Trans. JSASS Aerospace Tech. Japan Vol. 14, No. ists30, pp. Pe_87-Pe_94, 2016 Development of Supersonic Parachute for Japanese Mars Rover Mission By Hiroki TAKAYANAGI,1) Toshiyuki SUZUKI,1) Kazuhiko YAMADA,2) Yusuke MARU,2) Shingo MATSUYAMA3) and Kazuhisa FUJITA1) 1)Research and Development Directorate, JAXA, Chofu, Japan 2) Institute of Space and Astronautical Science, JAXA, Sagamihara, Japan 3) Aeronautical Technology Directorate, JAXA, Chofu, Japan (Received July 31st, 2015) For landing a rover on the Mars ground, supersonic parachute has been developed in JAXA. Key technologies are categorized in aerodynamic performance, mechanical strength, ejection system, and validation method of the design for pre-flight model. So far, we have performed experiments in low-speed, transonic, and supersonic wind tunnels in Chofu aerospace center and ISAS. From these experiments, we have investigated aerodynamic performance such as drag coefficients, opening load factor, and stability of the parachute. We have also evaluated the mechanical strength in these wind tunnel tests. In addition, ejection system with automobile airbag inflator has been developed and a vertical ground test is performed in Noshiro Rocket Testing Center. Key Words: Supersonic Parachute, Mars EDL Nomenclature China officially announced plans to go forward with their Mars mission planned for 2020. The program includes plans 2 A : Reference area, m for Mars sample return in 2030. India has already achieved CD : Drag coefficient their first interplanetary mission since 2014 called as D : Diameter Mangalyaan. As a next step, they also plan to land a rover on D0 : Nominal diameter the Mars ground in 2020’s. Dp : Projected diameter of inflated parachute In Japan, several missions to Mars have been planned. Fre : Unfurling resistance force, N NOZOMI was Japanese first Mars explorer and its main L : Length mission was to research Martian upper atmosphere by m : Mass, kg focusing on the interaction with solar wind. However, it was 2 q∞ : Free-stream dynamic pressure, N/m unable to achieve Mars orbit due to electrical failures. We TB : Tension at mouth of deployment bag, N have also planned a mission with the entry into the Martian η : Wake parameter (ratio of drag coefficient atmosphere called as MELOS. In order to achieve this of deployment bag in vehicle wake to that mission, supersonic parachute is needed to be developed in in free stream) order to decelerate in Martian atmosphere, which is thinner Subscripts than earth’s atmosphere. From a present trajectory plan, a 1) B : Band parachute is opened at around 8 km altitude and Mach 1.79. Bent : Bent At that time, a dynamic pressure is about 580 Pa. After D : Disk deceleration lower than 90 m/s, a lander is landed by a sky G : Gap crane. : Suspension line In United States, supersonic parachutes have been SL 2, 3) v : Vehicle developed for planetary explorations from 1950s. They have developed and used Disk-Gap-Band (DGB) parachutes 1. Introduction for a number of Mars missions from Viking in 1972 to MSL in 2012. In MSL mission, they developed a mortar-developed Recently, several missions with the entry into the Martian 21.5-m reference diameter DGB parachute, the largest atmosphere have been proposed all over the world. On parachute ever to be deployed on the surface of Mars. EDL August 6, 2012, Curiosity landed the Martian ground reconstruction indicates that parachute mortar deployment successfully. United States also plans to launch InSight in was initiated at a Mach number of approximately 1.75 and 4) 2016. ESA is now planning to launch ExoMars rover in 2018 dynamic pressure of 493.6 Pa. Parachute release occurred after the launch of the orbiter and the lander in 2016. In Asia, some 116.6 seconds after mortar fire, as responsibility for Copyright© 2016 by the Japan Society for Aeronautical and Space Sciences and1 ISTS. All rights reserved. Pe_87 Trans. JSASS Aerospace Tech. Japan Vol. 14, No. ists30 (2016) terminal descent was handed by the “Skycrane” thrusters. On dynamic pressure. the other hands, ESA has developed a 12.0 m nominal diameter DGB parachute for ExoMars mission.5) In this 3. Aerodynamic Performance and Mechanical Strength mission, the maximum deployment Mach number is 2.1. In Japan, although drop tests of supersonic parachute from a In this study, in order to evaluate aerodynamic performance balloon6) and a sounding rocket7) have been carried out in such as drag coefficients, stability, and mechanical strength, 1990s, the methodology of supersonic parachute wind tunnel tests were performed in low-speed, transonic and developments has not been established yet. Then, we started supersonic wind tunnels developed in Chofu aerospace center a development of supersonic parachute in 2012. So far, we and ISAS. have searched past supersonic parachutes, designed a concept, 3.1. Supersonic wind tunnel test in Chofu aerospace center and performed wind tunnel tests. When we want to design a Supersonic wind tunnel tests were performed with scaled new parachute, we need to perform various types of membrane parachute models manufactured by Fujikura Koso experiments and CFD calculations in order to optimize a lot of KK. An example picture of model is shown in Fig. 1. parameters, such as materials, shape, and sizes. In our research, Parameters of these models are shown in Tables 1 and 2. In we have developed a parachute with Viking scaled geometry these tables, drag coefficients at low velocity measured in to reduce our time and costs. So far, we have performed Fujikura Koso KK are also tabulated. Two types of parachute, experiments in low-speed, transonic, and supersonic wind tunnels in Chofu aerospace center and ISAS. From these experiments, we have investigated aerodynamic performance such as drag coefficients, opening load factor, and stability of the parachute. In addition, ejection system with automobile airbag inflator has been developed and a vertical ground test is performed in Noshiro Rocket Testing Center. 2. Development Scenario for Supersonic Parachute In order to develop a supersonic parachute for our Mars Mission, we categorized key technologies in aerodynamic performance, mechanical strength, ejection system, and validation method of the design for pre-flight model. So far, we have performed experiments in low-speed, transonic, and supersonic wind tunnels. From these experiments, we have investigated aerodynamic performance such as drag coefficients, opening load factor, and stability of the parachute. We have also evaluated the mechanical performance in these wind tunnel tests. However, we should take into account the effect of the differences in dynamic pressure, scale, and Fig. 1. Parachute model for wind tunnel tests. fabricate materials between the wind tunnel tests and real Mars entry conditions. Therefore, fluid structure interaction Forebody analysis will be performed in order to evaluate these differences. In addition, the effects of the mounting structure were observed in the wind tunnel tests as mentioned in section 3. Therefore, we will perform the drop tests from a helicopter, a scientific observation balloon, and a sounding rocket. First, Strut we will perform a drop test with a small-size DGB parachute from a helicopter in order to evaluate the ejection system at same dynamic pressure. In this case, the maximum Mach number will be about 0.3. As a second step, we will perform a drop test with a small-size DGB parachute from a scientific observation balloon in order to evaluate a drag coefficients, Flange at undersurface in opening load factor, and stability of the parachute at around measurement position M = 1.4. In this case, dynamic pressure will be about 5.1 kPa. Finally, we will perform a drop test with a small-size DGB parachute from a sounding rocket in order to evaluate a drag coefficients, opening load factor, and stability of the parachute at same Mach number and same dynamic pressure. In addition, we will perform a drop test with a full-scale parachute from a helicopter in order to evaluate the mechanical strength at same Fig. 2. Schematic of mounting structure in supersonic wind tunnel at Chofu aerospace center. 2 Pe_88 H. TAKAYANAGI et al.: Development of Supersonic Parachute for Japanese Mars Rover Mission six models, were used for these experiments. As mentioned in Table 1. Parameters of parachute small models for transonic and the introduction, the shape is DGB-type Viking scaled supersonic wind tunnel tests. geometry. The material of disk and band is 38-g woven nylon. Parameters Small - 2 Small - 3 Small -4 Its permeability is between 0.35 and 0.61 m3/m2/s. When the Nominal D0 156 158 158 fabric of band and disk was broken, it was repaired after diameter, mm experiments. The schematic of mounting structure for the Projected Dp 115 109 102 membrane parachute models is shown in Fig. 2. The shape of diameter of the forebody is consists of circular cone and cylinder. Two inflated types of the forebody, of which diameter were 20 and 32 mm, parachute were used for the experiments with the small-size models. Gap length, LG 7.3 6.0 5.6 The 40-mm-diameter forebody was used for the mm experiments with the large-size models. The parachute drag Band length, LB 18.5 20.2 20.2 was measured by means of a single-axis load cell mm (Measurement specialties Inc., XFTC-301) mounted within Vent diameter, Dv 9.3 9.8 9.8 the forebody after an amplifier (TEAC Inc., SA-59) at a rate mm of 2 kHz. Drag is calculated in the same method as the Viking Suspension L 287 282 283 era wind tunnel programs by following equation. 8) s line length, (1) mm ிವ Number of N 24 24 24 ஽ బ These measurement systemܥ ൌ ௤ௌwas calibrated with weights. gore The tests were recorded with Shclieren system on high speed Drag CD 0.69 0.58 0.64 video camera (1 kHz).