小行星探测任务

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屋融燕
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1 Cubesat: A Candidate Mission Strategy for the Multi-Asteroid Target Exploration Peng Wang

2 Contents 1 Chance & Problem 2 Mission Strategy 3 Design Method 4 Example: 2009BD 5 Summary 2

3 1 Chance & Problem Nowadays Multi-asteroid exploration gradually attracts many scientists and engineers ?? 成本 :( 亿美元 ) Galileo Ida 主带 S Near- Braille Shoemaker 未成像主带 Q Mathilde 主带 C Eros 近地 S Deep space 1 Stardust Annefrank 主带 S Rossetta New Horizons APL Steins Lutetia 主带 S 主带 E 主带 C Hayabusa CE-2 Toutatis 近地 S Vesta 主带 V Dawn Ceres 主带 C 概念探索及技术验证方向 ( 飞越绕飞 ): 获取小行星光谱图象探测小行星动态特性表面形态组成成分简单应用方向 ( 绕飞着陆 ): 单星内部结构及成分轨道演变形式 Itokawa 近地 S Hayabusa 2 Don Quijote OSIRIS-REX :1999 JU3 2020: 取样返回 2003SM 近地 C 或彗星 RD36 近地 S 实际应用方向 ( 附着采样返回撞击 ): 生命起源资源探测小行星防御 3

4 ROSETTA mission Duration: ~ 10 years 1 Chance & Problem 4x planet swing-bys (Earth, Mars) Cruise science: 2 x asteroids Earth/Mars fly-bys Science at comet: > 1 ½ years in orbit lander delivery 4

5 1 Chance & Problem We can get more useful information (scientific and others )from asteroid explorations. From Exploration to Application 5

6 1 Chance & Problem However, before we make a change, We have to conquer some problems. Top level Cost Time 10 Years 6

7 1 Chance & Problem Mission level multi-body exploration bring high complexity The dynamic behaviors become chaotic. The Lunch window become difficult... 7

8 1 Chance & Problem A multi-asteroids exploration based on Cubesat set is now developed which can reduce the mission cost and decouple the complexity. 8

9 Contents 1 Chance & Problem 2 Mission Strategy 3 Design Method 4 Example: 2009BD 5 Summary 9

10 2 Mission Strategy We proposed a mission strategy performed by a cubesat set from Sun-Earth L2/Earth-Moon L2 libration points Escape point Relay Halo orbit (Optional) Earth Asteroid v A Initial Halo orbit v D v M Capture point Unstable manifold segment Escape segment Escape trajectory Interplanetary segment & Unstable manifold segment Stable manifold segment Capture trajectory 10

the target asteroid from Halo orbit Transfer to Earth-Moon L2 Halo orbit

11 2 Mission Strategy Strategy 1 (Sun-Earth L2 ) Strategy 2 (Earth-Moon L2 ) Directly transfer to Sun-Earth L2 Halo orbit from Earth Orbit Transfer to the target asteroid from Halo orbit Transfer to Earth-Moon L2 Halo orbit from Earth Orbit Transfer to Sun-Earth L2 Halo orbit Transfer to the target asteroid 11

Novel Technology application Sun-Earth L2 Strategy Using the Pseudo-manifold to transfer 2 Mission Strategy Commonly, following the invariant manifold from Halo orbit to the vicinity

By increasing the perturbation: 1) perturbation is only applied on the velocity; 2) the direction of perturbation is the same as the stable and the unstable eigenvector; 3) the value

12 Novel Technology application Sun-Earth L2 Strategy Using the Pseudo-manifold to transfer 2 Mission Strategy Commonly, following the invariant manifold from Halo orbit to the vicinity of the planet takes a very long time. By increasing the perturbation: 1) perturbation is only applied on the velocity; 2) the direction of perturbation is the same as the stable and the unstable eigenvector; 3) the value of perturbation velocity is among. Earth-Moon L2 Strategy Using the LCS to connect Halo orbits LCS- Invariant manifold substitution Calculate Finite-Time Lyapunov Exponent (FTLE) on initial grid FTLE value λ is the largest eigenvalues of the Cauchy-Green Strain Tensor CGST G S S V V0 Vχ U U V V0 Vχ,, State transition matrix 12

13 Contents 1 Chance & Problem 2 Mission Strategy 3 Design Method 4 Example: 2009BD 5 Summary 13

14 3 Transfer Trajectory Equations of Motion CRTBP: x 2 y, x y 2 x, y z, z where the potential of the system is x y z r r L 3, y Sun/Earth L 4 L 5 L 1 r 1 r 2 L 2 Earth/Moon Spacecraft x 14

15 3 Transfer Trajectory Transfer Trajectory Design:Trajectory Searching Method The design parameters of low-energy transfer trajectory employing planetary gravity-assist and pseudo-manifold are: t 0 Z S D M D M A t,,,,,, 0 t V V V where is the moment when the spacecraft departs the initial Halo orbit, t S is the time between the escape point and capture point, D 0,1 and M 0,1 indicate the phase on the initial and final Halo orbit, V A is the perturbed velocity used for capturing for the target, V D is the perturbed velocity used for departing the initial Halo orbit, V M is the perturbed velocity used for departing the relay Halo orbit. Note that the () indicate the optional parameters depended on the transfer strategy T 15

16 The objective function is chosen as:, J V V V t t t Z D A M D S A where t denotes the time of the escape segment, t D A denotes the time of the capture segment, denotes penalty factor. The transfer trajectory must satisfy the terminal constraints ρ t0 X D D, t0 Z 0, 1 ρ tf X A A, tf where t f t0 td ts t ρ A denotes the states of spacecraft D X Adenote the states on the initial and target Halo orbit, respectively. X 3 Transfer Trajectory 16

17 Contents 1 Chance & Problem 2 Mission Strategy 3 Design Method 4 Example: 2009BD 5 Summary 17

18 4 Example Example target asteroid: 2009BD NEA 10m-size Small inclination 18

19 4 Example: 2009BD Initial Searching for Escape Time Date The initial orbit is Sun-Earth L2 Northern Halo orbit : e5 km. The range of launch time: The maximum allowable flying time: 500 days. The contour of total velocity increment is drawn in Figure. 19

20 4 Example: 2009BD Accurate iteration for searching the optimal solution The flying time reduces as the perturbed velocity increases. Several local extremes of velocity increment The required delta and transfer time V_D V_M V_A Total t Strategy km/s km/s d Strategy km/s 0.16km/s 0.13km/s d 20

Transfer Trajectories 4 Example: 2009BD From Sun-Earth L2 to the target From Earth-Moon L2 The total delta V for transfer to asteroids Target 2009BD

21 Transfer Trajectories 4 Example: 2009BD From Sun-Earth L2 to the target From Earth-Moon L2 The total delta V for transfer to asteroids Target 2009BD 2008EA Apophis Type Apollo, S type Amor type, C type Aten, S type Reference 0.41km/s 1.00km/s 2.39km/s This paper 0.40km/s 0.92km/s 2.33km/s 21

22 4 Example: 2009BD Cubesat concept CAN Optic & infrared Camera 22

23 Cubesat configuration 4 Example: 2009BD type weight(kg) 1 bus 10 2 thermal Attitude & Orbit Power House keeping Communication Payload 2.7 Weight: 47kg Size: 500 mm 420mm 500mm Data rate:512bps V:1050m/s Life: 3 years 8 Propellant based on AND 17 9 Margin 0.1 Total 47 23

24 Launch vehicle 4 Example: 2009BD Type: CZ-4C Ability:500kg(earth-moon orbit) 24

25 4 Example: 2009BD Mission profile Z Z Sun direction Z SEL1 EML5 Lunar Orbit X EML2 EML1 EML3 Y SEL2 Y EML4 We can independently apply 6 Cubesats asteroid mission chances for scientists launched by one rocket. Each mission only costs 20 million USD (including manufacture and launch) 25

26 Contents 1 Chance & Problem 2 Mission Strategy 3 Design Method 4 Example: 2009BD 5 Summary 26

27 5 Summary An economical asteroid exploration project As Primary Payload firstly Detecting multi-targets by a set of Cubsats orbiting Halo orbit Two candidate strategy: Sun-Earth L2 based/earth-moon L2 based Smaller Δ V than that of classical method Future: Real ephemeris model + Low thrust engine 27

28 Thanks

Microsoft Word - 092013-1203-6(du)(改2)

Microsoft Word - 092013-1203-6(du)(改2) 中国科学 : 技术科学 2014 年第 44 卷第 3 期 : 229 ~ 234 评述 www.scichina.com tech.scichina.com SCIENCE CHINA PRESS 载人飞船与专项技术专题载人飞船型谱发展研究何宇, 贾世锦, 石泳 *, 邵立民, 高旭中国空间技术研究院载