Solar System Observations with Radio/Millimeter/Submillimeter Assets in the 2020s Stefanie Milam December 14, 2015 NASA/GSFC Credit: NASA and E. Karkoschka (University of Arizona)

Our Solar System HOW DID WE GET HERE? Connect star formation/disks to planetary systems? HOW DID THE EARTH BECOME HABITABLE? Water? – D/H ratios in small bodies – Search for water across the Solar System IS EARTH UNIQUE? Compositional studies – Similar to presolar disk/cloud? – Volatile Isotopes Other planets/satellites in the solar system

Pristine material from early Solar System? -Pristine from molecular cloud -Processing in presolar nebula Isotope fractionation ratios? -Origin, formation and evolution of the Solar System (ex : Earth’s Water) -ISM-comet connection Primitive Bodies - Interstellar inheritance? Milam, 3

Comets – fossils from the early solar system Milam, 4

Oort Cloud vs. Kuiper Belt distinguishable?

Taxonomy? >30 comets observed in radio. No distinct classes as of yet as have been observed in radio. Crovisier et al. 2009

D/H Ratios Protosolar D/H ratio in H 2 is ~2.5x10 -5 (same as the Big Bang) Earth ocean ratio (Vienna Standard Mean Ocean Water) is 1.56x10 -4 D/H measured in several Oort cloud comets is ~2 times enrichment over the Earth ocean value Comets source of Terrestrial water?

Using HIFI on Herschel The first Kuiper Belt (Jupiter Family) comet in which D/H was measured HDO clearly detected (11σ) D/H in water (1.61±0.24)×10 -4 (1σ) A factor of 2 lower than the earlier measurements in Oort cloud comets and the same as VSMOW! Surprising result, because Jupiter Family comets, having formed farther away from the Sun, were expected to have higher D/H values than Oort cloud comets!

D/H in the Solar System Altwegg et al. 2015

Nitrogen Anomalies enrichment by a factor of 2 in 15-Nitrogen wrt the terrestrial value (=272) measured in 18 comets (mean = 148+/-6) 14 N/ 15 N identical in JFCs and OCCs Multiple sources of CN? Other molecules? Milam, 11

15 N and D fractionation relations δD=1000 % o δD=19400 % o δ 15 N=3200 % o δ 15 N=-320 % o δD=45000 % o 15 N/ 14 N = 2.5x10 -3, D/H = 1.5x10 -5 (D/H=1.56e-4) (15 N/ 14 N= 3.7e- 3) Wirstrom et al Milam, 12 Milam, Adande et al. in prep

Variable Targets Impact events Storms/weather pheneomena Small body rotation Jets Lisse et al min 60 min 120 min CH3OH in Hartley 2

Nucleus or Coma Chemistry? Cordiner et al HCN HNC H2CO ISON Lemmon Spatial and spectral asymmetries indicate complex coma structure and likely jet activity Milam, 14

Astrobiology in the Solar System Connecting the simple chemistry found in the Interstellar Medium to the complex chemistry found in Meteorites, IDPs, and NOW Comets. Pizzarello, S. (2004) OLEB, 34, 25 Milam, 15 Laboratory Spectra of Complex Organics Still Needed!!!

Broad Band Spectroscopy Multiple lines observed simultaneously. Averaging over transitions for new detections. Easier to conduct deep searches. Biver et al. 2015

The Happy Hour Comet “We report the detection of 21 molecules in comet C/2014 Q2 (Lovejoy), including the first identification of ethyl alcohol (ethanol, C 2 H 5 OH) and the simplest monosaccharide sugar glycolaldehyde (CH 2 OHCHO) in a comet.”

Motivation: Miniature Solar Systems Credit: © 2011 Emily Lakdawalla, the Planetary Society. Unique collection of icy moons with astrobiological implications Natural Laboratories to test our understanding of fundamental processes in extreme environments. Ring systems revealing processes at work in astrophysical discs. Contain fingerprints of the origins of our solar system; shaped planetary system architecture Paradigm for giant planets orbiting other stars Credit: L. Fletcher

Challenges SPACECRAFT Close-in views (lack spatial context) Short duration (lack temporal context) Long cruise & power Limited telemetry Once-a-generation ‘Yesterdays’ technology. SPACECRAFT Close-in views (lack spatial context) Short duration (lack temporal context) Long cruise & power Limited telemetry Once-a-generation ‘Yesterdays’ technology. OBSERVATORIES Tellurics, gaps, weather. Calibration. Large (1 arcmin) moving targets. Low signal. Spatial resolution. Instrument availability Intense competition. OBSERVATORIES Tellurics, gaps, weather. Calibration. Large (1 arcmin) moving targets. Low signal. Spatial resolution. Instrument availability Intense competition. GENERAL Wavelength coverage incomplete, non-contemporary. Insufficient temporal sampling for planet variability. GENERAL Wavelength coverage incomplete, non-contemporary. Insufficient temporal sampling for planet variability. Credit: L. Fletcher

Mission Synergies Cassini ends in 2017 – only observed one season of Titan. Follow seasonal distribution of species. Detection of new molecules. Vertical profiles – multiwavelength observations. Complimentary IR observations for symmetric species. Cordiner et al Titan

Exploring the Outer Solar System

Radio Futures and Planetary Science Comets and small bodies – Coma, tail, nucleus and ejecta investigations – Composition – Gas isotopic ratios – Water and/or proxies? Planetary Atmospheres – Search for minor organic species – Time Domain or Seasonal Studies – Multi-wavelength datasets enable us to disentangle brightness temperature variations from changes in the particle size distribution and non-icy material abundance – Future Mission Support? (Juice, Venus, Comet, etc) – Ground truth for exoplanets Other: Plumes? Volcanos? KBOs? Etc. Multiwavelength Studies

A Small Request… Improved Sensitivity – Isotope Measurements – Water? Or proxies – New Molecules (e.g. NH3, prebiotic species) Laboratory Spectra!!! High Angular and Spectral Resolution – Small Targets need global mapping – Line profiles in atmospheres access different altitudes Broadband – Multi-line approach to new detections and Simultaneity! Short Response – Outbursts, impacts, weather, etc. Angular Size ObjectSize (“) Mars7 Jupiter37 Saturn17 Uranus3.5 Neptune2.2 Pluto0.1 Titan0.75 Enceladus0.08

End

Multi-wavelength/facility studies Combined Effort to obtain simultaneous and/or complimentary data. Employ multiple techniques/wavelengths – IR: multiple lines simultaneously – Trot, H2O, symmetric species – Radio/mm/sub-mm: daytime, complex species – Interferometry: extended source, distant objects Multiple Species for Isotope Studies Consider source of molecules (nucleus or extended source)

Radio Observations of Planets Multi-wavelength datasets enable us to disentangle brightness temperature variations from changes in the particle size distribution and non-icy material abundance (e.g. de Pater et al. 1991). 2 cm 6 cm

Enceladus and H 2 O Credit: NASA/JPL. Bergin et al. 2000

TITAN Nixon et al Milam, 29

Future Synergies?