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The Internal Active Thermal Control System (IATCS) aboard the International Space Station (ISS) contains an aqueous, alkaline fluid (pH 9.5±0.5) that aids in maintaining a habitable environment for the crew. Because microbes have significant potential to cause disease, adverse effects on astronaut health, and microbe-induced corrosion, the presence of both bacteria and viruses within IATCS fluids is of concern. This study sought to detect and identify viral populations in IATCS samples obtained from the Kennedy Space Center as a first step towards characterizing and understanding potential risks associated with them. Samples were concentrated and viral nucleic acids (NA) extracted providing solutions containing 8.87-22.67 μg NA per mL of heat transfer fluid. After further amplification viral DNA and cDNA were then pooled, fluorescently labeled, and hybridized onto a Combimatrix panvira 12K microarray containing probes for ∼1,000 known human viruses.

NASA's Exploration Mission program is planning for a return to the Moon in 2020. The Exploration Systems Mission Directorate (ESMD)'s Lunar Architecture Team (LAT) is currently refining their lunar habitat architectures. The Advanced Thermal Control Project at the Johnson Space Center, as part of the Exploration Technology Development Program (ETDP) is developing technologies in support of the future lunar missions. In support of this project, a trade study was conducted at the Jet Propulsion Laboratory on the mechanically pumped two-phase and single-phase thermal loops for lunar habitats located at the South Pole for the LAT II architecture. This paper discusses the various trades and the results for a representative architecture which shares a common external loop for the single and two-phase system cases.

The Trace Gas Analyzer (TGA, Figure 1) is a self-contained, battery-powered mass spectrometer that is designed for use by astronauts during extravehicular activities (EVA) on the International Space Station (ISS). The TGA contains a miniature quadrupole mass spectrometer array (QMSA) that determines the partial pressures of ammonia, hydrazines, nitrogen, and oxygen. The QMSA ionizes the ambient gas mixture and analyzes the component species according to their charge-to-mass ratio. The QMSA and its electronics were designed, developed, and tested by the Jet Propulsion Laboratory (1,2). Oceaneering Space Systems supported JPL in QMSA detector development by performing 3D computer for optimal volumetric integration, and by performing stress and thermal analyses to parameterize environmental performance.

A Small Loop Heat Pipe (SLHP) featuring a wick of only 1.27 cm (0.5 inches) in diameter has been designed for use in spacecraft thermal control. It has several features to accommodate a wide range of environmental conditions in both operating and non-operating states. These include flexible transport lines to facilitate hardware integration, a radiator capable of sustaining over 100 freeze-thaw cycles using ammonia as a working fluid and a structural integrity to sustain acceleration loads up to 30 g. The small LHP has a maximum heat transport capacity of 120 Watts with thermal conductance ranging from 17 to 21 W/°C. The design incorporates heaters on the compensation chamber to modulate the heat transport from full-on to full-stop conditions. A set of start up heaters are attached to the evaporator body using a specially designed fin to assist the LHP in starting up when it is connected to a large thermal mass.

Candidate Aeroshell Test models composed of a quasi-isotropic Carbon/Carbon(C/C) front face sheet (F/S), eggcrate core, C/C back F/S, Carbon Aerogel insulation, C/C radiation shield and the C/C close-out were constructed based on the analytical temperature predictions presented in Part One of this work[1]. The analytical results obtained for a simulated Mars entry of a 2.9 meter diameter cone shaped Carbon-Carbon Aeroshell demonstrated the feasibility of the design. These results showed that the maximum temperature the front F/S reached during the decent was 1752 °C with the resulting rear temperature reaching 326 °C in the thermal model. Part Two of this work documents the thermal modeling and correlation for the Mars Aeroshell test sample and fixture. A finite difference, SINDA/G, thermal math model of the test fixture and sample was generated and correlated to data from an arc jet test conducted at the NASA Ames Research Center's interactive heating facility.

As part of the Mars Exploration Rover (MER) project, the National Aeronautics and Space Administration (NASA) launched two rovers in June and July of 2003 and successfully landed both of them on Mars in January of 2004. The cruise stage of each spacecraft (S/C) housed most of the hardware needed to complete the cruise from Earth to Mars, including the propulsion system. Propulsion lines brought hydrazine propellant from tanks under the cruise stage to attitude-control thrusters located on the periphery of the cruise stage. Hydrazine will freeze in the propellant lines if it reaches temperatures below 1.7°C. Thermal control of the propulsion lines was a mission critical function of the thermal subsystem; a frozen propellant line could have resulted in loss of attitude control and complete loss of the S/C.

Thermal characterization was performed on a vapor compression heat pump using a novel, hybrid two phase loop design. Previous work on this technology has demonstrated its ability to provide passive phase separation and flow control based on capillary action. This provides high quality vapor to the compressor without relying on gravity-based phase separation or other active devices. This paper describes the subsequent work done to characterize evaporator performance under various startup scenarios, tilt angles, and heat loads. The use of a thermal expansion valve as a method to regulate operation was investigated. The effect of past history of use on startup behavior was also studied. Testing under various tilt angles showed evaporator performance to be affected by both adverse and favorable tilts for the given compressor. And depending on the distribution of liquid in the system upon startup, markedly different performance can result for the same system settings and heat loads.

Human exploration of Mars as well as unmanned sample return missions from Mars can benefit greatly from the use of propellants produced from the resources available from the atmosphere of Mars. The first major step of any in-situ propellant production (ISPP) system is to acquire carbon dioxide (CO2) from the Mars atmosphere and compress it for further chemical processing. One system that performs this step is called a Mars Atmosphere Acquisition and Compression (MAAC) unit. A simple prototype MAAC was developed by JPL as part of the Mars ISPP Precursor (MIP) experiment package for inclusion on the Mars 2001 Surveyor Lander. The MAAC consists of a valved enclosure packed with a sorbent material which selectively adsorbs CO2 from the Mars atmosphere (valves open), desorbs and compresses the acquired CO2 by heating (valves closed) and then delivers the pressurized CO2 to an oxygen generating system where the CO2 is electrolyzed to produce oxygen.

Progress on the delivery of the Vehicle Cabin Atmosphere Monitor (VCAM) is reported. VCAM is an autonomous trace-species detector to be used aboard the International Space Station (ISS) for atmospheric analysis. The instrument is based on a low-mass, low-power miniature preconcentrator, gas chromatograph, and Paul ion trap mass spectrometer (PCGC/MS) capable of measuring volatile constituents in a space vehicle or planetary outpost at sub-ppm levels. VCAM detects and quantifies 40 target compounds at their 180-day Spacecraft Maximum Allowable Concentration (SMAC) levels. It is designed to operate autonomously, maintenance-free, with a self-contained carrier and calibration gas supplies sufficient for a one-year lifetime. Two flight units will be delivered for operation in the ISS EXPRESS rack.

Work is underway to deliver an instrument for analysis of the atmosphere aboard the International Space Station. The Vehicle Cabin Atmosphere Monitor (VCAM) is based on a low-mass, low-power miniature preconcentrator gas chromatograph/mass spectrometer (PCGC/MS) capable of providing sub-ppm measurements of volatile constituents in a space vehicle or outpost. VCAM is designed to operate autonomously, maintenance-free, once per day, with its own carrier and calibration gas supplies sufficient for a one-year lifetime. VCAM performance is sufficient to detect and identify 90% of the target compounds specified at their 180-day Spacecraft Maximum Allowable Concentration (SMAC) levels. The flight units will be delivered in mid-2008 and be operated in the ISS EXPRESS rack.

The Tropospheric Emission Spectrometer (TES), launched on NASA's Earth Observing System Aura spacecraft on July 15, 2004 has successfully completed over three years in space and has captured a number of important lessons. The instrument primary science objective is the investigation and quantification of global climate change. TES measures the three-dimensional distribution of ozone and its precursors in the lower atmosphere on a global scale. It is an infrared (IR) high resolution, imaging Fourier Transform Spectrometer (FTS) with a 3.3 to 15.4 μm spectral coverage required for space-based measurements to profile essentially all infrared-active molecules present in the Earth's lower atmosphere. The nominal on-orbit mission lifetime is 5 years. The Aura spacecraft flies in a sun-synchronous near-circular polar orbit with 1:38 pm ascending node.

Launched on NASA's Aura spacecraft on July 15, 2004, JPL's Tropospheric Emission Spectrometer (TES) has been operating successfully for over three years in space. TES is an infrared high resolution, imaging fourier transform spectrometer with spectral coverage of 3.3 to 15.4 μm to measure and profile essentially all infrared-active molecules present in the Earth's lower atmosphere. It measures the three-dimensional distribution of ozone and its precursors in the lower atmosphere on a global scale. The Aura spacecraft was successfully placed in a sun-synchronous near-circular polar orbit with a mean altitude of 705 km and 98.9 minute orbit period. The observatory is designed for a nominal 5 year mission lifetime. The instrument thermal design features include four temperature zones needed for efficient cryogenic staging to provide cooling at 65 K, 180 K, 230 K and 300 K.

The advent of lightweight fairings for new spacecraft and the increased thrust of new launch vehicles have intensified the need for better techniques for predicting and for reducing the low frequency noise environment of spacecraft at lift-off. This paper presents a VAPEPS (VibroAcoustic Payload Environment Prediction System) parametrical analysis of the noise reduction of spacecraft fairings and explores a novel technique for increasing the low frequency noise reduction of lightweight fairings by approximately 10 dB.

The microbial burdens of 69 cabin air samples collected in-flight aboard commercial airliners were assessed via culture-dependent and molecular-based microbial enumeration assays. Cabin air samples from each of four separate flights aboard two different carriers were collected via air-impingement. Microbial enumeration techniques targeting DNA, ATP, and endotoxin were employed to estimate total microbial burden. The total viable microbial population ranged from 0 to 3.6 × 104 cells per 100 liters of air, as assessed by the ATP-assay. When these same samples were plated on minimal medium, anywhere from 2 to 80% of the viable population was cultivable. Five of the 29 samples examined exhibited higher cultivable plate counts than ATP-derived viable counts, perhaps a consequence of the dormant nature (lower concentration of intracellular ATP) of cells inhabiting these air cabin samples.

Future planetary science missions planned for Mars are expected to be more complex and thermally challenging than any of the previous missions. For future rovers, the operational parameters such as landing site latitudes, mission life, distance traversed, and rover thermal energy to be managed will be significantly higher (two to five times) than the previous missions. It is a very challenging problem to provide an effective thermal control for the future rovers using traditional passive thermal control technologies. Recent investigations at the Jet Propulsion Laboratory (JPL) have shown that mechanical pump based fluid loops provide a robust and effective thermal control system needed for these future rovers. Mechanical pump based fluid loop (MPFL) technologies are currently being developed at JPL for use on such rovers. These fluid loops are planned for use during spacecraft cruise from earth to Mars and also on the Martian surface operations.

The Mars Science Laboratory (MSL) mission to land a large rover on Mars is being prepared for Launch in 2011. A Multi-Mission Radioisotope Thermoelectric Generator (MMRTG) on the rover provides an electrical power of 110 W for use in the rover and the science payload. Unlike the solar arrays, MMRTG provides a constant electrical power during both day and night for all seasons (year around) and latitudes. The MMRTG dissipates about 2000 W of waste heat to produce the desired electrical power. One of the challenges for MSL Rover is the thermal management of the large amount of MMRTG waste heat. During operations on the surface of Mars this heat can be harnessed to maintain the rover and the science payload within their allowable limits during nights and winters without the use of electrical survival heaters. A mechanically pumped fluid loop heat rejection and recovery system (HRS) is used to pick up some of this waste heat and supply it to the rover and payload.

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 mechanically 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.

NASA launched two rovers in June and July of 2003 as a part of the Mars Exploration Rover (MER) project. MER-A (Spirit) landed on Mars in Gusev Crater at 15 degrees South latitude and 175 degrees East longitude on January 4, 2004 (Squyres, et al., Dec. 2004). MER-B (Opportunity) landed on Mars in Terra Meridiani at 2 degrees South latitude and 354 degrees East longitude on January 25, 2004 (Squyres, et al., Aug. 2004). Both rovers have well exceeded their design lifetime (90 Sols) by more than a factor of 5. Spirit and Opportunity are still healthy and continue to execute their roving science missions at the time of this writing. This paper discusses rover flight thermal performance during the surface missions of both vehicles, covering roughly the time from the MER-A landing in late Southern Summer (aereocentric longitude, Ls = 328, Sol 1A) through the Southern Winter solstice (Ls = 90, Sol 255A) to nearly Southern Vernal equinox (Ls = 160, Sol 398A).

Mars Exploration Rover (MER) mission launched two spacecraft to Mars in June and July of 2003 and landed two rovers on Mars in January 2004. A Heat Rejection System (HRS) based on a mechanically pumped single-phase liquid cooling system was used to reject heat from electronics to space during the seven months cruise from Earth to Mars. Even though most of this HRS design was similar to the system used on Mars Pathfinder in 1996, several key modifications were made in the MER HRS design. These included the heat exchanger used in removing the heat from electronics, design of venting system used to vent the liquid prior to Mars entry, inclusion of pressure transducer in the HRS, and the spacecraft radiator design. Extensive thermal/fluids modeling and analysis were performed on the MER HRS design to verify the performance and reliability of the system. The HRS design and performance was verified during the spacecraft system thermal vacuum tests.

Mechanically pumped single-phase fluid loops are well suited for transporting and rejecting large amounts of waste heat from spacecraft electronics and power supplies. While past implementations of such loops on spacecraft have used moderate operating temperatures (less than 60ºC), higher operating temperatures would allow equivalent heat loads to be rejected by smaller and less massive radiators. A high temperature (100 to 150ºC) mechanically pumped fluid loop is currently being investigated at the Jet Propulsion Laboratory (JPL) for use on future Mars missions. This paper details the trade study used to select the high temperature working fluid for the system and the initial development testing of loop components.