Orbital Minotaur VI - Manual (Page 23)

Minotaur IV • V • VI User’s Guide Section 2.0 – Minotaur IV Configurations
2.3.3.1. Avionics
The Minotaur avionics system has heritage and commonality across the Minotaur fleet. The flight
computer is a 32-bit multiprocessor architecture. It provides communication with vehicle subsystems, the
LSE, and if required, the payload via standard RS-422 serial links and discrete I/O. The avionics system
design incorporates Orbital’s innovative, flight proven Modular Avionics Control Hardware (MACH). The
MACH consists of standardized, function-specific modules that are combined in stacks of up to 10
modules to meet mission requirements. The functional modules from which the MACH stacks are created
include power transfer, ordnance initiation, booster interface, communication, and telemetry processing.
These modules provide an array of functional capability and flexibility in mission tailoring.
2.3.3.2. Attitude Control Systems
The Minotaur IV Control System provides attitude control throughout both boosted flight and coast
phases. The Orbital-developed Booster Control Module (BCM) links the flight computer actuator
commands to the individual Thrust Vector Actuators (TVAs) located on each PK motor. The available
upper stage motors (Orion 38, STAR 48 and STAR 37) are commanded with the same Thrust Vector
Control (TVC) control methodology as Minotaur I. This control combines a single-nozzle
electromechanical TVC for pitch and yaw augmented with roll control from a three-axis, cold-gas Attitude
Control System (ACS) resident within the GCA. The cold-gas ACS also provides 3-axis control as
necessary during exoatmospheric coast and post-boost phases of flight.
Attitude control is achieved using a three-axis autopilot. Stages 1, 2 and 3 fly a pre-programmed attitude
profile based on trajectory design and optimization. Stage 4 uses a set of pre-programmed orbital
parameters to place the vehicle on a trajectory toward the intended insertion apse. An extended coast
between Stages 3 and 4 is used to orient the vehicle to the appropriate attitude for Stage 4 ignition based
upon a set of pre-programmed orbital parameters and the measured performance of the first three
stages. Stage 4 utilizes energy management to place the vehicle into the proper orbit. After the final boost
phase, the three-axis cold-gas attitude control system is used to orient the vehicle for spacecraft
separation, contamination and collision avoidance and downrange downlink maneuvers. The autopilot
design is modular, so additional payload requirements such as rate control or celestial pointing can be
accommodated with minimal development effort.
2.3.3.3. Telemetry Subsystem
The Minotaur IV telemetry subsystem provides real-time health and status data of the vehicle avionics
system, as well as key information regarding the position, performance and environment of the Minotaur
IV vehicle. This data is used by both Orbital and the range safety personnel to evaluate system
performance. The Minotaur IV baseline telemetry subsystem provides a number of dedicated payload
discrete (bi-level) and analog telemetry monitors through dedicated channels in the launch vehicle
encoder. The baseline telemetry system has a 1.5 Mbps data rate for both payload and Minotaur launch
vehicle telemetry. To allow for flexibility in supporting evolving mission requirements, the output data rate
can be selected over a wide range from 2.5 kbps to 10 Mbps (contingent on link margin and Bit Error
Rate (BER) requirements). The telemetry subsystem nominally utilizes Pulse Code Modulation (PCM)
with a RNRZ-L format. Other types of data formats, including NRZ-L, S, M, and Bi-phase may be
implemented if required to accommodate launch range limitations. Furthermore, the launch vehicle
telemetry system has the capability to take payload telemetry as an input, randomize if required, and
downlink that dedicated payload link from launch through separation. That capability is available as a
non-standard option.
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