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Institute of Space and Astronautical Science (ISAS), Japan, plans to undertake a lunar mission, named as LUNAR-A, which is to be launched in 1997. The scientific objective of the mission is to explore the lunar interior using seismometry and heat-flow measurement toward better understanding of the origin and evolution of the moon. The M-V, the newest version of the Mu series launch vehicles is used to send about 520 kg of spacecraft to the lunar transfer orbit. Three penetrators are deployed from a spacecraft onto the lunar surface, using the Rhumb-Line attitude control and constitute a seismic and heat-flow measurement network of a larger span than the Apollo ALSEP network. Each penetrator contains a three-axis seimometer and a heat flow probe and weighs 13 kg. The life time of the penetrator is limited by the battery capacity and is estimated to be one year.

The paper deals with an application of the modified Nussbaum Gain in connection with the adaptive stabilization of the process with completely (i.e. in the magnitude and sign) unknown high frequency gain. The original idea of the Nussbaum gain is to invert the sign of the gain of the controller periodically and to increase its gain. The stability of such schema was proved for first order systems. The proposed modification is to increase the period of the changing sign rather than the gain of the controller. The idea was applied to the adaptive stabilization of an undesired lateral motion of the balloon gondola. Laboratory experiments have shown higher damping of undesired oscillations in comparison with standard adaptive notch filter approach.

In order to verify the entire functions of a parachute deployment system, applicable to a small space capsule, and to examine the transonic dynamics of the capsule with a blunt nose, a free fall capsule experiment was successfully conducted using a balloon with 30,000 m in volume in September, 1996. The capsule weighed approximately 26 kg, and its configuration was 40 cm in diameter and 20 cm in height. The capsule was released from the balloon gondola at 36 km in altitude, and the maximum descent speed was 1.1 in Mach number 45 seconds after the release. As the velocity increased to supersonic, the capsule pitching amplitude was enlarged due to the dynamic instability, and the angle-of-attach was approximately 30 degrees at maximum. On the other hand, the velocity decreased to subsonic, the oscillation was little damped. The single stage cross-type parachute was directly pulled out by the parachute cover, using newly developed pyrotechnical cover openers. The opening shock was 24 G, and it corresponded with the opening shock coefficient of 1.3. The flight results well met the estimation based on the ground test results, except for the less damping efficiency. This paper presents the outline and the flight results of the balloon-borne drop test. Comparison with wind tunnel tests is also described. Penetrator. In MUSES-C (Mu-rocket Space Engineering Spacecraft #C) mission, which will launch a spacecraft towards a small asteroid, Nereus, in the early 2002, a reentry capsule will be applied so as to bring the asteroid material back to the ground. The current capsule design is tentatively as such the weight of the capsule is 18 kg, and the diameter is 40 cm. Besides, the capsule is covered with the relatively thick ablator materials of 2 to 3 cm in thickness. Thus, inside volume for equipments is quite severe. The capsule is not so heavy that the parachute enables to be a single-stage without a drogue nor a pilot chute. This simplification can reduce both weight and volume. Furthermore, the parachute is rigged in the torus-shaped container, so as to keep the maximum space for measurement and transmission instruments at the center of the capsule. Thus, the parachute is equipped in looping around the instruments, and it is directly pulled out by the cover of the parachute container. Therefore, it should be carefully discussed whether the rigid cover can generate the enough aerodynamic force to pull stably the parachute out in the back stream of the forebody. The shape of the capsule is conventional, which has a spherical nose of 20 cm in radius and a conical body of 45 degrees in half-cone-angle. Therefore, the dynamic instability should be carefully investigated. Capsule Configuration

The recovery operation of sounding rocket of ISAS takes much time and cost due to its long down range, amounted to approximately 300km off shore. The recovery system using gliding parachute is expected to be a hopeful candidate because of its maneuverability and high-glide performance. ISAS has been so far developing it through wind tunnel tests with sub-scaled model and drop test from helicopter at low altitude with full-scaled model. In June 1994, the opportunity was took for the autonomous flight test of recovery system with gliding parachute, released from balloon at altitude of about 8km. The autonomous flight control was carried out during descent by the on-boarded computer with GPS data and geomagnetic attitude data. The control was proportional to the directional deviation between the present attitude and the target. It was satisfactory below the altitude of 2km. In this paper the experiment using balloon was described in detail and the results obtained were also reported.

Prclirninary wind tunnel tcs1.5 have bccn madc in ISAS in order to study the characteristics of the parachutcs at transonic and supersonic Mach number regions. A device has bccn madc to eject a model parachute into a wind tunnel flow and to measure the drag force acting on it. Some experimental studies on parachute deployment have been carried out by using the device set on the inside wall of transonic and supersonic wind tunnels having t g t sections of 60cm square in ISAS with the flow conditions of Mach number from 0.8 to 3.0 and Reynords numbcr from 2.2 to 2.9*107/m. Parachute models employed in this study have been made of practical parachutc materials. Thcir shapcs arc similar to conical and equiflo types. The relations between the Mach number and the drag, parachutc diameter, oscillating angle arc obtained, and thcsc comparative acrodynamic characteristics were discussed, including the effect of forebody wake. Some typical phenomena such as "breathing" at supersonic spccd are obscrved and their frequencies are also measured. Furthermore, some qualitative invesligation was made on thcsc "breathing" phenomena.

In present ballooning missions, as payloads increasingly become heavier and more sophisticated, much higher reliability is required in the balloon itself and in the launch operational technique. Hence, ISAS (the Institute of Space and Astronautical Science) has developed a balloon made of relatively thick films reinforced with high-strength fiber fabric (ref. 1 to 3). In order to verify structural properties and manufacturing quality, partial strength tests together with a trial production of small scale balloons have been car ied 5 . out. In 1990, a sub-scale B5 (5,000 m In volume) size balloon was produced, and a full inflation test on the ground prior to a flight experiment was implemented on account of demonstrating the basic capability of the fiber reinforced balloon. This paper describes research and development of the proposed balloon associated with selection and verification study of the high-strength fiber reinforced film.