Sea Launch User's Guide

Ground processing
and transportation–second
phase
Following encapsulation in the PLF, the spacecraft environment is maintained
with a continuous, conditioned air supply. Air is ducted to the PLF
thermal conditioning inlet diffuser (fig. 5-15), and exits to the DM-SL
cavity through vent valves on the payload structure.
Air conditioning units on the spacecraft transporter, ACS, and LP are
dedicated to maintaining spacecraft environments within the PLF during
processing and handling at Home Port, in the ACS, and while in transit to
the launch site. The LP integrated launch vehicle (ILV) air conditioning
system satisfies conditioned air requirements of the PLU, Block DM-SL,
and boost vehicle on the launch pad during prelaunch phases. The flow
from the LP ILV air conditioning system is terminated at approximately
L-17 min (on retraction of the transporter/erector and separation of the
LV umbilicals). Conditioned airflow to the PLF is maintained through
the remainder of the countdown (and through an abort recycle operation)
by way of the LP high-pressure PLF purge system.
PLU environmental control system inlet conditions and control capabilities
are summarized in table 5-6. All air conditioning systems maintain
positive pressure inside the PLF to prevent air-transported contaminants
from entering the PLF. Air quality is maintained by providing purge air
that has been high efficiency particulate air (HEPA) filtered to class-
5,000 maximum per FED-STD-209E.
PLF volume
PLF
flight vents
Payload structure
PLS vents
(one-way valves)
Block
DM-SL
Block DM flight vents
Block DM-SL vents
IC vent
Spacecraft
Sidewall
diffuser
PLU thermostating
inlet (up to 5100 m 3 /hr)
Block DM
thermostating inlet
(5100 m 3 /hr)
IC
thermostating
inlet
(2000 m 3 /hr)
Zenit-2SL IC
IC membrane vents
Note: Drawing not to scale.
265807J3-010R4
Figure 5-15. Payload Unit Air Conditioning Venting Scheme
5-18 D688-10009-1 REV B