Chasing oxygen

The Infrared Space Observatory
(ISO) has detected Water inthe planetary nebula NGC7027. The ISO is
ideally suited for observations, since
it is outside the earth's atmosphere,
which acts a major absorber of
infrared radiations. Thus a major
advance has been made in solving
the "missing oxygen problem". The
amount of oxygen observed is only
half as much as one would infer
from solar observations. Theoretically, oxygen will exist mostly in the
form ofwater molecules and oxygen
gas. The ISO result has generated
considerable excitement in astronomers who are now waiting for more
results from ISO and other forth-
coming space missions to solve the
mystery of missing oxygen. (Nature,
March 21,1996).