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Uranus Exploration Challenges Steve Matousek Workshop on the Study of Icy Giant Planet (2014) July 30, 2014 (c) 2014 California Institute of Technology. Government sponsorship acknowledged. JPL URS clearance CL#14-3608 1

Outline Uranus System Summary Challenges Overview of Architectures How Architectures Meet Challenges Summary July 30, 2014 (c) 2014 California Institute of Technology. Government sponsorship acknowledged. JPL URS clearance CL#14-3608 2

A Brief History 1781 1986 2008 Higher Maturity Uranus Studies 2010 2011 2015? 202X? July 30, 2014 (c) 2014 California Institute of Technology. Government sponsorship acknowledged. JPL URS clearance CL#14-3608 3

Challenges Challenge Possible Solution 1) Large distance a) Long flight time Large launch vehicle, Solar Electric Propulsion b) Large solar distance Radioisotope power (not discussed) c) Large Earth distance Ka band and/or Optical comm (not discussed) 2) Measurement time Aerocapture to achieve orbit 3) Uranus system a) Extended atm Orbit farther out b) Rings Close orbit to avoid rings? c) Tilted pole Arrival date, propulsion to change orbit inclination 4) Budget Novel flyby, orbiter, probe, and nanosat architectures July 30, 2014 (c) 2014 California Institute of Technology. Government sponsorship acknowledged. JPL URS clearance CL#14-3608 6

Notional Net Spacecraft Delivered Mass These are rough estimates used for large trade space exploration Chemical Trajectories (Estimate) Launch Vehicle Flyby Mission Orbiter Mission Atlas V 401 800 400 Atlas V 551 2000 1000 SEP Trajectories (Estimate) Launch Vehicle Flyby Mission Orbiter Mission Atlas V 401 1000 600 Atlas V 551 2500 1500 July 30, 2014 (c) 2014 California Institute of Technology. Government sponsorship acknowledged. JPL URS clearance CL#14-3608 7

Uranus Trajectory Options Bi-propellant (chemical) trajectories to Uranus are possible Chemical trajectories require Jupiter or Saturn gravity assist in order to deliver useable mass to Uranus Chemical trajectories are typically 13 years flight time or greater Numerous families of Solar Electric Propulsion (SEP) trajectories to Uranus exist SEP provides 10 year flight times, with potential for 8 or 9 year flight times with Jupiter or Saturn gravity assist Aerocapture potentially enables larger mass into orbit Aerocapture requires thermal protection system and deployments July 30, 2014 (c) 2014 California Institute of Technology. Government sponsorship acknowledged. JPL URS clearance CL#14-3608 8

SEP Example: EEJU Chemical capture in Uranus orbit 1485 kg net mass 504 kg Xe 8.66 km/s V July 30, 2014 (c) 2014 California Institute of Technology. Government sponsorship acknowledged. JPL URS clearance CL#14-3608 9

SEP Example: Venus-Earth Zero-rev to Venus One-rev to Venus 1549 kg net mass (aero.) 1396 kg net mass (chem.) 505 kg Xe, 9.44 km/s V 1972 kg net mass (aero.) 1209 kg net mass (chem.) 688 kg Xe, 11.47 km/s V July 30, 2014 (c) 2014 California Institute of Technology. Government sponsorship acknowledged. JPL URS clearance CL#14-3608 10

Architecture Concepts Flybys A: Minimum Cost Flyby Flyby w/elements B: Flyby w/3 Probes C: Flyby + Nanosats Orbiter D: Orbiter with instruments E: Probiter Orbiter w/elements F: Fully Instrumented Orbiter w/probe G: Dual Orbiters w/probe H: Fully Instrumented Orbiter w/probe & Nanosats July 30, 2014 (c) 2014 California Institute of Technology. Government sponsorship acknowledged. JPL URS clearance CL#14-3608 12

Architectures A Bit More Detail Architecture A: Min Cost Flyby B: Flyby w/3 Probes Description Limited # of inst, +/- 6 mon planet obs, +/- 1 mon detailed planet and rings, +/- weeks to days for moons and detailed atm Flyby S/C with limited # of inst deploys 3 probes, then relays back probe data to Earth C: Flyby + Nanosats Flyby S/C deploys many nanosats D: Orbiter with instruments Orbiter with limited instruments. Could also carry nanosats to deploy from orbit. E: Probiter Orbiter with instruments. Then, deorbits and becomes a probe. F: Fully Instrumented Orbiter w/probe G: Dual Orbiters w/probe H: Fully Instrumented Orbiter w/probe & Nanosats Orbit with full set of instruments. Deploy probe before orbit insertion (easier), or after entering orbit (harder) Two orbiters, linked or not, one or both carry probes. Payload optimized for orbits (one polar, one equatorial for example) Large orbiter with probe, much like Decadal Survey probe. Add many nanosats that can go to risky areas and/or give simultaneous measurement by relaying back to orbiter July 30, 2014 (c) 2014 California Institute of Technology. Government sponsorship acknowledged. JPL URS clearance CL#14-3608 13

Meeting Challenges Summary (Subjective ratings) Architecture/Challenge Ext Atm Rings Tilted Pole Budget A: Min Cost Flyby Likely Unlikely B: Flyby w/3 Probes Possible C: Flyby + Nanosats D: Orbiter with instruments E: Probiter F: Fully Instrumented Orbiter w/probe G: Dual Orbiters w/probe H: Fully Instrumented Orbiter w/probe & Nanosats July 30, 2014 (c) 2014 California Institute of Technology. Government sponsorship acknowledged. JPL URS clearance CL#14-3608 14

Meeting Challenges Summary (2) Architecture Comments A: Min Cost Flyby Arrival geometry fixed, can target to miss rings B: Flyby w/3 Probes Probe entry constrained due to arrival geometry C: Flyby + Nanosats Nanosats can add simultaneous measurements D: Orbiter with instruments Might be able to avoid rings by going close E: Probiter Hard to avoid the rings on way to atmosphere F: Fully Instrumented Orbiter w/probe Might be able to avoid rings, high $ cost G: Dual Orbiters w/probe Easier to get best geometry, high $ cost H: Fully Instrumented Orbiter w/probe & Nanosats Most flexibility, high $ cost July 30, 2014 (c) 2014 California Institute of Technology. Government sponsorship acknowledged. JPL URS clearance CL#14-3608 15

Summary Hard to meet all constraints of inclination, avoid rings, probe atmosphere, and flyby large moons Lower cost architectures exist, but they cannot meet all desires Continue to invest in key technologies Solar Electric Propulsion Radioisotope power sources Low power electronics Aerocapture Nanosats Need studies to look at full extent of architectures July 30, 2014 (c) 2014 California Institute of Technology. Government sponsorship acknowledged. JPL URS clearance CL#14-3608 16