FEASIBILITY AND MASS-BENEFIT ANALYSIS OF AEROCAPTURE FOR SMALLSAT MISSIONS TO VENUS 16th Venus Exploration Analysis Group (VEXAG) Meeting Johns Hopkins University, Applied Physics Lab, Laurel, Maryland, Nov. 6 – 8, 2018

Athul Pradeepkumar Girija | [email protected] Y. Lu, J. M. Longuski, 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

VEXAG travel support is gratefully acknowledged Aerocapture Control Methods

Lift Modulation MSL-like low L/D aeroshell, HEEET TPS L

L

Drag Modulation

ADEPT-like system with β2/β1 > 10

D1 D2

β β1 2

1 400 x 400 km 1. Dedicated Mission to Venus final orbit

Orbit Insertion options – Propulsive – Bi-prop. (320 Isp) – Aerocapture (MSL-like aeroshell) – Propulsive + Aerobraking 400 x 60,000 km initial aerobraking orbit

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2 400 x 400 km 2. Rideshare with mission flying to/by Venus final orbit

Orbit Insertion options – Propulsive – Mono prop. (230 Isp) – Aerocapture (ADEPT-like aeroshell) – Propulsive + Aerobraking 400 x 60000 km Initial aerobraking orbit

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3 400 x 400 km 3. Rideshare with lunar mission final orbit

Orbit Insertion options – Propulsive – Mono prop. – SEP – Aerocapture (ADEPT) 400 x 60000 km – Propulsive + Aerobraking Initial aerobraking orbit

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4 1. Dedicated Mission to Venus: Capture options comparison

Propulsive + Aerobraking 0.7 (400 x 60,000 km)

Aerocapture (400 x 400 km)

2.3x 2.8x propulsive propulsive Propulsive (400 x 400 km)

5 2. Rideshare with mission flying to/by Venus

4.8x V = 5 km/s ∞ propulsive 3.6x propulsive

Propulsive Aerocapture Propulsive + Aerobraking (400 x 400 km) (400 x 400 km) (400 x 60,000 km)

6 2. Rideshare with mission flying to/by Venus

V∞ = 10 km/s

2.3x propulsive 2.8x propulsive Aerocapture (4003.6x x 400 km) 4.8x propulsive propulsive

Propulsive + Aerobraking (400 x 60,000 km) Propulsive (400 x 400 km)

7 3. Rideshare with lunar mission

Propulsive + Aerobraking SEP [6] (400 x 60,000 km) (bound large orbit) Aerocapture (400 x 400 km) 2.8x propulsive 4.8x 2.3x 2.9xpropulsive propulsive propulsive Propulsive (400 x 400 km)

8 Summary

1. Aerocapture at Venus is feasible using existing low L/D aeroshells, or using drag modulation systems in development. No new technology is required. 2. Propulsive capture + aerobraking to lower orbit allows most mass delivered, if the time (several months) for aerobraking is acceptable. 3. Aerocapture offers mass benefit over aerobraking if, − entry system payload mass fraction > 0.7

− or, for getting into orbit from high V∞ flyby mission 4. If low Venus orbit is desired immediately upon arrival, then compared to propulsive alone option, aerocapture offers: – 2.3x mass for dedicated large orbiter – 3.6x mass for SmallSat ride-along with Venus mission – 2.3x mass for SmallSat orbiter ride-along from lunar mission 9 Acknowledgements

The authors would like to thank Alec Mudek for help with the Earth Venus interplanetary trajectory data used in this study.

V-BOSS: Venus Bridge Orbiter and Surface System (S. Oleson et al.) study preliminary report was used for rideshare from lunar mission calculations.

10 References

1. M. K. Lockwood et al., “Systems Analysis for a Venus Aerocapture Mission”, NASA/TM-2006-214291, 2006. 2. D. W. Way et al., “MSL: Entry, Descent, and Landing Performance”, IEEE Aerospace Conf., Big Sky, MT, 2006. 3. B. Smith et al., “Nano-ADEPT: An Entry System for Secondary Payloads, IEEE Aerospace Conf., Big Sky, MT, 2015. 4. J. O. Arnold et al., “Arcjet Testing of Woven Carbon Cloth for use on ADEPT”, IEEE Aerospace Conf., Big Sky, MT, 2013. 5. D. Ellerby et al., “HEEET Development Status”, 13th International Planetary Probe Workshop (IPPW), Laurel, MD, 2016. 6. S. Spangelo, D. Dalle, and B. Longmier, “Integrated Vehicle and Trajectory Design of Small Spacecraft with Electric Propulsion for Earth and Interplanetary Missions”, 29th Annual AIAA/USU Conference on Small Satellites, Logan, UT, 2015 . 7. R. Grimm and M. Gilmore, “VEXAG Update to the NASA Planetary Advisory Committee”, 2018. 8. R. Grimm et al., “Venus Bridge: A SmallSat Program Through the Mid-2020s”, 12th Low-Cost Planetary Missions Conference, Pasadena, CA, 2017. 9. S. Oleson et al., “V-BOSS: Venus Bridge Orbiter and Surface System: Preliminary Report”, 2017. 10. P. Wercinski, “Adaptable, Deployable, Entry and Placement Technology (ADEPT)”, Presentation at NASA Ames Research Center, 2017.

11 Backup Slides

12 Venus Exploration Domains

Comm. relay Sample return CubeSat SmallSat orbiter (5 kg) (100 kg)

Aerial platforms (weeks) Ascent vehicle

Descent probe Short lived lander Long lived lander (hours) (days)

13 Aerocapture Science Orbit

Coast phase

Periapsis Raise Maneuver (PRM)

Too steep Too shallow

Approach navigation

14 Lift Modulation: Aerocapture Feasibility Chart

Aerocapture at Venus is feasible using existing low L/D aeroshells like MSL (L/D=0.24) and HEEET TPS material (7000 W/cm2).

15 Drag Modulation: Feasibility Chart

Aerocapture at Venus is feasible using ADEPT-like drag modulation systems in development, with a β2 / β1 of ~10, and carbon cloth TPS.

The entry corridor for drag modulation aerocapture is smaller than that for lift modulation.

Navigation studies will need to be done to assess if entry flight path angle errors can be reduced to a level required for it to fit within the drag modulation corridor.

16 Venus Aerocapture Payload Mass Fraction

Rigid lifting aeroshell ADEPT Nano-ADEPT

Payload Mass Frac. 57% * 50% 50%#

* Estimated for using an MSL-like aeroshell for Venus aerocapture # Estimated to be the same as full-scale ADEPT

17 Dedicated Launch to Venus – Trajectory Data

18 Rideshare with mission flying to/by Venus

19 Venus Mission Implementation Pathways

Dedicated Rideshare Launch Options

Missions GTO/Lunar to/flyby Venus

Transfer Option Low-thrust Chemical

Capture Option Propulsive Propulsive + AB Aerocapture

20