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STUDIES ON THE UTILIZATION OF SOLAR SAIL IN LUNAR-TRANSFER TRAJECTORY Zhao Yuhui 1,2 , Liu Lin 1,2 1. Astronomy Department, Nanjing University, Nanjing, 210093,China 2. Institute of Space Environment and Astrodynamics, Nanjing University, Nanjing, 210093, China. Outline
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STUDIES ON THE UTILIZATION OF SOLAR SAIL IN LUNAR-TRANSFER TRAJECTORY Zhao Yuhui1,2, Liu Lin1,2 1. Astronomy Department, Nanjing University, Nanjing, 210093,China 2. Institute of Space Environment and Astrodynamics, Nanjing University, Nanjing, 210093, China
Outline I. Primary Trajectory II. The orbit under real ‘dynamical model’ III. The acceleration due to light pressure IV. Numerical simulations and results V. Conclusions
Introduction Hohmann transfer: shorter transfer time, larger fuel consumption Use the instability of : energy- saving, long time consumption Reasonable use of light pressure: this paper studies
Introduction The force due to light pressure surface pressure: relative to the mass area ration conservative central repulsive force: It doesn’t accelerate or decelerate moving bodies continuously. Therefore, the normal direction of the solar sail usually point in a particular direction in order to use light pressure to guide a probe and save energy consumption.
Lunar gravity field Earth gravity filed The edge of Moon gravity field T=12h T=24h Earth parking orbit Transfer orbit T=48h H=200km Transfer orbit co-two body problem
Primary Trajectory Co-tow Body Problem (Hohmann Transfer) Earth parking orbit: 200km-height circular orbit T=12 hour orbit T=24 hour orbit T=48 hour orbit Transfer orbit: from earth parking orbit to the 300km high point above north pole of the moon Orbit around moon: 300km×200km lunar polar orbit we consider the two primaries separately, central gravitations in each gravitational field are: is used to calculate the accelerations.
The orbit under ‘real dynamical model’ • The kinematical equations are: • Earth’s central gravity acceleration: • Lunar central gravity acceleration: • The acceleration due to : • Solar gravity perturbing acceleration:
The acceleration due to light pressure • Acceleration due to light pressure: Generally this doesn’t accelerate or decelerate a probe continuously in space exploration. • Continuously accelerating: When the normal direction of the solar sail is along the bisector between the direction of the probe from the sun and the direction of motion of the probe
The acceleration due to light pressure • Acceleration due to light pressure:
Numerical Simulations • five simulation models: • 1) hohmann transfer orbits when the sun andthe moon are on two sides of the earth • 2) takes the light pressure into account on thebasis of 1) • 3) hohmann transfer orbits when the sun andthe moon are on the same side of the earth • 4) takes the light pressure into account on thebasis of 3) • 5) a transfer orbit ‘only’ guided by lightpressure
Numerical Simulations • trajectory: Model 1)-4) (4 times impulse) 200km-height circular orbit GT0 orbit GEO orbit transfer orbit300km×200km lunar polar orbit Model 5) (4 times impulse) 200km-height circular orbit GT0 orbit apogee=100,000km transfer orbit300km×200km lunar polar orbit By light pressure only
Numerical Simulations • Initial conditions: Choose the time that the position of the sun and the moon meets the above requirements during March 2007 as the launch time, and the normal direction of the solar sail in model 2),4),5) points the particular direction given above to accelerate the probes continuously. Suppose of the earth’s It’s about
Numerical Simulations Results:
Numerical Simulations • Analysis: 1),2)and 3),4): The relative position of the 3 bodies have effects on the acceleration due to light pressure and energy-saving. 2),4),5): The effect of light pressure used in a hohmann transfer is not obvious because of the short transfer time while a reasonable use will achieve energy saving along with a not very long transfer time.
Conclusions Acceleration due to light pressure is effected by therelative position of the moon and the sun, and has a slight effect in hohmann transfer orbit. However, if light pressure is reasonably used, energy saving could be actually realized with not too much time consumption by adjusting the solar sail’s normal direction to point a particular direction. This kind of orbits has applications and perspective in deep space exploration, it’s an alternative ‘propellant’ to guide a deep space detector