| Remote Sensing Hands-On Lesson, using TGO (IDL) |
Table of ContentsRemote Sensing Hands-On Lesson, using TGO (IDL) Overview Note About HTML Links References Tutorials Required Readings The Permuted Index Icy API Documentation Kernels Used Icy Modules Used Time Conversion (convtm) Task Statement Learning Goals Approach Solution Solution Meta-Kernel Solution Source Code Solution Sample Output Extra Credit Task statements and questions Solutions and answers Obtaining Target States and Positions (getsta) Task Statement Learning Goals Approach Solution Solution Meta-Kernel Solution Source Code Solution Sample Output Extra Credit Task statements and questions Solutions and answers Spacecraft Orientation and Reference Frames (xform) Task Statement Learning Goals Approach Solution Solution Meta-Kernel Solution Source Code Solution Sample Output Extra Credit Task statements and questions Solutions and answers Computing Sub-s/c and Sub-solar Points on an Ellipsoid and a DSK (subpts) Task Statement Learning Goals Approach Solution Solution Meta-Kernel Solution Source Code Solution Sample Output Extra Credit Task statements and questions Solutions and answers Intersecting Vectors with an Ellipsoid and a DSK (fovint) Task Statement Learning Goals Approach Solution Solution Meta-Kernel Solution Source Code Solution Sample Output Extra Credit Remote Sensing Hands-On Lesson, using TGO (IDL)
Overview
Note About HTML Links
In order for the links to be resolved, if not done already by installing the lessons package under the Toolkit's ``doc/html'' directory, create a subdirectory called ``lessons'' under the ``doc/html'' directory of the ``icy/'' tree and copy this document to that subdirectory before loading it into a Web browser. References
Of these documents, the ``Tutorials'' contains the highest level descriptions with the least number of details while the ``Required Reading'' documents contain much more detailed specifications. The most complete specifications are provided in the ``API Documentation''. In some cases the lesson explanations also refer to the information provided in the meta-data area of the kernels used in the lesson examples. It is especially true in case of the FK and IK files, which often contain comprehensive descriptions of the frames, instrument FOVs, etc. Since both the FK and IK are text kernels, the information provided in them can be viewed using any text editor, while the meta information provided in binary kernels---SPKs and CKs---can be viewed using ``commnt'' or ``spacit'' utility programs located in ``icy/exe'' of Toolkit installation tree. Tutorials
Name Lesson steps/routines it describes ---------------- ----------------------------------------------- Time Time Conversion SCLK and LSK Time Conversion SPK Obtaining Ephemeris Data Frames Reference Frames Using Frames Reference Frames PCK Planetary Constants Data CK Spacecraft Orientation Data DSK Detailed Target Shape (Topography) DataThese tutorials are available from the NAIF ftp server at JPL:
http://naif.jpl.nasa.gov/naif/tutorials.html Required Readings
Name Lesson steps/routines that it describes --------------- ----------------------------------------- ck.req Obtaining spacecraft orientation data dsk.req Obtaining detailed body shape data frames.req Using reference frames naif_ids.req Determining body ID codes pck.req Obtaining planetary constants data sclk.req SCLK time conversion spk.req Obtaining ephemeris data time.req Time conversion icy.req The Icy API The Permuted Index
This text document provides a simple mechanism by which users can discover which Icy procedures perform functions of interest, as well as the names of the source files that contain these procedures.
Icy API Documentation
For example, the document
icy/doc/html/icy/cspice_str2et.htmldescribes the cspice_str2et routine. Kernels Used
1. Generic LSK:
naif0012.tls
2. ExoMars-16 TGO SCLK:
em16_tgo_step_20160414.tsc
3. Solar System Ephemeris SPK, subsetted to cover only the time
range of interest:
de430.bsp
4. Martian Satellite Ephemeris SPK, subsetted to cover only the time
range of interest:
mar085.bsp
5. ExoMars-16 TGO Spacecraft Trajectory SPK, subsetted to cover only
the time range of interest:
em16_tgo_mlt_20171205_20230115_v01.bsp
6. Generic PCK:
pck00010.tpc
7. ExoMars-16 TGO FK:
em16_tgo_v07.tf
8. ExoMars-16 TGO Spacecraft CK, subsetted to cover only the time
range of interest:
em16_tgo_sc_slt_npo_20171205_20230115_s20160414_v01.bc
9. Low-resolution Mars DSK:
mars_lowres.bds
10. NOMAD IK:
em16_tgo_nomad_v02.ti
These SPICE kernels are included in the lesson package available from
the NAIF server at JPL:
ftp://naif.jpl.nasa.gov/pub/naif/toolkit_docs/Lessons/In addition to these kernels, the extra credit exercises require the following kernels:
11. Generic Jovian Satellite Ephemeris SPK:
jup310_2018.bsp
12. EDM lander FK:
em16_edm_v00.tf
13. EDM landing site SPK:
em16_edm_sot_landing_site_20161020_21000101_v01.bsp
These SPICE kernels are available from the NAIF server at JPL:
https://naif.jpl.nasa.gov/pub/naif/generic_kernels/spk/ https://naif.jpl.nasa.gov/pub/naif/EXOMARS2016/kernels/ Icy Modules Used
CHAPTER EXERCISE FUNCTIONS NON-VOID KERNELS
------- --------- ------------- ------------- ----------
1 convtm cspice_furnsh 1,2
cspice_str2et
cspice_etcal
cspice_timout
cspice_sce2s
cspice_unload
extra (*) cspice_sct2e cspice_unitim 1,2
cspice_et2utc
cspice_scs2e
2 getsta cspice_furnsh cspice_vnorm 1,3-5
cspice_str2et
cspice_spkezr
cspice_spkpos
cspice_convrt
cspice_kclear
extra (*) cspice_unload 1,3-6,11-13
cspice_bodn2c
3 xform cspice_furnsh cspice_vsep 1-8
cspice_str2et
cspice_spkezr
cspice_sxform
cspice_spkpos
cspice_pxform
cspice_mxv
cspice_convrt
cspice_kclear
extra (*) cspice_unload 1-8
4 subpts cspice_furnsh cspice_vnorm 1,3-6,9
cspice_str2et
cspice_subpnt
cspice_subslr
cspice_unload
extra (*) cspice_kclear cspice_dpr 1,3-6
cspice_reclat
cspice_bodvrd
cspice_recpgr
5 fovint cspice_furnsh cspice_dpr 1-10
cspice_str2et
cspice_bodn2c
cspice_getfov
cspice_sincpt
cspice_reclat
cspice_illumf
cspice_et2lst
cspice_kclear
(*) Additional APIs and kernels used in Extra Credit tasks.
Refer to the Icy HTML API documentation pages located under
``icy/doc/html/icy'' for detailed interface specifications of these
procedures.
Time Conversion (convtm)Task Statement
Learning Goals
Approach
When completing the ``calendar format'' step above, consider using one of two possible methods: cspice_etcal or cspice_timout. SolutionSolution Meta-Kernel
KPL/MK
This is the meta-kernel used in the solution of the ``Time
Conversion'' task in the Remote Sensing Hands On Lesson.
The names and contents of the kernels referenced by this
meta-kernel are as follows:
1. Generic LSK:
naif0012.tls
2. ExoMars-16 TGO SCLK:
em16_tgo_step_20160414.tsc
\begindata
KERNELS_TO_LOAD = (
'kernels/lsk/naif0012.tls',
'kernels/sclk/em16_tgo_step_20160414.tsc'
)
\begintext
Solution Source Code
PRO convtm
;;
;; Local Parameters
;;
METAKR = "convtm.tm"
SCLKID = -143
STRLEN = 50
utctim = ''
;;
;; Load the kernels this program requires.
;; Both the spacecraft clock kernel and a
;; leapseconds kernel should be listed in
;; the meta-kernel.
;;
cspice_furnsh, METAKR
;;
;; Prompt the user for the input time string.
;;
read, utctim, PROMPT="Input UTC Time: "
print, "Converting UTC Time: ", utctim
;;
;; Convert utctim to et.
;;
cspice_str2et, utctim, et
print, FORMAT="(A,F16.3)", " ET Seconds Past J2000: ", et
;;
;; Now convert ET to a formal calendar time
;; string. This can be accomplished in two
;; ways.
;;
cspice_etcal, et, calet
print, " Calendar ET (cspice_etcal): ", calet
;;
;; Or use cspice_timout for finer control over the
;; output format. The picture below was built
;; by examining the header of cspice_timout.
;;
cspice_timout, et , "YYYY-MON-DDTHR:MN:SC ::TDB", $
STRLEN, calet
print, " Calendar ET (cspice_timout): ", calet
;;
;; Convert ET to spacecraft clock time.
;;
cspice_sce2s, SCLKID, et, sclkst
print, " Spacecraft Clock Time: ", sclkst
cspice_unload, METAKR
END
Solution Sample Output
Input UTC Time: 2018 JUN 11 19:32:00
Converting UTC Time: 2018 JUN 11 19:32:00
ET Seconds Past J2000: 582017589.185
Calendar ET (cspice_etcal): 2018 JUN 11 19:33:09.184
Calendar ET (cspice_timout): 2018-JUN-11T19:33:09
Spacecraft Clock Time: 1/0070841719.26698
Extra Credit
These ``extra credit'' tasks are provided as task statements, and unlike the regular tasks, no approach or solution source code is provided. In the next section, you will find the numeric solutions (when applicable) and answers to the questions asked in these tasks. Task statements and questions
Solutions and answers
Julian Date TDB: 2458281.3146896
% CSPICE_STR2ET: SPICE(NOLEAPSECONDS): [str2et_c->STR2ET->TTRANS]
The variable that points to the leapseconds
(DELTET/DELTA_AT) could not be located in the
kernel pool. It is likely that the leapseconds
kernel has not been loaded via the routine
FURNSH.
% Execution halted at: CONVTM 32
/home/bsemenov/tmp/lessons_180518/lessons/remote_sensing_tgo/co
nvtm.pro
% $MAIN$
% CSPICE_SCE2S: SPICE(KERNELVARNOTFOUND):
[sce2s_c->SCE2S->SCE2T->SCTYPE->SCLI01]
SCLK_DATA_TYPE_143 not found. Did you load the
SCLK kernel?
% Execution halted at: CONVTM 63
/home/bsemenov/tmp/lessons_180518/lessons/remote_sensing_tgo/co
nvtm.pro
% $MAIN$
Earliest UTC convertible to SCLK: 2016-03-13T21:34:13.194
Spacecraft Clock Time: 1/0070841719.26698
UTC time from spacecraft clock: 2018-06-11T19:32:00.000
Obtaining Target States and Positions (getsta)Task Statement
Learning Goals
Approach
When deciding which SPK files to load, the Toolkit utility ``brief'' may be of some use. ``brief'' is located in the ``icy/exe'' directory for IDL toolkits. Consult its user's guide available in ``icy/doc/brief.ug'' for details. SolutionSolution Meta-Kernel
KPL/MK
This is the meta-kernel used in the solution of the
``Obtaining Target States and Positions'' task in the
Remote Sensing Hands On Lesson.
The names and contents of the kernels referenced by this
meta-kernel are as follows:
1. Generic LSK:
naif0012.tls
2. Solar System Ephemeris SPK, subsetted to cover only
the time range of interest:
de430.bsp
3. Martian Satellite Ephemeris SPK, subsetted to cover
only the time range of interest:
mar085.bsp
4. ExoMars-16 TGO Spacecraft Trajectory SPK, subsetted
to cover only the time range of interest:
em16_tgo_mlt_20171205_20230115_v01.bsp
\begindata
KERNELS_TO_LOAD = (
'kernels/lsk/naif0012.tls',
'kernels/spk/de430.bsp',
'kernels/spk/mar085.bsp',
'kernels/spk/em16_tgo_mlt_20171205_20230115_v01.bsp',
)
\begintext
Solution Source Code
PRO getsta
;;
;; Local Parameters
;;
METAKR = 'getsta.tm'
STRLEN = 50
utctim = ''
;;
;; Load the kernels that this program requires. We
;; will need a leapseconds kernel to convert input
;; UTC time strings into ET. We also will need the
;; necessary SPK files with coverage for the bodies
;; in which we are interested.
;;
cspice_furnsh, METAKR
;;
;; Prompt the user for the input time string.
;;
read, utctim, PROMPT = 'Input UTC Time: '
print, 'Converting UTC Time: ', utctim
;;
;; Convert utctim to et.
;;
cspice_str2et, utctim, et
print, FORMAT='(A,F16.3)', ' ET seconds past J2000: ', et
;;
;; Compute the apparent state of Mars as seen from
;; ExoMars-16 TGO in the J2000 frame. All of the ephemeris
;; readers return states in units of kilometers and
;; kilometers per second.
;;
cspice_spkezr, 'MARS', et , 'J2000', 'LT+S', $
'TGO', state, ltime
print, ' Apparent state of Mars as seen ' +$
'from ExoMars-16 TGO in the J2000'
print, ' frame (km, km/s): '
print, FORMAT='(A,F16.3)', ' X = ', state[0]
print, FORMAT='(A,F16.3)', ' Y = ', state[1]
print, FORMAT='(A,F16.3)', ' Z = ', state[2]
print, FORMAT='(A,F16.3)', ' VX = ', state[3]
print, FORMAT='(A,F16.3)', ' VY = ', state[4]
print, FORMAT='(A,F16.3)', ' VZ = ', state[5]
;;
;; Compute the apparent position of Earth as seen from
;; ExoMars-16 TGO in the J2000 frame. Note: We could have
;; continued using cspice_spkezr and simply ignored the
;; velocity components.
;;
cspice_spkpos, 'EARTH', et , 'J2000', 'LT+S', $
'TGO', pos, ltime
print, ' Apparent position of Earth as ' +$
'seen from ExoMars-16 TGO in the'
print, ' J2000 frame (km): '
print, FORMAT='(A,F16.3)', ' X = ', pos[0]
print, FORMAT='(A,F16.3)', ' Y = ', pos[1]
print, FORMAT='(A,F16.3)', ' Z = ', pos[2]
;;
;; We need only display LT, as it is precisely the
;; light time in which we are interested.
;;
print, ' One way light time between ExoMars-16 ' +$
'TGO and the apparent'
print, FORMAT='(A,F16.3)', ' position of Earth ' +$
'(seconds): ', ltime
;;
;; Compute the apparent position of the Sun as seen
;; from Mars in the J2000 frame.
;;
cspice_spkpos, 'SUN' , et , 'J2000', 'LT+S', $
'MARS', pos, ltime
print, ' Apparent position of Sun as seen ' +$
'from Mars in the '
print, ' J2000 frame (km): '
print, FORMAT='(A,F16.3)', ' X = ', pos[0]
print, FORMAT='(A,F16.3)', ' Y = ', pos[1]
print, FORMAT='(A,F16.3)', ' Z = ', pos[2]
;;
;; Now we need to compute the actual distance between
;; the Sun and Mars. The above SPKPOS call gives us
;; the apparent distance, so we need to adjust our
;; aberration correction appropriately.
;;
cspice_spkpos, 'SUN' , et , 'J2000', 'NONE', $
'MARS', pos, ltime
;;
;; Compute the distance between the body centers in
;; kilometers.
;;
dist = cspice_vnorm ( pos )
;;
;; Convert this value to AU using cspice_convrt.
;; Recall, cspice_convrt cannot overwrite the
;; input with the output. Use 'dist_au' for the
;; output value.
;;
cspice_convrt, dist, 'KM', 'AU', dist_au
print, ' Actual distance between Sun and Mars ' + $
'body centers:'
print, FORMAT='(A,F16.3)', ' (AU): ', dist_au
cspice_kclear
END
Solution Sample Output
Input UTC Time: 2018 JUN 11 19:32:00
Converting UTC Time: 2018 JUN 11 19:32:00
ET seconds past J2000: 582017589.185
Apparent state of Mars as seen from ExoMars-16 TGO in the J2000
frame (km, km/s):
X = 2911.822
Y = -2033.802
Z = -1291.701
VX = 1.310
VY = -0.056
VZ = 3.104
Apparent position of Earth as seen from ExoMars-16 TGO in the
J2000 frame (km):
X = -49609884.080
Y = 57070665.862
Z = 30304236.930
One way light time between ExoMars-16 TGO and the apparent
position of Earth (seconds): 271.738
Apparent position of Sun as seen from Mars in the
J2000 frame (km):
X = -24712734.289
Y = 194560532.943
Z = 89906636.789
Actual distance between Sun and Mars body centers:
(AU): 1.442
Extra Credit
These ``extra credit'' tasks are provided as task statements, and unlike the regular tasks, no approach or solution source code is provided. In the next section, you will find the numeric solutions (when applicable) and answers to the questions asked in these tasks. Task statements and questions
Solutions and answers
% CSPICE_SPKEZR: SPICE(SPKINSUFFDATA):
[spkezr_c->SPKEZR->SPKEZ->SPKACS->SPKGEO]
Insufficient ephemeris data has been loaded to
compute the state of -143 (EXOMARS 2016 TGO)
relative to 0 (SOLAR SYSTEM BARYCENTER) at the
ephemeris epoch 2018 JUN 11 19:33:09.184.
% Execution halted at: GETSTA 42
/home/bsemenov/tmp/lessons_180518/lessons/remote_sensing_tgo/ge
tsta.pro
% $MAIN$
BRIEF -- Version 4.0.0, September 8, 2010 -- Toolkit Version N0066
Summary for: kernels/spk/de430.bsp
Bodies: MERCURY BARYCENTER (1) w.r.t. SOLAR SYSTEM BARYCENTER (0)
VENUS BARYCENTER (2) w.r.t. SOLAR SYSTEM BARYCENTER (0)
EARTH BARYCENTER (3) w.r.t. SOLAR SYSTEM BARYCENTER (0)
MARS BARYCENTER (4) w.r.t. SOLAR SYSTEM BARYCENTER (0)
JUPITER BARYCENTER (5) w.r.t. SOLAR SYSTEM BARYCENTER (0)
SATURN BARYCENTER (6) w.r.t. SOLAR SYSTEM BARYCENTER (0)
URANUS BARYCENTER (7) w.r.t. SOLAR SYSTEM BARYCENTER (0)
NEPTUNE BARYCENTER (8) w.r.t. SOLAR SYSTEM BARYCENTER (0)
PLUTO BARYCENTER (9) w.r.t. SOLAR SYSTEM BARYCENTER (0)
SUN (10) w.r.t. SOLAR SYSTEM BARYCENTER (0)
MERCURY (199) w.r.t. MERCURY BARYCENTER (1)
VENUS (299) w.r.t. VENUS BARYCENTER (2)
MOON (301) w.r.t. EARTH BARYCENTER (3)
EARTH (399) w.r.t. EARTH BARYCENTER (3)
Start of Interval (UTC) End of Interval (UTC)
----------------------------- -------------------------
----
2018-JUN-09 23:30:00.000 2018-JUN-14 12:00:00.000
Summary for: kernels/spk/mar085.bsp
Bodies: EARTH BARYCENTER (3) w.r.t. SOLAR SYSTEM BARYCENTER (0)
MARS BARYCENTER (4) w.r.t. SOLAR SYSTEM BARYCENTER (0)
SUN (10) w.r.t. SOLAR SYSTEM BARYCENTER (0)
EARTH (399) w.r.t. EARTH BARYCENTER (3)
PHOBOS (401) w.r.t. MARS BARYCENTER (4)
DEIMOS (402) w.r.t. MARS BARYCENTER (4)
MARS (499) w.r.t. MARS BARYCENTER (4)
Start of Interval (UTC) End of Interval (UTC)
----------------------------- -------------------------
----
2018-JUN-09 23:30:00.000 2018-JUN-14 12:00:00.000
Summary for: kernels/spk/em16_tgo_mlt_20171205_20230115_v01.bsp
Body: EXOMARS 2016 TGO (-143) w.r.t. MARS (499)
Start of Interval (UTC) End of Interval (UTC)
----------------------------- ---------------------------
--
2018-JUN-09 23:30:00.000 2018-JUN-14 12:00:00.000
Additional kernels required for this task:
1. Generic Jovian Satellite Ephemeris SPK:
jup310_2018.bsp
available in the NAIF server at:
https://naif.jpl.nasa.gov/pub/naif/generic_kernels/spk/
satellites/a_old_versions
Actual position of Jupiter as seen from Mars in the
J2000 frame (km):
X = -536521483.294
Y = -384722940.461
Z = -145930841.439
Additional kernels required for this task:
1. EDM lander FK:
em16_edm_v00.tf
2. EDM landing site SPK:
em16_edm_sot_landing_site_20161020_21000101_v01.bsp
3. Generic PCK:
pck00010.tpc
available in the NAIF server at:
https://naif.jpl.nasa.gov/pub/naif/EXOMARS2016/kernels/
EDM_LANDING_SITE NAIF ID: -117900
Apparent position of EDM Landing Site as seen from
ExoMars-16 TGO in the J2000 frame (km):
X = -131.716
Y = -2168.989
Z = 208.792
Actual (geometric) position of Sun as seen from Mars in the
J2000 frame (km):
X = -24730874.909
Y = 194558449.463
Z = 89906170.829
Light-time corrected position of Sun as seen from Mars in the
J2000 frame (km):
X = -24730866.197
Y = 194558445.149
Z = 89906168.728
Apparent position of Sun as seen from Mars in the
J2000 frame (km):
X = -24712733.997
Y = 194560532.846
Z = 89906636.764
Spacecraft Orientation and Reference Frames (xform)Task Statement
Learning Goals
Approach
You may find it useful to consult the permuted index, the headers of various source modules, and the following toolkit documentation:
SolutionSolution Meta-Kernel
KPL/MK
This is the meta-kernel used in the solution of the ``Spacecraft
Orientation and Reference Frames'' task in the Remote Sensing
Hands On Lesson.
The names and contents of the kernels referenced by this
meta-kernel are as follows:
1. Generic LSK:
naif0012.tls
2. ExoMars-16 TGO SCLK:
em16_tgo_step_20160414.tsc
3. Solar System Ephemeris SPK, subsetted to cover only
the time range of interest:
de430.bsp
4. Martian Satellite Ephemeris SPK, subsetted to cover
only the time range of interest:
mar085.bsp
5. ExoMars-16 TGO Spacecraft Trajectory SPK, subsetted
to cover only the time range of interest:
em16_tgo_mlt_20171205_20230115_v01.bsp
6. ExoMars-16 TGO FK:
em16_tgo_v07.tf
7. ExoMars-16 TGO Spacecraft CK, subsetted to cover only
the time range of interest:
em16_tgo_sc_slt_npo_20171205_20230115_s20160414_v01.bc
8. Generic PCK:
pck00010.tpc
\begindata
KERNELS_TO_LOAD = (
'kernels/lsk/naif0012.tls',
'kernels/sclk/em16_tgo_step_20160414.tsc',
'kernels/spk/de430.bsp',
'kernels/spk/mar085.bsp',
'kernels/spk/em16_tgo_mlt_20171205_20230115_v01.bsp',
'kernels/fk/em16_tgo_v07.tf',
'kernels/ck/em16_tgo_sc_slt_npo_20171205_20230115_s20160414_v01.bc',
'kernels/pck/pck00010.tpc'
)
\begintext
Solution Source Code
PRO xform
;;
;; Local Parameters
;;
METAKR = 'xform.tm'
STRLEN = 50
utctim = ''
;;
;; Load the kernels that this program requires. We
;; will need:
;;
;; A leapseconds kernel
;; A spacecraft clock kernel for ExoMars-16 TGO
;; The necessary ephemerides
;; A planetary constants file (PCK)
;; A spacecraft orientation kernel for ExoMars-16 TGO (CK)
;; A frame kernel (TF)
;;
cspice_furnsh, METAKR
;;
;; Prompt the user for the input time string.
;;
read, utctim, PROMPT = 'Input UTC Time: '
print, 'Converting UTC Time: ', utctim
;;
;; Convert utctim to et.
;;
cspice_str2et, utctim, et
print, FORMAT='(A,F16.3)', ' ET seconds past J2000: ', et
;;
;; Compute the apparent state of Mars as seen from
;; ExoMars-16 TGO in the J2000 frame. All of the ephemeris
;; readers return states in units of kilometers and
;; kilometers per second.
;;
cspice_spkezr, 'MARS', et, 'J2000', 'LT+S', $
'TGO', state, ltime
;;
;; Now obtain the transformation from the inertial
;; J2000 frame to the non-inertial body-fixed IAU_MARS
;; frame. Since we want the apparent state in the
;; IAU_MARS reference frame, we need to correct the
;; orientation and angular velocity of this frame
;; for one-way light time; hence we subtract ltime from
;; et in the call below.
;;
cspice_sxform, 'J2000', 'IAU_MARS', et-ltime, sxfmat
;;
;; Now transform the apparent J2000 state into IAU_MARS
;; with the following matrix multiplication:
;;
bfixst = transpose(sxfmat) # state
;;
;; Display the results.
;;
print, ' Apparent state of Mars as seen ' +$
'from ExoMars-16 TGO in the IAU_MARS'
print, ' body-fixed frame (km, km/s):'
print, FORMAT='(A,F19.6)', ' X = ', bfixst[0]
print, FORMAT='(A,F19.6)', ' Y = ', bfixst[1]
print, FORMAT='(A,F19.6)', ' Z = ', bfixst[2]
print, FORMAT='(A,F19.6)', ' VX = ', bfixst[3]
print, FORMAT='(A,F19.6)', ' VY = ', bfixst[4]
print, FORMAT='(A,F19.6)', ' VZ = ', bfixst[5]
;;
;; It is worth pointing out, all of the above could
;; have been done with a single use of cspice_spkezr:
;;
;;
cspice_spkezr, 'MARS', et, 'IAU_MARS', 'LT+S', $
'TGO', state, ltime
;;
;; Display the results.
;;
print, ' Apparent state of Mars as seen ' +$
'from ExoMars-16 TGO in the IAU_MARS'
print, ' body-fixed frame (km, km/s) ' +$
'obtained using cspice_spkezr'
print, ' directly:'
print, FORMAT='(A,F19.6)', ' X = ', state[0]
print, FORMAT='(A,F19.6)', ' Y = ', state[1]
print, FORMAT='(A,F19.6)', ' Z = ', state[2]
print, FORMAT='(A,F19.6)', ' VX = ', state[3]
print, FORMAT='(A,F19.6)', ' VY = ', state[4]
print, FORMAT='(A,F19.6)', ' VZ = ', state[5]
;;
;; Note that the velocity found by using cspice_spkezr
;; to compute the state in the IAU_MARS frame differs
;; at the few mm/second level from that found previously
;; by calling cspice_spkezr and then cspice_sxform. Computing
;; velocity via a single call to cspice_spkezr as we've
;; done immediately above is slightly more accurate because
;; it accounts for the effect of the rate of change of
;; light time on the apparent angular velocity of the
;; target's body-fixed reference frame.
;;
;; Now we are to compute the angular separation between
;; the apparent position of Mars as seen from the orbiter
;; and the nominal instrument view direction. First,
;; compute the apparent position of Mars as seen from
;; ExoMars-16 TGO in the J2000 frame.
;;
cspice_spkpos, 'MARS', et, 'J2000', 'LT+S', $
'TGO', pos, ltime
;;
;; Now compute the location of the nominal instrument view
;; direction. From reading the frame kernel we know that
;; the instrument view direction is nominally the -Y axis
;; of the TGO_SPACECRAFT frame defined there.
;;
bsight = [ 0.D0, -1.D0, 0.D0]
;;
;; Now compute the rotation matrix from TGO_SPACECRAFT into
;; J2000.
;;
cspice_pxform, 'TGO_SPACECRAFT', 'J2000', et, pform
;;
;; And multiply the result to obtain the nominal instrument
;; view direction in the J2000 reference frame.
;;
cspice_mxv, pform, bsight, bsight
;;
;; Lastly compute the angular separation.
;;
cspice_convrt, cspice_vsep(bsight, pos), 'RADIANS', $
'DEGREES', sep
print, ' Angular separation between the ' +$
'apparent position of Mars and the'
print, ' ExoMars-16 TGO nominal instrument ' +$
'view direction (degrees):'
print, FORMAT='(A,F16.3)', ' ', sep
;;
;; Or alternatively we can work in the spacecraft
;; frame directly.
;;
cspice_spkpos, 'MARS', et, 'TGO_SPACECRAFT', 'LT+S', $
'TGO', pos, ltime
;;
;; The nominal instrument view direction is the -Y-axis
;; in the TGO_SPACECRAFT frame.
;;
bsight = [ 0.D0, -1.D0, 0.D0]
;;
;; Lastly compute the angular separation.
;;
cspice_convrt, cspice_vsep(bsight, pos), 'RADIANS', $
'DEGREES', sep
print, ' Angular separation between the ' +$
'apparent position of Mars and the'
print, ' ExoMars-16 TGO nominal instrument ' +$
'view direction computed'
print, ' using vectors in the ' +$
'TGO_SPACECRAFT frame (degrees):'
print, FORMAT='(A,F16.3)', ' ', sep
cspice_kclear
END
Solution Sample Output
Input UTC Time: 2018 JUN 11 19:32:00
Converting UTC Time: 2018 JUN 11 19:32:00
ET seconds past J2000: 582017589.185
Apparent state of Mars as seen from ExoMars-16 TGO in the IAU_MARS
body-fixed frame (km, km/s):
X = -2843.464125
Y = 2235.459544
Z = 1095.894969
VX = 0.311443
VY = -1.151929
VZ = 3.082123
Apparent state of Mars as seen from ExoMars-16 TGO in the IAU_MARS
body-fixed frame (km, km/s) obtained using cspice_spkezr
directly:
X = -2843.464125
Y = 2235.459544
Z = 1095.894969
VX = 0.311443
VY = -1.151929
VZ = 3.082123
Angular separation between the apparent position of Mars and the
ExoMars-16 TGO nominal instrument view direction (degrees):
5.438
Angular separation between the apparent position of Mars and the
ExoMars-16 TGO nominal instrument view direction computed
using vectors in the TGO_SPACECRAFT frame (degrees):
5.438
Extra Credit
These ``extra credit'' tasks are provided as task statements, and unlike the regular tasks, no approach or solution source code is provided. In the next section, you will find the numeric solutions (when applicable) and answers to the questions asked in these tasks. Task statements and questions
Solutions and answers
% CSPICE_PXFORM: SPICE(NOFRAMECONNECT): [pxform_c->PXFORM->REFCHG]
At epoch 5.8209996918462E+08 TDB (2018 JUN 12
18:26:09.184 TDB), there is insufficient
information available to transform from
reference frame -143000 (TGO_SPACECRAFT) to
reference frame 1 (J2000). TGO_SPACECRAFT is a
CK frame; a CK file containing data for
instrument or structure -143000 at the epoch
shown above, as well as a corresponding SCLK
kernel, must be loaded in order to use this
frame. Failure to find required CK data could
be due to one or more CK files not having been
loaded, or to the epoch shown above lying
within a coverage gap or beyond the coverage
bounds of the loaded CK files. It is also
possible that no loaded CK file has required
angular velocity data for the input epoch, even
if a loaded CK does have attitude data for that
epoch. You can use CKBRIEF with the -dump
option to display coverage intervals of a CK
file.
% Execution halted at: XFORM 134
/home/bsemenov/tmp/lessons_180518/lessons/remote_sensing_tgo/xf
orm.pro
% $MAIN$
CKBRIEF -- Version 6.1.0, June 27, 2014 -- Toolkit Version N0066
Summary for: kernels/ck/em16_tgo_sc_slt_npo_20171205_20230115_s201604
14_v01.bc
Segment No.: 1
Object: -143000
Interval Begin UTC Interval End UTC AV
------------------------ ------------------------ ---
2018-JUN-10 23:59:59.999 2018-JUN-12 06:26:53.918 Y
2018-JUN-12 06:56:53.918 2018-JUN-12 18:14:33.918 Y
2018-JUN-12 18:44:33.918 2018-JUN-13 04:02:13.918 Y
2018-JUN-13 04:32:13.918 2018-JUN-13 07:58:33.918 Y
2018-JUN-13 08:28:33.918 2018-JUN-13 11:59:59.999 Y
CKBRIEF -- Version 6.1.0, June 27, 2014 -- Toolkit Version N0066
Summary for: kernels/ck/em16_tgo_sc_slt_npo_20171205_20230115_s201604
14_v01.bc
Object: -143000
Interval Begin UTC Interval End UTC AV
------------------------ ------------------------ ---
2018-JUN-10 23:59:59.999 2018-JUN-13 11:59:59.999 Y
Angular separation between the apparent position of the Sun and the
ExoMars-16 TGO nominal instrument view direction (degrees):
130.543
Science Deck illumination:
ExoMars-16 TGO Science Deck IS NOT illuminated.
Computing Sub-s/c and Sub-solar Points on an Ellipsoid and a DSK (subpts)Task Statement
near point/ellipsoid
definition, and once using a DSK shape model and the
nadir/dsk/unprioritized
definition.
The program displays the results. Use the program to compute these quantities at "2018 JUN 11 19:32:00" UTC. Learning Goals
Approach
One point worth considering: how would the results change if the sub-solar and sub-observer points were computed using the
intercept/ellipsoid
and
intercept/dsk/unprioritized
definitions? Which definition is appropriate?
SolutionSolution Meta-Kernel
KPL/MK
This is the meta-kernel used in the solution of the
``Computing Sub-s/c and Sub-solar Points on an Ellipsoid
and a DSK'' task in the Remote Sensing Hands On Lesson.
The names and contents of the kernels referenced by this
meta-kernel are as follows:
1. Generic LSK:
naif0012.tls
2. Solar System Ephemeris SPK, subsetted to cover only
the time range of interest:
de430.bsp
3. Martian Satellite Ephemeris SPK, subsetted to cover
only the time range of interest:
mar085.bsp
4. ExoMars-16 TGO Spacecraft Trajectory SPK, subsetted
to cover only the time range of interest:
em16_tgo_mlt_20171205_20230115_v01.bsp
5. Generic PCK:
pck00010.tpc
6. Low-resolution Mars DSK:
mars_lowres.bds
\begindata
KERNELS_TO_LOAD = (
'kernels/lsk/naif0012.tls',
'kernels/spk/de430.bsp',
'kernels/spk/mar085.bsp',
'kernels/spk/em16_tgo_mlt_20171205_20230115_v01.bsp',
'kernels/pck/pck00010.tpc'
'kernels/dsk/mars_lowres.bds'
)
\begintext
Solution Source Code
PRO subpts
;;
;; Local Parameters
;;
METAKR = 'subpts.tm'
STRLEN = 50
utctim = ''
;;
;; Load the kernels that this program requires. We
;; will need:
;;
;; A leapseconds kernel
;; The necessary ephemerides
;; A planetary constants file (PCK)
;; A DSK file containing Mars shape data
;;
cspice_furnsh, METAKR
;;
;; Prompt the user for the input time string.
;;
read, utctim, PROMPT = 'Input UTC Time: '
print, 'Converting UTC Time: ', utctim
;;
;; Convert utctim to et.
;;
cspice_str2et, utctim, et
print, FORMAT='(A,F16.3)', ' ET seconds past J2000: ', et
for i = 0, 1 do begin
if i eq 0 then begin
;;
;; Use the "near point" sub-point definition
;; and an ellipsoidal model.
;;
method = 'NEAR POINT/Ellipsoid'
endif else begin
;;
;; Use the "nadir" sub-point definition
;; and a DSK model.
;;
method = 'NADIR/DSK/Unprioritized'
endelse
print
print, FORMAT='(A)', ' Sub-point/target shape model: ' $
+ method
print
;;
;; Compute the apparent sub-observer point of ExoMars-16 TGO
;; on Mars.
;;
cspice_subpnt, method, $
'MARS', et, 'IAU_MARS', 'LT+S', $
'TGO', spoint, trgepc, srfvec
print, ' Apparent sub-observer point of ExoMars-16 ' +$
'TGO on Mars'
print, ' in the IAU_MARS frame (km):'
print, FORMAT='(A,F16.3)', ' X = ', spoint[0]
print, FORMAT='(A,F16.3)', ' Y = ', spoint[1]
print, FORMAT='(A,F16.3)', ' Z = ', spoint[2]
print, FORMAT='(A,F16.3)', ' ALT = ', cspice_vnorm(srfvec)
;;
;; Compute the apparent sub-solar point on Mars
;; as seen from ExoMars-16 TGO.
;;
cspice_subslr, method, $
'MARS', et, 'IAU_MARS', 'LT+S', $
'TGO', spoint, trgepc, srfvec
print, ' Apparent sub-solar point on Mars ' +$
'as seen from ExoMars-16'
print, ' TGO in the IAU_MARS frame (km):'
print, FORMAT='(A,F16.3)', ' X = ', spoint[0]
print, FORMAT='(A,F16.3)', ' Y = ', spoint[1]
print, FORMAT='(A,F16.3)', ' Z = ', spoint[2]
endfor
print
cspice_unload, METAKR
END
Solution Sample Output
Input UTC Time: 2018 JUN 11 19:32:00
Converting UTC Time: 2018 JUN 11 19:32:00
ET seconds past J2000: 582017589.185
Sub-point/target shape model: NEAR POINT/Ellipsoid
Apparent sub-observer point of ExoMars-16 TGO on Mars
in the IAU_MARS frame (km):
X = 2554.165
Y = -2008.010
Z = -983.240
ALT = 385.045
Apparent sub-solar point on Mars as seen from ExoMars-16
TGO in the IAU_MARS frame (km):
X = 487.589
Y = -3348.610
Z = -286.697
Sub-point/target shape model: NADIR/DSK/Unprioritized
Apparent sub-observer point of ExoMars-16 TGO on Mars
in the IAU_MARS frame (km):
X = 2554.223
Y = -2008.057
Z = -983.263
ALT = 384.967
Apparent sub-solar point on Mars as seen from ExoMars-16
TGO in the IAU_MARS frame (km):
X = 488.096
Y = -3352.093
Z = -286.999
Extra Credit
These ``extra credit'' tasks are provided as task statements, and unlike the regular tasks, no approach or solution source code is provided. In the next section, you will find the numeric solutions (when applicable) and answers to the questions asked in these tasks. Task statements and questions
Solutions and answers
Apparent sub-solar point on Mars as seen from ExoMars-16 TGO in
the IAU_MARS frame using the 'Near Point: ellipsoid' method
(km):
X = 487.589
Y = -3348.610
Z = -286.697
Apparent sub-solar point on Mars as seen from ExoMars-16 TGO in
the IAU_MARS frame using the 'Intercept: ellipsoid' method
(km):
X = 487.547
Y = -3348.322
Z = -290.077
Geometric sub-spacecraft point of ExoMars-16 TGO on Phobos in
the IAU_PHOBOS frame using the 'Near Point: ellipsoid' method
(km):
X = 12.059
Y = 4.173
Z = -0.676
Planetocentric coordinates of the ExoMars-16 TGO
sub-spacecraft point on Phobos (degrees, km):
LAT = -3.030
LON = 19.088
R = 12.779
Planetographic coordinates of the ExoMars-16 TGO
sub-spacecraft point on Phobos (degrees, km):
LAT = -6.268
LON = 340.912
ALT = -0.202
Intersecting Vectors with an Ellipsoid and a DSK (fovint)Task Statement
At each point of intersection compute the following:
Additionally compute the local solar time at the intercept of the spectrometer aperture boresight with the surface of Mars, using both ellipsoidal and DSK shape models. Use this program to compute values at the UTC epoch:
Learning Goals
Approach
SolutionSolution Meta-Kernel
KPL/MK
This is the meta-kernel used in the solution of the
``Intersecting Vectors with an Ellipsoid and a DSK'' task
in the Remote Sensing Hands On Lesson.
The names and contents of the kernels referenced by this
meta-kernel are as follows:
1. Generic LSK:
naif0012.tls
2. ExoMars-16 TGO SCLK:
em16_tgo_step_20160414.tsc
3. Solar System Ephemeris SPK, subsetted to cover only
the time range of interest:
de430.bsp
4. Martian Satellite Ephemeris SPK, subsetted to cover
only the time range of interest:
mar085.bsp
5. ExoMars-16 TGO Spacecraft Trajectory SPK, subsetted
to cover only the time range of interest:
em16_tgo_mlt_20171205_20230115_v01.bsp
6. ExoMars-16 TGO FK:
em16_tgo_v07.tf
7. ExoMars-16 TGO Spacecraft CK, subsetted to cover only
the time range of interest:
em16_tgo_sc_slt_npo_20171205_20230115_s20160414_v01.bc
8. Generic PCK:
pck00010.tpc
9. NOMAD IK:
em16_tgo_nomad_v02.ti
10. Low-resolution Mars DSK:
mars_lowres.bds
\begindata
KERNELS_TO_LOAD = (
'kernels/lsk/naif0012.tls',
'kernels/sclk/em16_tgo_step_20160414.tsc',
'kernels/spk/de430.bsp',
'kernels/spk/mar085.bsp',
'kernels/spk/em16_tgo_mlt_20171205_20230115_v01.bsp',
'kernels/fk/em16_tgo_v07.tf',
'kernels/ck/em16_tgo_sc_slt_npo_20171205_20230115_s20160414_v01.bc',
'kernels/pck/pck00010.tpc',
'kernels/ik/em16_tgo_nomad_v02.ti'
'kernels/dsk/mars_lowres.bds'
)
\begintext
Solution Source Code
PRO fovint
;;
;; Local Parameters
;;
METAKR = 'fovint.tm'
STRLEN = 50
boolstr = [ 'false', 'true' ]
;;
;; BCVLEN is the maximum number of boundary corner
;; vectors we can retrieve. We've extended this array by 1
;; element to make room for the boresight vector.
;;
BCVLEN = 5
utctim = ''
scan_vecs = dblarr( 3, BCVLEN )
vecnam = ['Boundary Corner 1', $
'Boundary Corner 2', $
'Boundary Corner 3', $
'Boundary Corner 4', $
'TGO NOMAD LNO Nadir Boresight' ]
;;
;; Load the kernels that this program requires. We
;; will need:
;;
;; A leapseconds kernel.
;; A SCLK kernel for ExoMars-16 TGO.
;; Any necessary ephemerides.
;; The ExoMars-16 TGO frame kernel.
;; An ExoMars-16 TGO C-kernel.
;; A PCK file with Mars constants.
;; The ExoMars-16 TGO NOMAD I-kernel.
;; A DSK file containing Mars shape data.
;;
cspice_furnsh, METAKR
;;
;; Prompt the user for the input time string.
;;
read, utctim, PROMPT = 'Input UTC Time: '
print, 'Converting UTC Time: ', utctim
;;
;; Convert utctim to et.
;;
cspice_str2et, utctim, et
print, FORMAT='(A,F16.3)', ' ET seconds past J2000: ', et
print
;;
;; Now we need to obtain the FOV configuration of
;; the NOMAD LNO Nadir aperture. To do this we will
;; need the ID code for TGO_NOMAD_LNO_NAD.
;;
cspice_bodn2c, 'TGO_NOMAD_LNO_NAD', lnonid, found
;;
;; Stop the program if the code was not found.
;;
if ( ~ found ) then begin
print, 'Unable to locate the ID code for ' +$
'TGO_NOMAD_LNO_NAD'
return
endif
;;
;; Now retrieve the field of view parameters.
;;
cspice_getfov, lnonid, BCVLEN, shape, insfrm, bsight, bounds
;;
;; Rather than treat 'bsight' as a separate vector,
;; copy it and 'bounds' to 'scan_vecs'.
;;
scan_vecs[ 0:11] = bounds[0:11]
scan_vecs[12:14] = bsight[0:2]
;;
;; Set values of "method" string that specify use of
;; ellipsoidal and DSK (topographic) shape models.
;;
;; In this case, we can use the same methods for calls to both
;; cspice_sincpt and cspice_ilumin. Note that some SPICE routines
;; require different "method" inputs from those shown here. See
;; the API documentation of each routine for details.
;;
method = [ 'Ellipsoid', 'DSK/Unprioritized' ]
;;
;; Get Mars ID. We'll use this ID code later, when we
;; compute local solar time.
;;
cspice_bodn2c, 'MARS', marsid, found
;;
;; The ID code for MARS is built in to the library.
;; However, it is good programming practice to get
;; in the habit of checking your found-flags.
;; Return if the code was not found.
;;
if ( ~found ) then begin
print, 'Unable to locate the ID code for Mars.'
return
endif
;;
;; Now perform the same set of calculations for each
;; vector listed in the 'bounds' array.
;;
for i = 0, 4 do begin
print, 'Vector: ', vecnam[i]
for j = 0, 1 do begin
print
print, FORMAT = '(A)', ' Target shape model: ' + method[j]
print
;;
;; Call sincpt to determine coordinates of the
;; intersection of this vector with the surface
;; of Mars.
;;
cspice_sincpt, method[j], 'MARS', et, $
'IAU_MARS', 'LT+S', 'TGO', $
insfrm, scan_vecs[*,i], point, $
trgepc, srfvec, found
;;
;; Check the found flag. Display a message if
;; the point of intersection was not found,
;; otherwise continue with the calculations.
;;
if ( ~ found ) then begin
print, 'No intersection point found at ' +$
'this epoch for this vector.'
endif else begin
;;
;; Now, we have discovered a point of intersection.
;; Start by displaying the position vector in the
;; IAU_MARS frame of the intersection.
;;
print, ' Position vector of surface intercept ' +$
'in the IAU_MARS frame (km):'
print, FORMAT='(A,F16.3)', ' X = ', point[0]
print, FORMAT='(A,F16.3)', ' Y = ', point[1]
print, FORMAT='(A,F16.3)', ' Z = ', point[2]
;;
;; Display the planetocentric latitude and longitude
;; of the intercept.
;;
cspice_reclat, point, radius, lon, lat
print, ' Planetocentric coordinates of ' +$
'the intercept (degrees):'
print, FORMAT='(A,F16.3)', ' LAT = ', $
lat * cspice_dpr()
print, FORMAT='(A,F16.3)', ' LON = ', $
lon * cspice_dpr()
;;
;; Compute the illumination angles at this
;; point.
;;
cspice_illumf, method[j], 'MARS', 'SUN', $
et, 'IAU_MARS', 'LT+S', $
'TGO', point, trgepc, $
srfvec, phase, solar, $
emissn, visibl, lit
print, FORMAT='(A,F16.3)', $
' Phase angle (degrees): ', $
phase * cspice_dpr()
print, FORMAT='(A,F16.3)', $
' Solar incidence angle (degrees): ', $
solar * cspice_dpr()
print, FORMAT='(A,F16.3)', $
' Emission angle (degrees): ', $
emissn * cspice_dpr()
print, FORMAT='(A)', $
' Observer visible: ' + boolstr[visibl]
print, FORMAT='(A)', $
' Sun visible: ' + boolstr[lit]
;;
;; Lastly compute the local solar time at the boresight
;; intersection.
;;
if i eq 4 then begin
;; Compute local solar time corresponding to
;; the TDB light time corrected epoch at the
;; intercept.
;;
cspice_et2lst, trgepc, marsid, lon, 'PLANETOCENTRIC',$
hr, min, sc, time, ampm
print
print, ' Local Solar Time at boresight ' +$
'intercept (24 Hour Clock):'
print, ' ' + time
endif
;;
;; End of LST computation block.
;;
endelse
;;
;; End of intercept processing block.
;;
endfor
;;
;; End of shape model loop.
;;
print
endfor
;;
;; End of vector loop.
;;
cspice_kclear
END
Solution Sample Output
Input UTC Time: 2018 JUN 11 19:32:00
Converting UTC Time: 2018 JUN 11 19:32:00
ET seconds past J2000: 582017589.185
Vector: Boundary Corner 1
Target shape model: Ellipsoid
Position vector of surface intercept in the IAU_MARS frame (km):
X = 2535.004
Y = -2028.528
Z = -990.594
Planetocentric coordinates of the intercept (degrees):
LAT = -16.967
LON = -38.667
Phase angle (degrees): 48.207
Solar incidence angle (degrees): 43.872
Emission angle (degrees): 4.798
Observer visible: true
Sun visible: true
Target shape model: DSK/Unprioritized
Position vector of surface intercept in the IAU_MARS frame (km):
X = 2535.278
Y = -2028.712
Z = -990.688
Planetocentric coordinates of the intercept (degrees):
LAT = -16.967
LON = -38.667
Phase angle (degrees): 48.207
Solar incidence angle (degrees): 44.387
Emission angle (degrees): 4.326
Observer visible: true
Sun visible: true
Vector: Boundary Corner 2
Target shape model: Ellipsoid
Position vector of surface intercept in the IAU_MARS frame (km):
X = 2525.056
Y = -2042.075
Z = -988.196
Planetocentric coordinates of the intercept (degrees):
LAT = -16.925
LON = -38.963
Phase angle (degrees): 50.707
Solar incidence angle (degrees): 43.586
Emission angle (degrees): 7.432
Observer visible: true
Sun visible: true
Target shape model: DSK/Unprioritized
Position vector of surface intercept in the IAU_MARS frame (km):
X = 2525.359
Y = -2042.259
Z = -988.299
Planetocentric coordinates of the intercept (degrees):
LAT = -16.925
LON = -38.962
Phase angle (degrees): 50.707
Solar incidence angle (degrees): 42.457
Emission angle (degrees): 8.610
Observer visible: true
Sun visible: true
Vector: Boundary Corner 3
Target shape model: Ellipsoid
Position vector of surface intercept in the IAU_MARS frame (km):
X = 2525.201
Y = -2042.104
Z = -987.770
Planetocentric coordinates of the intercept (degrees):
LAT = -16.917
LON = -38.962
Phase angle (degrees): 50.708
Solar incidence angle (degrees): 43.585
Emission angle (degrees): 7.413
Observer visible: true
Sun visible: true
Target shape model: DSK/Unprioritized
Position vector of surface intercept in the IAU_MARS frame (km):
X = 2525.506
Y = -2042.289
Z = -987.874
Planetocentric coordinates of the intercept (degrees):
LAT = -16.917
LON = -38.961
Phase angle (degrees): 50.708
Solar incidence angle (degrees): 42.457
Emission angle (degrees): 8.593
Observer visible: true
Sun visible: true
Vector: Boundary Corner 4
Target shape model: Ellipsoid
Position vector of surface intercept in the IAU_MARS frame (km):
X = 2535.149
Y = -2028.558
Z = -990.170
Planetocentric coordinates of the intercept (degrees):
LAT = -16.960
LON = -38.666
Phase angle (degrees): 48.208
Solar incidence angle (degrees): 43.871
Emission angle (degrees): 4.769
Observer visible: true
Sun visible: true
Target shape model: DSK/Unprioritized
Position vector of surface intercept in the IAU_MARS frame (km):
X = 2535.423
Y = -2028.741
Z = -990.263
Planetocentric coordinates of the intercept (degrees):
LAT = -16.960
LON = -38.665
Phase angle (degrees): 48.208
Solar incidence angle (degrees): 44.387
Emission angle (degrees): 4.297
Observer visible: true
Sun visible: true
Vector: TGO NOMAD LNO Nadir Boresight
Target shape model: Ellipsoid
Position vector of surface intercept in the IAU_MARS frame (km):
X = 2530.122
Y = -2035.307
Z = -989.188
Planetocentric coordinates of the intercept (degrees):
LAT = -16.942
LON = -38.814
Phase angle (degrees): 49.457
Solar incidence angle (degrees): 43.729
Emission angle (degrees): 6.086
Observer visible: true
Sun visible: true
Local Solar Time at boresight intercept (24 Hour Clock):
14:51:36
Target shape model: DSK/Unprioritized
Position vector of surface intercept in the IAU_MARS frame (km):
X = 2530.471
Y = -2035.529
Z = -989.307
Planetocentric coordinates of the intercept (degrees):
LAT = -16.942
LON = -38.813
Phase angle (degrees): 49.457
Solar incidence angle (degrees): 44.387
Emission angle (degrees): 5.462
Observer visible: true
Sun visible: true
Local Solar Time at boresight intercept (24 Hour Clock):
14:51:36
Extra Credit
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