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Recent Results from NEOWISE

Recent Results from NEOWISE. Amy Mainzer JPL. WISE/NEOWISE. WISE 4 imaging channels covering 3 – 25 m m 40 cm telescope operating at <17K Surveyed entire sky 2x Surveyed from Jan 2010 – Feb 2011 PI : Ned Wright, UCLA. W ide Field I nfrared S urvey E xplorer. NEOWISE

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Recent Results from NEOWISE

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  1. Recent Results from NEOWISE Amy Mainzer JPL

  2. WISE/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

  3. 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)

  4. 1 YEAR NEOWISE SURVEY Sept. 29, 2010 Lost all 12 mm Sept. 29, 2010 - Feb. 1, 2011 3.4 & 4.6 mm only Aug. 5, 2010 Lost 22 mm • >158,000 asteroids detected • >34,000 new discoveries • ~750 NEOs detected • 135 new discoveries • 150 comets detected • 21 comets discovered NEOs – NEOWISE-discovered NEOs – others’ detected Comets – others’ detected Comets – NEOWISE-discovered All other detected objects

  5. 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

  6. 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 Shallower slope: -1.32+/-0.14 break

  7. 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)

  8. 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 GH7: 8±2 m, 11±3% albedo, rapid rotator 2010 FD6: 8±2 m, 55±15% albedo, rapid rotator 2010 TN4: 13±3 m, 12±6% albedo

  9. 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

  10. 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

  11. 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

  12. 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

  13. 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

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