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

Asteroid Approach - Kerry Snyder 1 ASTEROID APPROACH Kerry Snyder 12/10/14

Motivation 2 Credit: NASA Asteroid Approach - Kerry Snyder 12/10/14

Motivation 3 Credit: NASA Asteroid Approach - Kerry Snyder 12/10/14 Credit: NASA

Prior Work 4 � 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 Asteroid Approach - Kerry Snyder 12/10/14

Initial Assumptions 5 � 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 Asteroid Approach - Kerry Snyder 12/10/14

Control & Invariant 6 � Derive safety from equations of motion � Predict forward and check braking condition Asteroid Approach - Kerry Snyder 12/10/14

Fuel Use – Key Variables 7 � 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 � I sp – specific impulse, “engine efficiency” Asteroid Approach - Kerry Snyder 12/10/14

Fuel Use – Key Equations 8 � Dynamic braking acceleration � Dynamic mass � Conservative fuel mass bound Asteroid Approach - Kerry Snyder 12/10/14

Fuel Use – Application 9 � NEAR Shoemaker � I sp =325 Seconds � f = 450 Newtons � dm (dry mass) = 478 Kilograms � M (fuel mass) = 300 Kilograms � p i = 1000 Meters � v i = 3 Meters/Second � g = 0.0059 Meters/Second 2 � Predicts 735 Kilograms of fuel Asteroid Approach - Kerry Snyder 12/10/14

Fuel Use – Application 10 Credit: NASA Credit: NASA Asteroid Approach - Kerry Snyder 12/10/14

Questions? 11 Asteroid Approach - Kerry Snyder 12/10/14