Thermal Control

Question 1

What is the responsibility of thermal control?

Answer 1

maintaining all of the items of a spacecraft with in their allowed temperature limits during all mission phases using minimum spacecraft resources

Question 2

What is the basic equation for thermal?

Answer 2

heat out = heat in plus heat generated

Question 3

What are three ways of heat transfer?

Answer 3

1. conduction
2. convection
3. radiation

Question 4

The possibilities with incident radiation is?

Answer 4

absorption (into material), alpha
transmission (through material), towe
reflection (off of material), rho

Question 5

What is a black body?

Answer 5

perfect absorption and emitter of radiation

Question 6

Emissivity is?

Answer 6

energy radiated by material / energy radiated by black body

Question 7

More reflective =

Answer 7

lower emissivity

Question 8

blacker material =

Answer 8

close to emissivity of 1 (black body)

Question 9

What are some sources of heat (heat in)

Answer 9

solar thermal radiation flux (1365 W/m^2)
solar albedo (about 30% of solar flux)
earth infrared flux (LEO 237 W/m^2)
dissipated power from bud and payload

Question 10

What is the equation for heat in?

Answer 10

heat in = earth radiation heat + solar heat rate + albedo heat rate

Question 11

What is heat in based off of?

Answer 11

absorption and area

Question 12

Heat generated is from?

Answer 12

electrical components

1. batteries
2. RF transmission
3. heat generated from I^2R loss

Question 13

What is the basic equation for heat out?

Answer 13

heat out = heat in + heat generated

Question 14

What is passive thermal control and give examples

Answer 14

used without control systems
examples
coatings
multi layer insulation
conductive paths
radiator panels (heat pipes, mirrors or reflectors)

Question 15

What is active thermal control and give examples

Answer 15

uses a power source
examples
heat pipes
fluid pumps
cryogenic cooling system
louvers
electric heaters