KPL/IK VMC Instrument kernel =========================================================================== This instrument kernel (I-kernel) contains Mars Express Visual Monitoring Camera (VMC) optics, detector, and field-of-view parameters. Version and Date --------------------------------------------------------------------------- Version 0.4 -- April 20, 2021 -- Ricardo Valles Blanco, ESAC/ESA Alfredo Escalante Lopez, ESAC/ESA Corrected typos and updated contact information for Mars Express PDS3 V2.0 release. Corrected field-of-view definition. Version 0.3 -- April 5, 2020 -- Marc Costa Sitja ESAC/ESA Corrected field-of-view definitions and optical parameters. Updated Overview section. Version 0.2 -- January 15, 2019 -- Marc Costa Sitja ESAC/ESA Updated VMC IDs. Version 0.1 -- January 24, 2008 -- J. Diaz del Rio, MIG/ESA VMC camera details incorporated as described in the Flight User manual. Version 0.0 -- January 22, 2008 -- J. Vazquez, MIG/ESA Initial Release. References --------------------------------------------------------------------------- 1. ``Kernel Pool Required Reading''. 2. ``C-kernel Required Reading''. 3. Mars Express Frames Definition Kernel (FK), latest version. 4. ``VMC for MEX. Flight User Manual'', MEX-ESA-VMC-MA-0003, Issue 4, Revision 2, January 17, 2003. 5. ``Comments and questions on issues with VMC navigation'' as provided by Jorge Hernandez Bernal in an E-Mail communication ``VMC navigation issues. Mars DEM.'' on 13 October 2019. 6. ``VMC to Planetary Science Archive Interface Control Document (EAICD)'', DIAS ALMEIDA DATA PROCESSING AND SYSTEMS, Issue 1, Revision 1, January 2019. Contact Information --------------------------------------------------------------------------- If you have any questions regarding this file contact the ESA SPICE Service at ESAC: Alfredo Escalante Lopez (+34) 91-8131-429 spice@sciops.esa.int, or NAIF at JPL: Boris Semenov (818) 354-8136 Boris.Semenov@jpl.nasa.gov Implementation Notes -------------------------------------------------------- Applications that need SPICE I-kernel data must ``load'' the I-kernel file, normally during program initialization. Loading the kernel using the SPICELIB (CSPICE, ICY)routine FURNSH (furnsh_c, cspice_furnsh) causes the data items and their associated values present in the kernel to become associated with a data structure called the ``kernel pool''. The application program may then obtain the value(s) for any IK data item using the SPICELIB (CSPICE, ICY) routines GDPOOL (gdpool_c, cspice_gdpool), GIPOOL (gipool_c, cspice_gipool), GCPOOL (gcpool_c, cspice_gcpool). Routine GETFOV (getfov_c, cspice_getfov) may be used if the file contains instrument field-of-view (FOV) specification. See [1] for details. This file was created with, and can be updated with a text editor or word processor. Conventions for Specifying Data -------------------------------------------------------- Data items are specified using ``keyword=value'' assignments [1]. All keywords referencing values in this I-kernel start with the characters `INS' followed by the NAIF MEX instrument ID code, constructed using the spacecraft ID number (-41) followed by the NAIF three digit ID number for VMC camera (700): Instrument name ID -------------------- ------ MEX_VMC -41701 The remainder of the keyword is an underscore character followed by the unique name of the data item. For example, the focal length of the VMC camera is specified by INS-41701_FOCAL_LENGTH The upper bound on the length of all keywords is 32 characters. If a keyword is included in more then one file, or if the same keyword appears more than once within a single file, the last assignment supersedes any earlier assignments. Overview -------------------------------------------------------- The Visual Monitoring Camera (VMC) is a stand-alone digital camera installed on board the Mars Express spacecraft in order to take snapshots in colour of the Mars Lander, ``Beagle-2'', during separation, and of Mars later for Public Relations purposes. However in 2007, engineers from the Mars Express Flight Control Team started to use it for educational purposes. Since the VMC images are quite small in data volume, it was possible to acquire some images without impacting the rest of the Mars Express Payload. Finally in 2016 it was understood that there was scientific value for the VMC data, and the camera became a Scientific Experiment of Mars Express. The main data applications that are envisaged are as following: - Cloud Monitoring - Winds and Dynamical Phenomena - High Clouds at Terminator - Synergies with other payload on Mars Express The VMC accepts image capture and exposure control commands, performs image acquisition, and can store in the baseline configuration in a local memory buffer to facilitate asynchronous readout at a low data rate. The camera is located in the science deck (S/C +Z panel) and looks along the S/C +Z axis with an inclination of 19 degrees towards the S/C +Y axis [4], through an aperture in the upper panel. Mounting Alignment -------------------------------------------------------- Refer to the latest version of the Mars Express Frames Definition Kernel (FK) [3] for the VMC reference frame definitions and mounting alignment information. Detector Layout -------------------------------------------------------- The VMC camera comprises a single square CCD detector. The view directions of the corners and the axes of the MEX_VMC frame projected onto the Mars surface look like this: ^ +Xvmc (along-track) | | +--------------|-------------+ | | | -------> | | | direction of | | | flight 480 | | | (S/C +Y axis) lines | x-----------------> | +Zvmc | +Yvmc | boresight | (cross-track) | (into page) | | | (1,1)--------------------------+ Pixel 640 pixels/line Optical Parameters -------------------------------------------------------- The following VMC camera optical parameters are included in the data section below. These values were originally taken from [4] and have been updated with [5]: -------------------------------------------------- parameter VMC -------------------------------------------------- Focal Length, mm 12.3 f/ratio f/5.0 IFOV, rad/pixel 0.0011286 Field of view (rad) Cross-track 0.5417249 Along-track 0.7222999 -------------------------------------------------- Angular size values in the keywords are given in radians, with the cross-track size being the first value and the along-track size being the second value in each pair. \begindata INS-41701_FOCAL_LENGTH = ( 12.3 ) INS-41701_F/RATIO = ( 5.0 ) INS-41701_FOV_ANGULAR_SIZE = ( 0.5288348, 0.6928957 ) INS-41701_IFOV = ( 0.00108264955 ) \begintext Detector CCD Parameters -------------------------------------------------------- The VMC CCD detector geometry parameters are included in the data section below, taken from [4]: --------------------------------------------- parameter VMC --------------------------------------------- Pixel Size, microns Cross-track 14 Along-track 14 Detector Array Size Cross-track 480 Along-track 640 Detector Array Center Cross-track 240.5 Along-track 320.5 --------------------------------------------- The values are given in microns for PIXEL_SIZE keywords and in counts for PIXEL_SAMPLES, PIXEL_LINES, and CENTER keywords. \begindata INS-41701_PIXEL_SIZE = ( 14.0, 14.0 ) INS-41701_PIXEL_SAMPLES = ( 640 ) INS-41701_PIXEL_LINES = ( 480 ) INS-41701_CCD_CENTER = ( 240.5, 320.5 ) \begintext Wavelength Ranges --------------------------------------------------------------------------- This section contains assignments specifying VMC detector wavelength ranges. The Modulation Transfer Function (MTF) calculations performed at different field values within the FOV of the camera resolved the wavelength to be in the range between 400 and 800 nm.The wavelength range can be split into color and black/white as follows: --------------------------------------------- parameter VMC --------------------------------------------- General, nanometers Band Centre 600 Bandwidth 400 Colour, nanometers Band Centre 525 Bandwidth 250 Black/White, nanometers Band Centre 655 Bandwidth 170 --------------------------------------------- The set of assignments below specifies wavelength center and bandwidths for the general, the color and black/white ranges, with the same units as in the table above. \begindata INS-41701_BANDCENTER = ( 600.0 ) INS-41701_BANDWIDTH = ( 400.0 ) INS-41701_BANDCENTER_C = ( 525.0 ) INS-41701_BANDWIDTH_C = ( 250.0 ) INS-41701_BANDCENTER_BW = ( 655.0 ) INS-41701_BANDWIDTH_BW = ( 170.0 ) \begintext FOV Definitions --------------------------------------------------------------------------- This section contains definitions for the VMC camera FOV. These definitions are provided in a format consistent required by the SPICE (CSPICE, ICY) function GETFOV (getfov_c, cspice_getfov). The set of assignments in the data section below defines the VMC FOV with respect to the MEX_VMC frame to be a rectangle with the corners defined by the first and last pixels of the first and last lines of the CCD and the boresight along the +Z axis of the MEX_VMC frame. This FOV definition uses angular extent style specification with the cross and along track angular sizes taken from the ``Optics Parameters'' section above. The reference vector has been selected such the boundary vector returned from the function GETFOV (getfov_c, cspice_getfov) corresponds to pixel (1,1) as described in the ``Detector Layout'' section above. The following vectors returned from the function correspond to the corner points of the detector layout counted clockwise from (1,1). \begindata INS-41701_FOV_FRAME = 'MEX_VMC' INS-41701_FOV_SHAPE = 'RECTANGLE' INS-41701_BORESIGHT = ( 0.0 0.0 1.0 ) INS-41701_FOV_CLASS_SPEC = 'ANGLES' INS-41701_FOV_REF_VECTOR = ( -1.0 0.0 0.0 ) INS-41701_FOV_REF_ANGLE = ( 15.15 ) INS-41701_FOV_CROSS_ANGLE = ( 19.85 ) INS-41701_FOV_ANGLE_UNITS = 'DEGREES' \begintext Optical Distortion -------------------------------------------------------- This section provides optical distortion and geometric calibration data for VMC camera, as described in [4], and presented in the following table: --------------------------------------------- parameter VMC --------------------------------------------- Distortion, percentage 0.4 Field Curvature, mm 0.22 --------------------------------------------- \begindata INS-41701_DISTORTION_PERCENT = ( 0.4 ) INS-41701_FIELD_CURVATURE = ( 0.22 ) \begintext End of IK file.