ASTEROID APPROACH Kerry Snyder 12/10/14 Motivation 2 Credit: - - PowerPoint PPT Presentation

ASTEROID APPROACH

Kerry Snyder

12/10/14

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Motivation

Credit: NASA

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Motivation

Credit: NASA Credit: NASA

Prior Work

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Government Missions

Near Earth Asteroid Rendezvous Rosetta and Philae Asteroid Redirect Mission

Commercial

Planetary Resources Deep Space Industries

Verification

Monte Carlo methods Lunar landing Satellite rendezvous in low earth orbit

Initial Assumptions

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2 DOF system – approach axis translation and

rotation

Constant acceleration due to gravity Constant mass spacecraft Fixed braking acceleration Time-triggered controller No orbital mechanics

Control & Invariant

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Derive safety from equations of motion Predict forward and check braking condition

Fuel Use – Key Variables

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dm – dry mass of the satellite (no fuel) M – fuel mass mi – initial mass of the satellite, mi = dm + M m – current mass of satellite, initially mi f – constant force output of the thruster Isp – specific impulse, “engine efficiency”

Fuel Use – Key Equations

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Dynamic braking acceleration Dynamic mass Conservative fuel mass bound

Fuel Use – Application

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NEAR Shoemaker

Isp=325 Seconds f = 450 Newtons dm (dry mass) = 478 Kilograms M (fuel mass) = 300 Kilograms pi = 1000 Meters vi = 3 Meters/Second g = 0.0059 Meters/Second2 Predicts 735 Kilograms of fuel

Fuel Use – Application

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Credit: NASA Credit: NASA

Questions?

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Asteroid Approach - Kerry Snyder