On-board Experiments Research Articles

Intelligent optimisation of microsatellite on-board power systems

The Surrey Space Centre has pioneered the research and development of modern microsatellites technologies over the last twenty years. Obviously, the small volume of these satellites places severe constrains on power available for applications payloads on board the satellite therefore many research projects at Surrey have been carried out to reduce power consumption of both satellite platform and payloads. This paper describes one of these projects which is the use of an automatic power scheduling algorithm for the PICOSAT mission, a micro-satellite developed by SSTL under contract to the USAF SSP (Small Satellite Programme). The purpose of this algorithm is to predict the battery and memory levels on a short term basis and automatically schedule the on-board experiments activities in order to optimise the power and memory usage over the selected period, meeting the constraints and requirements for the mission. The algorithm makes use of a recursive feedback loop to reach the optimum output. An initial prototype of the algorithm has been implemented using matlab and, once fully tested, it is intended to port and run it on the satellite On Board Computer in orbit. The experiment priorities and payload characteristics are specified in separate modules, allowing the easy re-use and upgrade of the algorithm for different payload configurations under other SSTL satellites.

Bayesian estimation of directional wave spectra based on ship motions

New techniques are introduced into the Bayesian modeling procedure to estimate directional wave spectra based on ship motion data. In the proposed method, the triple-valued function problem in following seas is strictly taken into account and the optimum solution is obtained from the stochastic viewpoint. In order to examine the reliability of the proposed method, towing tank experiments and onboard experiments were carried out. Using the proposed method, it is shown that the directional wave spectra can be estimated from the vector-valued time series recorded on a running ship even in following seas.

舵減揺オートパイロットシステムの転舵速度影響に関する研究

This study treats with the effect of rudder speed to the Batch Adaptive Roll Reducible Autopilot System (BARRAS) which was developed by the authors. The onboard experiments are carried out using a newly developed oil pressure steering gear called Direct Drive Volume Control System (DDVC) which has high performances on rudder speed, fuel assumption and so on. The effects of the rudder speed are examined by changing the weight of performance index and analyzed from view points of power spectra, noise contribution and impulse response functions.

The solar wind interaction with Mars: Locations and shapes of the bow shock and the magnetic pile‐up boundary from the observations of the MAG/ER Experiment onboard Mars Global Surveyor

The Mars Global Surveyor spacecraft was inserted into an elliptical orbit around Mars on September 12, 1997. It includes the MAG/ER instrument with two magnetometers providing in‐situ sensing of the ambient magnetic field and an electron reflectometer measuring the local distribution function of the electrons in the energy range of 10 eV to 20 keV. This statistical study deals with the identification and the position of the Bow Shock (BS) and of another plasma boundary, the Magnetic Pile‐up Boundary (MPB), proved as permanent by MAG/ER. During the first year of the MGS mission, a total of 290 orbits have been considered to fit the geometric characteristics of these boundaries. The position and shape of these boundaries are compared with previous studies. Good agreement is found with the Phobos 2 observations, suggesting than the mean bow shock and MPB locations are independent of solar cycle phase. The great number of crossings shows that the Bow Shock position and nightside MPB position are highly variable.

Computer Simulation on Onboard Chilling and Freezing of Albacore Tuna

ABSTRACTWe extended the application of a commercial finite‐element computer program package, PDEase, to the simulation of chilling and freezing of albacore tuna. Tuna was described as an infinite elliptical cylinder, where nonuniform boundary conditions present complications in computer simulation. Equations were developed to define the elliptical boundary. Temperature‐dependent thermal properties and time‐dependent ambient temperature conditions were used. Onboard experiments were conducted to measure the core temperature of individual tuna in slush ice tanks and in air‐blast and brine‐spray freezing systems. Measured time‐temperature profiles were compared with those of the simulation. Predicted chilling and freezing curves agreed with experiments ±3 to 6%. This program enables testing of important fish industry operation strategies.

Адаптивний кореляційний аналіз локально-стаціонарних випадкових сигналів для бортових експериментів

Адаптивний кореляційний аналіз локально-стаціонарних випадкових сигналів для бортових експериментів

Project LINK: A Live and Interactive Network of Knowledge

Project LINK (A Live and Interactive Network of Knowledge), is a collaboration of Eureka Scientific, Inc., the San Francisco exploratorium Science Museum, and NASA/Ames Research Center. Project LINK has demonstrated video-conferencing capabilities from the Kuiper Airborne Observatory (KAO) to the San Francisco Exploratorium in the context of science education outreach to K-12 teachers and students. The project was intended to pilot-test strategies for facilitating the live interface between scientists and K-12 teachers aboard the KAO with their peers and students through the resources and technical expertise available at science museums and private industry. The interface was based on Internet/macintosh video conferencing capabilities which allowed teachers and students at the Exploratorium to collaborate in a live and interactive manner with teachers and scientists aboard the KAO. The teachers teams chosen for the on-board experiments represented rural and urban school districts in California. The teachers interfaced with colleagues as part of the NASA-Funded Project FOSTER (Flight Opportunities for Science Teacher Enrichment).

A multi-disciplinary plan for easier access, management, and analysis of science data

NASA’s COST LESS Team is pursuing strategies to reduce the cost and complexity of planning and executing space missions. The team’s technical goal is to reverse the trend of constructing unique solutions for similar problems. To this end, the team is exploring ways to represent mission functionality in terms of building blocks and is discovering approaches that could accommodate the same building blocks for seemingly disparate activities, such as organizing processed telemetry data, controlling onboard experiments, searching science archives, reducing and presenting information to science users, and supporting educational outreach. Reusable object technology (UOT), a research undertaking by the authors, is showing promise in recognizing similarities in functions which were previously viewed as unique because they appeared in different programs or mission phases. Since UOT is aimed at being implementation independent (i.e. the function performed could be accomplished manually, by an automated process, by a specialized instrument, etc.), no premature judgment for automation or autonomy need be made. In this paper, the authors attempt to strike a balance between theory and reality as they describe UOT, including its beginnings, its underpinning, its utility, and its potential for achieving substantive reductions in cost and complexity for the Agency’s space programs. The authors discuss their collaboration with the Center for EUV Astrophysics, University of California, Berkeley to reduce the cost and complexity of science investigations. Their multi-disciplinary plan incorporates both UOT and a complementary technology introduced in this paper, called interactive archives.

Multiple current sheets in a double auroral oval observed from the MAGION-2 and MAGION-3 satellites

Abstract. A case is described of multiple current sheets crossed by the MAGION-2 satellite in the near-midnight quieting auroral oval. The data were obtained by the magnetometer experiment onboard. Results show during a quieting period after a preceding substorm, or during an early growth phase of the next substorm, two double-sheet current bands, POLB and EQUB, located at respectively the polar and equatorial borders of the auroral oval separated by about 500 km in latitude. This is consistent with the double-oval structure during recovery introduced by Elphinstone et al. (1995). Within the POLB, the magnetic field data show simultaneous existence of several narrow parallel bipolar current sheets within the upward current branch (at 69.5–70.3° invariant latitude) with an adjacent downward current branch at its polar side at (70.5–71.3°). The EQUB was similarly stratified and located at 61.2–63.5° invariant latitude. The narrow current sheets were separated on average by about 35 km and 15 km, respectively, within the POLB and EQUB. A similar case of double-oval current bands with small-scale structuring of their upward current branches during a quieting period is found in the data from the MAGION-3 satellite. These observations contribute to the double-oval structure of the late recovery phase, and add a small-scale structuring of the upward currents producing the auroral arcs in the double- oval pattern, at least for the cases presented here. Other observations of multiple auroral current sheets and theories of auroral arc multiplicity are briefly discussed. It is suggested that multiple X-lines in the distant tail, and/or leakage of energetic particles and FA currents from a series of plasmoids formed during preceding magnetic activity, could be one cause of highly stratified upward FA currents at the polar edge of the quieting double auroral oval.

舶用レーダーによる波浪観測と解析-II : 実船実験

舶用レーダーによる波浪観測と解析-II : 実船実験

実験参与船員の意見に見られるTSL飛翔の安全な航行方法

A project of a high speed craft, Techno-Super-Liner had been held and a prototype ship "Hishou" was constructed. A part of final experiment of "Hishou" had been executed to investigate the way of safety navigation of a high speed craft encountering with an ordinary speed ship by Ship Research Institute in 1995. The experiment was done both at sea and on our simulator. We got some subjective evaluation results for safety navigation from participants who had evaluated Hishou's safety on the experiment. Based on their subjective evaluation results, we investigated the way of safety navigation for Hishou in congested sea area and reported it in our last paper of the Japan Institute of Navigation. In this paper we carried out more detailed investigation of the subjective evaluation results. The participant mariners were classified into 3 classes which were ordinary ship's captain, officer and Hishou classes. Their subjective evaluation results were compared among 3 classes. Then it was found that Hishou and the captain classes determined their recognition of the encountering situation severer than the officer's one. As the items which had been used on their judgement of collision danger were examined by Principal Components Analysis, we found differences between captain class and officer class. By comparison between the onboard experiments and the simulators', a simulator was conceded to be an effective tool getting mariner's characteristics. Finally we offered basic criteria of Hishou's safety navigation.

Comparison of lunar and terrestrial ion measurements obtained by the WIND and GEOTAIL spacecraft outside and inside the Earth's magnetosphere

The WIND spacecraft, launched on November 1, 1994, undergoes prior to its halo orbit insertion several lunar swing-by maneuvers. The GEOTAIL spacecraft, skimming around the dayside magnetopause (Dec. 1994), passes also several times behind the moon. The HEP-LD spectrometer onboard of GEOTAIL and the Solar Wind and Suprathermal Ion Composition (SMS) Experiment onboard of the WIND spacecraft are well positioned for observing ions in the mass range between II and Fe in the direct vicinity of the moon. We report first observations of lunar pickup-ions in the magnetotail at a distance of ≈ 80 R e .

Multiple current sheets in a double auroral oval observed from the MAGION-2 and MAGION-3 satellites

A case is described of multiple current sheets crossed by the MAGION-2 satellite in the near-midnight quieting auroral oval. The data were obtained by the magnetometer experiment onboard. Results show during a quieting period after a preceding substorm, or during an early growth phase of the next substorm, two double-sheet current bands, POLB and EQUB, located at respectively the polar and equatorial borders of the auroral oval separated by about 500 km in latitude. This is consistent with the double-oval structure during recovery introduced by Elphinstone et al. (1995). Within the POLB, the magnetic field data show simultaneous existence of several narrow parallel bipolar current sheets within the upward current branch (at 69.5–70.3° invariant latitude) with an adjacent downward current branch at its polar side at (70.5–71.3°). The EQUB was similarly stratified and located at 61.2–63.5° invariant latitude. The narrow current sheets were separated on average by about 35 km and 15 km, respectively, within the POLB and EQUB. A similar case of double-oval current bands with small-scale structuring of their upward current branches during a quieting period is found in the data from the MAGION-3 satellite. These observations contribute to the double-oval structure of the late recovery phase, and add a small-scale structuring of the upward currents producing the auroral arcs in the double- oval pattern, at least for the cases presented here. Other observations of multiple auroral current sheets and theories of auroral arc multiplicity are briefly discussed. It is suggested that multiple X-lines in the distant tail, and/or leakage of energetic particles and FA currents from a series of plasmoids formed during preceding magnetic activity, could be one cause of highly stratified upward FA currents at the polar edge of the quieting double auroral oval.

The Frog in Space (FRIS) experiment onboard Space Station Mir: final report and follow-on studies.

The "Frog in Space" (FRIS) experiment marked a major step for Japanese space life science, on the occasion of the first space flight of a Japanese cosmonaut. At the core of FRIS were six Japanese tree frogs, Hyla japonica, flown on Space Station Mir for 8 days in 1990. The behavior of these frogs was observed and recorded under microgravity. The frogs took up a "parachuting" posture when drifting in a free volume on Mir. When perched on surfaces, they typically sat with their heads bent backward. Such a peculiar posture, after long exposure to microgravity, is discussed in light of motion sickness in amphibians. Histological examinations and other studies were made on the specimens upon recovery. Some organs, such as the liver and the vertebra, showed changes as a result of space flight; others were unaffected. Studies that followed FRIS have been conducted to prepare for a second FRIS on the International Space Station. Interspecific diversity in the behavioral reactions of anurans to changes in acceleration is the major focus of these investigations. The ultimate goal of this research is to better understand how organisms have adapted to gravity through their evolution on earth.

高速船と一般船の見合い実験 : 実船実験とシミュレータ実験

高速船と一般船の見合い実験 : 実船実験とシミュレータ実験

船舶自動運航のための遠隔管理システムの構築 : 電子メールを用いた遠隔実験システムの構築

The authors propose a remote control system which uses the communication line to achieve an automatic operation of the ship. It is necessary to integrate the inormation which affects the ship operation. Recently, the computer system inboard, caled inboard LAN, is established to integrate the information generated inboard. However, the means to treat information integrated has not been established in the communication between land and the ship. Although the e-mail system which is one of communication methods in Internet can treat only the text data, the data of the voice, the image, and animation, etc. can be treated integrated by using the MIME expansion. It is useful for making of the communication between land and the ship to be integrated. However, because only the communication in a single direction is defined in the e-mail system, it will be impossible to use it for remote control of the ship without any improvement. Thus, the design of the remote control system which uses e-mail is examined in this paper. We take remote use of research data processing system installed in Shiojimaru of The Tokyo University of Mercantile Marine as an example of the remote control system of the ship. In this thesis, first of all, the outline of research data processing system of Shiojimaru is introduced. Next, the flow of information by the experiment onboard in the past is brought together and a necessary function for the experiment system is examined. We design the remote experiment system of Shiojimaru which used e-mail based on them.

Laboratory simulations of Titan's atmosphere: organic gases and aerosols

Titan, the main satellite of Saturn, has been observed by remote sensing for many years, both from interplanetary probes ( Pioneer and Voyager's flybys) and from the Earth. Its N 2 atmosphere, containing a small fraction of CH 4 (≈2%), with T ≈ 90 K and P ≈ 1.5 bar at the ground level, is irradiated by solar UV photons and deeply bombarded by energetic particles, i.e. Saturn magnetospheric electrons and protons, interplanetary electrons and cosmic rays. The resulting energy deposition, which takes place mainly below 1000 km, initiates chemical reactions which yield gaseous hydrocarbons and nitriles and, through polymerisation processes, solid aerosol particles which grow by coagulation and settle down to the ground. At the present time, photochemical models strongly require the results of specific laboratory studies. Chemical rate constants are not well known at low temperatures, charged-particle-induced reactions are difficult to model and laboratory simulations of atmospheric processes are therefore of great interest. Moreover, the synthesis of organic compounds which have not been detected to date provides valuable information for future observations. The origin and chemical composition of aerosols depend on the nature of chemical and energy sources. Their production from gaseous species may be monitored in laboratory chambers and their optical or microphysical properties compared to those deduced from the observations of Titan's atmosphere. The development of simulation chambers of Titan's extreme conditions is necessary for a better understanding of past and future observations. Space probes will sound Titan's atmosphere by remote sensing and in situ analysis in the near future (Cassini-Huygens mission). It appears necessary, as a preliminary step, to test on-board experiments in such chambers, and as a final step, when new space data have been acquired, to use them for more general scientific purposes.

‘SVET’ space greenhouse onboard experiment data received from ‘MIR’ station and future prospects

The paper describes operation of ‘SVET’ space greenhouse onboard the ‘MIR’ orbital station since 15 June 1990 and the adopted biotechnological principles. The microprocessor and measuring systems for monitoring and control of the environmental parameters in the Plants growth chamber are presented. Information about the dynamic of these parameters in the course of the first space experiments with vegetables, obtained by means of telemetric data processing, is given. A draft program for the development of next generations of greenhouses of the same type as ‘SVET’, but with a larger area and capabilities, is worked out.

The detector signal processing chain of the ISO long wavelength spectrometer

This paper describes the analogue signal processing chain for the detectors in the Long Wavelength Spectrometer (LWS) to be flown on board the Infrared Space Observatory (ISO) satellite. The satellite, its mission, and the on-board experiments are briefly reviewed, and the configuration of the LWS Detector Subsystem is described. Two possible signal readout and amplification schemes, based on the Transimpedance Amplifier (TIA) and the Integrating Amplifier (IA) are discussed. The reasons for the choice of the IA for the LWS are outlined. The design of the complete LWS detector signal chain is presented.

The first Mission of the Tethered Statellite

The first test flight of the Italian Tethered Satellite was carried out from July 31 to August 8, 1992 on board the Space Shuttle Atlantis. This paper, authored by one of the crewmembers, directly involved with the Tethered Statellite Mission, describes the on-board experiment environment and the Payload Crew experience.