Giant Planets. Mark Marley (NASA Ames) for the Planetary Decadal Survey Giant Planets Subpanel

Transcription

1 Giant Planets Mark Marley (NASA Ames) for the Planetary Decadal Survey Giant Planets Subpanel 1

2 GPP Membership Reta Beebe NMSU atmos. dynamics John Casani JPL engineer, NAE John Clarke Boston University aurorae, magnetos. Heidi Hammel Space Science Institute panel chair Brigette Hesman NRAO atm chemistry William Hubbard University of Arizona interiors Mark Marley NASA Ames exoplanets Phil Nicholson Cornell University rings Wayne Richie NASA Langley engineer Kunio Sayanagi CalTech dynamics, theory Amy Simon-Miller NASA Goddard panel vice-chair 2

3 Today Some highlights of giant planet science in the past decade that impact future exploration goals (personal perspective, neglecting Cassini) Stressing: Connection to brown dwarfs & 400+ exoplanets Decadal process whitepapers mission studies key technologies community input 3

4 Solar System Jovian Planets Serve as Waypoints in a Continuum of Objects 4

5 !f! /!f! (1.30µm) x Constant TiO K FeH K H 2 O H 2 O H 2 O H 2 O CO CH CH CIA H CH 4 CH 4 CH 4 CH 4 CH 4 NH 3 M6.5 V L5 T.5 Jupiter M6 L5 T5 NH 3 Jupiter CH Wavelength (µm) Marley & Leggett (2009) 5

6 oklo.org 6

7 15 Charbonneau et al. (2009) Radius (REarth) Mass (MEarth) Transiting planets reveal a continuum of M, R Microlensing suggests Neptunes are common 7

8 Some Highlights and Questions 8

9 signature of planethood? vary with mass? Owen et al. (1999) 9

10 What are Saturn s noble gas abundances and isotope ratios? Marty et al. (2009) 10

11 Saturn s Evolution He phase separation Fortney et al. (2006) 11

12 How well do we understand thermal evolution? Young hot planets? Role of clouds? Compositional gradients? Soon hundreds of directly images young planets. HR8799 b, c, d Marois et al. (2008) 12

13 Solar System Stratospheres Earth Titan Photochemistry is important in every case. 13

14 Neptune s Stratosphere mid-ir Gemini/Michelle at 11.7 µm Ethane Emission from the stratosphere Gemini/Michelle at 7.7 µm Methane Emission from the stratosphere All 3 images taken within a few minutes on 5 July 2005 Keck/NIRC2+AO at 1.6 µm Sunlight Scattering from tropospheric Clouds Hammel et al. (2007) Can we achieve a better understanding of the energetics of giant planet stratospheres? 14

15 Fortney et al. (2008) 15

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17 Strong downdrafts at Jovian hotspots (Showman & Dowling 2000) Hot Jupiter GCM (Showman et al. 2008) 17

18 Core Masses? oklo.org Fortney et al. (2009) 18

19 Ice Giant Magnetospheres Earth Jupiter Saturn Uranus Neptune Stanley & Bloxham (2006) Solid Stablystratified 19

20 Ring-Plane Crossing of Uranus Keck images of Uranus in 2007 show a rare view of the unlit side of the rings Such ring-plane crossings occur every 42 years; the last in 1965 was prior to the rings' discovery in 1977! 20

21 New Rings of Uranus Two new rings discovered with HST and Voyager by Showalter and Lissauer (2005) Keck images (de Pater et al. 2006) reveal ringsʼ colors and striking similarity with Saturnʼs rings Photo-Illustration compares the Saturn and Uranus ring systems Red = Saturn G ring, Uranus R2 Blue = Saturn E ring, Uranus R1 21

22 Nearly all aspects of the Neptune system detectable from Earth have changed significantly since Voyager fly-by in 1989 The ring system has changed Arcs evolved within <8 yrs The dynamic neptunian ring arcs: evidence for a gradual disappearance of Liberté and resonant jump of courage de Pater, Imke; Gibbard, Seran G.; Chiang, Eugene; Hammel, Heidi B.; Macintosh, Bruce; Marchis, Franck; Martin, Shuleen C.; Roe, Henry G.; Showalter, Mark Icarus, Volume 174, Issue 1, p Both the location and intensity of all arcs changed drastically relative to trailing arc Fraternité... Our data suggest that all arcs may have decayed over the last decade, while Liberté, in 2003, may be on the verge of disappearing completely. The observed changes in the relative intensities and locations of all arcs further indicate that material is migrating between resonance sites; leading arc Courage, for example, has jumped 8 (one full corotation potential maximum). Overall, our observations reveal a system that is surprisingly dynamic, and no comprehensive theory exists as of yet that can explain all the observed intricacies. 22

23 Kalas et al. (2008) 23

24 Decadal Process 24

25 White Papers ~ 100 white papers submitted mission concepts technologies existing facilities laboratory and theory work other topics All read and discussed and important basis for ongoing activities 25

26 Selected Three Targets for RMA Studies Neptune/Triton/KBO Uranus Saturn 26

27 Mission Studies Neptune-Triton-KBO flyby or Neptune orbiter entry probe free flying nanosats meetings complete, report in preparation Saturn entry probe(s) - ongoing Uranus orbiter - ongoing May choose some for point designs 27

28 Technology Issues Power Plutonium supply ASRG lifetime Communications (DSN) Aerocapture/Aerobraking Entry probes, daughter probes Nanosats Instrumentation 28

29 GPP Outreach Activities Date Meeting Location Plan 13 July 2009 OPAG Columbia, MD Attend/Follow-up July 2009 Mag. Outer Planets Cologne Attend/Follow-up Aug-Sep GPP Web survey Aug-Sep GPP Phone campaign Aug 2009 PANEL MEETING Washington, DC Oct 2009 DPS Puerto Rico Workshop Oct 2009 PANEL MEETING Irvine, CA Dec 2009 AGU San Francisco Attend/Follow-up 1-5 March 2010 LPSC Houston Attend/Follow-up 4-6 May 2010 PANEL MEETING Boston, MA - 29

30 Your Input 30