Variations in the orbital parameters of Mars

Does there exist any software or algorithms for determining the
eccentricity, obliquity, and longitude of perihelion for Mars as a
function of year?

A similar item was developed by NASA's Goddard Institute of Space
Studies for Earth, <http://aom.giss.nasa.gov/srorbpar.html>.

I would be using these parameters as part of an solar insolation
model.

For my undergraduate senior project, I am building upon the work done
is this paper, <http://www.pnas.org/cgi/content/full/98/5/2132>. They
combined Viking pressure and temperature data with Mars Orbital Laser
Altimeter topography data, and computed the fraction of the martian
year during which pressure and temperature allow for liquid water to
be stable on the martian surface.

As for my research, I want to test for stability of water-salt
solutions, < http://www.spacedaily.com/news/mars-water-science-00a.html>
at different stages of Mars's orbital variation
<http://www.aas.org/publications/baas/v33n3/dps2001/310.htm>.


Some secondary, unrelated questions:

Does anyone know where I can find the equations for the vaporization
and melting curves of water in the range of 0-100 millibar and 173K to
313K?

Also, given a variable distance, r, between Mars and the Sun what is
the
equation for the solar insolation on the cross section of Mars
perpendicular to the incoming solar radiation?