The J-MASS Marketplace: a new way for DoD to do business

It is current DoD policy to use commercial off-the-shelf software whenever it meets DoD requirements. The application of this policy to modeling and simulation has resulted in the concept of “The Joint Modeling and Simulation System (J-MASS) Marketplace.” J-MASS is designed as an Open Systems Architecture with the capability for the Simulation Support Environment (SSE) to be expanded by the addition of site specific software. In the “J-MASS Marketplace” industry will build commercial tools to work with J-MASS and individual organizations will license what they need for their particular site. The J-MASS SSE is a framework or backplane into which everything else plugs. A J-MASS product release would have the core capabilities, but the unique needs of various organizations would be satisfied by industry. This paper addresses how the J-MASS Marketplace could work and how compliance can be defined. It will outline opportunities for industry in both building software for the Marketplace and in defining the Marketplace concept     

Analysis of queuing behavior of automatic ESM systems

Radar electronic support measures (ESM) systems detect active emitters in a given area and determine their identities and bearings. The high arrival rate of radar pulses in dense emitter environments demands fast automatic processing of arriving pulses so that the ESM system can fulfill its functions properly in real time. Yet, the performance analysis of automatic ESM system in real life Is difficult since both pulse arrivals and widths can be specified only probabilistically. The success of queuing theory in many applications such as computer communication networks and flow-control has encouraged designers to utilize queuing theory in qualifying and judging the performance of automatic ESM systems in dense emitter environments. The queuing behavior of these systems is analytically evaluated under different service disciplines and elaborate computer simulations validate the results. The analysis involves statistical modeling of arrival and departure processes as well as distribution of service times. It permits estimating the blocking probability due to high arrival rates of intercepted radar pulses or due to limited speed of the deinterleaver processor. Queuing analysis is shown to be quite useful to quantitatively assess tradeoffs in ESM systems design     

Time-dependent thermal X-ray afterglows from GRBS

Time-dependent thermal X-ray spectra are calculated from physically plausible conditions around GRB. It is shown that account for time-dependent ionization processes strongly affects the observed spectra of hot rarefied plasma. These calculations may provide an alternative explanation to the observed X-ray lines of early GRBs afterglows (such as GRB 011211). Our technique will allow one to obtain independent constraints on the GRB collimation angle and on the clumpiness of circumstellar matter.     

The double-pulsar binary J0737–3039

A recent multibeam pulsar survey of the outer Galactic plane at Parkes has discovered the first-known double-pulsar binary, a very compact double neutron star system in which both stars are observable as radio pulsars. In this review, we briefly describe the discovery and the studies which have been enabled by the unique properties of the system. These range from the most precise confirmation yet of the theory of general relativity, with the possibility of even more new tests and the measurement of second-order post-Newtonian effects, to studies of the magnetospheres and emission properties of the two pulsars. The discovery also results in a significant increase in the expected rate of occurrence of the mergers of double neutron star systems, and hence the rate of detection of such events by the new ground-based gravitational wave detectors.     

Modelling of Spall in an Anisotropic Aluminium Alloy

Spall caused by hypervelocity impacts at the lower range of velocities could result in significant damage to spacecraft. A number of polycrystalline alloys, used in spacecraft manufacturing, exhibit a pronounced anisotropy in their mechanical properties. The aluminium alloy AA 7010, whose orthotropy is a consequence of the meso-scale phase distribution or grain morphology, has been chosen for this investigation. The material failure observed in plate impact was simulated using a number of spall models. The Hugoniot elastic limit and spall strength have been studied as a function of orientation, and compared to experimental results.     

Modeling the Modification of the Nighttime High-Latitude F-Region by Powerful HF Radiowaves

A mathematical model of the high-latitude F-region, taking the ionospheric plasma convection into account, is used for modeling a response of the auroral F-region to irradiation by powerful high-frequency (HF) radiowaves. The model enables us to calculate the time variations in the profiles of the electron concentration, the velocity of positive ions, and the ion and electron temperatures in the part of a magnetic-flux tube moving over an artificial ionospheric heater under the action of a convective electric field. The modeling was carried out for a part of the magnetic flux tube intersecting the F-layer irradiated by the Norwegian heater at Tromsö when it is located near the midnight magnetic meridian. The calculations were made for the equinox conditions under the high solar and low geomagnetic activity. The results of our modeling show that substantial variations in the profiles of the electron temperature, the velocity of positive ions, and the electron concentration can be produced in the nighttime high-latitude F-layer due to HF heating. The perturbation caused by a 20 s rectangular pulse should exist for about 20 min at the level of the F-layer maximum. The disturbed plasma volume can leave the region irradiated by the heater and move away for over 500 km within the above-mentioned time period.     

The conceptual design of a hybrid life support system based on the evaluation and comparison of terrestrial testbeds.

This report summarizes a trade study of different options of a bioregenerative Life Support System (LSS) and a subsequent conceptual design of a hybrid LSS. The evaluation was based mainly on the terrestrial testbed projects MELISSA (ESA) and BIOS (Russia). In addition, some methods suggested by the Advanced Life Support Project (NASA) were considered. Computer models, including mass flows were established for each of the systems with the goal of closing system loops to the extent possible. In order to cope with the differences in the supported crew size and provided nutrition, all systems were scaled for supporting a crew of six for a 780 day Mars mission (180 days transport to Mars; 600 days surface period) as given in the NASA Design Reference Mission Scenario [Hoffman, S.J., Kaplan, D.L. Human exploration of Mars: the Reference Mission of the NASA Mars Exploratory Study, 1997]. All models were scaled to provide the same daily allowances, as of calories, to the crew. Equivalent System Mass (ESM) analysis was used to compare the investigated system models against each other. Following the comparison of the terrestrial systems, the system specific subsystem options for Food Supply, Solid Waste Processing, Water Management and Atmosphere Revitalization were evaluated in a separate trade study. The best subsystem technologies from the trade study were integrated into an overall design solution based on mass flow relationships. The optimized LSS is mainly a bioregenerative system, complemented by a few physico-chemical elements, with a total ESM of 18,088 kg, which is about 4 times higher than that of a pure physico-chemical LSS, as designed in an earlier study.     

Biogeochemical evidence of microbial activity on Mars.

We suggest a new interpretation of the data on so-called SNC meteorites and delta 13C values of the calcium carbonate minerals and organic matter discovered in them. The delta 13C value of calcite (up to 15 ppt) is accounted for by the microbial reaction CO2 + H2 ---> CH4 + H2O. Methane-forming bacteria also synthesize organic carbon (in the form of biomass) from CO2, and this process is accompanied by 12C fractionation. Therefore, the organic carbon of SNC meteorites is enriched with 12C (delta 13C as low as -35 ppt). The environmental conditions under which the calcite of SNC meteorites was formed were favorable for the activity of methanogens.