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Accepted: 2013-04-17, 資料番号: SA1004888000

The rate constant for the vibrational transition and dissociation of CO by CO-O collision is calculated by molecular collision dynamics in a temperature range from 3000 K to 40000 K, which includes a temperature range where experimental studies are difficult to conduct. The thermal equilibrium dissociation rate constant and vibrational relaxation time of CO is obtained using this rate constant. The former is in good agreement with a conventional experimental model, and the latter is smaller than that by a factor of an order of magnitude at low temperatures. A discussion on the potential energy surface (PES) of this collision system indicates that the three-body term of the PES is probably large, and hence a quantitative calculation of the PES by an ab initio molecular orbital method is needed to estimate this term further.

A preliminary assessment of the heating environments during a hyperbolic entry to the planet Venus is conducted in order to investigate fundamental characteristics of flows in the shock layer, and to predict the convective and radiative heat flux transferred to the entry capsule at the peak-heating point. Thermochemical nonequilibrium flows are calculated using two-dimensional Navier-Stokes equations in the axisymmetric geometry, taking into account oxidation and sublimation of the heatshield surface, and pyrolysis-gas injection. Radiative heat transfer coupled with the flow is computed by a line-by-line method with a tangent-slab approximation. Influences of uncertainties in the thermochemical models on the predicted heat flux are also examined.

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