11.   Controllers ordered a shutdown of the errant fuel cell, which combines supercold liquid hydrogen and liquid oxygen to make electricity and water.

12.   Engineers also were looking at the quality of the liquid oxygen propellant used in the shuttle Thursday.

13.   Inside the HumVee, the two workers were equipped with spare air tanks as well as liquid oxygen.

14.   Launch controllers resumed the countdown, but they called it off seconds later because too much liquid oxygen propellant had drained away during the countdown hold.

15.   One possible use is rocket fuel in the form of liquid hydrogen or liquid oxygen, derived from hydrogen and oxygen atoms in the water.

16.   Over the last decade, scientists noticed that a special kind of honeycombed silicon will burn explosively when exposed to nitric acid or liquid oxygen.

17.   The company makes liquid oxygen, nitrogen and other gases for manufacturing and health care industries.

18.   The devices combine supercold liquid hydrogen and liquid oxygen to generate electrical power.

19.   The fuel cell mixes liquid oxygen and hydrogen to produce electricity for the shuttle.

20.   The propellants are liquid oxygen and liquid hydrogen.