Uncle Al wrote:
JKF wrote:

I'm very interested in physic and the big picture of space, it's
amazing. Anyhow I'm not a professor or any kind of professional. I
just
want to find out a little more about EVERYTHING. Just keep me
posted on
any discoveries. Please mail me @

(contributed by Dave Typinski)

Apollo 13 was screwed by a safety check of an O2 tank's internal
heater thermostat. KSC got re-engineered for 65-Volt power half way
through the space program. Somehow, North American never upgraded
the
old 28-Volt heater thermostats in the Apollo Service Modules.

Apollos XI and XII both had the 28-Volt thermostats, but their tank
heaters were never used on the pad. Apollo XIII's O2 Tank 2
thermostat *was* used on the pad (to empty the tank by boiling off
the
LOX), at 65 volts, and thus had its wiring's insulation fricasseed.


Note that the cause of the fricasee was that the thermostat contacts
fused on.

Having bare, charged wires in an O2 tank is bad juju. When Jack
Swigert turned on the O2 Tank 2 heater half way to the Moon, the
thermostat wires sparked - and you know the rest. Or so says Not A
Space Agency...


Actually it was the stirring motor that he turned on. Personally, I
think it's bad juju to have any electrical wires inside a LOx tank.

Paul Cardinale