QUESTION:
Why doesn't the KAO fly in the Mesosphere?

ANSWER from Kurt Richter on October 18,1995:
Greetings from Alaska, Nick!  Your question is a good one.  First, I must
tell you that I was pretty lucky this summer.  I have always wanted to work
with NASA and to work with scientists ever since I was 6 years old when the
first Sputnik was launched.  Finally, this past summer, I was selected as
the FOSTER teacher from Alaska.  FOSTER stands for Flight Opportunity for
Science Teacher EnRichment.  So...I am a teacher/scientist/astronomer.  The
teacher part of me works with fifth graders in Fairbanks, Alaska.  The
astronomer/scientist part of me worked with NASA in San Francisco and
Hawaii aboard the KAO...the Kuiper Airborne Observatory.  We observed NGC
1068...a star cluster containing a suspected black hole.  We flew between
38,000 and 41,000 feet while making our observations.

It took us almost 5 hours to reach 41,000 feet.  That is because our plane
only has the kind of wing lift that a normal airplane would have.  Since it
is a large and heavy plane, it is configured so that it can take off and
land on standard military runways.  Perhaps if its wings were broader and
the plane were lighter, it might have been able to go a bit higher...

The mesosphere is a layer of the atmosphere extending roughly from 50 km
(30 miles) to 80 km (50 miles) above sea level.  It lies between a lower
region of the atmospere called the stratosphere and an upper region called
the thermosphere.

A U-2 is capable of flying at roughly 65,000...perhaps higher.  This only
puts it at about 12 miles...roughly 60% of the altitude it might need to
reach the mesosphere.

The plane that I flew in...a C-141...can accomplish its goal at much lower
altitudes.  What is needed is not height...but lack of moisture.  We
achieve that at 41,000 feet quite nicely.  It is what makes infrared
spectroscopic analysis possible, because the infrared part of the spectrum
is absorbed in the presence of water.  As soon as we reach a height where
there is a lack of moisture in the air so that we can perform our readings,
we have accomplished the task of getting to where we can do our work
without the expense of going higher.

Additionally...the atmosphere in the mesosphere is so thin that the cost of
fuel as well as the design of the plane make it far too costly to go that
high...when the job can be accomplished at the much lower altitude.

Thanks for the great question.

Sincerely,

Kurt