & Charon 115
2015 Jun 25 23:2322.1Pluto & Charon 110
2015 Jun 25 23:2922.0Hydra 110
2015 Jun 27 05:3220.6Hydra 103
2015 Jun 27 05:3820.6Pluto & Charon 103
2015 Jun 27 23:1419.7Pluto & Charon 98.4
2015 Jun 27 23:2019.7Hydra 98.4
2015 Jun 29 04:5618.2Hydra 91.1
2015 Jun 29 05:0218.2Pluto & Charon 91.0
2015 Jun 29 23:0417.3Pluto & Charon 86.5
2015 Jun 29 23:1017.3Hydra 86.6
2015 Jul 01 04:1115.9Hydra 79.5
2015 Jul 01 04:1715.9Pluto & Charon 79.3
2015 Jul 01 22:4715.0Nix 74.9
2015 Jul 01 22:5314.9Pluto & Charon 74.7
2015 Jul 01 22:5915.0Hydra 74.8
2015 Jul 03 04:3813.5Hydra 67.5
2015 Jul 03 04:4513.5Pluto & Charon 67.3
2015 Jul 03 22:1512.6Nix 63.0
2015 Jul 03 23:2512.5Pluto & Charon 62.6
2015 Jul 03 23:3012.6Hydra 62.8
2015 Jul 05 03:0411.2Nix 55.8
2015 Jul 05 04:3311.1Hydra 55.6
2015 Jul 05 04:3711.1Pluto & Charon 55.4
2015 Jul 05 22:2710.2Pluto & Charon 50.9
2015 Jul 05 22:3210.2Hydra 51.2
2015 Jul 06 08:369.69Nix 48.4
2015 Jul 07 04:188.70Nix 43.5
2015 Jul 07 04:288.75Hydra 43.7
2015 Jul 07 04:338.69Pluto & Charon 43.5
2015 Jul 07 22:367.85Hydra 39.2
2015 Jul 07 22:417.79Pluto 39.0
2015 Jul 07 22:467.80Charon 39.0
2015 Jul 09 04:136.37Hydra 31.9
2015 Jul 09 04:186.33Pluto 31.6
2015 Jul 09 04:236.32Charon 31.6
2015 Jul 09 22:205.41Nix 27.0
2015 Jul 09 22:275.47Hydra 27.3
2015 Jul 09 22:325.42Pluto 27.1
2015 Jul 09 22:375.41Charon 27.0
2015 Jul 11 02:463.99Nix 19.9
2015 Jul 11 04:013.99Hydra 20.0
2015 Jul 11 04:053.96Pluto 19.8
2015 Jul 11 04:103.94Charon 19.7
2015 Jul 11 22:223.05Pluto 15.2
2015 Jul 11 22:283.04Charon 15.2
2015 Jul 12 08:452.53Pluto 12.7
2015 Jul 12 08:502.53Charon 12.6

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