Notetaker: Electrical Power Subsystem

Question 1

Identify

Generates, stores and distributes power throughout the spacecraft

Subsystem

Answer 1

Electrical Power Subsystem (EPS)

Question 2

Identify

Most common source of power for earth orbit satellite

Answer 2

Solar Panels

Question 3

What are the solar panel configurations?

Answer 3

• Body Mounted
• Sun Tracking
• Roll Out

Question 4

Identify

Simpler and more robust, but less effective at producing power

Solar Panel Configurations

Answer 4

Body Mounted

Question 5

Identify

Not always within visibility of the sun; only capable of producing limited power for limited time

Solar Panel Configurations

Answer 5

Body Mounted

Question 6

Identify

Effective for spin-stabilized satellites with lower power requirements

Solar Panel Configurations

Answer 6

Body Mounted

Question 7

Identify

More complex than body mounted solars panels

Solar Panel Configurations

Answer 7

Sun Tracking

Question 8

Identify

Provides higher level of power-to-weight efficiency, compared to body mounted

Solar Panel Configurations

Answer 8

Sun Tracking

Question 9

Identify

Successfully tested 2017 on ISS, can be deployed and retracted

Solar Panel Configurations

Answer 9

Roll Out

Question 10

Identify

20% lighter, 4x smaller, boost

Solar Panel Configurations

Answer 10

Roll Out

Question 11

What are the Solar Panel Deployments?

Answer 11

• Low Cycle
• High Cycle

Question 12

Identify

Exploding Bolts Solar Arrays

Solar Panel Deployment

Answer 12

Low Cycle

Question 13

Identify

Deployed once and are never retracted (for sun-tracking solar panels)

Solar Panel Deployment

Answer 13

Low Cycle

Question 14

Identify

Repeatable Deployment Solar Arrays

Solar Panel Deployment

Answer 14

High Cycle

Question 15

Identify

High strain composite boom on both sides of solar arrays use stored energy, no motor, to change from a coil shape into a support arm

Solar Panel Deployment

Answer 15

High Cycle

Question 16

Identify

Can use a motor to retract solar array

Solar Panel Deployment

Answer 16

High Cycle

Question 17

Identify

Roll-out Solar Array

Solar Panel Deployment

Answer 17

High Cycle

Question 18

Identify

Solar cells produce most power when directly facing the sun; perpendicular to source of radiation

Solar Panel Operations

Answer 18

Incidence Angle

Question 19

Identify

Incidence angle and materials directly effect effectiveness of solar cells

Solar Panel Operations

Answer 19

Efficiency

Question 20

What are the two tasks of Solar Array Drive Mechanism (SADM)?

Answer 20

• Positioning: Positions solar arrays to face the sun as directly as possible
• Tracking: Constantly operate to track the sun while spacecraft maintains operational, earth-pointing attitude

Solar Array Drive Mechanism (SADM) is also “how to maintain it” in terms of solar panels.

Question 21

What are the two tasks of Sun Sensors?

Answer 21

• Evaluation: Solar cells produce most power when directly facing the sun; perpendiculat to source of radiation
• Determination: Incidence angle and materials directly affect effectiveness of solar cells

Sun Sensors are also “how to get feedback” in terms of solar panels.

Question 22

Identify

Supply power to components when needed

Answer 22

Batteries

Question 23

Identify

Capable of more power than batteries wired in parallel

Battery Configuration

Answer 23

Series

Question 24

Identify

If a single cell fails, the entire series of cells is nonfunctional

Battery Configuration

Answer 24

Series

Question 25

# Identify Hold a charge longer than batteries in series ## Footnote Battery Configuration

Answer 25

Parallel

Question 26

# Identify Inherently redundant; failure of a single cell will not affect any other cells which require higher temperatures ## Footnote Battery Configuration

Answer 26

Parallel

Question 27

# Identify First battery used in space ## Footnote Battery Cell Material

Answer 27

Nickel Cadmium (NiCd)

Question 28

# Identify Large and susceptible to memory effect ## Footnote Battery Cell Material

Answer 28

Nickel Cadmium (NiCd)

Question 29

# Identify Store a relatively small amount of power relative to mass and volume ## Footnote Battery Cell Material

Answer 29

Nickel Hydrogen (NiH2)

Question 30

# Identify Solved the memory effect issue ## Footnote Battery Cell Material

Answer 30

Nickel Hydrogen (NiH2)

Question 31

# Identify Not susceptible to memory effect ## Footnote Battery Cell Material

Answer 31

Lithium Ion (Li-ion)

Question 32

# Identify Significantly lighter and more efficient than Nickel Hydrogen batteries ## Footnote Battery Cell Material

Answer 32

Lithium Ion (Li-ion)

Question 33

# Identify Highly volatile and have the potential to explode if exposed to extreme heat or pressure ## Footnote Battery Cell Material

Answer 33

Lithium Ion (Li-ion)

Question 34

# Identify During an eclipse: Solar arrays are unable to produce power, so batteries must be used to continue satellite operations ## Footnote Battery Use and Material

Answer 34

Operational Usage

Question 35

# Identify When power demand is greater than generation: Batteries temporarily supplement until power load is decreased ## Footnote Battery Use and Material

Answer 35

Operational Usage

Question 36

# Identify The life of battery is repeatedly overcharged, it builds up electrolyte crystals on the cathodes; results in lower discharge voltage ## Footnote Battery Use and Material

Answer 36

Voltage Depression

Question 37

# Identify Combated by only charging the batteries when they need to be charged and stopping when they are fully charged ## Footnote Battery Use and Material

Answer 37

Voltage Depression

Question 38

# Identify Mitigate effects of memory effect, voltage depression, and deep discharge ## Footnote Battery Use and Material

Answer 38

Reconditioning

Question 39

# Identify Process of completely discharging then recharging ## Footnote Battery Use and Material

Answer 39

Reconditioning

Question 40

What is responsible for allocating power in the correct voltages and current to the rest of the satellite?

Answer 40

Power Management Distribution (PMaD) System

Question 41

What is the process of prioritizing components and shutting off power to less vital components?

Answer 41

Load Shedding