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Section 4
Nitrogen compounds, caused by RCS and Auxiliary Propulsion Unit (APU) exhaust
product ingestion into the payload bay, were not detected.
Relative humidity during descent ranged from 15 to 25 percent. Air temperature in the
payload bay was 10° to 20° C.
TQCMs were used to measure deposition during descent. Levels on most of the
sensors rose steadily to a worst case of approximately 370 ng/cm2 for a +X sensor.
Deposition depended upon sensor location and axis. The -Y sensors decreased in
weight during descent.
Table 4.2.3.4-1. Descent particle measurement summary
Particle size
µm
Flight results
3
(µg/m )
>5
10
10
20
1 to 5
250
10
10
0.3 to 1
125
10
NF*
*NF - Nonfunctional
Optical (253 nm) transmittance losses of one percent were detected. Unfortunately, this
loss covered not only descent but also landing, ferry flight, and deintegration, a period of
about four weeks.
Table 4.2.3.4-2. Descent air sample summary
Species
Detection method
Flight results
Reactives
NO, NO2, NH3
Reaction with rutheniumtrichloride
surfaces
None detected to
ppm sensitivity
Volatile
hydrocarbons*
Concentration on absorbent; postflight
GC/MS analysis
20 ppm by weight
4 ppm by volume
*Covers C9 to C24 range and uses ~ C12 as average molecular weight to obtain ppm by volume
4.2.4
Mechanical
Significant loading of payload structure occurs during various Space Shuttle mission
events. Major mission events include lift-off, high-Q boost, SRB staging, main engine
cutoff, entry, and landing. Other events requiring consideration include on-orbit and
cargo handling loads. Sources of loading during these events include transient
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