KPL/FK Chandrayaan-1 Frames Kernel ======================================================================== This frame kernel contains complete set of frame definitions for the Chandrayaan-1 Spacecraft (CH1) including definitions for the Chandrayaan-1 spacecraft Chandrayaan-1 Mission NAIF ID Codes -- Summary Section ======================================================================== The following names and NAIF ID codes are assigned to the Chandrayaan-1 spacecraft, its structures and science instruments (the keywords implementing these definitions are located in the section "Chandrayaan-1 Mission NAIF ID Codes -- Definition Section" at the end of this file): Chandrayaan-1 Spacecraft and Spacecraft Structures names/IDs: CHANDRAYAAN-1 -86 CH1 -86 CH1_SPACECRAFT -86000 SIR2 names/IDs: CH1_SIR2 -86700 D-CIXS names/IDs: CH1_C1XS -86400 Chandrayaan-1 Frames ======================================================================== The following Chandrayaan-1 frames are defined in this kernel file: Name Relative to Type NAIF ID ====================== =================== ============ ======= CH1_SPACECRAFT J2000 CK -86000 SIR2 Frames: ------------ CH1_SIR2 CH1_SPACECRAFT FIXED -86700 Frame Tree ======================================================================== The diagram below shows the frame hierarchy for the Chandrayaan-1 spacecraft and its structure frame. "J2000" INERTIAL +-----------------------------------------------------+ | | | |<-pck |<-ck |<-pck | | | V | V "IAU_MOON" | "MOON_PA" MOON BFXD | MOON HIGH-PREC BFXD ------------- | ------------------- | | | | | "CH1_SN1/2" | ----------- | ^ | | | |<-fixed | | V | "CH1_SPACECRAFT" +-----------------------------------------------------+ | | | | |<-ck |<-ck |<-fixed |<-fixed | | | | V V V V "CH1_SA_GIMBAL" "CH1_HGA_GIMBAL" "CH1_TMC" "CH1_LLRI" --------------- --------------- ------------ ---------- | | | | |<-fixed |<-fixed |<-fixed |<-fixed | | | | V V V V "CH1_SA" "CH1_HGA" "AFT" "NADIR" "FORE" "BEAM" "RECEIVER" -------- --------- ----- ------- ------ ------ ---------- CH1 Spacecraft Frame ======================================================================== CH1_SPACECRAFT J2000 CK -86000 CH1 Spacecraft Frame -------------------------------------- The CH1 spacecraft frame is defined as follows: - +Z towards solar array side -- positive or negative normal to orbit plane - +X is along instrument boresights - towards Moon - +Y towards MIP side -- along velocity or along anti-velocity - the origin of this frame is the launch vehicle interface point. These diagrams illustrate the CH1_SPACECRAFT frame: To be completed. Since the orientation of the CH1_SPACECRAFT frame is computed on-board, sent down in telemetry, and stored in the s/c CK files, it is defined as a CK-based frame. \begindata FRAME_CH1_SPACECRAFT = -86001 FRAME_-86001_NAME = 'CH1_SPACECRAFT' FRAME_-86001_CLASS = 3 FRAME_-86001_CLASS_ID = -86001 FRAME_-86001_CENTER = -86 CK_-86001_SCLK = -86 CK_-86001_SPK = -86 OBJECT_-86_FRAME = 'CH1_SPACECRAFT' \begintext SIR2 frames: ======================================================================== This section of the file contains the definitions of the SIR2 frames. SIR2 Frame Tree -------------------------------------- The diagram below shows the SIR2 frame hierarchy. "J2000" INERTIAL +---------------------------------------------------+ | | | | | | |<-pck | pck->| | | | V | V "IAU_MOON" | "IAU_EARTH" MOON BODY-FIXED | EARTH BODY-FIXED --------------- | ---------------- | |<-ck | V "CH1_SPACECRAFT" ---------------- | | | |<-fixed | V "CH1_SIR2" ---------- SIR2 Detector Frame -------------------------------------- Since the SIR2 detector receives radiation through a prism and essentially has a single pixel in terms of spatial resolution, its frame, CH1_SIR2, is orientated in such a way that the SIR2 boresight direction is nominally co-aligned with the spacecraft +X axis. The SIR2 Detector frame -- CH1_SIR2 -- is defined as follows: - +Z axis points along the camera boresight; - +X axis is nominally co-aligned with the s/c +Z axis; - +Y axis completes the right hand frame; - the origin of the frame is located at the fiber tip focal point. +X s/c side view: ----------------- ^ ____________|______________ | | | | |+Zsc |____________ | | | | | | | | | | | | | o---------> | | | +Ysc | | | | | | | ^ | | |___|_______| | | |+Xsir |_________________________|___|___ | | | <--------o | +Ysir |_____| +Xsc and +Zsir are out of page Exactly nominal mounting would require this rotation: Angles: ( 0.0, -90.0, 180.0 ) Axes: ( 1, 2, 3 ) Additionally to this rotation, we have to take into account devi- ations from the nominal mounting. The alignment values given below have been provided by SPACECRAFT ALIGNMENT SECTION MECHANICAL INTEGRATION DIVISION SIG, ISAC on 2008-Oct-31 in the form of two tables. This is the first table: +----------------------+-----------+----------------+----------------+ | | Rotation | Rotation | Rotation | +----------------------+-----------+----------------+----------------+ | | about YAW | about ROLL | about PITCH | +----------------------+-----------+----------------+----------------+ |Pre dynamic | - | - 0 deg0' 40'' | + 0 deg2' 35'' | +----------------------+-----------+----------------+----------------+ |Post dynamic | - | + 0 deg1' 07'' | + 0 deg2' 44'' | +----------------------+-----------+----------------+----------------+ |Difference (Pre-Post) | - | - 0 deg1' 47'' | - 0 deg0' 09'' | +----------------------+-----------+----------------+----------------+ It is noted that all the alignment values given are cube normals only. Cube errors are accounted for in the second table provided: +-------------+-----------+-------------------+-------------------+ | | Rotation | Rotation | Rotation | +-------------+-----------+-------------------+-------------------+ | | about YAW | about ROLL | about PITCH | +-------------+-----------+-------------------+-------------------+ |Post dynamic | - | - 0 deg8' 18.16'' | - 0 deg3' 12.53'' | +-------------+-----------+-------------------+-------------------+ Thus we take the values from the second table. These angles are so small that the sequence of rotations does not really matter, however, we assume that the required sequence of rota- tions is first yaw (which is zero), second pitch, third roll. We assume that the negative values indicate a left-handed rotation around the specified axes. Converted to degrees, we have this rotation angles: First rotation around PITCH: -0.05348055555555556 Second rotation around ROLL: -0.138377777777778 The above sequence and signs of rotations would transform the instrument from the nominal mounting position to the actual mounting position. In this kernel we have to provide the opposite transforma- tion, from the actual to the nominal position of the instrument. Thus we have to reverse the sequence of rotations and negate the angles: First rotation around ROLL: 0.138377777777778 Second rotation around PITCH: 0.05348055555555556 In the instrument frame's coordinate system --- this is the sys- tem in which the rotation axes have to be defined ---, this corre- sponds to First rotation around -Y: 0.138377777777778 Second rotation around +X: 0.05348055555555556 To replace -Y by +Y, we have to negate the angle, thus: First rotation around +Y: -0.138377777777778 Second rotation around +X: 0.05348055555555556 In SPICE encoding, this rotation is described by Angles: ( 0.05348055555555556, -0.138377777777778, 0.0 ) Axes: ( 1, 2, 3 ) This rotation transforms the instrument from the actual mounting to the nominal mounting. We have first to apply this rotation and then apply the rotation which transforms the axes of the instrument frame to the respective axes of the spacecraft frame. As stated above, this second rotation is described by Angles: ( 0.0, -90.0, 180.0 ) Axes: ( 1, 2, 3 ) To compute the combination of these two rotations we use the SPICE routines eul2m, mxm, and m2eul. The resultant rotation is Angles: ( -21.1305922, -89.8516471, -158.869343 ) Axes: ( 1, 2, 3 ) The resultant rotation is reflected in the below data section. \begindata FRAME_CH1_SIR2 = -86700 FRAME_-86700_NAME = 'CH1_SIR2' FRAME_-86700_CLASS = 4 FRAME_-86700_CLASS_ID = -86700 FRAME_-86700_CENTER = -86 TKFRAME_-86700_RELATIVE = 'CH1_SPACECRAFT' TKFRAME_-86700_SPEC = 'ANGLES' TKFRAME_-86700_UNITS = 'DEGREES' TKFRAME_-86700_ANGLES = (-21.1305922, -89.8516471, -158.869343) TKFRAME_-86700_AXES = ( 1, 2, 3 ) \begintext \begindata NAIF_BODY_NAME += ( 'CHANDRAYAAN-1' ) NAIF_BODY_CODE += ( -86 ) NAIF_BODY_NAME += ( 'CH1' ) NAIF_BODY_CODE += ( -86 ) NAIF_BODY_NAME += ( 'CH1_SPACECRAFT' ) NAIF_BODY_CODE += ( -86001 ) \begintext SIR2 IDs -------------------------------------- This table summarizes SIR2 IDs: Name ID --------------------- ------- CH1_SIR2 -86700 Name-ID Mapping keywords: \begindata NAIF_BODY_NAME += ( 'CH1_SIR2' ) NAIF_BODY_CODE += ( -86700 ) \begintext