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PHOBOS 2 MARS TERMOSCAN THERMAL/VISIBLE IMAGING EDR V1.0 (PDS)

NSSDCA ID: PSSB-00371

Availability: Archived at NSSDC, accessible from elsewhere

Description

This description was generated automatically using input from the Planetary Data System. These data are saved for historical reasons; they are not considered to be of archival quality. The 'edited data' referenced here are in the PDS data set PHB2-M-TS-2-EDITED-THRM/VIS-IMG-EDR-V1.0.

Data Set Overview ================= In February and March, 1989, the Termoskan instrument on board the Phobos '88 spacecraft of the USSR acquired a limited set of very high resolution simultaneous observations of the reflected solar flux (hereafter referred to as the visible channel) and emitted thermal flux (thermal infrared (IR)) from Mars's equatorial region. These are, so far, the highest spatial resolution thermal data ever obtained for Mars. Four slightly overlapping thermal panoramas (also called scans or swaths) cover a large portion of the equatorial region from 30 deg.S to 6 deg.N latitude. Simultaneous visible panoramas were taken during each of the four observing sessions; due to spacecraft memory limitations, visible channel processing was stopped early relative to the thermal channel for 2 of the sessions (2 and 4). Thus, the visible channel panoramas are shorter than the thermal panoramas for these sessions. The instrument was fixed to the spacecraft with the optical axis pointing in the anti-solar direction. As a consequence, all observations are at approximately zero degrees phase angle and only daytime observations were acquired. Scan lines were acquired approximately going from North to South on the planet at a rate of 1 line per second. In the first session (taken Feb 11, 1989), the periapse altitude of the spacecraft's elliptical orbit was 1150 km and the resolution at nadir was approximately 300 m per pixel. The thermal and visible channel panoramas from this session exhibit longitudinal gaps of varying size between scan lines. Within each scan line (acquired in the North-South direction), however, full resolution and coverage were maintained. In the remaining three sessions (one taken on March 1, 1989 and two on March 26, 1989), the panoramas were acquired from a circular orbit of altitude 6300 km with a resolution at nadir of approximately 1.8 km per pixel. In these panoramas, line and frame scanning correspond; therefore, there are not significant gaps between scan lines and geometrical distortions primarily occur only because of the sphericity of the planet.

Each image consists of 384 samples. The number of lines varies depending upon how long the instrument was on in any given panorama. The data is 8 bit data with dn values ranging from 0 to 255 for both the thermal and the visible channels. West is towards the top of each image file and North is to the right. All of the Termoskan data is contained in the 23 files of this data set. These files were delivered by the Institute of Space Devices Engineering (ISDE) (Moscow) to Caltech (Pasadena) in April, 1990 (except for session 1 which was delivered a few months earlier). The only difference between the files included here and those delivered from the Institute of Space Devices is that I have mirror flipped some of the files (resulting files all with the extension img: pan1irr1, pan1irr2, pan1vir1, pan1vir2, pan3irr1, pan3irr2, pan3irr3, pan3irr4, pan4vir1, and pan4vir2) as necessary. This was needed because some, but not all, of the image files were delivered from ISDE with the images appearing as Mars would appear if you saw it in a mirror.

Each of the thermal channel files in this data set has 512 samples because in addition to the 384 data pixels per line there are also 126 pixels on one side of the image used for temperature stripes - each stripe representing the dn level for an additional 10 K. The visible channel files each have 384 pixels (except for session 1 which has filler pixels to 512 samples).

Each of these files are fragments of larger panoramas. The pixels in the thermal channel files and visible channel files are not aligned (do not correspond to the same location on Mars) in this data set. See confidence level notes for more details and see the edited data set for complete panoramas that have been corrected so as to have the thermal data aligned geometrically with the visible channel data. No attempt has been made to validate or upgrade any labels that might be present, or to add labels where none existed. These data have not been reviewed. They are not considered to be of archival quality in their present state. These data are available on-line from the Planetary Data System (PDS) at: http://pdssbn.astro.umd.edu/holdings/phb2-m-ts-2-therm_vis-imgedr-v1.0/

Alternate Names

  • PHB2-M-TS-2-THERM/VIS-IMGEDR-V1.0

Discipline

  • Planetary Science: Small Bodies

Additional Information

Spacecraft

Experiments

Questions and comments about this data collection can be directed to: Dr. Edwin V. Bell, II

 

Personnel

NameRoleOriginal AffiliationE-mail
Dr. Yuri GektinGeneral ContactInstitut Kosmicheskich Issledovaniya (IKI)
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