Hypersonic Reentry Dynamics Faculty Advisors Professor Mease (UC Irvine) Dr. Helen Boussalis (CSULA) Student Assistants Katie Demko Shing Chi Chan 7/12/2015NASA Grant URC NCC NNX08BA44A1

Mission Contribute to the guidance of future hypersonic re-entry vehicles. Objective: Step 1:Understand the mechanics and control of space vehicle re-entry via modeling and simulation in Matlab. Approach: 7/12/20152NASA Grant URC NCC NNX08BA44A

7/12/20153NASA Grant URC NCC NNX08BA44A Background Constellation project Constellation is one of NASA’s current missions which emphasizes expanding space exploration to a higher level. The goal of Constellation is to return to the Moon and eventually to make it to Mars. Orion Crew Exploration Vehicle For this reason, a capsule- shaped crew module is developed for maximum crew operability and safety. This brings the birth of Orion Crew Exploration Vehicle. Image and Video from reference 4

Orion vs. Apollo Orion is required to be reusable and will therefore have to perform accurate land landings instead of water landings Land landings require more precision than water landings Less landing spots on land To achieve greater distances re-entry trajectory might require a skip 7/12/20154NASA Grant URC NCC NNX08BA44A

Basic Forces Variable definitions:L = LiftD = DragT = ThrustW = Weightρ = Air Densityv = VelocityS = Reference AreaC L = Coefficient of LiftC D = Coefficient of Drag AIRPLANE 7/12/20155NASA Grant URC NCC NNX08BA44A The orientation of the LIFT vector is typically the means of control.

ORION SPACE CAPSULE Images from Reference 1 Basic Forces 7/12/20156NASA Grant URC NCC NNX08BA44A

Trajectory Control via Drag Tracking 7/12/20157NASA Grant URC NCC NNX08BA44A γ Drag is used to track the trajectory because it is the most robust.

Equations of Motion for Reentry (Drag) 7/12/20158NASA Grant URC NCC NNX08BA44A

Simulation Parameters for Lifting Entry Bank Angle (σ) = 0 deg or 60 degVehicle Cross Sectional Area (S) = 23.8 m 2 Vehicle Mass (m) = 9500 kgC L = 0.44C D =1.25 Latitude (θ)=0 Longitude (Φ)=0 Radius (r)=6498 km Heading (Ψ)=0 Flight Path Angle (γ)= -9 deg Initial Conditions: 7/12/20159NASA Grant URC NCC NNX08BA44A

Simulation Conditions Note:The initial energy corresponds to an altitude of 120km.The final energy corresponds to an altitude of 20km. 7/12/201510NASA Grant URC NCC NNX08BA44A

Lifting Entry with σ=0° In this case, the vehicle performs a skip Comments 7/12/201511NASA Grant URC NCC NNX08BA44A

Lifting Entry with σ=0° The graph of the flight path angle is related to the change in the altitude from: The regions of positive slope indicate a slower descent rate. Comments: 7/12/201512NASA Grant URC NCC NNX08BA44A

Lifting Entry (σ=0°) Since there is no bank angle and the initial heading is 0 deg the vehicle enters above the equator and continues to fly in the equatorial plane in the absence of wind. 7/12/201513NASA Grant URC NCC NNX08BA44A

Lifting Entry (σ=0°) The heading remains Eastward because there is no bank angle to change it Comments: Heading Convention (UCI): 0 °= E 270 ° = S 180° = W 90° = N 7/12/201514NASA Grant URC NCC NNX08BA44A

Lifting Entry with σ=60° In this case the vehicle doesn’t perform a skip and covers a smaller downrange distance Comments: 7/12/201515NASA Grant URC NCC NNX08BA44A

Lifting Entry with σ=60° The graph of the flight path angle is related to the change in the altitude from: The regions of positive slope indicate a slower descent rate. Comments: 7/12/201516NASA Grant URC NCC NNX08BA44A

Lifting Entry with σ=60° The graph indicated that the vehicle flies in a Southeastern direction. Comments: 7/12/201517NASA Grant URC NCC NNX08BA44A Heading Convention (UCI): 0 °= E 270 ° = S 180° = W 90° = N

Lifting Entry with σ=60° As a result of the nonzero bank angle the vehicle veers South of the equatorial plane. Comments: 7/12/201518NASA Grant URC NCC NNX08BA44A

Advantages to Skip Entry 7/12/201519NASA Grant URC NCC NNX08BA44A Downrange Distance Earth Moon Entry into the Atmosphere Landing Spot In order to be able to return from the moon at any time during the day, need to have large downrange capability Comments:

The Next Step To account for the path constraints due to maximum g-loads, heat and dynamic pressure that the vehicle can withstand To include feedback tracking control in the Matlab simulation 7/12/201520NASA Grant URC NCC NNX08BA44A

References 1) Bairstow, Sarah H., and Gregg H. Barton. "Reentry Guidance with Extended Range Capability for Low L/D Spacecraft." AIAA Guidance, Navigation and Control Conference and Exhibit Hilton Head, SC, August ) Benito, Joel, and Kenneth D. Mease. "Nonlinear Predictive Controller for Drag tracking in Entry Guidance." American Institute of Aeronautics and Astronautics :14. 3) Lickly, D.J., H.R. Morth, and B.S. Crawford. "Apollo Reentry Guidance." MASSACHUSETTS INSTITUTE OF TECHNOLOGY N (1963): 23. 4) "NASA - Constellation Main." NASA - Constellation Main. 26 Oct /12/201521NASA Grant URC NCC NNX08BA44A