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Decoding Mars Images
Decoding Mars Images
10 Mar 2004
(Source: Jet Propulsion Laboratory)

How To Decode The MER Image Filenames

File name code

Below is a chart that will help you decode the 27 character file names associated with the Mars Exploration Rover mission. There is enough info below to allow you to make stereograms and construct color pictures and determine when and where the raw images were taken. Enjoy!

Character Function

1 Spacecraft ID
1 = Opportunity
2 = Spirit

2 Camera
F = Forward HAZCAM
M = Microscopic Imager
E - EDLcam (Descent Imager)

3 to 11 Spacecraft clock
This is the number of seconds since January 1, 2000
at 11:58:55.816 UTC.

12 to 14 Product type
Product types are differentiated as having camera-induced distortion removed (geometrically "linearized") or not removed (nominal), and, as being thumbnail-sized or not. Four special flag characters follow:

a) Beginning E - Type of EDR, which are raw with no camera model linearization or radiometric correction. If no beginning E, then it is a Reduced Data Record (RDR).
b) Ending T - EDR or RDR that is Thumbnail -sized.
c) Ending L - If no beginning E , denotes an RDR that is Linearized, except for Thumbnail sized RDRs.
d) Ending N - If no beginning E , denotes an RDR that is ThumbNail-sized and Linearized .

Valid values for MER camera instrument input data products:
Data Product Identifier

full frame EDR EFF Sub-frame EDR ESF
Downsampled EDR EDN
Thumbnail EDR ETH
Row Summed EDR ERS
Column Summed EDR ECS
Reference Pixels EDR ERP
Histogram EDR EHG

15 to 16 Site number
Site location count (indicates rover's location).
Valid values: 00, 01, 02,...99, A0, A1,..., A9, AA, AB...etc.

17 to 18 Drive number
Position-within-Site count (indicates rover's position within site)
Valid values: 00, 01, 02,...99, A0, A1,..., A9, AA, AB...etc.

19 to 23 Command sequence number (one letter, 4 numbers)
Denotes a group of images that were all obtained within a single command sequence.

Valid values for character (position 1) in field:
C - Cruise
E - Engineering
F - Flight Software (Seq rejected)
G - (spare)
K - (spare)
M - Master (Surface only)
N - In-Situ instr. (APXS, MB, MI)
P - PMA & Remote Sensing instr. (Pancam, Navcam, Hazcam, MI, Mini-TES)
R - Rover Driving
S - Submaster
T - Test
W - Seq triggered by a Communications Window
X - Contingency
Y - (spare)
Z - SCM Seqs

Valid values for integers (positions 2 thru 5) in field:

0000 thru 4095 - Valid Sequence number, commanded by Ground

If P in character position 1:
0000 through 0499 - Misc. imaging setup/parm sequences
0500 through 0999 - Unallocated, for possible future use
1000 through 1499 - Hazcam sequences
1500 through 1999 - Navcam sequences
2000 through 2899 - Pancam sequences
2900 through 2999 - MI sequences
3000 through 3999 - Mini-TES sequences
4000 through 4095 - Misc. PMA actuation sequences (deploy, etc.)

24 Camera eye
R = Right
L = Left
M - Monoscopic (non-stereo camera)
N - Not Applicable

25 Camera Filter (PANCAM only, 0 otherwise)
1 = EMPTY (clear) 1 = 436nm (37nm Short-pass)
2 = 753nm (20nm bandpass) 2 = 754nm (20nm bandpass)
3 = 673nm (16nm bandpass) 3 = 803nm (20nm bandpass)
4 = 601nm (17nm bandpass) 4 = 864nm (17nm bandpass)
5 = 535nm (20nm bandpass) 5 = 904nm (26nm bandpass)
6 = 482nm (25nm bandpass) 6 = 934nm (25nm bandpass)
7 = 432nm (32nm Short-pass) 7 = 1009nm (38nm Long-pass)
8 = 440nm (20) Solar ND 5.0 8 = 880nm (20) Solar ND 5.0
See Filter Wheels on Pancam

Microscopic Imager "Filter" positions:

1. MI window/cover closed (500-700 nm response)
2. MI window/cover open (400-700 nm response)
26 Product producer
A - Arizona State University
C - Cornell University
F - USGS at Flagstaff
J - Johannes Gutenberg Univ. (Germany)
N - NASA Ames Research (L. Edwards)
P - Max Plank Institute (Germany)
U - University of Arizona
V - SSV Team (E. De Jong) at JPL
X - Other

27 Product version number
Version identifier providing uniqueness for book keeping.

Valid values: 1, 2, 3, ... 9, A, B, ... Z


A photo with the file name
2P126471340EDN0000P2303L5M1.JPG would be from Spirit (2), taken by the left PANCAM through the 535nm (green) filter. By matching the spacecraft times (in this case 126471340) with other pictures that have a similar time, you can find sets that were taken at the same time of the day. Use similar sets to build stereograms and color composites. This picture was downsampled (EDN) at site 0 (00) and position 0 (00) (On the lander in this case!) It was taken with command sequence P2303 for MIPL (OPGS) at JPL and is version 1.

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Last Updated: 12 Mar 2004