The comprehensive spacecraft testing continues through this week.
This photo shows one step in the qualification of the quick disconnect
joints (QD). The QD connects the cryostat's safety vent to the safety vent
attached to the L-1011 carrier aircraft during the captive carry portion of
the Pegasus launch. If the cryostat were to warm and vent hydrogen during
captive carry, this system will carry the hydrogen to a safe location
where it will vent to the atmosphere. The QD breaks at drop, and a door
covers the hole in the Pegasus fairing. The QD must go through a thorough
qualification program since it is part of this safety critical system. Forty
QD's were built by the same process at the same time from the same lot of
material; we test the entire lot, some to failure, to ensure that any of the
five units we call "flight" will do its job. This photo shows a QD undergoing
vibration testing. The bellows at the top is the load-isolation system which
flys on the L-1011. The QD is the straight piece of pipe in the middle with
instrumentation wires attached. The notch in the pipe is not readily visible.
The pipe is designed to break at the notch. Below the QD is the angled
bracket representing the output of the cryostat safety vent. It is attached
to a mass which is instrumented for control of the vibration levels.
These three photos were taken during the fairing fit check at Orbital in
Chandler, AZ. The engineering test unit (ETU) structure and the instrument
thermal simulator were used to represent the spacecraft. The center photo
shows the inside of one half of the fairing. The right photo shows the
spacecraft mated to the Pegasus third stage (inert model) and ready for the
fairing. The fit check went well, and the team got some practice installing
the QD and load isolation system.
These photos show the instrument aperture shade during its thermal balance
testing. We verified that the inside of the shade will run cold enough during
flight.
These photos show the thermal coatings on the Pegasus separation ring.
This is the half of the separation system which stays with the spacecraft
after launch. In the right photo, Grace Miller and John Petro display their
handiwork. The thermal coatings ensure that the ring will not get too hot in
the sun or too cold in the shade.
Previous updates:
August 18, 1997
October 20, 1997
October 31, 1997
November 7, 1997
November 14, 1997
November 21, 1997
December 5, 1997
December 23, 1997
January 9, 1998
January 16, 1998
January 23, 1998
January 30, 1998
February 6, 1998
February 20, 1998
March 12, 1998
March 23, 1998
April 3, 1998
April 20, 1998
April 25, 1998
May 29, 1998
June 3, 1998
June 17, 1998