Recent  Results  from  NEOWISE  

Amy  Mainzer  JPL  

WISE    •  4    imaging  channels  covering  3  –  25  µm    

•  40  cm  telescope  opera7ng  at  <17K  •  Surveyed  en7re  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  µm  

Sept.  29,  2010  Lost  all  12  µm    

Sept.  29,  2010    -­‐  Feb.  1,  2011  3.4  &  4.6  µm  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  detecbons,  each  with  2x  more  detecbons/object  (10  20)  

•  Stacking  on  all  known  cataloged  objects  

•  Creabng  catalog  of  physical  properbes  in  PDS  

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  

Shallower  slope:  -1.32+/-0.14

NEOWISE  Detecbons  of  Small  NEOs  

•  Smallest  NEOs  detected  by  NEOWISE  are  8m  in  diameter  –  Detected  in  band  W2  at  3-­‐4  lunar  distances  from  the  spacecrah,  so  similar  objects  could  be  detected  if  WISE  is  restarted  

– More  in  data  that  haven’t  been  idenbfied  yet  

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

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

Determining  Sizes  

•  IR  radiometry  allows  determinabon  of  size  &  albedo,  can  indicate  rapid  rotabon  and/or  high  thermal  inerba  

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.  2013  ApJ  770,  7  “Asteroid  Family  Idenbficabon  using  the  Hierarchical  Clustering  Method  and  WISE/NEOWISE  Physical  Properbes”  

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

•  Link  ~38,300  asteroids  into  76  families  

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

4.6  µm)  •  No  consumables  now,  but  limited  lifebme  due  to  orbit  precession  

•  Orbital  plane  drih  rate  depends  on  solar  acbvity  

Restarbng  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  aher  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  populabon  

•  Same  data  delivery  policies  as  before  

How  Restarbng  Would  Work  •  Spacecrah  currently  power-­‐posibve  but  poinbng  at  Earth  for  half  of  each  orbit  

•  Need  to  resume  zenith  poinbng  &  wait  for  cooldown  (3-­‐4  months)  

•  Need  ~1-­‐2  months  to  recalibrate  distorbon,  remap  bad  pixels,  etc.  •  Possible  to  alter  cadence  –  might  improve  NEO  detectability  

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

publicabons  –  Total  citabon  count  for  WISE  ~500  refereed  publicabons  

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