posted on Jan, 20 2004 @ 01:43 AM
First off, thank you Kano for such an excellent article on the complicated issue of color pictures on Mars. The least I can do is answer some of your
The little silver pole is the low-gain antenna. It is used for low data rate communication, a few hundred bits per second, directly with Earth using
X-band frequencies (around 8 GHz). It works over a wide range of angles, and so doesn't have to be pointed like the high-gain dish antenna. We use
the low-gain antenna to send commands to the rover at low rates, around 30 bits per second, when the rover is awake but not using the high-gain to
send data to us at the time. The low-gain is also a backup in case the high-gain pointing isn't working for some reason. We can work through the
low-gain to fix it.
Now the secret decoder ring for the image file names. Taking one example file name from your article:
The breakdown is:
"2" for Spirit. "1" is Opportunity. (Don't ask.)
"P" is Pancam. Other choices are N - navcam, F - front hazcam, R - rear hazcam, M - microscopic imager, and E - EDL camera.
The next nine digits are the time the image was taken in seconds since noon UTC on January 1st, 2000.
The "ESF" is the product identifier, meaning a raw sub-framed image. There are many three-letter identifiers. Some common ones: EFF - raw full
frame, FFL - full frame linearized, SFL - sub-frame linearized, EDN - downsampled raw image, DNL - linearized down-sampled, ETH - raw thumbnail, THN -
thumbnail linearized (doesn't quite follow the convention). Linearized means that geometric optical distortions have been corrected. There are
others for various levels of processing of the images.
"0200" is site 2 and position 0. We increment those counters when driving. Position is automatically incremented for each piece of a drive. We
decide when we want to declare a new "site" to help distinguish the images.
"P2095" is the identifier of the command sequence that produced the image. This makes it easy, for example, for the person who wrote the sequence
to find the images that were taken by their sequence.
"L" is the left eye. It can also be R - right, B - both, M - microscopic, or N - not an image.
"2" is the filter position, in the range 0..8 where 0 is no filter or not applicable.
"M" is the product creator, in this case the MIPL automatic image processing that is part of the MER downlink system. Other choices are A - Arizona
State University, C - Cornell, F - USGS at Flagstaff, J - Johannes Gutenburg University, N - NASA Ames, P - Max Planck Institute, S - science
operations team at JPL, U - University of Arizona, V - visualization team at JPL, or X - other.
"1" is the version identifier.
Dr. Mark Adler
Spirit Mission Manager