Recent Results from NEOWISE

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Recent Results from NEOWISE Amy Mainzer JPL

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Recent Results from NEOWISE. Amy Mainzer JPL. WISE/NEOWISE. WISE 4 imaging channels covering 3 – 25 m m 40 cm telescope operating at

Transcript of Recent Results from NEOWISE

Page 1: Recent Results from NEOWISE

Recent Results from NEOWISE

Amy MainzerJPL

Page 2: Recent Results from NEOWISE

WISE • 4 imaging channels covering 3 – 25 mm • 40 cm telescope operating at <17K• Surveyed entire sky 2x• Surveyed from Jan 2010 – Feb 2011 • PI: Ned Wright, UCLA

Wide Field Infrared Survey Explorer

NEOWISE• WISE not a dedicated asteroid mission• NEOWISE is Planetary Science-funded enhancement to

the main WISE pipeline• Two tasks:

– Create archive of individual epoch images + solar system-friendly query tool

– Discover new asteroids with WISE– Tracklets delivered to Minor Planet

Center within 10 days– WISE Moving Object Pipeline (WMOPS)

derived from PS MOPS

WISE/NEOWISE

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NEOWISE Team• PI: Amy Mainzer• James Bauer: JPL/IPAC• Roc Cutri: IPAC• Tommy Grav: PSI• Robert Jedicke: IfA• Joe Masiero: NPP postdoc JPL staff scientist• Bob McMillan: LPI• Carrie Nugent: NPP postdoc• Rachel Stevenson: NPP postdoc• Dave Tholen: IfA• Russ Walker: MIRA • Ned Wright: UCLA• Students: ~15 so far, including Emily Kramer (UCF), Carrie Nugent (UCLA), Jessica

Watkins (UCLA)

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Aug. 5, 2010Lost 22 mm

Sept. 29, 2010Lost all 12 mm

Sept. 29, 2010 - Feb. 1, 20113.4 & 4.6 mm only

NEOs – NEOWISE-discoveredNEOs – others’ detectedComets – others’ detectedComets – NEOWISE-discoveredAll other detected objects

1 YEAR NEOWISE SURVEY

• >158,000 asteroids detected• >34,000 new discoveries• ~750 NEOs detected• 135 new discoveries• 150 comets detected• 21 comets discovered

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NEOWISE Science Data Analysis

• Final release of NEOWISE Post-Cryo survey phase data 5/22/2013

• Rerunning WMOPS at lower SNR– Test runs at SNR=3.5 yielded 20% more detections, each with

2x more detections/object (10 20)

• Stacking on all known cataloged objects

• Creating catalog of physical properties in PDS

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Near-Earth Asteroid Numbers & Sizes

• Use well-known sensitivity & uniformity of four band survey to compute total numbers from observed sample

• 20,500+/-3000 @ 100m vs. prior estimates of 36,000 – 100,000

• >90% of 1 km and larger NEAs have been discovered: Spaceguard goal

• Mainzer et al. 2011 ApJ 743, 156

break

Shallowerslope: -1.32+/-0.14

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NEOWISE Detections of Small NEOs• Smallest NEOs detected by NEOWISE are 8m in diameter

– Detected in band W2 at 3-4 lunar distances from the spacecraft, so similar objects could be detected if WISE is restarted

– More in data that haven’t been identified yet

• 12 NEOs detected with diameters <25m so far, 7 in band W2, so could be detected with reactivated NEOWISE

• 100 additional close-approaching NEOs recovered from NEOWISE data in addition to ~550 published to date; 66 detected in band W2– Diameters & albedos computed (Mainzer et al. in prep)

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Determining Sizes

• IR radiometry allows determination of size & albedo, can indicate rapid rotation and/or high thermal inertia

2010 XA11: 10±2 m,57±25% albedo

2010 TN4: 13±3 m,12±6% albedo

2010 GH7: 8±2 m, 11±3% albedo,rapid rotator

2010 FD6: 8±2 m, 55±15% albedo,rapid rotator

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Asteroid Families• Masiero et al. 2013 ApJ 770, 7 “Asteroid Family Identification using the Hierarchical

Clustering Method and WISE/NEOWISE Physical Properties”

• Use albedo + velocity cuts in HCM method to identify new families/family members w/ ~120,000 Main Belt Asteroids detected by NEOWISE

• Link ~38,300 asteroids into 76 families

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Restarting NEOWISE• Possible to restart NEOWISE & resume survey using bands W1 and W2 only (3.4 &

4.6 mm)• No consumables now, but limited lifetime due to orbit precession• Orbital plane drift rate depends on solar activity

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Restarting NEOWISE• With baseline cadence, would discover ~50-60 new NEOs/year, 25% of which are

PHAs (vs. <10% from ground)

• Expect to detect & obtain diameters/albedos for ~2000 NEOs in total after 3 year survey

• 3 coorbitals detected by NEOWISE in Post-Cryogenic survey phase, including 2 discoveries: horseshoe + Earth Trojan

• Possible to discover more coorbitals & set improved limits on population

• Same data delivery policies as before

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How Restarting Would Work• Spacecraft currently power-positive but pointing at Earth for half of each orbit• Need to resume zenith pointing & wait for cooldown (3-4 months)• Need ~1-2 months to recalibrate distortion, remap bad pixels, etc.• Possible to alter cadence – might improve NEO detectability

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NEOWISE Data Use• Total citation count using NEOWISE data & discoveries up to ~100 refereed publications

– Total citation count for WISE ~500 refereed publications

• NEOWISE is a synoptic mid-infrared all-sky survey, so its science spans many areas of astrophysics & planetary science:– Asteroids– Meteoritics – Variable stars– Icy bodies in the outer solar system – Distance ladder determinations for cosmology– Human exploration– Supernovae– Pulars– Exoplanets– Black hole accretion disks