JOSH STAMPS ROBIN HEGEDUS THERMAL SUBSYTEM JOSH STAMPS ROBIN HEGEDUS

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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