Mass balances for a biological life support system simulation model.

Design decisions to aid the development of future space-based biological life support systems (BLSS) can be made with simulation models. Here we develop the biochemical stoichiometry for 1) protein, carbohydrate, fat, fiber, and lignin production in the edible and inedible parts of plants; 2) food consumption and production of organic solids in urine, feces, and wash water by the humans; and 3) operation of the waste processor. Flux values for all components are derived for a steady-state system with wheat as the sole food source. The large-scale dynamics of a materially-closed (BLSS) computer model is described in a companion paper. An extension of this methodology can explore multi-food systems and more complex biochemical dynamics while maintaining whole-system closure as a focus.     

Conceptual design of a hypervelocity asteroid intercept vehicle (HAIV) and its flight validation mission

An intercept mission with nuclear explosives is the most effective of the practical mitigation options against the impact threat of near-Earth objects (NEOs) with a short warning time (e.g., much less than 10 years). The existing penetrated subsurface nuclear explosion technology limits the intercept velocity to less than approximately 300 m/s. Consequently, an innovative concept of blending a hypervelocity kinetic impactor with a subsurface nuclear explosion has been developed for optimal penetration, fragmentation, and dispersion of the target NEO. A proposed hypervelocity asteroid intercept vehicle (HAIV) consists of a kinetic-impact leader spacecraft and a follower spacecraft carrying nuclear explosives. This paper describes the conceptual development and design of a baseline HAIV system and its flight validation mission architecture for three mission cost classifications (e.g., $500 M, $1 B, and $1.5 B).     

Results of cosmic radiation dose field measurements aboard the “Salyut-6” orbital station

During the 3rd main expedition on board the “Salyut-6” orbital station in 1979 the integral characteristics of cosmic radiation were measured in various positions inside the manned modules (experiment “Integral”). Measurements were performed with thermoluminescent dosimeters, photographic films and solid state plastic detectors supplied for the experiment by specialists of the USSR, Bulgaria, Hungary, GDR and Romania. The dose gradient inside the manned modules of the station amounted to 70 % for long intervals of time. During the experimental period the dose rate inside the station was 15 to 30 mrad per day. The mean flux of particles with z 6 and LET 200 keV/μm was found to be 0.22 cm⁻² day⁻¹.     

Cataractogenic potential of ionizing radiations in animal models that simulate man.

Aspects of experiments on radiation-induced lenticular opacification during the life spans of two animal models, the New Zealand white rabbit and the rhesus monkey, are compared and contrasted with published results from a life span study of another animal model, the beagle dog, and the most recent data from the ongoing study of the survivors from radiation exposure at Hiroshima and Nagasaki. An important connection among the three animal studies is that all the measurements of cataract indices were made by one of the authors (A.C.L.), so variation form personal subjectivity was reduced to a minimum. The primary objective of the rabbit experiments (radiations involved: 56Fe, 40Ar and 20Ne ions and 60Co gamma photons) is an evaluation of hazards to astronauts from galactic particulate radiations. An analogous evaluation of hazards from solar flares during space flight is being made with monkeys exposed to 32, 55, 138 and 400 MeV protons. Conclusions are drawn about the proper use of animal models to simulate radiation responses in man and the levels of radiation-induced lenticular opacification that pose risks to man in space.     

LONG-TERM RIGOROUS NUMERICAL INTEGRATION OF NAVIER-STOKES EQUATION BY NEWTON-GMRES ITERATION

The recent result of an orbit continuation algorithm has provided a rigorous method for long-term numer- ical integration of an orbit on the unstable manifold of a periodic solution. This algorithm is matrix-free and em- ploys a combination of the Newton-Raphson method and the Krylov subspace method. Moreover, the algorithm adopts a multiple shooting method to address the problem of orbital instability due to long-term numerical integra- tion. The algorithm is described through computing the extension of unstable manifold of a recomputed Nagata~s lower-branch steady solution of plane Couette flow, which is an example of an exact coherent state that has recently been studied in subcritical transition to turbulence.     

Luni-solar perturbations in the extended phase space representation of the Vinti problem

Perturbation theory is applied to the Vinti problem—motion about an oblate spheroid—to include the gravitational effects of the sun and moon. The problem is formulated using the extended phase space method which introduces a new independent variable similar to the true anomaly. The disturbing Hamiltonian H₁ for third bodies is of order J₂² (second order) and the final goal is a theory including second order short and long period terms and third order secular terms. The current paper however carries the development only to the second order in the secular terms and the first order in the periodic terms. Problems of including the higher orders are discussed. Therefore, in the development of H₁ all terms of order 10^?9 or larger are retained. The lunar emphemeris retains terms to e′² in the lunar eccentricity. The perturbation analysis is carried out by means of Lie series and is developed through the first order only which is consistent with the final accuracy desired. The generating function W₁ is obtained and separated into the long period, short period and secular terms. From W₁ the coordinates are defined from the Lie series by means of a transformation equation. These coordinates are non-singular for small eccentricity and inclination. Because of the complexity of the equations all algebraic computations were accomplished by means of a computerized Poisson series manipulator developed at the Naval Research Laboratory.     

Magnetic holes in the solar wind and their relation to mirror-mode structures

Data obtained by the Ulysses magnetometer and solar wind analyzer have been combined to study the properties of magnetic holes in the solar wind between 1 and 5.4 AU and to 23° south latitude. Although the plasma surrounding the holes was generally stable against the mirror instability, there are indications that the holes may have been remnants of mirror mode structures created upstream of the points of observation. Those indications include: (1) For the few holes for which proton or alpha-particle pressure could be measured inside the hole, the ion thermal pressure was always greater than in the plasma adjacent to the holes. (2) The plasma surrounding many of the holes was marginally stable for the mirror mode, while the plasma environment of all the holes was significantly closer to mirror instability than was the average solar wind. (3) The plasma containing trains of closely spaced holes was closer to mirror instability than was the plasma containing isolated holes. (4) The near-hole plasma had much higher ion (ratio of thermal to magnetic pressure) than did the average solar wind.     

Remote sensing of precipitation by a satellite-borne microwave remote sensor

The problem of remote sensing of precipitation by a satellite-borne microwave rain scatterometer is discussed. A downward-looking scanning pencil-beam antenna system is used. The combination of the range-gate method and low side lobe level is used to separate echoes from precipitation layers in the main lobe from ground clutter in the side lobes. Various parameters of the satellite-borne microwave rain scatterometer are calculated and characteristics of systems at 10 and 34.45 GHz are considered. The transmitter peak power needed to observe precipitation with sufficient signal-to noise ratio is calculated by means of the radar equation. The signal (i.e. the received power from the resolution volume of the precipitation) and the received power due to the ground clutter are calculated and the signal-to-clutter ratio is obtained by applying the radar equation. An airborne microwave rain scatterometer is proposed for preliminary experiments.     

Periodic behaviour in three galactic bulge sources

Evidence for periodicities of several days in the three bright galactic bulge sources GX349+2, GX17+2 and Ser X-1 has been found in Ariel V RMC data collected over 4 years.     

14.5-14.8 GHz Frequency Sharing by Data Relay Satellite Uplinks and Broadcasting-Satellite Uplinks

Data relay satellites are being developed to provide real-time data links between research satellites in low earth orbits and central data acquisition and processing facilities. Frequency assignments for data relay satellite links will be made in bands allocated internationally to the space research service. One of the bands which will be used lies between 14.5 and 15.35 GHz, where the space research service has had a frequency allocation as a secondary service since 1971. During the General World Administrative Radio Conference of the International Telecommunication Union, held in Geneva in 1979, a primary frequency allocation was made in the band 14.5-14.8 GHz to the fixed-satellite service, specifically for use by earth-to-space links of the broadcasting satellite service. The feasibility of shared band operation is evaluated between data relay satellite uplinks and broadcasting-satellite feeder links in the band 14.5-14.8 GHz. Relationships for predicting interference power levels are formulated, as functions of satellite separation and of earth station separation. Tradeoffs between satellite separation angle and earth station separation are explored, and conclusions are drawn regarding the feasibility of band sharing. Co-channel operation is demonstrated to be technically feasible for typical systems, provided appropriate separations are maintained.