This document summarizes the SPICE Toolkit, a software library that interprets data from NASA space science missions. The toolkit was initially developed in FORTRAN in 1982 but has since been ported to C and other languages. While the C API is complex, third-party wrappers like SpiceRub have created more intuitive interfaces in languages like Ruby. SpiceRub provides Ruby classes and methods that abstract away the low-level C API. It can be used to calculate values like the distance between objects in space using SPICE kernel data from past and current NASA missions.

1. Wrapping NASA's CSPICE Toolkit
Gaurav Tamba

2. What is SPICE
● 1982 – Archival treatment of data returned from NASA's
Space Science Missions
● Software that can correctly interpret the data from space
science instruments was commissioned
● FORTRAN was the initial deployment
● F2C , converted it to a C API
No improvement in API, FURNSH became furnsh_c

3. Relevance of SPICE Today
● Missions that are still ongoing and recently completed still
have their data archived for the SPICE Toolkit
● Toolkit still maintained, has a new port to Matlab, but still no
high level language.
● Many 3rd Party wrappers exists in Python (SpiceyPy,
spiceminer)
● In general a non software programmer wouldn't want to
deal with the idiosyncrasies of a language like FORTRAN
or C (Like a space researcher)

4. After a really lengthy explanation of the required programming
details :-

5. Basic Wrapper Hierarchy : SpiceRub
Middle layer doesn't really provide much functionality, simply a
direct port of C to Ruby to map C datatypes to Ruby objects.
The top layer has a more intuitive Ruby API

6. How bad the C API can get ...

7. Some SPICE Terminology :-
● Kernels :- Archived data files in either binary or text format
that contains data from past and ongoing space flight missions
Ephemeris :- An object in space that is being observed
geometrically. (Can be a planet, satellite, star or even an
instrument attached to a spacecraft!)
SPICE is a complex combination of routines that serve a rich
variety of use cases, with a very DULL API. (IMO)
● furnsh_c (“Furnish” or load kernels)
● spkpos_c (Gets a position vector referencing an SPK kernel)

8. Some abstracted objects
● SpiceRub::Body
SpiceRub::Time
SpiceRub::KernelPool
SpiceRub::SpiceKernel

9. Using NMatrix as a storage container
● Mxvg : Multiply matrix with a vector
● Vsub : Subtract two vectors
● Vdot : Inner Dot product of two vectors
● Vrss : Cross product of two vectors
●
Porting these can be ommitted since NMatrix has inbuilt and
optimized methods for these calculations

10. ● Vector2 [x , y , z]
● Vector1 [0, 0 , 0]
● SquareRoot(X^2 + Y^2 + Z^2) gets you the distance from
origin.

11. How far is the moon from us??
[
[ 105119748.94398701] [-100394985.79680407] [-43522737.335541375] ]
]
395791.1464913574 (Km)
( Google says 384,400 Km =) )

12. Thank You
https://github.com/gau27/spice_rub
● Many thanks to my mentors from SciRuby
@mohawkjohn
@sstewart26
@zverok
@v0dro