Doug... wrote:


Just one minor nit, Pat. The seasonal change is, indeed, responsible
for a lowering in the amount of sunlight getting to the solar cells, but
it doesn't have a lot to do with how high the sun gets in the sky. The
height of the sun at zenith isn't changing a whole lot yet -- remember,
both rovers are located near the equator.

What's making a really significant difference is that, as Mars heads
into southern summer and northern winter, it's also moving away from
periapsis and towards apoapsis. Since Mars' orbital eccentricity is
currently *much* greater than Earth's, that means that the change in the
solar energy reaching the ground on Mars between periapsis and apoapsis
is *far* greater.


Works fine as to total hours of sunlight per season, but not as fine as
regards the Sun in position in the sky for any rover that has solar
arrays facing straight up toward the zenith of the heavens; only at the
periods balanced between the two seasons of the two Martian hemispheres
does the light fall upon the solar arrays at a near perpendicular angle.
Equinoxes good.
Movement toward the solstices bad.

Pat