HYBRID AEROCAPTURE USING LOW L/D AEROSHELLS FOR ICE GIANT MISSIONS

Transcription

1 HYBRID AEROCAPTURE USING LOW L/D AEROSHELLS FOR ICE GIANT MISSIONS 15 th International Planetary Probe Workshop (IPPW-15) Boulder, Colorado, June 2018 Athul Pradeepkumar Girija A. Arora, and S. J. Saikia School of Aeronautics and Astronautics, Purdue University, IN, USA J. A. Cutts NASA Jet Propulsion Laboratory, California Institute of Technology, CA, USA This work was supported in part by the NASA Jet Propulsion Laboratory, California Institute of Technology. Travel funding provided by IPPW is gratefully acknowledged. Artist s concept of a low L/D aeroshell used for aerocapture at the Ice Giants. MSL entry vehicle used for representative purpose only, credit: NASA/JPL.

2 Ice Giants Uranus and Neptune Rocky Gas Giants Ice Giants Image credits: Top: Solar System, Wikipedia.org, CC BY-SA 3.0; Bottom left: NASA/Lunar and Planetary Institute; Bottom right: NASA Ames/W. Stenzel 1

3 Ice Giants - Science Objectives Constrain interior Magnetosphere Bulk composition Winds, circulation Satellite composition Ring structure Heat flow Graphics credit: NASA Ice Giants Pre-Decadal Study Report,

4 NASA Ice Giants Pre-Decadal Study, 2017 Uranus Orbiter with probe and ~50 kg payload, no SEP Launch TOF (y.) Arrival V Arrival Mass OI ΔV Mass in Orbit km/s 3582 kg 1.7 km/s 1913 kg Neptune Orbiter with probe and ~50 kg payload, with SEP stage Launch TOF (y.) Arrival V Arrival Mass OI ΔV Mass in Orbit km/s 5033 kg 2.7 km/s 2012 kg Source: NASA Ice Giants Pre-Decadal Study Report, JPL D

5 Mission Design Challenges Chemical OI limit is the major design constraint. Aerocapture uses atmospheric drag to perform orbit insertion. Chemical OI limit Low TOF, high V Max. RPS design life = 15y High TOF, low V Acknowledgement: A. Petropoulos, N. Arora, JPL; K. Hughes, A. Mudek, Purdue University 4

6 Aerocapture Coast phase Science Orbit Not captured Periapsis Raise Maneuver (PRM) Atmospheric flight Too steep Too shallow Interplanetary cruise, Arrival V Approach navigation 5

7 Corridor Width 1. Theoretical Corridor Width (TCW) 2. Required Corridor Width (RCW) Navigation errors Atmospheric uncertainties Aerodynamic dispersions Vehicle (L/D)max Arrival V TCW RCW TCW RCW 6

8 Aerocapture Vehicles Low L/D with flight heritage Expt. vehicles Mid-high L/D, concept vehicles Dragon 0.18 MSL 0.24 Apollo CM 0.36 ESA IXV 0.7 Ellipsled 0.8 Biconic 1.0 Concept Asymmetric ADEPT Vehicle L/D Image Credits: SpaceX, NASA,/JPL ESA 7

9 Neptune Aerocapture Max.possible Max. arrival V 2 for deg TCW kj/cm g W/cm deceleration arrival heat 2 heat V atmfrom stag. chemical OI constraint load rate constraint trajectory pres. constraint data Which vehicle do we need? Mid L/D aeroshell Implications Cost Risk Can we lower the L/D? Reduce uncertainties Hybrid aerocapture Design Space 8

10 Hybrid Aerocapture Aerodynamic and propulsive forces used for orbit insertion How? Feasibility Can we use low L/D aeroshells? ΔV Risk vs. Benefit 9

11 Hybrid Aerocapture Approach #1: Small capture orbits Benefits Increases TCW Cost Risks Reduces risk of accidental escape ΔV G-load, heating Ring plane crossing hazard Autonomous navigation 20 day science orbit 10 day capture orbit 1 day 0.5 day 0.25 day ΔV 10

12 Hybrid Aerocapture Approach #1: Cost-Benefit Analysis RCW = 2.0 ΔV=2.1 km/s ΔV=2.1 ΔV=2.1 km/s km/s ΔV=1.2 km/s ΔV=1.2 ΔV=1.2 ΔV=1.2 km/s km/s km/s ΔV=0 km/s ΔV=0 ΔV=0 km/s km/s ΔV=0 km/s ΔV=0 km/s RCW = 1.5 ΔV=3.6 km/s Capture Orbit = 1 day Prop. ΔV = 1.2 km/s RCW L/D V (km/s) ΔV=3.6 km/s ` 11

13 Hybrid Aerocapture Approach #2: Exit speed targeting Benefits Allow a wide range of exit speeds Increased TCW Reduced ring plane crossing hazard Cost and Risk ΔV Possible escape Science orbit after PRM Science orbit after PRM Propulsive ΔV boost Too slow for science orbit Shallo w ent St ry ee pe nt ry ΔV Propulsive ΔV completes capture Too fast, not captured ΔV TCWΔV 12

14 Hybrid Aerocapture Approach #2: Cost-Benefit Analysis RCW = 2.0 RCW = 1.5 ΔV budget = 2.0 km/s RCW L/D V (km/s)

15 Hybrid Aerocapture Mission Concept TOF < 10y L/D: ΔV < 2 km/s Low TOF, high V Max. RPS design life = 15y High TOF, low V Acknowledgement: A. Petropoulos, N. Arora, JPL; K. Hughes, A. Mudek, Purdue University 14

16 Summary of Options and Impact on Investment G-load GOAL: Increase the surface area (design space) More Structural Mass More Instrument Mass Heat-Rate Stag. Press Decrease RCW - Improved navigation - Atmospheric obs, modeling Increase TCW - New TPS Material Dev. - Significant Investment Heat-Load More TPS material (more mass) - Hybrid aerocapture - Direct force control Large Launch Vehicle to deliver high V 15

17 Questions? Crescents of Neptune and Triton acquired by Voyager 2 on its outbound journey from the Neptune system, Aug. 28, Credits: NASA/JPL 16