Orbital Antares - Manual (Page 77)

Antares
®
OSP-3
User’s Guide
Section 8.0
– Non-Standard Services
Release 1.1 July 2013 66
8.2. Conditioned Air
Conditioned air is included in the baseline vehicle cost and is described previously in Section 4.4. The
Nitrogen Purge and Enhanced Contamination Control enhancements complement this capability as de-
scribed in the enhancements in Section 8.3 and 8.6.
8.3. Nitrogen Purge
As an enhancement, Orbital provides a gaseous nitrogen purge to the payload after fairing encapsulation
through lift-off. This Antares nitrogen purge enhancement delivers gaseous nitrogen to system distribution
lines routed along the inner surface of the fairing to meet payload purge requirements. The Antares in-
strument purge supply system is equipped with flow rate metering that can be configured to meet payload
requirements for flow rate and particulate filtering. The flow rate metering equipment features a replacea-
ble metering orifice that can be selected to provide a purge system flow rate in the range of 0.01 to 25
Standard Cubic Feet Per Minute (SCFM). The system also includes a particulate filter and pressure
switches to continuously monitor and control system operation. The entire instrument system is precision
cleaned to IEST-STD-CC1246D, Level 100A. The purity of the GN
2
flowing through the system is certified
to meet Grade B cleanliness specifications as defined in MIL-P- 27401C. The Antares purge system’s
regulators are set to a desired flow rate during prelaunch processing, and power to the purge system is
controllable from the launch equipment vault and the launch control room. As such, the Antares purge
rate cannot be adjusted after the launch pad is cleared of personnel.
8.4. Additional Access Panel
As an enhancement, Orbital provides one additional access door of standard size, 610 mm by 610 mm
(24 in. x 24 in.), in the Antares fairing within the allowable door envelope defined in Section 5.1.2, as illu-
strated in Figure 5.1.2-1. The location of the fairing access door is documented within the mission-
specific ICD. Note that the additional door location must have a minimum axial distance between doors of
16.6 in. (422 mm), a minimum radial distance between doors of 14.6 degrees, and a minimum of 305 mm
(12 in.) between the access door edge and the fairing joint. Orbital performs analyses to verify the struc-
tural integrity of the fairing with the additional door in the desired location. The door location will be fur-
ther validated in the acceptance test of the flight fairing structure. If more than one additional door is re-
quired, this enhancement can be exercised multiple times provided the location restrictions defined above
are met.
8.5. Enhanced Telemetry
Orbital offers enhanced telemetry to provide for mission specific instrumentation and telemetry compo-
nents to support additional payload, LV, or experiment data acquisition requirements. This enhancement
provides a dedicated telemetry link with a baseline data rate of up to 3 Mbps for Antares. Additional in-
strumentation such as strain gauges, temperature sensors, accelerometers, analog data, and digital data
can be configured to meet mission specific requirements.
The first flight of the Antares vehicle included extensive instrumentation on a dedicated payload simulator
telemetry package. While this first-flight instrumentation is not included for operational missions, an en-
hanced telemetry package may be derived from the first-flight telemetry system design. Depending on a
specific mission’s desired measurements, development is necessary to design the encoder, cabling, and
software. Updates to the integration and test procedures are also necessary. Typical enhanced teleme-
try instrumentation includes accelerometers to capture high frequency transients such as shock and ran-
dom vibration, microphones to measure lift-off acoustics, and strain gages to determine flight loads.