Orbital Minotaur I - Manual (Page 20)

Minotaur I User’s Guide Section 2.0 – Minotaur I Configurations
2.3.2.2. Attitude Control Systems
The Minotaur I Control System provides three-axis attitude control throughout boosted flight and coast
phases. Stages 1 and 2 utilize the Minuteman Thrust Vector Control (TVC) systems. The Stage 1 TVC is
a four-nozzle hydraulic system, while the Stage 2 system combines liquid injection for pitch and yaw
control with hot gas roll control. Stages 3 and 4 utilize the same TVC systems as Minotaur IV. They
combine single-nozzle electromechanical TVC for pitch and yaw control with a three-axis cold-gas
Attitude Control System (ACS) resident in the avionics section providing roll control.
Attitude control is achieved using a three-axis autopilot. Stages 1 and 2 fly a pre-programmed attitude
profile based on trajectory design and optimization. Stage 3 uses a set of pre-programmed orbital
parameters to place the vehicle on a trajectory toward the intended insertion apse. The 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 a modular object oriented software design, so additional payload requirements such as rate
control or celestial pointing can be accommodated with minimal additional development.
2.3.2.3. Telemetry Subsystem
The Minotaur I 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 I
vehicle. This data is used by both Orbital and the range safety personnel to evaluate system
performance. The Minotaur I 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.
The Enhanced Telemetry option as described in the Enhancements section 8.5 augments the existing
baseline telemetry system by providing a dedicated telemetry link with a baseline data rate of 2 Mbps.
This Enhanced Telemetry link is used to provide further insight into the mission environment due to
additional payload, LV, or experiment data acquisition requirements. Supplementary instrumentation or
signals such as strain gauges, temperature sensors, accelerometers, analog, or digital data can be
configured to meet payload mission-specific requirements.
An Over the Horizon Telemetry option can also be added to provide real-time telemetry coverage during
ground-based telemetry receiving site blackout periods. The Telemetry Data Relay Satellite System
(TDRSS) is used for this capability, and has been successfully demonstrated on past Minotaur missions.
Close to the time when telemetry coverage is lost by ground based telemetry receiving sites, the LV
switches telemetry output to the TDRSS antenna and points the antenna towards the designated satellite.
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