KPL/IK
MAVEN SWIA Instrument Kernel
===============================================================================
This Instrument Kernel (IK) file contains parameters for the MAVEN
SWIA (Solar Wind Ion Analyzer) instrument.
Version and Date
-------------------------------------------------------------------------------
Version 1.0 -- January 14, 2014 -- Jasper Halekas, MAVEN P&F Team
References
-------------------------------------------------------------------------------
1. Kernel Pool Required Reading
2. GETFOV, getfoc_c, cspice_getfov headers
3. MAVEN FK file, latest version
4. "The Solar Wind Ion Analyzer for MAVEN", J.S. Halekas, et al., Space Science
Reviews, DOI 10.1007/s11214-013-0029-z, in press, 2014.
Contact Information
-------------------------------------------------------------------------------
Jasper Halekas, MAVEN P&F Team, 510-643-4310, jazzman@ssl.berkeley.edu
Implementation Notes
-------------------------------------------------------------------------------
This file is used by the SPICE system as follows: programs that make
use of this kernel must ``load'' the kernel, normally during program
initialization. The SPICE routine FURNSH loads a kernel file into
the pool as shown below.
CALL FURNSH ( 'frame_kernel_name; ) -- FORTRAN
furnsh_c ( "frame_kernel_name" ); -- C
cspice_furnsh, frame_kernel_name -- IDL
cspice_furnsh( 'frame_kernel_name' ) -- MATLAB
Once the file has been loaded, the SPICE routine GETFOV (getfov_c in
C, cspice_getfov in IDL and MATLAB) can be used to retrieve FOV
parameters for a given instrument or structure.
This file was created and may be updated with a text editor or word
processor.
Naming Conventions
----------------------------------------------------------
All names referencing values in this IK file start with the
characters `INS' followed by the NAIF MAVEN ID number (-202)
followed by a NAIF three digit ID code for SWIA or one of
its detectors or components. This is the full list of names
and IDs described by this IK file:
MAVEN_SWIA_BASE -202140
MAVEN_SWIA -202141
MAVEN_SWIA_SWTSPOT -202142
MAVEN_SWIA_FRONT -202143
MAVEN_SWIA_BACK -202144
The remainder of the keyword name is an underscore character
followed by the unique name of the data item. For example, the -202142
boresight direction provided as a part of its FOV definition is
specified by:
INS-202142_BORESIGHT
The upper bound on the length of the name of any data item is 32
characters.
If the same item is included in more than one file, or if the same
item appears more than once within a single file, the latest value
supersedes any earlier values.
Mounting Alignment
--------------------------------------------------------
Refer to the latest version of the MAVEN Frames Definition Kernel
(FK) [3] for the MAVEN structures reference frame definitions and
mounting alignment information. Briefly, the SWIA instrument
is deck-mounted, with its X-axis aligned with the spacecraft
Z-axis (nominally sunward), its Y-Axis aligned opposite the
spacecraft X-axis (+X S/C is nominally nadir-ward), and its
Z-axis aligned opposite the spacecraft Y-axis (along the axis
of the solar panels). This diagram illustrates the s/c and SWIA frames:
+Z s/c side:
------------ ._____. APP
\_____|
|
|
| +Xsc
| ^
._________._________..-----|-----.._________._________.
| | || .--|--. || | |>
MAG .-| | +Ysc / | || | |-. MAG
< | | <-------o || | | >
`-| | | \ || | |-'
<|_________|_________|HGA`-----' ||_________|_________|
`----------'o------->
.-' | ` | +Zswia
.-' | | -.
.-' @ | `-.
.-' SWEA V `-.
LPW .-' +Yswia `-. LPW
+Zsc and +Xswia are out of the page.
Instrument and Data Product Description
---------------------------------------------------------
The Solar Wind Ion Analyzer (SWIA) is an electrostatic analyzer that
measures energy per charge of incident solar wind ions with a nominal
field of view of 360 degrees (covered by 24 anodes) by 90 degrees
(covered by electrostatic deflection). The undeflected field of view
lies in the spacecraft X-Z plane, which is the SWIA X-Y plane. The
~sunward direction (spacecraft Z, SWIA X) is covered by 10 4.5-degree
anodes, and the rest of the field of view is covered by 14 22.5-degree
anodes.
This diagram illustrates the undeflected anode layout:
^ +Zswia
Undeflected | -Ysc
360 deg FOV |
(-Xswia) (-Yswia) (+Xswia) (+Yswia) (-Xswia)
(-Zsc) (+Xsc) (+Zsc) (-Xsc) (-Zsc)
Phi = -180 -90 0 +90 +180
| | | | |
| | | | |
.--.-- --.--.--.--.--.-----.--.--.--.--.--.--.--.
'--'--'--'--'--'--'--'--o--'--'--'--'--'--'--'--'
7 x 22.5 deg anodes 7 x 22.5 deg anodes
/ \
/ \
Undeflected 45 deg / 10 x 4.5-deg \
sweet-spot FOV .-.-.-.-.-.-.-.-.-.-.
'-'-'-'-'-o-'-'-'-'-'
| | |
| | |
Phi= -22.5 0 +22.5
(+Xswia)
(+Zsc)
The nominal energy range is ~5-25000 eV. For energies up to
~4.75 keV, deflection covers the full 90 degree angular range; however,
for energies above this threshold, angular coverage is proportionally
reduced.
This diagram illustrates the full deflected FOV detector layout for
energies up to ~4.75 keV:
^ +Zswia
Full deflected | -Ysc
360 x 90 deg FOV |
(-Xswia) (-Yswia) (+Xswia) (+Yswia) (-Xswia)
(-Zsc) (+Xsc) (+Zsc) (-Xsc) (-Zsc)
Phi = -180 -90 0 +90 +180
| | | | | Theta =
.--.--.--.--.--.--.--.-----.--.--.--.--.--.--.--. --- +45
'--'--'--'--'--'--'--' '--'--'--'--'--'--'--'
'--'--'--'--'--'--'--' '--'--'--'--'--'--'--'
'--'--'--'--'--'--'--' '--'--'--'--'--'--'--'
'--'--'--'--'--'--'--' '--'--'--'--'--'--'--'
'--'--'--'--'--'--'--' '--'--'--'--'--'--'--'
'--'--'--'--'--'--'--' '--'--'--'--'--'--'--'
'--'--'--'--'--'--'--' '--'--'--'--'--'--'--'
'--'--'--'--'--'--'--' '--'--'--'--'--'--'--'
'--'--'--'--'--'--'--' '--'--'--'--'--'--'--'
'--'--'--'--'--'--'--' '--'--'--'--'--'--'--'
'--'--'--'--'--'--'--' '--'--'--'--'--'--'--' 24
'--'--'--'--'--'--'--' o '--'--'--'--'--'--'--' --- 0 3.75 deg
'--'--'--'--'--'--'--' '--'--'--'--'--'--'--' deflection
'--'--'--'--'--'--'--' '--'--'--'--'--'--'--' steps
'--'--'--'--'--'--'--' '--'--'--'--'--'--'--'
'--'--'--'--'--'--'--' '--'--'--'--'--'--'--'
'--'--'--'--'--'--'--' '--'--'--'--'--'--'--'
'--'--'--'--'--'--'--' '--'--'--'--'--'--'--'
'--'--'--'--'--'--'--' '--'--'--'--'--'--'--'
'--'--'--'--'--'--'--' '--'--'--'--'--'--'--'
'--'--'--'--'--'--'--' '--'--'--'--'--'--'--'
'--'--'--'--'--'--'--' '--'--'--'--'--'--'--'
'--'--'--'--'--'--'--' '--'--'--'--'--'--'--'
'--'--'--'--'--'--'--'-----'--'--'--'--'--'--'--' --- -45
7 x 22.5 deg anodes 7 x 22.5 deg anodes
/ \
/ \
Theta =
Full deflected / 10 x 4.5-deg \
45 x 90 deg .-.-.-.-.-.-.-.-.-.-. --- +45
sweet-spot FOV '-'-'-'-'-'-'-'-'-'-'
'-'-'-'-'-'-'-'-'-'-'
'-'-'-'-'-'-'-'-'-'-'
'-'-'-'-'-'-'-'-'-'-'
'-'-'-'-'-'-'-'-'-'-'
'-'-'-'-'-'-'-'-'-'-'
'-'-'-'-'-'-'-'-'-'-'
'-'-'-'-'-'-'-'-'-'-'
'-'-'-'-'-'-'-'-'-'-'
'-'-'-'-'-'-'-'-'-'-' 24
'-'-'-'-'-'-'-'-'-'-' 3.75 deg
'-'-'-'-'-o-'-'-'-'-' --- 0 deflection
'-'-'-'-'-'-'-'-'-'-' steps
'-'-'-'-'-'-'-'-'-'-'
'-'-'-'-'-'-'-'-'-'-'
'-'-'-'-'-'-'-'-'-'-'
'-'-'-'-'-'-'-'-'-'-'
'-'-'-'-'-'-'-'-'-'-'
'-'-'-'-'-'-'-'-'-'-'
'-'-'-'-'-'-'-'-'-'-'
'-'-'-'-'-'-'-'-'-'-'
'-'-'-'-'-'-'-'-'-'-'
'-'-'-'-'-'-'-'-'-'-'
'-'-'-'-'-'-'-'-'-'-' --- -45
| | |
Phi= -22.5 0 +22.5
(+Xswia)
(+Zsc)
The Fine 3d product consists of counts from the 10 4.5-degree anodes,
for 48 energies and 12 deflection steps surrounding the peak count rate.
In other words, the Fine 3d product returns counts from the 4.5-degree
anodes, but only those counts for half of the energy steps and half of the
deflection steps. The energy and deflection steps returned are framed around
the location of the peak count rate. In other words, this data product tracks
the peak count rate in phase space. This is particularly useful for the solar
wind, because most of the counts are localized in a narrow region of phase
space around the supersonic proton beam.
The following diagram illustrates the coverage of this product in angle, for
a nominal centered framing of the peak [if the peak is close to the edge
of the full theta range it may not be centered, and the framing of the peak
is configurable], and assuming energies < 4.75 keV. The coverage of the
product moves in theta and energy as the peak moves in the field of view.
.-.-.-.-.-.-.-.-.-.-. --- [theta_peak + 22.5] < 45
'-'-'-'-'-'-'-'-'-'-'
'-'-'-'-'-'-'-'-'-'-'
'-'-'-'-'-'-'-'-'-'-'
'-'-'-'-'-'-'-'-'-'-' 12
'-'-'-'-'-'-'-'-'-'-' 3.75 deg
'-'-'-'-'-o-'-'-'-'-' --- theta_peak deflection
'-'-'-'-'-'-'-'-'-'-' steps
'-'-'-'-'-'-'-'-'-'-'
'-'-'-'-'-'-'-'-'-'-'
'-'-'-'-'-'-'-'-'-'-'
'-'-'-'-'-'-'-'-'-'-'
'-'-'-'-'-'-'-'-'-'-' --- [theta_peak - 22.5] > -45
| | |
Phi= -22.5 0 +22.5
(+Xswia)
(+Zsc)
This results in a product with 10 phi x 12 theta x 48 energies. The level 2
data files contain 96x24 theta directions (in MAVEN_SWIA coordinates), and
10 phi directions (in MAVEN_SWIA coordinates), along with the index of the
starting energy step and deflection step for the actual 48 energies and 12
thetas. At some times, only the 6 phi x 8 theta x 32 energies forming the
center of this fine distribution are telemetered. In this case, the level 2
metadata files still contain 10x12x48 values, with the edges filled with zeros,
to simplify data analysis for the end user. Care should be taken to note
the binning mode of the data, also specified in the level 2 data files.
The Coarse 3d product consists of the counts for the 14 22.5-degree anodes,
plus the 10 4.5-degree anodes summed into two 22.5-degree groups, energy
steps summed in pairs, and deflection steps summed in groups of six, to
provide a data product with 16 phi x 4 theta x 48 energies. This product
therefore covers all of the phase space accessible to SWIA, but with
more coarse resolution than the Fine 3d product. Therefore, this product
is more useful for regions inside Mars' bow shock, where the distribution
tends to be hotter and more thermalized, as well as subsonic. For this
product, the 48x4 theta directions (in MAVEN_SWIA coordinates), and the
16 phi directions (in MAVEN_SWIA coordinates), are provided in the level 2
metadata file.
This diagram illustrates the full deflected coarse FOV detector layout for
energies up to ~4.75 keV:
^ +Zswia
Full deflected | -Ysc
360 x 90 deg FOV |
(-Xswia) (-Yswia) (+Xswia) (+Yswia) (-Xswia)
(-Zsc) (+Xsc) (+Zsc) (-Xsc) (-Zsc)
Phi = -180 -90 0 +90 +180
| | | | | Theta =
.--.--.--.--.--.--.--.-----.--.--.--.--.--.--.--. --- +45
| | | | | | | | | | | | | | | | |
| | | | | | | | | | | | | | | | |
'--'--'--'--'--'--'--'--'--'--'--'--'--'--'--'--'
| | | | | | | | | | | | | | | | | 4
| | | | | | | | | | | | | | | | | 22.5 deg
'--'--'--'--'--'--'--'--o--'--'--'--'--'--'--'--' --- 0 summed-up
| | | | | | | | | | | | | | | | | deflection
| | | | | | | | | | | | | | | | | steps
'--'--'--'--'--'--'--'--'--'--'--'--'--'--'--'--'
| | | | | | | | | | | | | | | | |
| | | | | | | | | | | | | | | | |
'--'--'--'--'--'--'--'--'--'--'--'--'--'--'--'--' --- -45
7 x 22.5 deg anodes / \ 7 x 22.5 deg anodes
/ \
2 summed-up 22.5 deg
sectors
+Xswia and +Zsc are
out of the page.
At some times, the 48 energies are summed into either 24 or 16
energy bins. At these times, we resample the 24 or 16 bins into 48 elements,
to simplify data analysis for the end user. Care should be taken to note
the binning mode of the data, also specified in the level 2 data files.
SWIA also computes moments onboard for the ion distribution, including
density, temperature, and velocity. Finally, summed energy spectra (48
energy bins) are computed onboard and telemetered. For these final two
products, the fields of view are not necessary.
SWIA has a mechanical attenuator, actuated automatically in response to
peak count rate, that provides a factor of ~15 attenuation in the ~sunward
portion of the field of view, with full attenuation in the Fine 3d field
of view, a gradual reduction beyond that, reducing to no attenuation in
the ~anti-sunward (-Z in spacecraft coordinates) hemisphere. The attenuator
status is provided in all level 2 data files.
Instrument Detector/Sensor Layout
----------------------------------------------------------
24 anodes cover look directions in the spacecraft X-Z plane (SWIA X-Y plane),
with 10 4.5 degree anodes covering angles symmetrically around the nominal sun
direction (Spacecraft +Z, MAVEN_SWIA +X), and an additional 14 22.5 degree
anodes covering the rest of the 360 degrees. The field of view covered
by the 10 small anodes is defined as the "Sweet Spot", and the counts from
these anodes are contained in the Fine 3d distributions, and also summed into
two groups in the Coarse 3d distributions. The particle velocity
directions corresponding to the center angles of these anodes are contained
in the level 2 metadata files for coarse and fine 3d data products, as defined
in MAVEN_SWIA coordinates. Electrostatic deflection allows us to
cover angles up to 45 degrees in either direction (+/-Z in MAVEN_SWIA
coordinates) from this 2-d FOV. This electrostatic deflection depends on the
sweep table loaded in the instrument, and can change. The theta angles
corresponding to each deflection bin are contained in the level 2 metadata files
for coarse and fine 3d data products, as a function of energy.
Instrument Pixel-to-3D Coordinate Mapping
----------------------------------------------------------
The pixel to 3d-coordinate mapping is defined in the level 2 metadata files,
since it is energy-dependent, and thus depends on the sweep table loaded in the
instrument. The phi angle mapping of the anodes (in MAVEN_SWIA coordinates) is
independent of the sweep, but the deflection (theta) angles depend on energy.
This energy dependence implies that the look directions depend on sweep table,
so we do not define individual look angles in this kernel, but instead define
them in the level 2 metadata files. These look angles will be defined in terms of
instrument phi and theta, in the MAVEN_SWIA coordinate frame, and are
referenced in terms of particle velocity directions, rather than look angles.
In other words, the phi and theta defined in the l2 files are the complement
of the look direction. This simplifies the calculation of the moments
of the ion distribution for the end user, if applied correctly.
As an example, for a normal sun-pointing orientation, in the MAVEN-SWIA
coordinates, the sun is at (phi = 0, theta = 0). As a result, the nominal
solar wind velocity (neglecting aberration) is at (phi = 180, theta = 0).
The nominal solar wind lies in the sweet spot field of view, which is
covered by Fine 3d distributions. The Fine 3d distributions thus have
look directions within 22.5 degrees in phi from 0, and within 45 degrees
in theta from 0; however, the velocity angles listed in the level 2
data files will be within 22.5 degrees in phi from 180, and within
45 degrees in theta from 0.
Instrument Detector/Sensor Parameters
----------------------------------------------------------
All relative sensitivities are defined in the relevant level 2 metadata files.
Also, level 2 data files contain both raw counts and calibrated differential
energy fluxes, providing a consistency check on the data and geometric factors.
Instrument FOV Definition(s)
----------------------------------------------------------
This section defines the following FOVs:
ID SHAPE FRAME SIZE1 SIZE2 BSIGHT
------- -------- --------------------- ----- ----- ------
-202142 POLYGON MAVEN_SWIA 45. 90. +X
-202143 POLYGON MAVEN_SWIA 179.9 90. +X
-202144 POLYGON MAVEN_SWIA 179.9 90. -X
The FOVs are defined in this data block. The "SWTSPOT" FOV is the
FOV telemetered in the Fine 3d product, and should contain the
solar wind for nominal spacecraft orientations. The "FRONT" and "BACK"
FOVs cover the nominal maximum Coarse field of view envelope, valid for
energies up to ~4.75 keV (reduced in theta coverage for higher energes),
with "FRONT" covering the sunward-looking hemisphere, and "BACK" covering
the anti-sunward-looking hemisphere.
This diagram illustrate SWIA FOVs relative to the s/c and SWIA frames:
-Y s/c side:
------------
+Xswia
^ Sweetspot FOV
_ | _ (45x90)
Front FOV . \ | /.
(180x90) / \ | / \
| \|/ | .___.
+Yswia <--------o------ --.===========| .' APP
| | | `-'
Back FOV \ / +Zsc|
(180x90) ` _ _ _ ' ^ |
| |
| | |
.-.-----|-----'
.-'.' `- x------->
.-' .' +Xsc
.-' @
LPW .-' SWEA
+Ysc is into the page.
+Zswia is out of the page.
This diagram illustrate each of the SWIA FOVs relative SWIA frame:
Front FOV:
----------
Front FOV Front FOV
boresight boresight
+Xswia +Xswia
^ ^
| Theta= |
|0 -45 |0 +45
_..--+--.._ .-------------------.
.' | '. |, | .|
.' | '. | `. | .' |
/ | \ | `. | .' |
Phi= . | . | `. | .' |
+90| | |-90 | `.|.' |
<----+-----------o-----------+- ---+---------o---------+--->
+Yswia | +Zswia +Yswia | +Zswia
| |
Back FOV:
---------
+Xswia +Xswia
^ ^
| |
Phi= . .
+90 | -90 |
<----+-----------o-----------+- ---+---------o---------+--->
+Yswia | | +Zswia | | +Yswia.'|`. | +Zswia
' | ' | .' | `. |
\ | / | .' | `. |
'. | .' | .' | `. |
'. _ | _ .' |' | `|
''--+--'' `-------------------'
180 | -45 |0 +45
V Theta= V
Back FOV Back FOV
boresight boresight
Sweet spot FOV:
---------------
Sweet spot FOV Sweet spot FOV
boresight boresight
+Xswia +Xswia
^ ^
| Theta= |
|0 -45 |0 +45
Phi= _..--+--.._ .-------------------.
22.5 \ | / -22.5 `-------------------'
\ | / `. | .'
\ | / `. | .'
\ | / `. | .'
\|/ `.|.'
<----------------o------------- -------------o------------->
+Yswia | +Zswia +Yswia | +Zswia
| |
The sweet spot is defined as a polygon.
The front-looking and rear-looking FOVs are also defined as polygons. There
is a very small phi portion (~0.2 deg) not contained in either of these FOV;
however, that FOV is blocked by the solar panel and mounting foot of the
instrument anyway.
\begindata
INS-202142_FOV_SHAPE = 'POLYGON'
INS-202142_FOV_FRAME = 'MAVEN_SWIA'
INS-202142_BORESIGHT = ( 1.0, 0.0, 0.0 )
INS-202142_FOV_BOUNDARY = (
0.653281 0.270598 0.707107
0.679471 0.195752 0.707107
0.697116 0.118445 0.707107
0.705994 0.0396478 0.707107
0.705994 -0.0396478 0.707107
0.697116 -0.118445 0.707107
0.679471 -0.195752 0.707107
0.653281 -0.270598 0.707107
0.653281 -0.270598 -0.707107
0.679471 -0.195752 -0.707107
0.697116 -0.118445 -0.707107
0.705994 -0.0396478 -0.707107
0.705994 0.0396478 -0.707107
0.697116 0.118445 -0.707107
0.679471 0.195752 -0.707107
0.653281 0.270598 -0.707107
)
INS-202143_FOV_SHAPE = 'POLYGON'
INS-202143_FOV_FRAME = 'MAVEN_SWIA'
INS-202143_BORESIGHT = ( 1.0, 0.0, 0.0 )
INS-202143_FOV_BOUNDARY = (
0.00000 0.707107 0.707107
0.146935 0.691672 0.707107
0.287456 0.646041 0.707107
0.415427 0.572206 0.707107
0.525262 0.473391 0.707107
0.612167 0.353910 0.707107
0.672346 0.218977 0.707107
0.703173 0.0744855 0.707107
0.703302 -0.0732583 0.707107
0.672727 -0.217804 0.707107
0.612783 -0.352841 0.707107
0.526088 -0.472474 0.707107
0.416425 -0.571481 0.707107
0.288583 -0.645538 0.707107
0.148142 -0.691414 0.707107
0.00123403 -0.707106 0.707107
0.00123403 -0.707106 -0.707107
0.148142 -0.691414 -0.707107
0.288583 -0.645538 -0.707107
0.416425 -0.571481 -0.707107
0.526088 -0.472474 -0.707107
0.612783 -0.352841 -0.707107
0.672727 -0.217804 -0.707107
0.703302 -0.0732583 -0.707107
0.703173 0.0744855 -0.707107
0.672346 0.218977 -0.707107
0.612167 0.353910 -0.707107
0.525262 0.473391 -0.707107
0.415427 0.572206 -0.707107
0.287456 0.646041 -0.707107
0.146935 0.691672 -0.707107
0.00000 0.707107 -0.707107
)
INS-202144_FOV_SHAPE = 'POLYGON'
INS-202144_FOV_FRAME = 'MAVEN_SWIA'
INS-202144_BORESIGHT = ( -1.0, 0.0, 0.0 )
INS-202144_FOV_BOUNDARY = (
-0.00123439 -0.707106 0.707107
-0.148142 -0.691414 0.707107
-0.288583 -0.645538 0.707107
-0.416425 -0.571481 0.707107
-0.526088 -0.472474 0.707107
-0.612783 -0.352841 0.707107
-0.672727 -0.217804 0.707107
-0.703302 -0.0732583 0.707107
-0.703173 0.0744855 0.707107
-0.672346 0.218977 0.707107
-0.612167 0.353910 0.707107
-0.525263 0.473391 0.707107
-0.415427 0.572206 0.707107
-0.287456 0.646041 0.707107
-0.146935 0.691672 0.707107
0.00000 0.707107 0.707107
0.00000 0.707107 -0.707107
-0.146935 0.691672 -0.707107
-0.287456 0.646041 -0.707107
-0.415427 0.572206 -0.707107
-0.525263 0.473391 -0.707107
-0.612167 0.353910 -0.707107
-0.672346 0.218977 -0.707107
-0.703173 0.0744855 -0.707107
-0.703302 -0.0732583 -0.707107
-0.672727 -0.217804 -0.707107
-0.612783 -0.352841 -0.707107
-0.526088 -0.472474 -0.707107
-0.416425 -0.571481 -0.707107
-0.288583 -0.645538 -0.707107
-0.148142 -0.691414 -0.707107
-0.00123439 -0.707106 -0.707107
)
\begintext
End of the IK file.