Don Yeomans NASA/JPL

Near-Earth Objects

Finding Them Before They Find Us

Itokawa

What are Near-Earth Objects?

Comets (Weak and very black icy dirt balls)

•Weak collection of talcum-powder sized silicate dust

•About 30% ices (mostly water ice) just below surface dust. CO2 ices also present further below surface.

•Fairly recent resurfacing and few impact craters

Asteroids (run the gamut from wimpy ex-comet fluff balls to slabs of iron

•Most are shattered fragments of larger asteroids

•Rubble rock piles - like Itokawa

•Shattered (but coherent) rock - like Eros

•Solid rock

•Solid slabs of iron like Meteor crater object

Comet Hartley 2, Nov. 4, 2010

Itokawa

2

18001800

History of Known NEO Population

ArmaghObservatory

OutsideEarth’s Orbit

EarthCrossing

3

180018001900

History of Known NEO Population

ArmaghObservatory

OutsideEarth’s Orbit

EarthCrossing

4

1800180019001950

History of Known NEO Population

ArmaghObservatory

OutsideEarth’s Orbit

EarthCrossing

5

1800180019001950

History of Known NEO Population

ArmaghObservatory

1990

OutsideEarth’s Orbit

EarthCrossing

6

1800180019001950

History of Known NEO Population

ArmaghObservatory

19901999

OutsideEarth’s Orbit

EarthCrossing

7

1800180019001950

History of Known NEO Population

ArmaghObservatory

19901999

OutsideEarth’s Orbit

EarthCrossing

ScottManley

2012Known• 600,000 minor planets • 9450 NEOs• 1350 PHAs

The Inner Solar System in 2006

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The Importance of Near-Earth Asteroids

• Science• Future Space Resources• Exploration• Planetary Defense

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Human Accessible Targets11

JPL’s SENTY NEO Risk Pagehttp://neo.jpl.nasa.gov/risk/

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NASA’s NEO Observation Program

LINEAR

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NEO-WISE

Catalina Sky Survey Pan-STARRS

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Radar Studies

14Shape, Size of 6489 Golevka

Study of Shape, Size, Motion and mass of near-Earth object 66391 (1999 KW4)

Goldstone, CA Arecibo, Puerto Rico

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NASA’s NEO Program Office at JPL

Automatic orbit updates Are any of the NEOs a threat?Relational databaseStudy deflection strategies

Additional Information Impact warnings & outreach

http://www.jpl.nasa.gov/asteroidwatch/Widget available giving next 5 Earth close approachesNEO Program Office: http://neo.jpl.nasa.gov/

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Recent NEO Program Office Activities

• Human Exploration Target Body Identification– Which NEAs are desirable RT mission targets?– When are they next observable (optical & radar)?

• Deflection mission study for asteroid 2011 AG5 IP = 1/500 for Feb. 5, 2040

• Educational site for designing asteroid deflection missions.

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2011 AG517

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Near-Earth Asteroid ApophisPredicted Close

Approach of Apophis(~270m Object)

on April 13, 2029

CLOSE-UP VIEW

Geosynchronous Orbit

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Near-Earth Asteroid 2012 DA14 in Feb. 2013 21

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2012 DA14

Asteroid 2012 DA14February 15, 2013

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Deep ImpactComet Tempel 1 on July 4, 2005

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Comet ISON25

Observing Comet ISON26

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