[Spice_discussion] SPICE versus windows

[Henry DeWitt]

Ed:

I am using Visual Studio 6 with all service packs installed.  I am 
running on Windows XP at the moment.  I am currently using the most 
recent release of SPICE (6.2) but had the same problem with the previous 
release.

I have an application which controls a satellite ground station.  One 
station it is used at (Johns Hopkins University Applied Physics 
Laboratory) plans to use SPICE kernels to track Chandrayaan.  The SPICE 
code will be part of a DLL that is loaded at run time.

I did have to make some minor changes to SPICE to get it to compile and 
link (exclude a few routines, a couple of defines changed).

My problem is as follows:

I can load the planetary ephemeris (de418.bsp) and the leap seconds 
kernel.  With these loaded, I can successfully calculate antenna 
pointing angles for the Moon.  I can also load a spacecraft kernel as 
long as it is loaded after the planetary ephmeris (I am testing with 
Stereo) and still track the Moon.  However,  if I try to track Stereo, 
SPICE stops returning valid information for anybody (i.e. if I reset my 
body ID to the Moon, it also gets invalid data).

When I first change the tracked object to Stereo, I get the message:

Insufficient ephemeris data has been loaded to compute the state of -235 
(STEREO BEHIND) relative to 0 (SOLAR SYSTEM BARYCENTER) at the ephemeris 
epoch Epoch before 5879611 B.C. JUN 24 00:00:00.000.

Subsequent calls get the messages (The software attempts to use the 
backup object when failure occurs):


Insufficient ephemeris data has been loaded to compute the state of 301 
(MOON) relative to 0 (SOLAR SYSTEM BARYCENTER) at the ephemeris epoch 
2008 MAY 28 16:01:30.184.

and

Insufficient ephemeris data has been loaded to compute the state of -235 
(STEREO BEHIND) relative to 0 (SOLAR SYSTEM BARYCENTER) at the ephemeris 
epoch 2008 MAY 28 16:01:31.184.

According to spacit, the Stereo kernel has valid data from Apr 16, 2008 
to Aug 28, 2008.

My suspicion is that the initial failure is leaving things in an invalid 
state.  It is not clear why the first message has such a bizarre time, I 
pass the current time to spkez_c.  I am able to get Stereo state 
information when running a Windows Console application.

I also use SPICE calls to determine coverage of the current time and 
always get an indication that it is covered, even after I am getting 
error messages.

Henry

Ed Wright (JPL) wrote:
> To: Henry DeWitt
> From: Ed Wright
>
> On May 28, 2008, at 6:17 AM, Henry DeWitt wrote:
>
>> I have been able to use SPICE in a windows console application, but 
>> am having
>> difficulties when I try to incorporate it into a MS Windows DLL for 
>> use in a
>> Windows application.  Does anyone have any experience with this?
>>
>> Henry DeWitt
>
> Can you provide more information concerning these difficulties?
> In particular, which compiler do you use, which computer platform/OS,
> and which toolkit SPICELIB (Fortran) or CSPICE (C)?
>
> As always,
> Ed Wright
> ed.wright at jpl.nasa.gov
> 1-818-354-0371
>