SO-50 will be 22 years old in December and seems to be still be going strong, in sunlight and in eclipse.  No other satellite launched since then has lived near that long.  So what is SO-50s key to long life?  Is it how the satellite was built?  Something in its operation, like lower power on transmit?  Its orbital setup?  

Any ideas why it has lived so much longer than the recent crop of AMSATS?

73 John AF5CC