Orbital Antares - Manual (Page 70)

Antares
®
OSP-3
User’s Guide
Section 7.0
– Ground and Launch Operations
Release 1.1 July 2013 59
using abbreviated timelines. All aspects of the team’s performance are exercised, as well as simulated
holds, scrubs, and recycle procedures. The operations and team performance are evaluated and lessons
learned are incorporated prior to the MDR.
The MDR is performed 2 days before vehicle roll-
out to certify the launch team’s readiness for launch.
The MDR is the final rehearsal prior to entering countdown operations, and ensures that any issues en-
countered during the launch dress rehearsal have been resolved. The MDR is typically a half day in du-
ration and is a key criterion for approving launch readiness.
7.5.3. Launch Countdown
Orbital’s launch countdown operations are designed to methodically transition the vehicle and launch site
from a safe state to that of launch readiness (Figure 7.5.3-1). Payload tasks are integrated into the
launch countdown operations, as required, as coordinated by the Antares Launch Conductor. Launch
countdown operations begin 24 hours prior to launch (L-24:00), after positive readiness response from
Antares and Range personnel.
Stage 1 core commodity loading operations commence at T-5.5 hours. After fueling operations are com-
plete, Orbital transitions the vehicle from a safed to a launch-ready state (i.e., on internal power, final FTS
destruct test, safe and arms rotated to ―Armed,‖ open loop telemetry, etc.) through controlled steps. A
final launch readiness poll is performed to verify that the team is ―Go‖ for launch. At T-3 minutes, the au-
to-sequence is started and the sequencing of the vehicle (except for abort functions) is controlled by the
on-board flight computer. Stage 1 engine ignition to 58% thrust level is initiated at L-0, after which the
flight computer performs an automated health check of each engine’s critical operating parameters. Once
the engine health is verified, the flight computer commands engine throttle up to 108% power coincident
with vehicle release from the pad.
Figure 7.5.3-1. Antares Launch from WFF