KPL/IK Mars Polar Lander LIDAR Instrument Kernel. =============================================================================== This SPICE System Instrument Kernel (IK) file contains external and internal and FOV geometry characteristics for the Mars Polar Lander (MPL) Light Detection and Ranging (LIDAR) Instrument. Version and Date -------------------------------------------------------- Version 1.0, July 22, 1999, by Boris Semenov, NAIF/JPL Initial Release. References -------------------------------------------------------- 1. LIDAR ICD, Document MSP-96-1052, rev A, November 7, 1997. 2. JPL MPL WWW Server, July 1999. 3. ``Kernel Pool Required Reading'' 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 [3] 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 MPL spacecraft ID number (-116) followed by the NAIF three digit LIDAR instrument reference number (300). 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 instrument is specified by INS-116300_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. LIDAR Overview -------------------------------------------------------- From [2]: "The LIDAR [Light Detection and Ranging] is an upward viewing lidar mounted on the Lander deck. It consists of a sensor assembly, an electronics assembly, and the interconnecting cable assembly. The LIDAR is provided by the Space Research Institute (IKI) of the Russian Academy of Science, under the sponsorship of the Russian Space Agency (RSA). The Principal Investigator is S. Linkin. The LIDAR transmitter uses a pulsed GaAlAs laser diode which emits 400 nJ energy in 100 nsec pulses at a rate of 2.5 kHz and at 0.88 m wavelength. The LIDAR has two sounding modes. During active sounding, light pulses are emitted and their return timed in order to locate and characterize ice and dust hazes in the lowest few kilometers (< 2-3 km). An acoustic device [microphone] will also be included as part of the LIDAR assembly." LIDAR Location and Mounting Alignment -------------------------------------------------------- The following LIDAR nominal location information is provided in the Appendix A "LIDAR Mechanical Interface Drawing #902L1240120" of [1]: X = +235.76 +/- 2.54 mm Y = -365.00 +/- 2.54 mm Z = +799.31 +/- 2.54 mm The coordinates are provided for the LIDAR mounting reference point which is center of the mounting bolt hole located at the left corner of the sensor module side opposite to the electronics module 2 mounting side (as seen from above): ^ +X lnd | o | 365.00 | EM2 /'. |<----------------->| /'./ O '. | | / / O /o ------------------|----- './ /. / | | ^ / / / / | | | o/ / / / | | | '. '/ / | | | '. /<--->| 12 degrees | | 235.76 LIDAR Sensor 'o | | | Module | | | | | V x----------------> +Y lnd +Z lnd (into page) Given that the size of the LIDAR sensor unit is 70.0 x 80.0 x 131.0 mm (with corresponding XY plane mounting hole dimensions of 61.00 x 71.00 mm), the location of the LIDAR sensor unit geometric center is at: X = + 235.76 - (71.0/2)*cos(12) + (61.0/2)*sin(12) = 207.38 mm Y = - 365.00 - (71.0/2)*sin(12) - (61.0/2)*cos(12) = -402.21 mm Z = + 799.31 - (131.0/2) = 733.81 mm The keyword ``INS-116300_LOCATION'' contains coordinates in meters: INS-116300_LOCATION = ( 0.20738, -0.40221, 0.73381 ) Note that the keyword above is NOT enclosed between \begindata -- \begintext tokens and, therefore, it is NOT available to SPICE System toolkit. This is done to encourage use of the SPICE fixed offset SPK file that provides a more flexible interface to instrument location information. Refer to the latest MPL Structures SPK file comments for details. LIDAR Location and Mounting Alignment -------------------------------------------------------- As seen on the diagram above based on the "LIDAR Mechanical Interface Drawing" (see [1]) the LIDAR points up -- in the direction opposite to the lander +Z axis -- and is nominally rotated by 12 degrees counterclockwise about it. Then the following set of rotation angles defines orientation of the LIDAR frame: M = [ 0.0 ] [ -12.0 ] [ 180.0 ] Y Z X where M is a matrix rotating vectors from LANDER frame to LIDAR frame. In other words, nominally LANDER frame can be transformed to the LIDAR frame by two subsequent rotations, first of 180.0 degrees about X axis, second by -12.0 degrees about new position of Z axis. The keywords ``INS-116300_EULER_ANGLES'' and ``INS-116300_EULER_AXES'' contain the angle values and the indexes of the corresponding rotation axes ( 1 -- 'X', 2 -- 'Y', 3 -- 'Z'): INS-116300_EULER_ANGLES = ( 0.0, -12.0, 180.0 ) INS-116300_EULER_AXES = ( 2, 3, 1 ) 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 MPL Frames Kernel file for details. LIDAR FOV Geometry -------------------------------------------------------- The LIDAR FOV is described in [1] as "a 3 milliradian half cone angle for transmit and a 2 milliradian half cone angle for receive." These values are given in the keywords below in radians. \begindata INS-116300_FOV_TRANSMIT_SIZE = ( 0.003 ) INS-116300_FOV_RECEIVE_SIZE = ( 0.002 ) \begintext LIDAR Pulse Parameters -------------------------------------------------------- The following LIDAR pulse parameters are included in the data section below (based on the table provided in the Overview section of this file): --------------------------------------------------- parameter value --------------------------------------------------- Pulse energy, nJ 400 Pulse duration, sec 0.0000001 Pulse rate, Hz 2500 Pulse wavelength, m 0.88 --------------------------------------------------- The values in the keywords are given in the same units as in the table above. \begindata INS-116300_PULSE_ENERGY = ( 400.00 ) INS-116300_PULSE_DURATION = ( 0.0000001 ) INS-116300_PULSE_RATE = ( 2500 ) INS-116300_PULSE_WAVELENGTH = ( 0.88 ) \begintext Platform ID -------------------------------------------------------- The LIDAR instrument is mounted on the MPL spacecraft body. Therefore the value for the platform ID keyword below is -116000. \begindata INS-116300_PLATFORM_ID = ( -116000 ) \begintext