1. JOSH STAMPS ROBIN HEGEDUS
THERMAL SUBSYTEM
JOSH STAMPS
ROBIN HEGEDUS

2. Colorado Space Grant Consortium
REQUIREMENTS
We must stay at or preferably below all budgeted items
Money
Needed to buy thermistors and various thermal control items
Mass
0.4 kg for main satellite
0.1 kg for tip-mass
Power
1.0 Watts during lit portion of orbit
0.2 Watts during eclipse
Colorado Space Grant Consortium

3. Colorado Space Grant Consortium
REQUIREMENTS
From other teams
We must keep various components within a specified temperature range specific to each component
Operational and non-operational ranges
ADCS -40 – 85oC
C&DH 0 – 70oC
Comm -20 – 60oC
Power 0 – 40oC
Structures -60 – 65oC
We also need to monitor the temperatures of components during flight
Colorado Space Grant Consortium

4. Colorado Space Grant Consortium
REQUIREMENTS
From us to others
We need C&DH to be able to take readings from the thermistors and give us a temperature as an output
We also need to be given operating temperatures for all of the components so we can remain in their operating temperature
Software will also be needed to create a program to convert the resistance from the thermistors to a temperature
Need thermal properties of all materials
Colorado Space Grant Consortium

5. Colorado Space Grant Consortium
THERMISTORS
Why do we need them?
Monitors the temperature of different components in the satellite during orbit.
Monitors the temperatures of the satellite during testing of the satellite to determine accuracy of the model.
What are they?
Non-linear resistors, which change resistance with the temperature
Colorado Space Grant Consortium

6. Colorado Space Grant Consortium
THERMISTORS
Power 9
Structures 5
Science 3
ADCS 4
C&DH 2
Comm
Tip-mass
Where are we going to put them?
They will be put on sensitive parts of the satellite
How many do we need?
We’ll need about 27
Could change depending on placement of items and if items are added
Colorado Space Grant Consortium

7. Colorado Space Grant Consortium
THERMISTORS
How will we get the data?
Thermistors
Interface Board
Multiplexer
A/D Converter
Flight Computer
Colorado Space Grant Consortium

8. Colorado Space Grant Consortium
THERMISTORS
What will we use?
Probably Getting it from BCcomponents
It’s cheap
Between 10K ohm and 100K ohm
High resistance to draw less current
Temperature range of -40 to 125 oC
Fits within required temperature range
Costs between $0.50 and $1.50 each
Colorado Space Grant Consortium

9. Colorado Space Grant Consortium
PHYSICAL MODEL
The first step in our model is establishing and defining nodes:
Colorado Space Grant Consortium

10. Colorado Space Grant Consortium
MODELING
SUPVIEW
Each of the nodes are defined by corners which are described with respect to a reference point currently selected as the absolute middle of the DINO satellite
This is then processed by a program called SUPVIEW provided by Bob Pulley at Ball Aerospace.
By the end of the modeling process this model will be run for both the inside and the outside of the satellite and each of the compartments it contains
Our error is generally about 10^ -6
Nodes and Corners
SUPVIEW
Fluxes
View Factors
Nodal
Dimensions
Colorado Space Grant Consortium

11. MODELING ASSUMPTIONS: FINDB6 Orbit Starting Day (Spring Solstice)
Orbit Ending Day (1 year later)
Universal time of launch (3600 Seconds)
Altitude (350 km)
Inclination (0-51)
Period (1.525 hours)
ASSUMPTIONS:
FINDB6
This program simulates its orbit in efforts to establish how much energy each node is exposed to due to:
SUN, EARTH IR, EARTH ALBEDO
This is where the coldest and hottest cases are established with respect to Inclination range.
FINDB6
INCIDENT ANGLES
FROM
SUN AND EARTH
Colorado Space Grant Consortium

12. MODELING ALBEDO ASSUMPTIONS:
Knowing incident angles of sun and earth on the satellite we can then estimate the amount of energy hitting each surface
This is where we establish two separate models for the absolute hottest and coldest orbits our satellite can be a part of, which is based on beta angles
Turns out the hottest case possible is actually a fully sunlit orbit, while the coldest is the case where the satellite spends most of its orbit behind the earth.
ASSUMPTIONS:
Solar and Earthshine Constants
Beta angles
Orbital Positions of Interest
SUPVIEW, FINDB6 outputs
ALBEDO
Energy Fluxes
per node
per orbital position
Colorado Space Grant Consortium

13. Colorado Space Grant Consortium
MODELING
REFLECT
Knowing how much energy each node is exposed to, it is essential to determine how much of this energy is absorbed and how much is emitted out of the material.
Node by node energy
Emmited and absorbed
FINDB6
Energy Emmitted
Energy Absorbed
Colorado Space Grant Consortium

14. Colorado Space Grant Consortium
MODELING
TAK III
This is the final program that will predict temperatures for each node at any time during the orbit
All information from previous programs are interfaced here into one model
Node to Node conductance values are calculated based on heat capacity and dimensions of each material represented by nodes
The internal model is combined with the external model however there are still two separate models for the hot and cold cases
Colorado Space Grant Consortium

15. Colorado Space Grant Consortium
PRELIMINARY RESUTLS
NODES
MIN
MAX
Top Side
-76 C
20 C
Bottom Side
Earth Face
-80 C
Sun Face
Leading Edge
-77 C
Airfoils (outside)
Airfoils (inside)
Trailing Edge
NODAL TEMP. RANGES FOR HOT CASE
With information presented today an internal model will be created which will give more accurate values and we’ll see that these ranges will change significantly
Colorado Space Grant Consortium

16. Colorado Space Grant Consortium
AFTER THE RESULTS
If the model and or tests show that the satellite does not keep the satellite within the required temperature range, some adjustments must be made to the satellite
We can use insulation such as MLI blankets to insulate the satellite or a radiator to radiate heat
White and black paint can be used to change absorptivity and emissivity of surfaces
Most other means of thermal control are out of our budget for weight, cost and power
Colorado Space Grant Consortium

17. Colorado Space Grant Consortium
CONCLUSION
More accurate models will be produced in the future to include the tip-mass
The current model will need to be fine tuned
More data from other teams are needed
Operating temperatures
Placement and dimensions of structures
Thermal properties
Colorado Space Grant Consortium