DONE--SPS II Flashcards
Spacecraft Subsystems
Which portion of the satellite consists of subsystems and components that support the mission? (70% of the vehicle’s size?)
Bus
Which portion of the satellite accomplishes the mission? (30% of the vehicle’s size?)
Payload
Communication with the satellite through the bus?
Out-of-band
Communication with the satellite through the payload?
In-band
Satellite to satellite communication as a relay for up/downlink?
Cross-link
What is uplink used for?
Command
What is downlink used for?
Telemetry
What are the 2 communications subsystems?
- Telemetry, Tracking, & Commanding (TT&C)
- Commanding & Data Handling (C&DH)
What are the 2 control subsystems?
- Attitude Determination & Control (ADCS)
- Guidance, Navigation, & Control (GNC)
What is the collection of satellite subsystems performance, state of health data, and payload data which is transmitted to the RTS?
Telemetry
What is the reception and transmission of radiometric ranging signals received from and sent to the RTS?
Tracking
What is the reception of uplink commands for the operation of the satellite?
Command
What are the 3 components of the Telemetry, Tracking, and Commanding subsystem?
- Transmitters
- Receivers
- Antennas
Which subsystem processes, stores, and controls all ground commands, payload data, and telemetry during every phase of the mission?
Commanding & Data Handling
What are the 4 components of the C&DH?
- CPU
- Memory
- Links
- Software
What element receives, validates, demodulates, and distributes commands to the other spacecraft subsystems?
Command Decoder
What element gathers, processes, and formats spacecraft housekeeping and mission data for downlink or use by another subsystem?
Data Handling Unit
What are the 5 steps of a closed loop control system?
- Input
- Controller
- Actuator
- Output
- Feedback
Which subsystem is responsible for the satellite’s orientation and pointing?
Attitude Determination and Control
What are the 3 components of the Attitude Determination and Control subsystem?
- Controller
- Instruments
- Sensors
What are the 6 ADCS methods for determining attitude?
Eyes:
1. Earth sensors
2. Sun sensors
3. Star sensors
Inner ear:
4. Gyroscopes
5. Magnetospheres
Other:
6. Global Navigation Satellite System
What are the 6 attitude instruments?
Passive:
1. Gravity-gradient stabilization
2. Spin stabilization
3. Dampers
Active:
4. Thrusters
5. Magnetic torquers
6. Momentum-control device
Which subsystem is responsible for the satellite’s orbital position?
Guidance, Navigation, and Control (GNC)
Which portion of the GNC generates thrust in a specific direction?
Guidance
Which portion of the GNC determines orbital positioning using the velocity vector (V) and positional vector (R) derived from various sensors?
Navigation
Which portion of the GNC compares current versus desired position and velocity and sends commands to the actuators?
Control
What are the 3 on-board GNC methods for determining orbital positioning?
- Global Navigation Satellite System
- Earth, sun, and star sensors
- Inertial sensors
What are the 3 off-board GNC methods for determining orbital positioning?
- Remote Tracking System ranging
- Space Surveillance Network
- Space Domain Awareness
Which subsystem regulates and maintains temperature throughout the spacecraft?
Thermal Control Subsystem (TCS)
What are the 3 external heat sources?
- Direct sunlight
- Albedo
- Planetary infrared
What are the 2 internal heat sources?
- Internal electronics
- Isolated heat
What is the transfer of heat between substances in direct contact?
Conduction
What is the transfer of heat by means of a fluid (gas or liquid) away from the heat source?
Convection
What is the transfer of heat by electromagnetic waves?
Radiation
What are the 4 passive (open-loop) thermal controls?
- Thermal blankets
- Heat pipes
- Coatings
- Louvers
What are the 5 active (closed-loop) thermal controls?
- Heaters
- Radiators
- Refrigerators
- Pumps
- Louvers
Which subsystem generates, stores, and distributes power through the spacecraft?
Electrical Power Subsystem (EPS)
Which solar panel configuration is simpler, more robust, but less effective at producing power?
Body-mounted
Which solar panel configuration is more complex and provides a higher power-to-weight efficiency?
Sun-tracking
Which solar panel configuration can be deployed and retracted?
Roll out
Which type of solar panel mechanism uses exploding bolts?
Low cycle
Which type of solar panel configuration mechanism uses a motor and is repeatable?
High cycle
What mechanism constantly operates to track the sun and maintain the proper incidence angle for Earth/Space-pointing attitude?
Solar Array Drive Mechanism
What stores energy and supplies power to components as needed?
Batteries
What battery configuration increases battery voltage but maintains the same current and charge capacity as a single cell?
Wired in series
What battery configuration increases current and charge capacity but maintains the same voltage as a single cell?
Wired in parallel
Which battery cell material is susceptible to the Memory Effect (voltage depression caused by repeatedly discharging the battery to a fixed percentage)?
Nickel Cadmium
Which battery cell material is not susceptible to the Memory Effect but stores a relatively small amount of power relative to its mass-to-volume ratio?
Nickel hydrogen
Which battery cell material is not susceptible to the Memory Effect and is significantly lighter and more efficient?
Lithium ion
What is the result of buildup of large electrolyte crystals within the internal chemistry of the battery cell resulting in decreased discharge voltages which appears as decreased charge capacity?
Voltage depression
What is the discharge of a battery beyond the manufacturer’s specified lower voltage limit, but still above zero volts?
Deep discharge
What is the process of discharging the battery to the lower voltage limit then charging it at a controlled speed back to full charge without overcharging?
Reconditioning
What is responsible for allocating power in the correct voltages and currents to the rest of the satellite’s subsystems and payload?
Power Management and Distribution (PMAD)
What is the process of prioritizing components and shutting off power to less vital components to preserve energy?
Load shedding
Which subsystem involves the satellite frame, how the other subsystems are attached to the frame, and the threats the frame must face?
Structures
Which structure type has a specific shape with a honeycomb structure inside where equipment boxes attach?
Open truss
Which structure type attaches equipment directly to the structure and has no specific shape?
Body-mounted
Which structure type has a specific shape with some equipment attached to the exterior?
Combined
What are the 4 types of structural load?
- Tension
- Compression
- Shear
- Torsion
What are the 4 causes of structural load?
- Acceleration
- Vibration
- Pyrotechnic Shock
- Thermal stress
What are the 2 effects of structural load?
- Stress - load is applied as pressure, force per area
- Strain - temporary deformation due to applied load
What are the 5 space hazards to the structural subsystem?
- Thermal radiation
- Space vacuum
- Micrometeroids and debris
- Charged particle radiation
- Atomic oxygen
What is the rocket which supplies the necessary acceleration needed to transport the satellite into it’s temporary or final orbit?
Launch vehicle
What is the process of detecting, identifying, observing, and measuring an object without making direct contact?
Remote sensing
What type of remote sensing measures and records energy that is externally produced off-board? Examples: Electro-Optical Sensors and Infrared Sensors
Active
What type of remote sensing measures and records energy that it produces on-board? Example: Synthetic Aperture Radar
Passive
What are the 5 classifications of payload sensors, their type, and energy used?
- Electro-Optical - passive - EM light
- Radar - active - microwaves
- Infrared - passive or active - IR energy
- SATCOM - passive and active - radio frequency
- PNT - passive - radio frequency
