# 2008-11-21 Mission Analysis Geometric Visibility and Manoeuvre Calculations Tommy Yuen.

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2008-11-21 Mission Analysis Geometric Visibility and Manoeuvre Calculations Tommy Yuen

Presentation Outline Requirements How Are We Getting There? Geometric Visibility Theoretical Hohmann Transfer Verifying STK Results Conclusion Future Work 2008-11-21 2Tommy Yuen

Requirements The Penetrator shall: Penetrate a depth of 2 ± 0.5 m Have sufficient link time to be able to transmit segments of data in packets periodically Be able to communicate with the relay satellite of Selene I 2008-11-21 3Tommy Yuen

How Are We Getting There? Selene I – Satellite information 2008-11-21 4Tommy Yuen Main Orbiter (SELENE I) Circular Orbit Orbit100[km] Inclination90[°] Relay Satellite (OKINA) Elliptical Orbit Orbit100 x 2400[km] Inclination90[°] Simplifications: The apoapsis is at -90° lattitude Selene I Okina

Geometric Visibility Ideal case geometric link time: Approximately 7000 s Ideal case regolith transmission thickness: Approximately 11.8 m Worst case geometric link time: Approximately 80 s Simplifications: 90° latitude Only communicates with Okina 2008-11-21 5Tommy Yuen 0.8° 80° 2.5 m 0.45 m 80° Worst and Ideal Case Comparison Ideal Case

Geometric Visibility 2008-11-21 6Tommy Yuen

Theoretical Hohmann Transfer 2008-11-21 7Tommy Yuen Circular Orbit Elliptical Orbit Change in Velocity Required RpRp RaRa

Theoretical Hohmann Transfer 2008-11-21 8Tommy Yuen

Verifying STK Results Conservation of Energy: Tsiolkovsky's Rocket Equation: Simplifications: Tangential Velocity is Cancelled Prior to Free Fall Booster Engines Apply Impulsive Burns and have an I sp of 285 s The Mass of the Penetrator is 10 kg 2008-11-21 9Tommy Yuen

Verifying STK Results Scenario 1 – A vertical burn was used to slow the penetrator down to 0 m/s at the desired altitude of about 28.1 km – Amount of fuel required is about 11.2 kg Scenario 2 – A vertical burn was used to slow the penetrator down to 300 m/s at the surface of the moon – Amount of fuel required is about 9.7 kg 2008-11-21 10Tommy Yuen

Conclusion Geometric link time is about 80 to 7000 s Hohmann transfer is not a plausible option STK results agree with back of the envelope calculations 2008-11-21 11Tommy Yuen

Future Work Refine communication visibility simulations for different impact locations and craters Determine post impact mission time line 2008-11-21 12Tommy Yuen

2008-11-21 Questions?

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