Research on Gas Dynamics in Relation to Performance of Sail-type Spacecraft for Exploration to Outer Planets and Interstellar Region

研究了利用大气通过时的气动力增强帆型航天器能力的方法。采用全pic方法对太阳风在磁帆周围的等离子体流进行了数值分析。磁帆可以产生推力，但与同等尺寸的太阳帆相比，推力要小得多。因此，应选择太阳帆作为第一代帆型航天器。帆的第二个用途是作为航天器的空气动力减速器，以插入环绕行星的轨道，使我们能够进行几乎不需要燃料的行星探测轨道器任务。低弹道系数大气入口拓宽了入口走廊，降低了气动热负荷。在高超声速风洞中对环形支撑膜飞行器的气动性能进行了研究，结果表明，采用环形记忆合金可以实现气动壳体的自动展开。该系统适用于小型大气进入探测器。采用多箍结构可获得三角翼外形。外形优化后，升阻比有望达到5左右。研制了稀薄氢等离子体风洞，用于模拟大气层进入外行星时的空气动力学加热环境。加热试验表明，高温膜与高强度膜相结合制备的多层材料具有广阔的应用前景。研究了太阳帆与航空重力辅助系统的结合。轨道分析表明，长220 m、质量410 kg的膜航天器将以30 km/s的速度离开太阳系，并在30年后到达柯伊伯带。作为第一代星际探测器，这个提议的飞行器看起来很有希望。

The methods to augment the ability of the sail type spacecraft by using the aerodynamic force during the atmospheric pass are investigated.1. The plasma flow of the solar wind around the magnetic sail is numerically analyzed by full-PIC method. The magnetic sail can generate the thrust, but it is much smaller than that obtained by the solar sail with the same size. Consequently, the solar sail should be chosen as the first generation's sail-type spacecraft.2. The secondary use of the sail as an aerodynamic decelerator for the spacecraft to be inserted into an orbit around a planet enables us to make the nearly fuel-free orbiter mission for planetary exploration. The low ballistic coefficient atmospheric entry widens the entry corridor, and reduces the aerodynamic heat and load.3. The aerodynamic performance of the hoop-supported membrane vehicle is investigated in the hypersonic wind tunnel It is demonstrated that the automatically deployed aeroshell can be realized by using the shape memory alloy for the hoop. This system is suitable for small atmospheric entry probes. Shape like delta wing can be obtained by the multi-hoop structure. High lift-to-drag ratio of about 5 is expected after shape optimization.4. The rarefied hydrogen plasma wind tunnel has been developed to simulate the aerodynamic heating environment at atmospheric entry to outer planets. The heating tests suggest that the multi-layer material made by the combination of high temperature membranes and high strength ones is promising.5. The combination of the solar sail and the aero-gravity-assist is investigated. The trajectory analysis shows that the membrane spacecraft with length 220 m and mass 410 kg will leave the solar system at velocity 30 km/s and reach the Kuiper belt in 30 years. The proposed vehicle seems promising as the first generations interstellar probe.