Ulysses charged particle measurements between 1 and 5 AU from the sun.

Proton fluxes obtained by two instruments carried on the ESA/NASA Ulysses spacecraft are reported for the period from launch in October 1990 till Jupiter encounter in February 1992. Proton energy ranges are 24-59, 71-99, 130-320, 320-2100 and > 2100 MeV. The Sun was very active during this period, the events of March 1991 being some of the largest of the solar cycle. The relationship between events on the Sun and the observed proton flux is discussed.     

Microelectronics effects as seen on CRRES.

A MicroElectronics Test Package (MEP) measured total dose degradation and single event upsets (SEUs) on 60 device types on the Combined Release and Radiation Effects Satellite (CRRES) in an 18 degrees inclination orbit between 350 km and 36000 km from July 1990 to October 1991. Simultaneous measurements of the high energy particle environment were used to make a direct cause and effect comparison of the energetic particle backgrounds and microelectronic performance characteristics. The galactic cosmic ray background for the period of the CRRES mission was at a minimum. The SEUs experienced from the cosmic ray background were correspondingly few in number, but surprisingly produced an equal probability of upset over an L-shell range of 8.5 Earth radii (RE) down to less than 3.0 RE. Cosmic ray induced upset frequencies in proton sensitive chips were over 2 orders of magnitude lower than those produced by protons in the heart of the inner proton radiation belts. Multiple upsets, those produced when a single particle upsets more than one memory location, were just as common from protons as from cosmic rays.     

Effects of large-scale magnetic fields in the Venus ionosphere

Theoretical models of the ionosphere of Venus have been constructed in the past without due consideration of the fact that the ionosphere is sometimes magnetized. This paper examines some differences between the magnetized and unmagnetized dayside Venus ionosphere using the Pioneer Venus Orbiter Langmuir probe and magnetometer data. Particular attention is given to the evaluation of the altitude profiles of the thermal electron heating and comparison of the magnitude of the magnetic force(¯vׯB) ׯB with other forces in the ionosphere. Several examples illustrate how heating profiles are different in the magnetized ionosphere with effective heating below ～200 km altitude reduced by orders of magnitude compared to the field-free ionosphere. The force associated with the magnetic field is comparable to other forces in the magnetized ionosphere. The measured plasma density, electron temperature and magnetic field thus suggest that large-scale magnetic fields should be included in future ionosphere models.     

Cosmic ionizing radiation effects in plant seeds after short and long duration exposure flights.

Recently, comparison of biophysical data obtained from orbital flights of short and long duration led to results which will be significant for long and/or repeated stay of man in space. Under orbital conditions biological stress is induced in dry seeds of Arabidopsis thaliana by cosmic radiation especially its high energetic, densely ionizing component, the heavy ions (HZE). For comparison of radiation impact during different space flights a biological attempt at estimating the impact of single particles with high mass and energy (HZE-particles) on seeds was developed. Subdivision into LET-groups showed a remarkable contribution of an intermediate group (LET = 35 to 100 keV/micrometer) due to medium heavy ions (Z = 6 to 10). Efficiency factors for radiation damage experimentally determined and assigned to different LET-classes were compared to radiation quality factors discussed in literature.     

Realistic computerized human phantoms.

To estimate the risk resulting from exposures to ionizing radiation, the organ and tissue doses should be assessed. A convenient method is the calculation of these doses using representations of the human body, called models or phantoms, together with computer codes simulating the transport of radiation in the body. Most commonly used are mathematical phantoms whose external and internal volumes are defined by simple geometric bodies. More recently, phantoms constructed from computed tomographic data of real persons were introduced as an improvement. These phantoms present advantages concerning the location and shape of the organs, in particular the hard bone and bone marrow, whose distribution can be assessed with high resolution. So far, three of these phantoms were constructed at the GSF, a fourth is under process. The construction technique is described, and some calculational results of organ doses due to external photon irradiation are presented.     

Spacecraft Application of Expert Systems

Artificial Intelligence (AI) will play a major role in future spacecraft operation. Because the technology has not matured, knowledge-based systems will be incorporated in an evolutionary manner, with increasing responsibility as their performance is proven. Internal research at Boeing Aerospace Company has demonstrated that AI software development techniques, knowledge-based systems in particular, can be used to provide limited spacecraft subsystem automation. This capability represents a first step toward an evolutionary path to spacecraft automation. A likely progression will proceed to integrated subsystem control, automated planning and scheduling, plan execution, anomoly handling, and eventually to autonomous spacecraft operation. Although this paper is written in the context of Space Station the ideas and techniques identified should be easily transferable to spacecraft automation in general.     

Studies toward birth and early mammalian development in space.

Sustaining life beyond Earth on either space stations or other planets will require a clear understanding of how the space environment affects key phases of mammalian reproduction and development. Pregnancy, parturition (birth) and the early development of offspring are complex processes essential for successful reproduction and the proliferation of mammalian species. While no mammal has yet undergone birth within the space environment, studies spanning the gravity continuum from 0- to 2-g are revealing startling insights into how reproduction and development may proceed under gravitational conditions deviating from those typically experienced on Earth. In this report, I review studies of pregnant Norway rats and their offspring flown in microgravity onboard the NASA Space Shuttle throughout the period corresponding to mid- to late gestation, and analogous studies of pregnant rats exposed to hypergravity (hg) onboard the NASA Ames Research Center 24-ft centrifuge. Studies of postnatal rats flown in space or exposed to centrifugation are reviewed. Although many important questions remain unanswered, the available data suggest that numerous aspects of pregnancy, birth and early mammalian development can proceed under altered gravity conditions.     

Teratogenic effects of gravitational changes.

In investigating the effect of gravitational changes on development, it is instructive to think of altered gravity (delta g) as a teratogen--that is, an environmental factor influencing development. Observed effects on skeletal development include: suppression of morphogenesis in centrifuged mouse limb buds; advanced fusion stages in centrifuged mouse palates; smaller crown rump lengths (CRL) and decreased number of pregnancies in centrifuged rats and mice; altered differentiation of growth plates in young growing rats in space; and decreased length of calcified long bone regions in fetal rats exposed to microgravity in utero. These studies show that delta g is able to alter development in vivo and in vitro and suggest that delta g operates, at least in part, at the cellular level.     

Kinematics of Saturn's spokes

Voyager 2 images of Saturn's rings have been analyzed for spoke activity. More than 80 and 40 different spokes have been measured at the morning and at the evening ansa, respectively. Higher rate of spoke formation has been found at 145° ± 15° SLS and at 305° ± 15° SLS which persisted for at least 3 Saturn revolutions. Higher spoke activity (formation and growth in width) by more than a factor 3 has been observed over the nightside hemisphere of Saturn than over the dayside hemisphere. The age distribution (i.e. time from radial formation until observation, assuming Keplerian shear) of the leading (old) edges of spokes has its maximum at ～ 9,000 s and ～ 6,000 s for spokes observed at the morning ansa and at the evening ansa, respectively. The highest spoke age observed is ～ 20,000 s. The age distribution of the trailing (young) edges of spokes peaks at < 2,000 s at both ansae but has its mean at ～ 4,500 s and ～ 3,500 s, respectively. On the average the observed spokes grew in width for ～ 4,500 s at the morning ansa and for ～ 2,500 s at the evening ansa. The maximum time of growth in width was ～ 12,000 s.     

Creation of biological module for self-regulating ecological system by the way of polymerization of composite materials in free space.

The large-size frame of space ship and space station can be created with the use of the technology of the polymerization of fiber-filled composites and a liquid reactionable matrix applied in free space or on the other space body when the space ship or space station will be used during a long period of time. For the polymerization of the station frame the fabric impregnated with a long-life polymer matrix (prepreg) is prepared in terrestrial conditions and, after folding, can be shipped in a compact container to orbit and kept folded on board the station. In due time the prepreg is carried out into free space and unfolded. Then a reaction of matrix polymerization starts. After reaction of polymerization the durable frame is ready for exploitation. After that, the frame can be filled out with air, the apparatus and life support systems. The technology can be used for creation of biological frame as element of self regulating ecological system, and for creation of technological frame which can be used for a production of new materials on Earth orbit in microgravity conditions and on other space bodies (Mars, Moon, asteroids) for unique high price mineral extraction. Based on such technology a future space base on Earth orbit with volume of 10(6) m3 and a crew of 100 astronauts is considered.