Satellite VI Research Articles

Teratogenic Toxicity of Ethanol Extract of Mahkota Dewa Fruit Flesh (Phaleria macrocarpa (Scheff.) Boerl)

Mahkota Dewa is known as one of the medicinal plants in Indonesia. It contains bioactive compounds and potentially has pharmacological activity. This study aimed to determine the possible toxic effects of Mahkota DewaThe ethanol extract of Mahkota Dewa fruit flesh was given to rats. Group I (control 0.5% Na-CMC), groups II, III and IV as a treatment group (Mahkota Dewa at doses of 100, 500 and 1000 mg/kg bw, respectively). Group V as a control satellite (Na-CMC 0, 5%) and group VI as a satellite of the ethanol extract at a dose of 1000 mg/kg bw., Each groups were treated on day 6 to 15 of gestational. On the 19th day getation, the rats were dissected and observed the skeletal malformations. The data were analyzed using one-way ANOVA followed by a post-hoc tukey. The results toxicity showed that no fetuses had external malformations. On fetal skeletal appearance, all skeletal bone preparations were normal. Based on the study, the ethanolic extract of Mahkota Dewa Fruit Flesh did not cause a teratogenic effect on the fetus during the organogenesis period at doses of 100 mg/kg bw, 500 mg/kg bw, and 1000 mg/kg bw

Organization and evolution of a novel cervid satellite DNA with yeast CDEI-like repeats

AbstractBackgroundIt has been proposed that pericentromeric satellite DNA arises from the progressive proximal expansion of ancient centromeric DNA. In an attempt to recover putative ancestral centromeric DNA, we microdissected the pericentromeric/centromeric DNA from the chromosome X + 3 of Indian muntjac (Muntiacus muntjak vaginalis) and constructed a microclone-library of the X + 3 centromeric DNA.ResultsA new cervid satellite DNA element, designated as satellite VI, was isolated from this library. Fluorescence in situ hybridization (FISH) studies revealed that satellite VI is predominately located on the distal pericentromeric region of the Indian muntjac chromosome X + 3 and on the pericentromeres of several Old World deer species studied. Its sequence is organized as 11-bp monomeric (ATCACGTGGGA) tandem repeats. Further sequencing on a BAC clone of Indian muntjac harboring this repeat showed that an array of this repeat stretches over approximately 5 kb followed by approximately 3 kb of interspersed repetitive sequences, such as long interspersed elements (LINEs), short interspersed elements (SINEs), and long terminal repeats (LTRs).ConclusionsBased on the chromosomal localization, genomic and sequence organization, and copy numbers of satellite VI in deer species studied, we postulate that this newly found satellite DNA could be a putative ancient cervidic centromeric DNA that is still preserved in some Old World deer. Interestingly, the first eight nucleotides of the 11-bp monomeric consensus sequences are highly conserved and identical to the CDEI element in the centromere of the budding yeastSaccharomyces cerevisiae. The centromeric/pericentromeric satellite DNA harboring abundant copies of CDEI sequences is the first found in a mammalian species. Several zipper-like d (GGGA)2motifs were also found in the (ATCACGTGGGA)nrepeat of satellite VI DNA. Whether the satellite VI is structurally and functionally correlated with the CDEI of centromere of budding yeast and whether a zipper-like structure forms in satellite VI require further studies.

Overview of the Attitude and Orbit Control Systems (AOCS) Developed for NASDA/JAXA Engineering Test and Applications Satellites

Dating back to the middle of the early 1990's, the Engineering Test Satellite VI (ETS-VI) was developed with a strong intention to establish the AOCS for the applications satellites. Although injection of the ETS-VI into the GTO was failed, the developed AOSC had proven its performance and at the same time revealed some technical issues to be solved for the real applications. After the ETS-VI, the ETS-VII was launched and completed the intended missions on the rendezvous and docking as well as the robotics experiments. To follow these tests satellites, the Advanced Earth Observation Satellite I and II were launched and the AOCS of these had proven its performance in spite of the fact that the satellites missions were terminated before the end of life because of the failures in the electric power systems. Now a small satellite called Micro-LabSat-1 is in operation to continue the AOCS experiments with some ambitious missions. This overview will cover the history and technical issues of the efforts made by NASDA (now JAXA) and the related industries. This will disclose the reality of the control technologies of Japan in these two decades.

In-orbit measurements of short term attitude and vibrational environment on the Engineering Test Satellite VI using laser communication equipment

Morio ToyoshimaNational Space Development Agency ofJapan2-2-1 SengenTsukuba, Ibaraki 305-8505JapanE-mail: toyoshima.morio@nasda.go.jpKenichi ArakiCommunications Research Laboratory4-2-1 Nukui-KitamachiKoganei, Tokyo 184-8795JapanE-mail: araki@crl.go.jpAbstract. Angular microvibrations of platform jitter on a three-axisattitude-stabilized satellite are measured in space using an onboard la-ser communication terminal. Stable optical tracking control allows themeasurement of relative angular variations from the reference line ofsight of the optical link. The tracking accuracy in this measurement isless than 1 mrad rms. The angular variation and the drift rate on thesatellite are measured at a sampling rate of 500 Hz, and these data aredownlinked to a ground station via a satellite-to-ground optical commu-nication link. The power spectral density of the satellite microvibration iscalculated by a Fourier transform analysis. The frequency spectrum ofthe gimbal mirror’s angular variation is also obtained when the coarsetracking control is operational. The rms value agrees with the residualcoarse tracking error estimated before launch of the satellite. These re-sults will be useful for the future design of a tracking control loop foroptical communication systems.

Real-time trajectory estimation experiments with the COMETS spacecraft

NASDA has developed a new trajectory estimation program capable of estimation in real-time. NASDA conducted experiments to verify the performance of the program with Engineering Test Satellite VI(ETS-VI) in 1994, as well as with Communications and Broadcasting Engineering Test satellite (COMETS), in March and May 1998. This paper presents an overview of the real-time trajectory estimation experiments with COMETS.

On-orbit attitude control experiments using ETS-VI by [formula omitted] control and two-degree-of-freedom control

The engineering Test Satellite VI (ETS-VI) is a three-axis-stabilized satellite launched by NASDA in 1994. On-orbit experiments, which consist of identification and attitude-control experiments, were planned as one of the ETS-VI on-board experimental programs, and were carried out in 1995. This experimental program was called ‘FLEX’ (FLexible EXperiments). The purpose of FLEX was to establish fundamental attitude-controller design methods for a flexible-structure satellite. In this paper, attitude controller design methods for FLEX are discussed, and some results of the attitude-control experiments are presented. The attitude controllers were designed using an H ∞ control method and a two-degree-of-freedom control method. H ∞ controllers were derived using the specified stability degree method. On the other hand, conventional two-degree-of-freedom control design methods could not be applied for the FLEX, because the program memory area was restricted to about 2.6 Kbytes. In this paper, feedforward control design methods which never increase the order of the controller were proposed and applied. Experimental results showed a rapid tracking response and high disturbance-attenuation performance, which have been anticipated by simulations on the ground. Noting that the on-orbit experiments presented here have not previously been carried out, the authors believe these results will be utilized for attitude controller design in the future.

On-orbit measurement of phased arrays in satellites by rotating element electric field vector method

This paper discusses the measurement of the excitation amplitude and phase of each element antenna of phased arrays in satellite orbit. In a phased array, the excitation amplitude and the phase of each element antenna deviate from the desired values, due to the nearby satellite structure, the error of attachment to the satellite, and thermal deformation in the orbit. The errors in the amplitude and the phase must be known for beam scanning and the synthesis of various antenna patterns. The rotating element electric field vector method is useful in measuring the amplitude and the phase of phased arrays. In this method, the amplitude and the phase of the element antenna can be determined simply by varying the phase of the element antenna by a phase-shifter and measuring the amplitude change of the electric field as a result of composition by the array. This is suited to the measurement of phased arrays in satellite orbit, where direct measurement of the phase is difficult. In this study, the above method is used to measure the excitation amplitude and phase of the phased array installed on Engineering Test Satellite VI in orbit. Based on the measured phase, the phase is corrected to realize the designed value. The accuracy of the beam directivity is examined and the validity of the measurements is evaluated. © 1998 Scripta Technica. Electron Comm Jpn Pt 1, 81(1): 1–13, 1998

Satellite interference location system using on‐board multibeam antenna

In satellite communication using a high-gain on-board antenna, there may be a problem with up-link interference, which depends on the directivity of the on-board antenna or the position of the satellite on the orbit. In order to cope with radio frequency interference, it is important to locate (specify) the position of the interference wave radiation source, as seen from the position of the satellite. Technical difficulties are that the characteristics of the interference wave are unknown and there is a limit in the installed weight, making it difficult to add dedicated on-board equipment for location. In a conventional location system, the wave is received simultaneously by two or more satellites. Correlation processing is applied on the ground to the interference waves in order to estimate the location of the radiating source based on the frequency and time differences. In this paper, the following location system is discussed. Angle measurement, based on the received amplitude comparison of multiple beams, is applied to the interference, overlapping with the communication signals received by the multibeam satellite antenna where the interference power ratio between the beams is measured on the ground. A feature of the system is that the source can be located using only a single satellite and no additional on-board equipment. An experimental system was constructed using the S-band multibeam phased array antenna on the experimental Engineering Test Satellite VI. The results of the experiment, for an interference source with known position and for a radiation source with the properties of a radar wave with an unknown position, are presented, together with a discussion of the estimation error and of its improvement. © 1997 Scripta Technica, Inc. Electron Comm Jpn Pt 1, 80(11): 22–33, 1997

Antenna pattern measurement of S-band active phased array on ETS-VI

Of the evaluation methods for antenna patterns of a satellite-borne antenna on an orbit, measurement using the spin of the satellite is effective for high-function antennas such as an antenna with a wide beam, a phased array, and a multibeam antenna because a wide-angle pattern can be acquired. By actually using the spin of the Engineering Test Satellite VI (ETS-VI), antenna patterns of a phased array for S-band intersatellite communication (SIC) were measured. It was not possible to carry out the antenna pattern measurement of the SIC phased array with a beam width of approximately 5° by using the attitude bias control of the satellite because the angle offset limit in the attitude bias of the satellite is only 2° in the three-axis attitude control condition of the ETS-VI. In addition, the attitude bias has an operational problem. By using the spin of the satellite in the measurement, a wide-angle antenna pattern was acquired. In an actual spin of the ETS-VI satellite, a small amount of attitude bias is added. Since the satellite's orbit is elliptical, the location of the ground station as seen from the satellite changes. Errors in the antenna pattern measurement due to these factors are also investigated. Also, the evaluation of the G/T using the antenna pattern and the noise power is described. © 1997 Scripta Technica, Inc. Electron Comm Jpn Pt 1, 80 (4): 29–38, 1996

Evaluation of system noise temperature of S-band intersatellite communications equipment onETS-VI satellite

The intersatellite communication antenna installed on a data relay satellite has a wide antenna beam scan range so that the existence of the background brightness temperature and the artificial interference noise in the antenna pointing direction affect the receiving system noise temperature. In the data relay satellite system, the receiving performance of the intersatellite link significantly influences the channel quality of the entire system. Hence, it is important to evaluate the antenna pointing direction dependence of the system noise temperature. In regard to the S-band intersatellite communications, a phased array antenna installed on the engineering test satellite VI (ETS-VI), the noise temperature was evaluated with attention to the characteristics of both spin condition and the three-axis control condition. The distribution of the system noise temperature agrees well with the results predicted by the background brightness temperature. On the other hand, distribution is found to be affected by the artificial noise dependent on the pointing direction. © 1997 Scripta Technica, Inc. Electron Comm Jpn Pt 1, 80 (1): 62–69, 1997

On-Orbit Experiments of Frequency-Shaped H.INF. Control for Flexible Space Structure.

Flexible control experiments have been performed as one type of on-orbit experiment for the Engineering Test Satellite VI (ETS-VI) which was launched in August, 1994. The aim of the flexible control experiments is the feasibility study of new attitude control schemes for future flexible space structures. We have designed two types of controllers. One is a controller designed according to the Low Authority Control (LAC)/High Authority Control (HAC) scheme. The purpose of LAC is damping augmentation of structural vibration modes, while that of HAC is achievement of high control performance. The other controller is a HAC-only controller: this HAC controller is designed for high-performance attitude control of a rigid body, as well as for damping augmentation of the vibration modes. The HAC controllers in both cases are designed using H∞ control theory with the frequency-shaping technique. These control schemes have been tested on orbit by ETS-VI. The experimental results have been analyzed in both time and frequency domains. It is shown from the analysis that both control schemes can be accurately realized on orbit and perform well with respect to damping augmentation and attitude control.

Attitude Control of an Artificial Satellite Using H∞ and Two-Degree-of-Freedom Control -On-Orbit Experiments Using ETS-VI-

In this paper, results of attitude control experiments using Engineering Test Satellite VI (ETS-VI) on orbit are introduced. ETS-VI is a three-axis-stabilized satellite launched by the National Space Development Agency of Japan (NASDA) in August 1994. Identification and attitude control experiments on orbit were one of the ETS-VI mission programs and were carried out from January to March in 1995. The attitude controllers were designed using H∞ control method and two-degree-of-freedom control method. Experimental results show the effectiveness of these controllers for artificial satellite control.

技術試験衛星VI型による通信実験

技術試験衛星VI型による通信実験

Natural Frequency Prediction of Deployable Satellite Antennas in Orbit.

An analytical method to predict the natural frequency of deployable antennas for satellite use is proposed. We consider a structural system in which an elastic body is supported by a coil spring. Displacement of the antenna in the system is expressed as the sum of the elastic displacement and rigid-body displacement due to rotation. The system vibration equation is obtained by substituting kinetic energy and potential energy into Lagrange's equation. Numerical examples are based on a deployable antenna for the Japanese Experimental Test Satellite VI (ETS-VI). The antenna natural frequency measured in orbit is compared with the predicted frequency. Results show that the proposed method is effective for natural frequency prediction of satellite antennas.

技術試験衛星ＶＩ型による柔構造制御実験

技術試験衛星ＶＩ型による柔構造制御実験

Development of multibeam phased array antenna on ets‐vi for s‐band intersatellite communications

AbstractThis paper describes the S‐band intersatellite communication (SIC) antenna to be carried on the Engineering Test Satellite VI scheduled for launch in 1994, to undertake the first intersatellite data relay experiments in Japan. The SIC antenna is an on‐board formed multibeam phased array antenna, the first of this kind in the world to be carried on a satellite. The SIC antenna is capable of simultaneous data relays to several orbiting satellites (user satellites) by means of an electrically scanned beam. With an on‐board microprocessor, the location of a user satellite can be computed, and the beam is pointed toward that direction automatically.In comparison with the system used in the data relay satellite of the United States, the on‐board beam‐forming system has several advantages, such as the effective use of power and frequency in the case in which the number of user satellites is small, as in Japan. In this paper, the function and the configuration of an SIC antenna are described first. Next, analysis of the antenna is presented, including the effect of the phase and amplitude errors caused by temperature fluctuations. Further, as the main components, the newly developed broadband microstrip antenna, a small beam‐forming network with small phase errors, and the phase shifter controller making the computation of the orbit of the user satellite are presented. Finally, the total test results of the on‐board model of the SIC antenna are described.

Ground verification of deployment dynamics of large deployable spacestructures

This paper describes a precise verification procedure for antenna-deployment mechanisms using ground-deployment test data. Ground-deployment tests are carried out for a communication antenna reflector for the Engineering Test Satellite VI (ETS-VI). The antenna-deployment mechanism studied consisted of a bearing, a helical spring, a chassis, and a latch mechanism. The characteristics of individual parts were measured under space and ground conditions. Then the initial characteristic of a deployment mechanism is statistically predicted. Ground verification of a deployment mechanism is usually difficult because of atmospheric and gravitational effects especially at the system level. Therefore, a new verification procedure is employed. Two kinds of suspending system are developed to compensate for gravity effects. The characteristics of a deployment mechanism can be estimated by identifying system parameters for the equation of deployment motion. This estimation procedure covers all development stages, so that a characteristic history of a deployment mechanism can be easily obtained. Atmospheric and gravitational effects on deployment motion are taken into account as system parameters. It is clarified that all mechanical parts retain their initial characteristics during assembly and environmental testing.

38-GHz-band high-power MMIC amplifier module for satellites on board use

The design and development results of 38-GHz high-power MMIC amplifier modules for use in the solid-state power amplifier (SSPA) to be carried aboard Engineering Test Satellite VI in 1993 are presented. This amplifier will be used in millimeter-wave intersatellite communication experiments. For the development of this amplifier, high-power, highly reliable FETs with 0.25- mu m-long gates were designed. The FET large-signal impedance was accurately measured using an improved load-pull method and MMIC transformers. The measurements were used to design two types of MMICs: one composed of two FET cells with 600- mu m-wide gates and the other of four FET cells with 400- mu m-wide gates. A two-stage amplifier package consisting of two of these MMICs that can be used at 38 GHz is also developed. A P/sub o/(1 dB) of 25 dBm and a gain of 11 dB are obtained. A 38-GHz test conducted during chip screening achieves a high production yield without circuits adjustment.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Compact equipment for on-board communications subsystem supervisory and control system

Onboard equipment for the communications subsystem supervisory and control (CSC) system of a next-generation multibeam high-capacity communications satellite is discussed. In order to keep the equipment as compact, lightweight, and low in power consumption as possible, an onboard data bus system using four kinds of LSIs was developed. It will be carried on-board the Japanese Engineering Test Satellite VI for launch in 1993. Configuration and functions of the CSC equipment, design philosophy of the LSIs, and characteristics of the LSIs developed are discussed.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Pyroelectric infrared detector for precision earth sensor

Two new types of infrared detectors have been developed for the precision earth sensor in the three axis stabilized satellite, Engineering Test Satellite VI (ETS-VI). Both detectors have a pair of infrared sensing elements, each of which is made of a pyroelectric material and mounted on an immersion lens. A-type element is a flake of lead titanate ceramic, and B-type is a sputtered epitaxial film of calcium-modified lead titanate. The precision earth sensor consists of a scanning mirror and an infrared telescope containing an objective lens, plus either type of infrared detector. Detectivity of each type at 120Hz, which is the nominal frequency of the earth sensor's signal, is 1.5×109Hz1/2/W(A-type) and 2.7×109Hz1/2/W(B-type) at 14∼16.25μm. Each value is 2.5 and 4.5 times as high as the previous model in ETS-V. A-type detector passed the space environmental test and the random error cf attitude measurement was 0.03 deg with the preliminary model of the earth sensor being ahead of the breadboard model. This measurement accuracy is nearly equal to that of the foremost earth sensor. A-type was chosen as the detector for ETS-VI. The random error of the earth sensor with B-type detector is 0.012deg, smaller than a half of the A-type sensor's error. Investigation of B-type is being continued in order to confirm its reliability for space use.