The insulating properties of the vacuum of space are examined in this
paper. Generic electrode configurations are introduced to calculate th
e leakage current to the electrodes and the breakdown potential of the
''space-vacuum'' as a function of altitude above ground. The conditio
n that defines the breakdown threshold is dependent on the size of the
sheath, r(L-B), relative to the interelectrode separation, r(e). Resu
lts for the leakage currents and breakdown voltage are presented for b
oth cases r(L-B) > r(e) and r(L-B) < r(e), and discussed in the contex
t of space power systems and the SPEAR Program in particular.