Table of contents
CSPICE_SPKW09 writes a type 9 segment to an SPK file.
Given:
handle the file handle of an SPK file that has been opened for
writing.
[1,1] = size(handle); int32 = class(handle)
body the NAIF integer code for an ephemeris object whose state
relative to another body is described by the segment to be
created.
[1,1] = size(body); int32 = class(body)
center the NAIF integer code for the center of motion of the object
identified by body.
[1,1] = size(center); int32 = class(center)
frame the NAIF name for a reference frame relative to which the
state information for body is specified.
[1,c1] = size(frame); char = class(frame)
or
[1,1] = size(frame); cell = class(frame)
first,
last are, respectively, the start and stop times of the time
interval over which the segment defines the state of body.
[1,1] = size(last); double = class(last)
segid the segment identifier.
[1,c2] = size(segid); char = class(segid)
or
[1,1] = size(segid); cell = class(segid)
An SPK segment identifier may contain up to 40 characters.
degree the degree of the Lagrange polynomials used to interpolate
the states.
[1,1] = size(degree); int32 = class(degree)
All components of the state vectors are interpolated by
polynomials of fixed degree.
states contains a time-ordered array of geometric states (x, y, z,
dx/dt, dy/dt, dz/dt, in kilometers and kilometers per second)
of body relative to center, specified relative to frame.
[6,n] = size(states); double = class(states)
epochs an array of epochs corresponding to the members of the state
array.
[1,n] = size(epochs); double = class(epochs)
The epochs are specified as seconds past J2000, TDB.
the call:
cspice_spkw09( handle, body, center, frame, first, last, ...
segid, degree, states, epochs )
returns:
None.
See -Particulars for a description of the effect of this routine.
MAXDEG is the maximum allowed degree of the interpolating
polynomial.
The current value of MAXDEG is 15.
Any numerical results shown for this example may differ between
platforms as the results depend on the SPICE kernels used as input
and the machine specific arithmetic implementation.
1) Suppose that you have a time-ordered array of geometric states
of a new object that follows Phobos, with a delay of 1 hour,
in its orbit around Mars and are prepared to produce a segment
of type 09 in an SPK file. Create a new SPK file with this
segment. Use an existing SPK to create the input data for the
SPK segment.
Use the meta-kernel shown below to load the required SPICE
kernels.
KPL/MK
File: spkw09_ex1.tm
This meta-kernel is intended to support operation of SPICE
example programs. The kernels shown here should not be
assumed to contain adequate or correct versions of data
required by SPICE-based user applications.
In order for an application to use this meta-kernel, the
kernels referenced here must be present in the user's
current working directory.
The names and contents of the kernels referenced
by this meta-kernel are as follows:
File name Contents
--------- --------
mar097.bsp Mars satellite ephemeris
naif0012.tls Leapseconds
\begindata
KERNELS_TO_LOAD = ( 'mar097.bsp',
'naif0012.tls' )
\begintext
End of meta-kernel
Example code begins here.
function spkw09_ex1()
%
% Local parameters.
%
SPKNAM = 'spkw09_ex1.bsp';
DEGREE = 3;
MARS = 499;
NEPOCS = 800;
NOBJ = 403;
%
% Local variables.
%
epochs = zeros(NEPOCS,1);
states = zeros(6,NEPOCS);
%
% Load the input SPK file.
%
cspice_furnsh( 'spkw09_ex1.tm' );
%
% Convert the input UTC to ephemeris time
%
[et] = cspice_str2et( '2018 Apr 03 08:35' );
%
% Create the time-ordered array of geometric states,
% at unequal time steps.
%
time = et;
step = 60.0;
delta = 10.0;
for i=1:NEPOCS
[states(:,i), lt] = cspice_spkezr( 'PHOBOS', time, 'J2000', ...
'NONE', 'MARS' );
epochs(i) = time + 3600.0;
time = time + step ...
+ sin( cspice_halfpi * i / 2.0 ) * delta;
end
%
% Open a new SPK file, with 5000 characters reserved
% for comments.
%
ifname = 'Test SPK type 9 internal filename.';
[handle] = cspice_spkopn( SPKNAM, ifname, 5000 );
%
% Create a segment identifier.
%
segid = 'MY_SAMPLE_SPK_TYPE_9_SEGMENT';
%
% Write the segment.
%
cspice_spkw09( handle, NOBJ, MARS, 'J2000', ...
epochs(1), epochs(NEPOCS), segid, DEGREE, ...
states, epochs );
%
% Close the new SPK file.
%
cspice_spkcls( handle );
%
% Compute the state of Phobos as seen from Mars,
% 12 hours after the input UTC time.
%
et = et + 43200.0;
[state, lt] = cspice_spkezr( 'PHOBOS', et, 'J2000', ...
'NONE', 'MARS' );
fprintf( 'Phobos as seen from Mars at t0:\n' )
fprintf( ' Epoch (s): %19.5f\n', et )
fprintf( ' Position (km): %13.5f %13.5f %13.5f\n', ...
state(1), state(2), state(3) )
fprintf( ' Velocity (km/s): %13.5f %13.5f %13.5f\n', ...
state(4), state(5), state(6) )
fprintf( '\n' )
%
% Load the newly created kernel, and compute the state
% of the new object as seen from Mars, 13 hours after
% the input UTC time.
%
cspice_furnsh( SPKNAM );
et = et + 3600.0;
[state, lt] = cspice_spkezr( '403', et, 'J2000', 'NONE', 'MARS' );
fprintf( 'Object 403 as seen from Mars at t0 + 1h:\n' )
fprintf( ' Epoch (s): %19.5f\n', et )
fprintf( ' Position (km): %13.5f %13.5f %13.5f\n', ...
state(1), state(2), state(3) )
fprintf( ' Velocity (km/s): %13.5f %13.5f %13.5f\n', ...
state(4), state(5), state(6) )
%
% It's always good form to unload kernels after use,
% particularly in Matlab due to data persistence.
%
cspice_kclear
When this program was executed on a Mac/Intel/Octave6.x/64-bit
platform, the output was:
Phobos as seen from Mars at t0:
Epoch (s): 576059769.18566
Position (km): -7327.26277 2414.32655 5207.10638
Velocity (km/s): -0.94289 -1.89473 -0.39671
Object 403 as seen from Mars at t0 + 1h:
Epoch (s): 576063369.18566
Position (km): -7327.26277 2414.32655 5207.10638
Velocity (km/s): -0.94289 -1.89473 -0.39671
Note that after run completion, a new SPK file exists in
the output directory.
This routine writes an SPK type 09 data segment to the open SPK
file according to the format described in the type 09 section of
the SPK Required Reading. The SPK file must have been opened with
write access.
If any of the following exceptions occur, this routine will return
without creating a new segment.
1) If `frame' is not a recognized name, the error
SPICE(INVALIDREFFRAME) is signaled by a routine in the call
tree of this routine.
2) If the last non-blank character of `segid' occurs past index 40,
the error SPICE(SEGIDTOOLONG) is signaled by a routine in the
call tree of this routine.
3) If `segid' contains any nonprintable characters, the error
SPICE(NONPRINTABLECHARS) is signaled by a routine in the call
tree of this routine.
4) If `degree' is not at least 1 or is greater than MAXDEG, the
error SPICE(INVALIDDEGREE) is signaled by a routine in the
call tree of this routine.
5) If the number of states `n' is not at least degree+1, the
error SPICE(TOOFEWSTATES) is signaled by a routine in the call
tree of this routine.
6) If `first' is greater than or equal to `last', the error
SPICE(BADDESCRTIMES) is signaled by a routine in the call tree
of this routine.
7) If the elements of the array `epochs' are not in strictly
increasing order, the error SPICE(TIMESOUTOFORDER) is
signaled by a routine in the call tree of this routine.
8) If the first epoch, epochs(1), is greater than `first', the
error SPICE(BADDESCRTIMES) is signaled by a routine in the
call tree of this routine.
9) If the last epoch, epochs(n), where `n' is the number of
states, is less than `last', the error SPICE(BADDESCRTIMES) is
signaled by a routine in the call tree of this routine.
10) If any of the input arguments, `handle', `body', `center',
`frame', `first', `last', `segid', `degree', `states' or
`epochs', is undefined, an error is signaled by the Matlab
error handling system.
11) If any of the input arguments, `handle', `body', `center',
`frame', `first', `last', `segid', `degree', `states' or
`epochs', is not of the expected type, or it does not have the
expected dimensions and size, an error is signaled by the Mice
interface.
12) If the input vector arguments `states' and `epochs' do not
have the same dimension (n), an error is signaled by the Mice
interface.
A new type 9 SPK segment is written to the SPK file attached
to `handle'.
None.
MICE.REQ
NAIF_IDS.REQ
SPC.REQ
SPK.REQ
TIME.REQ
None.
J. Diaz del Rio (ODC Space)
-Mice Version 1.0.0, 26-NOV-2021 (JDR)
write SPK type_9 ephemeris data segment
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