KPL/IK MARCI Instrument kernel =========================================================================== This instrument kernel (I-kernel) contains the Mars Surveyor Color Imager (MARCI) instrument mounting alignment, optics and detector parameters. Version and Date --------------------------------------------------------------------------- Version 1.0 -- August 5, 1999 -- Boris Semenov, NAIF/JPL Initial Release. References --------------------------------------------------------------------------- 1. ``IDC for MARCI'', MSP-96-1006, Revision B, September 8, 1998 2. ``MSPSAL009SS Spreadsheet: Final MARCI Summary Sheet'', September 29, 1998 3. ``C-kernel Required Reading'' 4. ``Kernel Pool Required Reading'' 5. "Mars Surveyor '98 Orbiter Color Imager (MARCI)", Complete Proposal, MSSS MCO Web pages; July 1999. 6. MARCI Fact Sheet, JPL MCO Web pages; July 1999. Implementation Notes -------------------------------------------------------- User programs that need I-kernel data must `load' the I-kernel file, normally during program initialization. Loading the kernel using SPICELIB routine LDPOOL causes the data items and their associated values present in the kernel to become associated with a data structure called the ``kernel pool''. Then a user's program can obtain the value(s) for any data item using the SPICELIB routines GDPOOL, GIPOOL and GCPOOL. See [4] for details. This file was created and can be updated with a text editor or word processor. Naming Conventions -------------------------------------------------------- All names referencing values in this I-kernel start with the characters `INS' followed by the NAIF MCO spacecraft ID number (-127) followed by the NAIF three digit MARCI MAC instrument reference number (030) or MARCI WAC instrument reference number (031). The remainder of the name is an underscore character followed by the unique name of the data item. For example, the focal length of the MARCI MAC camera is specified by INS-127030_FOCAL_LENGTH The upper bound on the length of the name of any data item is 32 characters. If the same item is included in more then one file, or if the same item appears more than once within a single file, the latest value supersedes any earlier values. MARCI Overview -------------------------------------------------------- From [6]: "MARCI combines Wide Angle (WA) and Medium Angle (MA) cameras with individual optics but identical focal plane assemblies, data acquisition system electronics, and power supplies. Each camera is small in size ( 6 x 6 x 12 cm, including baffle) and mass (combined mass 2 kg). Both cameras operate in a "pushframe" mode, with their CCD detectors overlaid with spectral ("color") filter strips. The cameras are electronically shuttered at intervals timed so that the spacecraft motion spatially overlaps each filter strip view, thereby providing a "color" composite. The MARCI Principal Investigator is Dr. Michael Malin (Malin Space Science Systems, San Diego). Near the end of the Orbiter's cruise phase, MARCI acquires approach images of Mars. Once in the mapping orbit, MARCI provides daily global images of the Mars atmosphere (and surface) with the WA camera and monitors surface changes with the MA camera during mission periods with high data rates. The WA camera has seven spectral bands [5 visible, 2 UV] and has spatial resolutions on the planet better than 7.2 km/pixel, for nominal orbital altitude and downlink data rates. Kilometer-scale resolutions are possible, when data rates permit. Limb observations detail the atmospheric structure of clouds and hazes at 4 km resolution. The MA camera has a 6_ FOV covering 40 km at 40 m/pixel (nadir) and accessing all positions of the planet (except the rotational poles due to the slight inclination of the spacecraft orbit). Ten spectral channels from 425 to 1000 nm provide the ability to discriminate both atmospheric and surface features on the basis of composition." MARCI Mounting Alignments -------------------------------------------------------- This section describes the offset of the MARCI MAC and WAC camera fixed frame (defined below) relative to the MCO spacecraft frame. Nominal MARCI Frames Orientation --------------------------------------- The MARCI camera fixed frame is defined the same way for both cameras: * +Z is along the boresight vector, * +X is along camera detector (image) lines and points the direction of increasing samples; * +Y complements to the right hand frame and is along camera detector (image) columns points in the direction of increasing lines. * the origin of the frame is at the camera focal point; Nominal orientation of the MARCI camera frames axes relative to the MCO S/C frame is shown on the diagram below: MCO S/C Frame: +Zsc | +Xs | _- | _- | _- ________|- +Ysc MARCI MAC and \ +Zmarci WAC frames: \ (boresight) -_ \ +Xmarci -_ \ -_\ _- _- _- _- +Ymarci This orientation can be achieved by two rotations (see [1]) -- first about +X axis of the S/C frame by -5 degreees: +Z' ^ +Zsc \ | \ | \<-* -5 degrees \ | +Ysc \| <--------_x +Xsc (+X') _- (into page) _- _- +Y' and second rotation by -10 degrees about new position of the Y axis: +Z'' ^+Z' \ | \ | _- X'' -10 \<-| _- degrees \ | _- \|_- x---------> +Y'(+Y'') +X' (into page) plus an additional rotation by +90 degrees about +Z; the third rotation makes camera +X axis parallel to the detector (image) lines: ^ X'' | | |-. | \ +90 degrees | v +Zmarci(+Z'') x---------> (into page) | +Xmarci(+Y'') | | | | V +Ymarci From these rotations which can be treated as Euler angles, a rotation matrix can be constructed that will transform the components of a vector expressed in the spacecraft frame to components expressed in the MARCI MAC or WAC camera fixed frame: [ X ] [ ] [ ] [ ] [ x ] | Y | = [ 90.0 ] [-10.0] [-5.0 ] | y | [ Z ] [ ] [ ] [ ] [ z ] MARCI Z Y X S/C Actual MARCI Camera Frame Orientation ------------------------------------- Actual MARCI camera frames orientation was measured during multiple metrology sessions during S/C assembly and testing at LMA facilities in Denver. The following adjusted values for three rotation angles described above were specified in [2]: MAC: first rotation (about X): -5.0 degrees (nominal value) second rotation (about Y): -10.0 degrees (nominal value) third rotation (about Z): 90.0 degrees (nominal value) WAC: first rotation (about X): -5.0 degrees (nominal value) second rotation (about Y): -10.0 degrees (nominal value) third rotation (about Z): 90.0 degrees (nominal value) I-Kernel variables below store these values in radians: INS-127030_EULER_ANGLES = ( -0.0872664626 -0.1745329252 1.5707963268 ) INS-127030_EULER_AXES = ( 1 2 3 ) INS-127031_EULER_ANGLES = ( -0.0872664626 -0.1745329252 1.5707963268 ) INS-127031_EULER_AXES = ( 1 2 3 ) Note that the keywords above are NOT enclosed between \begindata -- \begintext tokens and, therefore, they are NOT available to SPICE System toolkit. This is done to encourage use of the SPICE Frames subsystem that provides a more flexible interface to instrument mounting alignment information. Refer to the latest MCO Frames Kernel file for details. MARCI Optics Parameters -------------------------------------------------------- The following MARCI MAC and WAC first order optical parameters are included in the data section below (provided in [5]): ----------------------------------------------------------------- parameter MAC WAC ----------------------------------------------------------------- Focal Length, mm 87.9 4.3 f/ratio f/2 f/5 (*) FOV Angular Size, deg 6 140 IFOV, mrad/pixel 0.102 2.4 Radial distortion coeff. (?) (?) ----------------------------------------------------------------- (*) the f/ratio for WAC short UV optics is f/6; The values in the keywords are given in the same units as in the table above except for angles which are given in radians. \begindata INS-127030_FOCAL_LENGTH = ( 87.9 ) INS-127030_F/RATIO = ( 43.95 ) INS-127030_FOV_ANGULAR_SIZE = ( 0.10471976, 0.10471976 ) INS-127030_IFOV = ( 0.000102, 0.000102 ) INS-127030_ALPHA0 = ( 0.0 ) INS-127031_FOCAL_LENGTH = ( 4.3 ) INS-127031_F/RATIO = ( 0.86 ) INS-127031_FOV_ANGULAR_SIZE = ( 2.44346095, 2.44346095 ) INS-127031_IFOV = ( 0.0024, 0.0024 ) INS-127031_ALPHA0 = ( 0.0 ) \begintext MARCI Detector Parameters -------------------------------------------------------- The following MARCI MAC and WAC detector geometry parameters are included in the data section below (provided in [5]): ----------------------------------------------------------------- parameter MAC WAC ----------------------------------------------------------------- Pixel size, mm 0.009 0.009 Number of pixels/mm 111.1111111 111.1111111 Detector Size (physical) 1024 x 1024 1024 x 1024 Detector Array Center 511.5, 511.5 511.5, 511.5 Detector Size (proactive) 1018 x 1008 1018 x 1008 Detector Array Center 508.5, 503.5 508.5, 503.5 ----------------------------------------------------------------- The values in the keywords are given in the same units as in the table above. \begindata INS-127030_PIXEL_SIZE = ( 0.009 ) INS-127030_K = ( 111.11111111 ) INS-127030_PIXEL_SAMPLES = ( 1024 ) INS-127030_PIXEL_LINES = ( 1024 ) INS-127030_CENTER = ( 511.5, 511.5 ) INS-127031_PIXEL_SIZE = ( 0.009 ) INS-127031_K = ( 111.11111111 ) INS-127031_PIXEL_SAMPLES = ( 1024 ) INS-127031_PIXEL_LINES = ( 1024 ) INS-127031_CENTER = ( 511.5, 511.5 ) \begintext Relationship Between Filters and Detector Areas --------------------------------------------------------------------------- From [5]: "Each MARCI subsystem uses a filter plate mounted directly over the area-array detector on the focal plane. On each plate are multiple narrowband filter strips, each covering the entire cross-track width of the detector but only a fraction of the along-track portion of the detector. To acquire complete multi-color coverage, consecutive images are taken each time the instrument footprint has advanced by one filter's size in the downtrack direction. Band selection is accomplished by selectively reading out only part of the resulting frame for transmission to the spacecraft computer. This approach can be called "push-frame" or "frame-scan." Owing to the desire to minimize misregistration effects from along-track optical distortion, the WA system uses only the center-most portion of the detector. The filter bands are only about 20 pixels in along-track dimension, and together cover only 100 pixels. These pixels are read out every 5.5 seconds during mapping. The image acquired on the remaining area of the detector is nominally discarded. However, it can be used for approach or transition orbit observations, or for special observations of the fore and aft limbs (as might be desired for coordinated PMIRR observations). Table 4 lists the bandpasses and bandwidths for both cameras. Table 4: MARCI Filter Description WA Filter ID WA Bandpass MA Filter ID/ center and Bandpass center & half-width half-width UV1 250 ± 25 nm 425 ± 25 nm UV2 330 ± 25 nm 500 ± 25 nm BLU 425 ± 25 nm 550 ± 25 nm RED 600 ± 25 nm 650 ± 25 nm NIR 750 ± 25 nm 750 ± 25 nm 860 ± 25 nm 900 ± 25 nm 930 ± 25 nm 950 ± 25 nm 975* *Bandpass on-set Since the chosen detector has little response in the UV, the detector side of the filter plate will be coated with UV-fluorescent material (e.g., Lumogen(r) ). The Medium Resolution camera uses 10 "strips" each about 100 pixels in along-track extent. The entire detector is read out every 1.2 seconds. Table 4 lists the ten bandpasses and bandwidths." Assuming that WAC filter plate is ideally centered with respect to the optics and detector and that each filter covers exactly 20 pixels, the following detector areas will be illuminated through the filters: WAC Filter ID First line Last line ------------- ---------- --------- UV1 462 481 UV2 482 501 BLU 502 521 RED 522 541 NIR 542 561 Assuming that MAC filter plate is ideally centered with respect to the optics and detector and that each filter covers exactly 102 pixels, the following detector areas will be illuminated through the filters: MAC Filter ID First line Last line ------------- ---------- --------- 425 3 104 500 105 206 550 207 308 650 309 410 750 411 512 860 513 614 900 615 716 930 717 818 950 819 920 975 921 1022 Set of keywords below contains start and stop line numbers for each detector/filter pair. \begindata INS-127030_425_LINES = ( 1, 104 ) INS-127030_500_LINES = ( 105, 206 ) INS-127030_550_LINES = ( 207, 308 ) INS-127030_650_LINES = ( 309, 410 ) INS-127030_750_LINES = ( 411, 512 ) INS-127030_860_LINES = ( 513, 614 ) INS-127030_900_LINES = ( 615, 716 ) INS-127030_930_LINES = ( 717, 818 ) INS-127030_950_LINES = ( 819, 920 ) INS-127030_975_LINES = ( 921, 1024 ) INS-127031_UV1_LINES = ( 462, 481 ) INS-127031_UV2_LINES = ( 482, 501 ) INS-127031_BLU_LINES = ( 502, 521 ) INS-127031_RED_LINES = ( 522, 541 ) INS-127031_NIR_LINES = ( 542, 561 ) \begintext Platform ID --------------------------------------------------------------------------- This number is the NAIF instrument ID of the platform on which the cameras are mounted. \begindata INS-127030_PLATFORM_ID = ( -127000 ) INS-127031_PLATFORM_ID = ( -127000 ) \begintext