Advanced materials with large and dynamic variation in thermal properties, sought for urgent defense and space applications, have heretofore been elusive. Conducting polymers (CPs) have shown some intrinsic variation of mid‐ to far‐infrared (IR) signature in this respect, but the practical utilization of this has remained elusive. We report herein the first significant IR electrochromism in any material, to our knowledge, in the 0.4 through 45 μm region. This is seen in practical CP devices in the form of thin (<0.5 mm), flexible, entirely solid‐state, variable area (1 cm2 to 1 m2) flat panels. Typical properties include: very high reflectance variation; switching times <2 s; cyclabilities of 105 cycles; emittance variation from 0.32 to 0.79; solar absorptance variation from 0.39 to 0.79; operating temperatures of –35 to +85 °C; durability against γ‐radiation to 7.6 Mrad, vacuum to 10–6 torr, and simulated solar wind (e.g., 6.5 × 1016 e/cm2 @ 10 keV).

Technology development is inevitably a dynamic process in search of an elusive goal. It is never truly clear whether the need for a particular technology drives its development, or the existence of a new capability initiates new applications. Technology development for the thermal control of spacecraft presents an excellent example of this situation.Nevertheless, it is imperative to have a basic plan to help guide and focus such an effort.Although this plan will be a living document that changes with time to reflect technological developments, perceived needs, perceived opportunities, and the everchanging funding environment, it is still a very useful tool. This presentation summarizes the current efforts at NASNGoddard and NASNJPL to develop new thermal control technology for future robotic NASA missions.Kev Words: advanced thermal control, capillary pumped loops, loop heat pipes, variable emissivity surface, cryogenic, heat switches, thermal storage

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The Mars Science Laboratory (MSL 1) mission to land a large rover on Mars is being planned for Launch in 2009. As currently conceived, the rover would use a Multimission Radioisotope Thermoelectric Generator (MMRTG) to generate about 110 W of electrical power for use in the rover and the science payload. Usage of an MMRTG allows for a large amount of nearly constant electrical power to be generated day and night for all seasons (year around) and latitudes. This offers a large advantage over solar arrays. The MMRTG by its nature dissipates about 2000 W of waste heat to produce 110 W of electrical power. The basic architecture of the thermal system utilizes this waste heat on the surface of Mars to maintain the rover's temperatures within their limits under all conditions. In addition, during cruise, this waste heat needs to be dissipated safely to protect sensitive components in the spacecraft and the rover. Mechanically pumped fluid loops 2 are used to both harness the MMRTG heat during surface operations as well as reject it to space during cruise. This paper will describe the basic architecture of the thermal control system, the challenges and the methods used to overcome them by the use of an innovative architecture to maximize the use of heritage from past projects while meeting the requirements for the design. MISSION OVERVIEW CRUISE CONFIGURATION-While the MSL mission is still in the earliest stages of its design cycle, the mission will follow the general design paradigm of the previous JPL rover missions to Mars (Mars Pathfinder, MPF 3 and Mars Exploration Rovers, MER 4). MSL will feature a rover enclosed in an aero-shell for protection during entry and descent onto the planet's surface. A cruise stage will carry the lander and aero-shell enclosure from Earth to Mars and will separate from the lander just prior to entry, descent and landing (EDL). Figure 1 shows a rendering of the rover packed into the aero-shell enclosure with the cruise stage attached at the top.

One of the new technologies successfully demonstrated on the recent Mars Pathfinder mission was the active Heat Rejection System (HRS). This system consisted of a mechanicaily pumped cooling loop, which actively controlled the temperatures of the various parts of the spacecraft. A single phase Refrigerant 11 liquid was mechanically circulated through the lander and cruise electronics box heat exchangers. This liquid transferred the excess heat to an external radiator on the cruise stage. This is the first time in unmanned spacecraft history that an active heat rejection system of this type has been used on a long duration spacecraft mission. Pathfinder was launched in December 1996 and landed on the Martian surface on July 4, 1997. The system functioned flawlessly during the entire seven months of flight from Earth to Mars. A life test set up of the cooling loop was used to verify the life of the system. The life test system was run for over 14, 000 hours before complete examination of the components used in the life test was made. Some of the components used in the system were tested in the life test set up. The results from the life test loop indicate no major issues that would hinder the pumped loop operation for many more years.