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NASA NTRS2002

Structure Corrections in Modeling VLBI Delays for RDV Data

Since 1997, bimonthly S- and X-band observing sessions have been carried out employing the VLBA (Very Long Baseline Array) and as many as ten additional antennas. Maps of the extended structures have been generated for the 160 sources observed in ten of these experiments (approximately 200,000 observations) taking place during 1997 and 1998. This paper reports the results of the first massive application of such structure maps to correct the modeled VLBI (Very Long Baseline Interferometry) delay in astrometric data analysis. For high-accuracy celestial reference frame work, proper choice of a reference point within each extended source is crucial. Here the reference point is taken at the point of maximum emitted flux. Overall, the weighted delay residuals (approximately equal to 30 ps) are reduced by 8 ps in quadrature upon introducing source maps to model the structure delays of the sources. Residuals of some sources with extended or fast-varying structures improve by as much as 40 ps. Scatter of 'arc positions' about a time-linear model decreases substantially for most sources. Based on our results, it is also concluded that source structure is presently not the dominant error source in astrometric/geodetic VLBI.

Sovers, Ojars J.↗

NASA NTRS2004

Red light regulation of ethylene biosynthesis and gravitropism in etiolated pea stems

During gravitropism, the accumulation of auxin in the lower side of the stem causes increased growth and the subsequent curvature, while the gaseous hormone ethylene plays a modulating role in regulating the kinetics of growth asymmetries. Light also contributes to the control of gravitropic curvature, potentially through its interaction with ethylene biosynthesis. In this study, red-light pulse treatment of etiolated pea epicotyls was evaluated for its effect on ethylene biosynthesis during gravitropic curvature. Ethylene biosynthesis analysis included measurements of ethylene; the ethylene precursor 1-aminocyclopropane-1-carboxylic acid (ACC); malonyl-conjugated ACC (MACC); and expression levels of pea ACC oxidase (Ps-ACO1) and ACC synthase (Ps-ACS1, Ps-ACS2) genes by reverse transcriptase-polymerase chain reaction analysis. Red-pulsed seedlings were given a 6 min pulse of 11 micromoles m-2 s-1 red-light 15 h prior to horizontal reorientation for consistency with the timeline of red-light inhibition of ethylene production. Red-pulse treatment significantly reduced ethylene production and MACC levels in epicotyl tissue. However, there was no effect of red-pulse treatment on ACC level, or expression of ACS or ACO genes. During gravitropic curvature, ethylene production increased from 60 to 120 min after horizontal placement in both control and red-pulsed epicotyls. In red-pulsed tissues, ACC levels increased by 120 min after horizontal reorientation, accompanied by decreased MACC levels in the lower portion of the epicotyl. Overall, our results demonstrate that ethylene production in etiolated epicotyls increases after the initiation of curvature. This ethylene increase may inhibit cell growth in the lower portion of the epicotyl and contribute to tip straightening and reduced overall curvature observed after the initial 60 min of curvature in etiolated pea epicotyls.

Non-NASA Center↗

NASA NTRS2005

Processing and Synthesis of Pre-Biotic Chemicals in Hypervelocity Impacts

Hypervelocity impacts (HVIs) may have played a significant role in establishing the initial organic inventory for pre-biotic chemistry on the Earth and other planetary bodies. In addition to the delivery of organic compounds intact to planetary surfaces, generally at velocities below approx.20 km/s, HVIs also enable synthesis of new molecules. The cooling post-impact plasma plumes of HVIs in the interstellar medium (ISM), the protosolar nebula (PSN), and the early solar system comprise pervasive conditions for organic synthesis. Such plasma synthesis (PS) can operate over many length scales (from nm-scale dust to planets) and energy scales (from molecular rearrangement to atomization and recondensation). HVI experiments with the flexibility to probe the highest velocities and distinguish synthetic routes are a high priority to understand the relevance of PS to exobiology. We describe here recent studies of PS at small spatial scales and extremely high velocities with pulsed laser ablation (PLA). PLA can simulate the extreme plasma conditions generated in impacts of dust particles at speeds of up to 100 km/s or more. When applied to carbonaceous solids, new and pre-biotically relevant molecular species are formed with high efficiency [1,2].

Brickerhoff, W. B.↗

NASA NTRS2011

Positronium and Electron Scattering on Helium

A recent work [1] establishes experimentally that Positronium scattering by atoms of various elements is surprisingly close in total cross-section to that of an isolated electron of the same velocity. In this work we will look at the scattering of Ps on Helium and compare it to a determination of the scattering of an e- with the same element. For both the Ps scattering and the e- scattering on He, we assume the symmetrization of the e- with the closed shell He electrons is the dominant interaction. A local effective potential employed in [2] and [3] is used to model the electron exchange and cross- sections are determined for a set of partial waves. For the Ps scattering we include as a secondary effect the Van der Waals interaction. For single e- scattering of He, we also employ a short range Coulomb potential and dispersion as contributing effects. Results of the cross-sections determined in each case are then compared

DiRienzi, Joseph↗

NASA NTRS2011

Molecular Dynamics Simulation of the Antiamoebin Ion Channel: Linking Structure and Conductance

Molecular dynamics simulations were carried out in order to ascertain which of the potential multimeric forms of the transmembrane peptaibol channel, antiamoebin, is consistant with its measured conductance. Estimates of the conductance obtained through counting ions that cross the channel and by solving the Nernst-Planck equation yield consistent results, indicating that the motion of ions inside the channel can be satisfactorily described as diffusive.The calculated conductance of octameric channels is markedly higher than the conductance measured in single channel recordings, whereas the tetramer appears to be non-conducting. The conductance of the hexamer was estimated to be 115+/-34 pS and 74+/-20 pS, at 150 mV and 75 mV, respectively, in satisfactory agreement with the value of 90 pS measured at 75 mV. On this basis we propose that the antiamoebin channel consists of six monomers. Its pore is large enough to accommodate K(+) and Cl(-) with their first solvation shells intact. The free energy barrier encountered by K(+) is only 2.2 kcal/mol whereas Cl(-) encounters a substantially higher barrier of nearly 5 kcal/mol. This difference makes the channel selective for cations. Ion crossing events are shown to be uncorrelated and follow Poisson statistics. keywords: ion channels, peptaibols, channel conductance, molecular dynamics

Wilson, Michael A.↗

NASA NTRS2011

Summary of Almost 20 Years of Storm Overflight Electric Field, Conductivity, Flash Rates, and Electric Current Statistics

We determined total conduction currents and flash rates for around 900 high-altitude aircraft overflights of electrified clouds over 17 years. The overflights include a wide geographical sample of storms over land and ocean, with and without lightning, and with positive (i.e., upward-directed) and negative current. Peak electric field, with lightning transients removed, ranged from -1.0 kV m(sup -1) to 16. kV m(sup -1), with mean (median) of 0.9 kV m(sup -1) (0.29 kV m(sup -1)). Total conductivity at flight altitude ranged from 0.6 pS m(sup -1) to 3.6 pS m(sup -1), with mean and median of 2.2 pS m(sup -1). Peak current densities ranged from -2.0 nA m(sup -2) to 33.0 nA m(sup -2) with mean (median) of 1.9 nA m(sup -2) (0.6 nA m(sup -2)). Total upward current flow from storms in our dataset ranged from -1.3 to 9.4 A. The mean current for storms with lightning is 1.6 A over ocean and 1.0 A over land. The mean current for electrified shower clouds (i.e. electrified storms without lightning) is 0.39 A for ocean and 0.13 A for land. About 78% (43%) of the land (ocean) storms have detectable lightning. Land storms have 2.8 times the mean flash rate as ocean storms (2.2 versus 0.8 flashes min(sup -1), respectively). Approximately 7% of the overflights had negative current. The mean and median currents for positive (negative) polarity storms are 1.0 and 0.35 A (-0.30 and -0.26 A). We found no regional or latitudinal-based patterns in our storm currents, nor support for simple scaling laws between cloud top height and lightning flash rate.

Blakeslee, Richard J.↗

NASA NTRS2011

Simultaneous Ka-Band Site Characterization: Goldstone, CA, White Sands, NM, and Guam, USA

To statistically characterize atmospheric effects on Ka-band links at NASA operational sites, NASA has constructed site test interferometers (STI s) which directly measure the tropospheric phase stability and rain attenuation. These instruments observe an unmodulated beacon signal broadcast from a geostationary satellite (e.g., Anik F2) and measure the phase difference between the signals received by the two antennas and its signal attenuation. Three STI s have been deployed so far: the first one at the NASA Deep Space Network Tracking Complex in Goldstone, California (May 2007); the second at the NASA White Sands Complex, in Las Cruses, New Mexico (February 2009); and the third at the NASA Tracking and Data Relay Satellite (TDRS) Remote Ground Terminal (GRGT) complex in Guam (May 2010). Two station-years of simultaneous atmospheric phase fluctuation data have been collected at Goldstone and White Sands, while one year of data has been collected in Guam. With identical instruments operating simultaneously, we can directly compare the phase stability and rain attenuation at the three sites. Phase stability is analyzed statistically in terms of the root-mean-square (rms) of the tropospheric induced time delay fluctuations over 10 minute blocks. For two years, the time delay fluctuations at the DSN site in Goldstone, CA, have been better than 2.5 picoseconds (ps) for 90% of the time (with reference to zenith), meanwhile at the White Sands, New Mexico site, the time delay fluctuations have been better than 2.2 ps with reference to zenith) for 90% of time. For Guam, the time delay fluctuations have been better than 12 ps (reference to zenith) at 90% of the time, the higher fluctuations are as expected from a high humidity tropical rain zone. This type of data analysis, as well as many other site quality characteristics (e.g., rain attenuation, infrastructure, etc.) will be used to determine the suitability of all the sites for NASA s future communication services at Ka-band.

Acosta, Roberto↗

NASA NTRS2012

Two Years of Simultaneous K(sub a)-Band Measurements: Goldstone, CA; White Sands, NM; and Guam, USA

In order to statistically characterize the effect of the Earth's atmosphere on Ka-Band links, site test interferometers (STIs) have been deployed at three of NASA s operational sites to directly measure each site's tropospheric phase stability and rain attenuation. These STIs are composed of two antennas on a short baseline (less than 1km) that observe the same unmodulated beacon signal broadcast from a geostationary satellite (e.g., Anik F2). The STIs are used to measure the differential phase between the two received signals as well as the individual signal attenuation at each terminal. There are currently three NASA sites utilizing STIs; the Goldstone Deep Space Communications Complex near Barstow, California; the White Sands Complex in Las Cruces, New Mexico; and the Guam Remote Ground Terminal on the island of Guam. The first two sites are both located in desert regions that have highly similar climates in terms of their seasonal temperatures, average humidity, and annual rain fall (the primary factors in determining phase stability). In contrast, Guam is in a tropical region with drastically higher annual rainfall and humidity. Five station years of data have been collected in Goldstone, three in White Sands, and two in Guam, yielding two years of simultaneous data collection across all three sites. During this period of simultaneous data collection, the root-mean-square (RMS) of the time delay fluctuations stayed under 2.40 picoseconds for 90% of the time in Goldstone, under 2.07 picoseconds for 90% of the time in White Sands, and under 10.13 picoseconds for 90% of the time in Guam. For the 99th percentile, the statistics were 6.32 ps, 6.03 ps, and 24.85 ps, respectively. These values, as well as various other site quality characteristics, will be used to determine the suitability of these sites for NASA s future communication services at Ka-Band.

Acosta, Roberto J.↗

NASA NTRS2008

Displaying Composite and Archived Soundings in the Advanced Weather Interactive Processing System

In a previous task, the Applied Meteorology Unit (AMU) developed spatial and temporal climatologies of lightning occurrence based on eight atmospheric flow regimes. The AMU created climatological, or composite, soundings of wind speed and direction, temperature, and dew point temperature at four rawinsonde observation stations at Jacksonville, Tampa, Miami, and Cape Canaveral Air Force Station, for each of the eight flow regimes. The composite soundings were delivered to the National Weather Service (NWS) Melbourne (MLB) office for display using the National version of the Skew-T Hodograph analysis and Research Program (NSHARP) software program. The NWS MLB requested the AMU make the composite soundings available for display in the Advanced Weather Interactive Processing System (AWIPS), so they could be overlaid on current observed soundings. This will allow the forecasters to compare the current state of the atmosphere with climatology. This presentation describes how the AMU converted the composite soundings from NSHARP Archive format to Network Common Data Form (NetCDF) format, so that the soundings could be displayed in AWl PS. The NetCDF is a set of data formats, programming interfaces, and software libraries used to read and write scientific data files. In AWIPS, each meteorological data type, such as soundings or surface observations, has a unique NetCDF format. Each format is described by a NetCDF template file. Although NetCDF files are in binary format, they can be converted to a text format called network Common data form Description Language (CDL). A software utility called ncgen is used to create a NetCDF file from a CDL file, while the ncdump utility is used to create a CDL file from a NetCDF file. An AWIPS receives soundings in Binary Universal Form for the Representation of Meteorological data (BUFR) format (http://dss.ucar.edu/docs/formats/bufr/), and then decodes them into NetCDF format. Only two sounding files are generated in AWIPS per day. One file contains all of the soundings received worldwide between 0000 UTC and 1200 UTC, and the other includes all soundings between 1200 UTC and 0000 UTC. In order to add the composite soundings into AWIPS, a procedure was created to configure, or localize, AWIPS. This involved modifying and creating several configuration text files. A unique fourcharacter site identifier was created for each of the 32 soundings so each could be viewed separately. The first three characters were based on the site identifier of the observed sounding, while the last character was based on the flow regime. While researching the localization process for soundings, the AMU discovered a method of archiving soundings so old soundings would not get purged automatically by AWl PS. This method could provide an alternative way of localizing AWl PS for composite soundings. In addition, this would allow forecasters to use archived soundings in AWIPS for case studies. A test sounding file in NetCDF format was written in order to verify the correct format for soundings in AWIPS. After the file was viewed successfully in AWIPS, the AMU wrote a software program in the Tool Command Language/Tool Kit (Tcl/Tk) language to convert the 32 composite soundings from NSHARP Archive to CDL format. The ncgen utility was then used to convert the CDL file to a NetCDF file. The NetCDF file could then be read and displayed in AWIPS.

Barrett, Joe H., III↗

NASA NTRS2007

Electrostatic Properties of Polymers Subjected to Atmospheric Pressure Plasma Treatment; Correlation of Experimental Results with Atomistic Modeling

this study, PE, PTFE, PS and PMMA were exposed to a He+O2, APGD and pre and post treatment surface chemistries were analyzed by X-ray photoelectron spectroscopy and contact angle measurements. Semi-empirical and ab-initio calculations were performed to correlate the experimental results with sonic plausible molecular and electronic structure features of the oxidation process. For the PE and PS, significant surface oxidation showing C-O, C=O, and O-C=O bonding, and a decrease in the surface contact angles was observed. For the PTFE and PM MA, little change in the surface composition was observed. The molecular modeling calculations were performed on single and multiple oligomers and showed regardless of oxidation mechanism, e.g. -OH, =O or a combination thereof, experimentally observed levels of surface oxidation were unlikely to lead to a significant change in the electronic structure of PE and PS, and that the increased hydrophilic properties are the primary reason for the observed changes in its electrostatic behavior. Calculations for PTFE and PMMA argue strongly against significant oxidation of those materials, as confirmed by the XPS results.

Trigwell, S.↗

NASA NTRS2014

Forecasting Sensorimotor Adaptability from Baseline Inter-Trial Correlations

One of the greatest challenges surrounding adaptation to the spaceflight environment is the large variability in symptoms, and corresponding functional impairments, from one crewmember to the next. This renders preflight training and countermeasure development difficult, as a "one-size-fits-all" approach is inappropriate. Therefore, it would be highly advantageous to know ahead of time which crewmembers might have more difficulty adjusting to the novel g-levels inherent to spaceflight. Such knowledge could guide individually customized countermeasures, which would enable more efficient use of crew time, both preflight and inflight, and provide better outcomes. The primary goal of this project is to look for a baseline performance metric that can forecast sensorimotor adaptability without exposure to an adaptive stimulus. We propose a novel hypothesis that considers baseline inter-trial correlations, the trial-to-trial fluctuations in motor performance, as a predictor of individual sensorimotor adaptive capabilities. To-date, a strong relationship has been found between baseline inter-trial correlations and adaptability in two oculomotor systems. For this project, we will explore an analogous predictive mechanism in the locomotion system. METHODS: Baseline Inter-trial Correlations: Inter-trial correlations specify the relationships among repeated trials of a given task that transpire as a consequence of correcting for previous performance errors over multiple timescales. We can quantify the strength of inter-trial correlations by measuring the decay of the autocorrelation function (ACF), which describes how rapidly information from past trials is "forgotten." Processes whose ACFs decay more slowly exhibit longer-term inter-trial correlations (longer memory processes), while processes whose ACFs decay more rapidly exhibit shorterterm inter-trial correlations (shorter memory processes). Longer-term correlations reflect low-frequency activity, which is more easily measured in the frequency domain. Therefore, we use the power spectrum (PS), which is the Fourier transform of the ACF, to describe our inter-trial correlations. The decay of the PS yields a straight line on a log-log frequency plot, which we quantify by Beta = - (slope of PS on log-log axes). Hence, Beta is a measure of the strength of inter- trial correlations in the baseline data. Larger Beta values are indicative of longer inter-trial correlations. Experimental Approach: We will begin by performing a retrospective analysis of treadmill-gait adaptation data previously collected by Dr. Bloomberg and colleagues. Specifically, we will quantify the strength of inter-trial correlations in the baseline step cadence and heart rate data and compare it to the locomotor adaptability performance results already described by these investigators. Incorporating these datasets will also allow us to explore the applicability of (and potential limitations surrounding) the use of Beta in forecasting physiological performance. We will also perform a new experiment, in which Beta will be derived from baseline data collected during over-ground (non-treadmill) walking, which will enable us to consider locomotor performance, through the parameter Beta, under the most functionallyrelevant, natural gait condition. This experiment will incorporate two baseline and five post-training over-ground locomotion tests to explore the consistency and potential adaptability of the Beta values themselves. HYPOTHESES: We hypothesize that the strength of baseline inter-trial correlations of step cadence and heart rate will relate to locomotor adaptability. Specifically, we anticipate that individuals who show weaker longer-term inter-trial correlations in baseline step cadence data will be the better adaptors, as step cadence can be modified in real-time (i.e., online corrections are an inherent property of the locomotor system; analogous to results observed in the VOR). Conversely, because heart rate is not altered mid-beat, we expect that individuals who demonstrate stronger longer-term correlations in heart rate will be the better adaptors (analogous to results observed in the saccadic system). CONCLUSIONS: At the conclusion of this project we hope to uncover a baseline predictor of locomotor adaptability. If our hypotheses hold true, our results will demonstrate that the temporal structure of baseline behavioral data contains important information that may aid in forecasting adaptive capacities. The ability to predict such adaptability in the sensorimotor system has significant implications for spaceflight, where astronauts must adjust their motor programs following a change in g-level to retain movement accuracy.

Beaton, K. H.↗

NASA NTRS2014

Using SpF to Achieve Petascale for Legacy Pseudospectral Applications

Pseudospectral (PS) methods possess a number of characteristics (e.g., efficiency, accuracy, natural boundary conditions) that are extremely desirable for dynamo models. Unfortunately, dynamo models based upon PS methods face a number of daunting challenges, which include exposing additional parallelism, leveraging hardware accelerators, exploiting hybrid parallelism, and improving the scalability of global memory transposes. Although these issues are a concern for most models, solutions for PS methods tend to require far more pervasive changes to underlying data and control structures. Further, improvements in performance in one model are difficult to transfer to other models, resulting in significant duplication of effort across the research community. We have developed an extensible software framework for pseudospectral methods called SpF that is intended to enable extreme scalability and optimal performance. Highlevel abstractions provided by SpF unburden applications of the responsibility of managing domain decomposition and load balance while reducing the changes in code required to adapt to new computing architectures. The key design concept in SpF is that each phase of the numerical calculation is partitioned into disjoint numerical kernels that can be performed entirely inprocessor. The granularity of domain decomposition provided by SpF is only constrained by the datalocality requirements of these kernels. SpF builds on top of optimized vendor libraries for common numerical operations such as transforms, matrix solvers, etc., but can also be configured to use open source alternatives for portability. SpF includes several alternative schemes for global data redistribution and is expected to serve as an ideal testbed for further research into optimal approaches for different network architectures. In this presentation, we will describe our experience in porting legacy pseudospectral models, MoSST and DYNAMO, to use SpF as well as present preliminary performance results provided by the improved scalability.

DYNAMO↗

NASA NTRS1974

Microcraters formed in glass by projectiles of various densities

An experiment was conducted investigating the effect of projectile density on the structure and size of craters in soda lime glass and fused quartz. The projectiles were spheres of polystyrene-divinylbenzene (PS-DVB), aluminum, and iron with velocities between 0.5 and 15 km/sec and diameters between 0.4 and 5 microns. The projectile densities spanned the range expected for primary and secondary particles of micrometer size at the lunar surface, and the velocities spanned the lower range of micrometeoroid velocities and the upper range of secondary projectile velocities. There are changes in crater morphology as the impact velocity increases, and the transitions occur at lower velocities for the projectiles of higher density. The sequence of morphological features of the craters found for PS-DVB impacting soda lime glass for increasing impact velocity, described in a previous work (Mandeville and Vedder, 1971), also occurs in fused quartz and in both targets with the more dense aluminum and iron projectiles. Each transition in morphology occurs at impact velocities generating a certain pressure in the target. High density projectiles require a lower velocity than low-density projectiles to generate a given shock pressure.

Vedder, J. F.↗

NASA NTRS1976

Technological development of high energy density capacitors

A study was conducted to develop cylindrical wound metallized film capacitors rated 2 micron F 500 VDC that had energy densities greater than 0.1J/g. Polysulfone (PS) and polyvinylidene (PVF2) were selected as dielectrics. Single film PS capacitors of 0.2J/g (uncased) were made of 3.75 micron material. Single film PVF2 capacitors of 0.19J/g (uncased) were made of 6.0 micron material. Corona measurements were made at room temperature, and capacitance and dissipation factor measurements were made over the ranges 25 C to 125 C and 120 Hz to 100 kHz. Nineteen of twenty PVF2 components survived a 2500 hour dc plus ac life test. Failure analyses revealed most failures occurred at wrinkles, but some edge failures were also seen. A 0.989g case was designed. When the case was combined with the PVF2 component, a finished energy density of 0.11J/g was achieved.

Parker, R. D.↗

NASA NTRS1976

Mode-locked frequency doubled Nd:YAG laser

The design, fabrication, test, and delivery of two mode-locked, frequency doubled Nd:YAG laser systems are described. Each system was comprised of two units, the laser head and optics on an Invar plate and the electronics control unit in a relay rack chassis panel. Laser number one operated at a repetition rate of 400 MHz and was designed for use in an optical communication system. Laser number two operated at 200 MHz repetition rate and was designed for optical ranging and target signature experiments. Both lasers had a pulse width of 200 ps at the 10% amplitude points at 1.064 micrometer wavelength (150 ps at 0.532 micrometers) with an amplitude stability of + or - 4%. Output power exceeded the design goals.

Brookman, J. S.↗

NASA NTRS1978

The 1.06 optical receiver

High performance 1.06 micron m avalanche photodetectors (APDs), fabricated in the GaAlSb system, have high quantum efficiency (90 percent), high speed (risetime less than 60 ps) and low leakage currents (less than 50 na). The dark current represents more than an order of magnitude reduction compared to previously reported results. The high speed avalanche gain of these devices is between 20 and 50. The area uniformity is better than + or - 10 percent. GaAlAs APDs at 0.53 micron m have even faster speed, lower dark currents, and high speed gains of 100 to 200. Optical rangefinders based on measured APD performance parameters have far superior performance when compared to even ideal photomultiplier tubes in either a one color or two color rangefinder system. For a one color system, f factor of two lower time jitter can be achieved with identical transmitted power. The superiority of the APD based two color receiver is significant and exists in the entire range of desired time jitters (less than 100 ps) and received power levels.

Tomasetta, L. R.↗

NASA NTRS1979

Long period perturbations of earth satellite orbits

All the equations involved in extending the PS phi solution to include the long periodic and second order secular effects of the zonal harmonics are presented. Topics covered include DSphi elements and relations for their conconical transformation into the PS phi elements; the solution algorithm based on the Von Zeipel method; and the elimination of long periodic terms and analytical integration of primed variables. The equations were entered into the ASOP program, checked out, and verified. Comparisons with numerical integrations show the long period theory to be accurate within several meters after 800 revolutions.

Wang, K. C.↗

NASA NTRS1981

Materials Experiment Carrier Thermal Control System study

The Materials Experimental Carrier (MEC) vehicle currently under study at NASA-Marshall Space Flight Center presents unique power and heat rejection problems to the 25 kW Power System (PS). In order to determine how these requirements can best be met on both the Power System and MEC vehicle, Thermal Control System Trade Studies were conducted. The results of these trade studies indicated total weight to orbit would be minimized for multiple MEC launches by centralized radiators on the Power System. A split loop arrangement of Power System Thermal Control Subsystem, with separate loops for payload and PS heat rejection, appeared favorable from these trades. FC72 fluid was recommended for the high temperature MEC heat transport loop.

Fleming, M.↗