QUESTION:
Could you please supply more information about the solar cells you are using
on both spacecraft - i.e. type, voltage, current, efficiency, and
degradation characteristics. Are they available for purchase? If so, where?

ANSWER from Guy Beutelschies on July 22, 1997:
The Pathfinder spacecraft had 3 solar arrays: the cruise stage array (which
was jettisoned along w/ the cruise stage hardware just before Mars
atmoshpere entry), the lander array (on the lander petals), and the small
rover array.

The solar arrays were built by ASEC Corp (now called Tecstar) in City of
Industry, Ca. Each array is made up of the same type of solar cell:

Cell:
2 x 4 cm
Gallium Arsenide on Germanium substrate
5.5 mil thick
ave efficiency of 18.3%

Cruise Array:
115 strings, w/ about 40 cells per string
total power 815 watts at 1 sun

Lander Array:
66 strings, w/ 22 cells per string
total power 490 watts at 1 sun
about 160 watts on Mars at noon

Rover Array:
13 strings, w/ 18 cells per string
total power 42 watts at 1 sun
about 15 watts on Mars at noon

The cells do degrade primarily due to exposure to the space radiation
environment, however for our short mission the degradation is very small. I
would suggest you contact Tecstar for information about purchasing the
cells.

Also, you may want to check out the Rover Power System Website:
http://mpfwww.jpl.nasa.gov/roverpwr/power.html