Tenma observations of bright binary X-ray sources

Spectroscopic study of bright binary X-ray sources, performed with the gas scintillation proportional counters on board Tenma, is reviewed. Properties of an iron emission line from two classes of bright binary X-ray sources: X-ray pulsars and low-mass binary sources, are first presented. It is shown that a most likely candidate for the line emitting region is an Alfven shell in case of X-ray pulsars, whereas that of low mass binary sources is an outer accretion disk. Next, nature of the continuum emission from low-mass binary sources is consistently interpreted by a picture that an optically thick accretion disk extends down to very near the surface of a weakly magnetized neutron star. Origin of ultrasoft spectra of black hole candidate sources is also discussed.     

A model of the rapid burster

A new burst mode of MXB 1730 - 335, the rapid burster, as discovered by Hakucho in August 1979, is characterized by a train of long X-ray bursts whose behaviour is dictated by the accretion rate. In this mode the burst luminosity reaches the Eddington limit, so that the X-ray pressure controls the accretion from a reservoir in the magnetopause and accretion columns in the polar regions explain general features of the rapid burster observed in August 1979.     

LIFE: Life Investigation For Enceladus A Sample Return Mission Concept in Search for Evidence of Life

Abstract Life Investigation For Enceladus (LIFE) presents a low-cost sample return mission to Enceladus, a body with high astrobiological potential. There is ample evidence that liquid water exists under ice coverage in the form of active geysers in the "tiger stripes" area of the southern Enceladus hemisphere. This active plume consists of gas and ice particles and enables the sampling of fresh materials from the interior that may originate from a liquid water source. The particles consist mostly of water ice and are 1-10?μ in diameter. The plume composition shows H(2)O, CO(2), CH(4), NH(3), Ar, and evidence that more complex organic species might be present. Since life on Earth exists whenever liquid water, organics, and energy coexist, understanding the chemical components of the emanating ice particles could indicate whether life is potentially present on Enceladus. The icy worlds of the outer planets are testing grounds for some of the theories for the origin of life on Earth. The LIFE mission concept is envisioned in two parts: first, to orbit Saturn (in order to achieve lower sampling speeds, approaching 2 km/s, and thus enable a softer sample collection impact than Stardust, and to make possible multiple flybys of Enceladus); second, to sample Enceladus' plume, the E ring of Saturn, and the Titan upper atmosphere. With new findings from these samples, NASA could provide detailed chemical and isotopic and, potentially, biological compositional context of the plume. Since the duration of the Enceladus plume is unpredictable, it is imperative that these samples are captured at the earliest flight opportunity. If LIFE is launched before 2019, it could take advantage of a Jupiter gravity assist, which would thus reduce mission lifetimes and launch vehicle costs. The LIFE concept offers science returns comparable to those of a Flagship mission but at the measurably lower sample return costs of a Discovery-class mission. Key Words: Astrobiology-Habitability-Enceladus-Biosignatures. Astrobiology 12, 730-742.     

A space station experiment on large antenna assembly and measurement

The large assembly antenna in space can meet future requirements of both high frequency and large aperture. This paper proposes an experiment on assembling a large antenna at the Space Station, and discusses a realizable procedure of the experiment. The objective of this experiment is that a large antenna of a 10-m diameter is assembled in space and at the same time problems occurring in the assembling process are clarified by conducting the following experiments: assembly of test articles by manipulators, measurement of both mechanical and electrical performance of the assembled antenna, test of the pointing control system, and operational test. In the operational test, the weather radar development test and the large aperture microwave radiometer development test are conducted. Furthermore, the problem areas and items of further study are discussed in this paper.     

On the correlation of the solar wind observed at the L5 point and at the Earth

The L5 point is a promising location for forecasting co-rotating high-speed streams in the solar wind arriving at the Earth. We correlated the solar wind data obtained by the Nozomi spacecraft in interplanetary space and by the Advanced Composition Explorer (ACE) at the L1 point, and found that the correlation is significantly improved from that of the 27-day recurrence of ACE data. Based on the correlation between the two spacecraft observations, we estimated the correlation of the solar wind velocity between the L5 point and at the Earth, and found that the correlation coefficient was about 0.78 in late 1999, while that of the 27-day recurrence was 0.51. Eighty-eight percent of the velocity difference falls within 100 km/s between the L5 point and the Earth. This demonstrates the potential capability of solar wind monitoring at the L5 point to forecast the geomagnetic disturbances 4.5 days in advance.     

Planetary protection on international waters: An onboard protocol for capsule retrieval and biosafety control in sample return mission

Planetary protection has been recognized as one of the most important issues in sample return missions that may host certain living forms and biotic signatures in a returned sample. This paper proposes an initiative of sample capsule retrieval and onboard biosafety protocol in international waters for future biological and organic constituent missions to bring samples from possible habitable bodies in the solar system. We suggest the advantages of international waters being outside of national jurisdiction and active regions of human and traffic affairs on the condition that we accept the Outer Space Treaty. The scheme of onboard biological quarantine definitely reduces the potential risk of back-contamination of extraterrestrial materials to the Earth.     

Current status of the BepiColombo/MMO spacecraft design

This paper shows the current baseline of the conceptual design of the BepiColombo/MMO (mercury magnetospheric orbiter) spacecraft, which is conducted by the ISAS Mercury Exploration Working Group. The MMO is a spinning spacecraft of 200 kg mass whose spin axis is nearly perpendicular to the Mercury orbital plane. The current status of the overall MMO system and subsystems such as thermal control, communication, power, etc. are described. The latest status of the development of critical technologies for the MMO and the outline of the international cooperation between ESA and ISAS are also presented.     

A study of land transformation processes after the atomic bombing damage in Hiroshima

We first analyzed aerial, satellite and surface photographs of Hiroshima taken in 1939, 1945, 1947, 1972, 1980 and 1982, in time sequence. It is rather difficult to recognize traces of damage caused by the atomic bombing from surface level with the few exceptions such as the Atomic Bomb Memorial Dome. However, the ground surface pattern of central Hiroshima analyzed by LANDSAT MSS data shows similarities to damage caused by the atomic bombing and the distribution of residual radioactivities.     

Mercury Dust Monitor (MDM) Onboard the Mio Orbiter of the BepiColombo Mission

Space Science Reviews - In this chapter, we review the contribution of space missions to the determination of the elemental and isotopic composition of Earth, Moon and the terrestrial planets, with...