https://ntrs.nasa.gov/search.jsp?R=20200000682 2020-03-28T18:47:38+00:00Z Hubble OPAL Amy Simon Observations (NASA GSFC) Michael H Wong of Uranus and (U.C. Berkeley) Neptune: Glenn Orton 2014-2019 (Caltech/JPL) Hubble Outer Planets Atmospheres • Legacy (OPAL) program Yearly Hubble (UV-Vis) imaging of the outer planets; two global maps per planet, began in 2014 with Uranus, 2015 for Neptune and Jupiter, 2018 for Saturn Trend changes in: Uranus Neptune brightness, HSTWFC3/UVIS HSTWFC3/UVIS cloud activity, F547M F657N 2D and zonal wind fields, F763M ["C'/~C\1 storm size, color, other changes 1 · b-,,. ._) 1,/: Serendipitous events All data are public, Maps are posted at STScI https://archive.stsci.edu/prepds/opal/ Simon et al. 2015 ApJ 812, 55 MAPS Neptune 2019 Uranus 2019 Generated in 5 continuum filters: • F467, F547, F657, F763, F845 2 methane absorption bands: • F619, F727 2014 Uranus 2017 Polar haze has continued to brighten Small storm activity 2019 Toledo et al. 2019 Icarus 333, 1-11 Toledo et al. 2018 Geophys. Res. Letters 45, 5329-5335 E. 2015.71 : RGB I. 2015.71 : F467M -20 -20 _ -30 _-30 Neptune "' "' ~ -40 ~ -40 -8 -8 ~ -50 ~ -50 1ij 1ij -' -60 -' -60 30 20 10 0 -10 -20 30 20 10 0 -10 -20 West Longitude (deg) West Longitude (deg) F. 2016.37: RGB J. 2016.37: F467M -20 -20 _-30 -g, -30 g, :9.., -40 :9.-40., "O "O a -50 ~ -50 ~ .§ -60 -60 -70 155 140 125 110 170 155 140 125 110 It’s all about the storms! Longitude (deg) Longilude (deg) G. 2016.76: RGB K. 2016.76: F467M -20 -20 Hubble’s high spatial resolution at short - .30 _-30 I., -40 I., -40 wavelengths allows us to see dark vortices ] -50 ] -50 ~ -60 ~ -60 not otherwise visible -70 175 160 145 130 115 160 145 130 115 Longitude (deg) Longitude (deg) H. 2017.76: RGB L. 2017.76: F467M New storm first seen in 2015 (SDS-2015) -20 -20 _-30 g, -g, -30 Moved poleward and dissipated by 2018 :9.., -40 :9.., -40 ~ -50 ] -50 j -60 ~ -60 150 135 120 105 150 135 120 105 Longitude (deg) Longttude (deg) 0.63 0.76 Wong et al. 2018 Astronomical Journal 155, 117 Neptune, cont. Voyager 1989 Hubble 2018 Another large storm found in 2018 (NDS-2018) (C) Similar in size and drift rate as the i 20 Voyager Great Dark Spot, even ::, ~ 10 though opposite hemispheres HST/UVIS Nov. 20 18 F467M Data from prior years allows a look 90 80 70 60 50 40 30 20 90 80 70 60 50 40 30 20 West Longitude (deg) West Longitude (deg) Voyager 1989 at cloud activity in the region over 0.75 the preceding years (D) 0.70 ~ C: <3 0.65 .>: Cl) 0 0.60 HST/UVIS Nov. 2018 F467M 0.55 - ~~~~~-------~~~~~-------~~~~~------- 90 80 70 60 50 40 30 20 West Longitude (deg) 7 October 2017 10 September 2018 Long coverage allowed us to track likely pre-cursor clouds to this storm forming May be able to use shape to determine deeper atmosphere structure goo 1.5x10-4 60° ~ 1.0x10-4 --s 30° --5 0.5x10-4 Sromovsky et al. (1993) wind shear oo 0 NDS-2018 asRect ratio 4 -30° -0.5x10- 1.0 1.5 3.0 -60° Simon, Wong & Hsu 2019 GRL 46, 3108-3113 -90° Frequency and Lifetime of Dark Spots Counted dark spots seen by Voyager (2) and Hubble (4) Time coverage is sparse, but * 100 * * * * -C -(I) maximum lifetimes could be I •. • • ~ constrained to 1 - 6 years s(I) 80 ~ Also looked at time coverage :0 cu 60 .0 and how many observations ,._0 0.. had no spots detected Cl) 40 .ECl) ,._I Monte Carlo simulations then ~ (I) 20 Post-Voyager- '\ C -. • .. campaign I, run to determine the likelihood Cl) ••• -. --Cl) . ~ a of a spot forming, and of ~ 0 - - failing to detect it, based on 1995•• 2000I II " 2010I I 2015I these observing statistics Can’t see a spot, if not observing! Hsu, Wong & Simon 2019 AJ 157, 152 Summary Seeing a lot of activity on both Ice Giants Uranus Smaller, high latitude, storms persist Polar haze continues to brighten over time Neptune Two new dark vortices detected Occurrence of a spot every 4-6 years, with lifetimes from 1 to 6 years Frequent observations are invaluable, but any future mission will see interesting atmospheric activity, regardless of timing A Neptune orbiter with a lifetime of 6 years would be ideal for ensuring a dark vortex is observed.