Why Would Someone Want to Put an Asteroid in Orbit Around the Moon?

1. Why Would Someone Want to Put an Asteroid in Orbit Around the Moon? Joseph A. Nuth III Solar System Exploration Division NASA’s Goddard Space Flight Center

2. Why an Asteroid Orbiting the Moon? • If something goes wrong, it does not hit Earth. • The Moon is close. Manned missions to the asteroid can be <10% transit, >90% operations. • What can be done at the asteroid? • Piloted proximity operations and remote sensing • Manned interactions with the surface including dealing with dust, grappling with the surface, etc. • Prospecting for and extraction of resources • If something goes wrong, get home fast.

3. What is feasible with current technology? (Image Credit: Rick Sternbach / KISS)

4. What Size Asteroid Can be Returned? • A 40KW Solar-Electric Power System could retrieve a 500 ton asteroid in < 10 years. • A 500 ton asteroid is ~ 7m in diameter. • A 500 ton, carbonaceous C-type asteroid may contain up to 200 tons of volatiles (~100 tons water and ~100 tons carbon-rich compounds), 90 tons of metals (approximately 83 tons of iron, 6 tons of nickel, and 1 ton of cobalt), and 200 tons of silicate residue (aka: shielding). • At $10K/kg the asteroid “value” is $5B.

5. What “Challenges” Exist? We will not know the mass of the asteroid we are trying to capture until we get there: visible photometry plus Infrared can determine the size but not the density of a target NEO.

6. Rotation Period vs. Diameter for all Asteroids What “Challenges” Exist? Small bodies are more likely to be rapidly rotating: they are strongly affected by both the YORP and Yarkovsky effects that increase their rotation rate and perturb their orbit. Small bodies are therefore most likely to be “lost” after initial discovery.

7. How many targets are available? Time Since Discovery Rate(#/day) Rate (#/year) Follow-Up 12 hrs 10 3,600 Astrometry 24 hrs 0.5 180 Astrometry, colors 48 hrs 0.2 70 Lightcurves 48 hrs 0.1 36 Spectroscopy 72 hrs 0.06 20 Radar Net Rate of Target Discovery 0.013 5 Note that we are looking for targets less than 10m in diameter. They can only be detected as they approach the Earth. The albedos of carbonaceous objects are typically very low (<5%) so spectroscopy is only possible at close range with most ground based telescopes. On the positive side, an ideal candidate is in almost the same orbit as the Earth and so it passes very slowly and there will be ample time to launch the mission.

8. Are there alternatives to tiny bodies? Yes: all small bodies have regolith of about the right size. “Pick up a rock” Scenario

9. “Pick up a rock” Scenario • Advantage: • Allows a well planned mission to a target with a precisely determined orbit. • Disadvantages: • Unless previously visited by a spacecraft, we can’t be certain that the body has appropriately-sized boulders for the taking. • Near surface operations with large solar arrays can be complex and risky. • Is the boulder we want easily retrieved?

10. Mission Scenario to a Small Body Conceptual design of the Single Spacecraft Architecture in the deployed configuration.

11. Asteroid Return Mission Concept

12. Mission Design Parameters & Targets

13. Capturing the Asteroid

14. Put the Target into High Lunar Orbit • Trajectory calculations indicate that a high lunar orbit is stable for at least 20 years. • Missions to this target can proceed at leisure. • Dust and Debris that is generated by asteroid operations will fall to the Moon. Example mission returning 1300 t of a small (~7 m) NEA with a radar opportunity in 2016.

15. Backup Slides

16. Authors and Study Participants John Brophy Co-Leader / NASA JPL Fred Culick Co-Leader / Caltech Louis Friedman Co-Leader / The Planetary Society Carlton Allen / NASA JSC David Baughman / Naval Postgraduate School Julie Bellerose NASA ARC/Carnegie Mellon Univ. Bruce Betts / The Planetary Society Mike Brown / Caltech Michael Busch / UCLA John Casani / NASA JPL Marcello Coradini / ESA John Dankanich / NASA GRC Paul Dimotakis/ Caltech Martin Elvis / Harvard-Smithsonian Center forAstrophysics Ian Garrick-Bethel / UCSC Bob Gershman/ NASA JPL Tom Jones / Florida Institute for Human and Machine Cognition Damon Landau / NASA JPL Chris Lewicki/ ArkydAstronautics John Lewis / University of Arizona Pedro Llanos / USC Mark Lupisella / NASA GSFC Daniel Mazanek /NASA LaRC PrakharMehrotra/ Caltech Joe Nuth / NASA GSFC Kevin Parkin / NASA ARC/Carnegie Mellon Univ. Rusty Schweickart / B612 Foundation Guru Singh / NASA JPL Nathan Strange / NASA JPL Marco TantardiniT/ he Planetary Society Brian Wilcox / NASA JPL Colin Williams / NASA JPL Willie Williams / NASA JSC Don Yeomans/ NASA JPL Sponsor: Keck Institute for Space Studies

17. Meeting a National Goal • The Manned Space Program was tasked with sending astronauts to rendezvous with a Near Earth Asteroid by 2025 along the Flexible Path. • Unfortunately, humans are quite fragile and have a tendency to develop various cancers when exposed to space radiation for the times required to reach most NEOs (>180 days). • In going to a NEO, >90% of the mission is spent in transit with <10% at the asteroid.

18. Why Do We Want to Visit NEAs? • As part of the Flexible Path, NEAs were a deep space target to demonstrate new capabilities. • As part of long term plans to expand humanity into the Solar System, they contain all of the resources needed to sustain life without any reliance on terrestrial materials (@ $10K/Kg). • Can we tweek the rules in order to achieve most of the HSF goals and add some new ones as well? That was the purpose of the study.

19. One-time Stunt or Long-term Facility? • At a minimum, several missions to an orbiting lunar asteroid can be done for the cost of a single manned mission to a deep space target and much more can be accomplished. • Begin “bootstrap” construction of a long-term space manufacturing facility that can produce water, fuel, structural metals and shielding. • Bring additional asteroids to lunar orbit at regular intervals for processing. • Practice moving asteroids (Hazard mitigation)

20. Why now? • Asteroid retrieval and industrial-scale processing is enabled by three key technology developments: • the ability to discover and characterize an adequate number of sufficiently small near-Earth asteroids for capture and return; • the ability to implement sufficiently powerful solar electric propulsion systems to enable transport of the captured NEA to the vicinity of Earth; • the planned human presence in cislunarspace in the 2020s, enabling exploration and exploitation of the returned NEA.

21. Number of Known Asteroids • 1980 < 10,000 • 1985 < 12,000 • 1990 < 15,000 • 1995 ~ 25,000 • 2000 ~ 125,000 • 2005 ~ 325,000 • 2010 ~ 525,000 • “The Near-Earth Object Surveys and Hazard Mitigation Strategies: Interim Report” from the NAS estimates that we have found only about 10% of the >140 m class objects as of 2010. We have only classified about 5000 of the known asteroids.

22. Why do we care about classification? If the goal of a manned mission is making specific measurements or emplacement and testing of specialized equipment, then that equipment will be designed for a specific set of requirements and will only work on certain types of material (e.g. spectral classes).

23. Asteroid classification is the basis for the exploration of the solar system Commercial exploitation of nearby asteroids, as well as the far future selection of asteroid resources to support independent habitats , will require prior knowledge of their composition and structure before retrieval.

24. Outline of the Presentation • Why might we want to put an asteroid in orbit around the Moon? • What size asteroid would we be able to relocate to lunar orbit with our current technology? • How would this be accomplished?