Recent Results from NEOWISE Amy Mainzer JPL

WISE 4 imaging channels covering 3 – 25  m 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

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)

Aug. 5, 2010 Lost 22  m Sept. 29, 2010 Lost all 12  m Sept. 29, Feb. 1, & 4.6  m only NEOs – NEOWISE-discovered NEOs – others’ detected Comets – others’ detected Comets – NEOWISE-discovered All 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

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

Near-Earth Asteroid Numbers & Sizes Use well-known sensitivity & uniformity of four band survey to compute total numbers from observed sample 100m vs. prior estimates of 36,000 – 100,000 >90% of 1 km and larger NEAs have been discovered: Spaceguard goal Mainzer et al ApJ 743, 156 break Shallower slope: /-0.14

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)

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

Asteroid Families Masiero et al 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

Restarting NEOWISE Possible to restart NEOWISE & resume survey using bands W1 and W2 only (3.4 & 4.6  m) No consumables now, but limited lifetime due to orbit precession Orbital plane drift rate depends on solar activity

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

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

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