Thermal Control

Requirements

• Define high level diagram of thermal control• Identify major components required• Define system and hardware requirements

sufficiently to allow future thermal control architecture definition and hardware trade studies

• Passive Thermal Control– Multilayer Insulation (MLI)– Surface Finishes

• Active Thermal Control– Panel (strip) heaters

• Closed switch controlled by PRTs (Platinum Resistance Thermometers) monitoring optimal temperature for spacecraft components

• Used to heat hydrazine thrusters before initial burns

Structures | Propulsion | GN&C | Telecommunications | Carla 3

Basic Hardware Required

Thermal Control

Structures | Propulsion | GN&C | Telecommunications | Carla 4

Assume Passive Thermal Control

Calculated Temperature of Equipment and

Spacecraft

PRT Monitor Equipment

Temperature

Panel Heating ON/OFF

Activate Heat for Thrusters

Plume Protection Trade StudyMaterial Basic

InformationPros Cons

Molybdenum Alloys

Used in turbine blades

Meets temperature requirements

Unsure of space worthiness

PICA Used as heat shield for entry into Earth/Mars atmospheres

Light weight, used in previous space missions

Unsure of cost

Plume Protection Trade Study Cont.

Molybdenum PICA

Density Okay Good

Space worthiness Unknown Good

Temperature Appropriate

Good Good

Basic Material Properties

Molybdenum Alloy (TZM)• Density of 10.22 g/cm3

• Melting temperature 2610 degrees C• Can retain integrity until at least 1300 degrees C

PICA (ablative material) (Phenolic Impregnated Carbon Ablators)• Used on heat shield of Stardust Sample Return Capsule• Designed by Lockheed Martin• Density of 0.224- 0.321 g/cm3

• Withstand at least 2700 degrees C

WILL UPDATE SLIDE WITH JUST ONE APPROPRIATE MATERIAL