1. Solar-system observations with Herschel/ALMA T. Encrenaz, D. Bockelée-Morvan, J. Crovisier, E. Lellouch LESIA, Observatoire de Paris

2. Outline Why the far-IR/submm/mm range? Major objectives of solar-system research Venus, Mars and the giant planets Satellites, distant asteroids and TNOs Comets

3. Why the far-IR/submm/mm range? Solar-system objects are COLD objects which radiate at low frequencies Strong molecular rotational transitions Ideal for: – planetary atmospheres –cometary atmospheres –distant objects (TNOs)

4. Many major discoveries in planetary and cometary science First detection of HCN in Comet Halley (1986) Over 20 parent molecules detected in Hale-Bopp (1997) First detection of a stable atmosphere (SO 2 ) around Io (1990); also SO and NaCl(2002) Detection of new molecules in Jupiter after the SL9 collision (1994): CO, CS, OCS, HCN First detection of H 2 O 2 on Mars (2004)

5. Major issues in solar-system sciences Origin of the solar system: –Giant planets ’ composition: D/H, He/H, oxygen source –Comets ’ composition and link with ISM: minor constituents, D/H in various species –TNOs: Ts/albedo Evolution of solar-system objects –Minor constituents and dynamics of planetary and satellite atmospheres –Comets ’ activity, physico-chemistry and thermodynamics

6. Venus CO, H 2 O/HDO observed in the mm range -> vertical distributions + wind measurements No observation with ISO nor Herschel Perspective with ALMA: –velocity field from CO, H 2 O, H 2 18 O maps (-> D/H) dynamics of the mesosphere (z = 100 km): zonal super-rotation, global circulation –Search for minor mesospheric species (HCl, H 2 S, SO 2 ) Follow-up of Venus Express

7. Mars: a prime objective of planetary exploration Questions: –Past and present climate –Water cycle –Evidence for liquid water in the past? –Evidence for traces of fossil life? An extensive space exploration with orbiters and landers (« Follow the water »)

8. Mars: High-resolution spectroscopy CO, H 2 O/HDO/H 2 18 O observed in the mm range - > vertical distributions ISO, Odin, SWAS -> water distribution Perspectives with Herschel and ALMA: –H 2 O, CO and isotopes (in part. D/H) –Minor species: H 2 O 2, O 2, O 3 –Search for undetected species: HCl, NH 3, HO 2, H 2 CO, SO 2, H 2 S, OCS…

9. MARS: OBSERVATIONS WITH ODIN Biver et al., 2004

10. Ozone on Mars with Herschel

11. NH 3 on Mars with Herschel and ALMA (Q= 5 10 -10 ) Herschel ALMA

12. Mars: A 3-D dynamical picture of the middle atmosphere ( winds, T(P) and water mapping) First maps using CO(2-1) at IRAM (30m & PdB) Comparison with GCM: good overall agreement but strong retrograde winds observed whatever the season -> future observations important for better understanding the martian climate -> Major objective for ALMA Complementarity with space missions (Mars Express and future orbiters )

13. Mars velocity field, IRAM PdB (Moreno, 2001) z = 50 -70 km Perspectives with ALMA:  V = 3-5 m/s, spatial resolution on Mars: about 100 km

14. Giant planets: formation D/H: a tracer of giant planets ’ formation –In Jupiter and Saturn (mostly made of protosolar gas): reflects the protosolar value –In Uranus and Neptune ( mostly made of an icy core): enriched vs protosolar value –Expected: (D/H) PS =(D/H) J <(D/H) S <(D/H) U,N <(D/H) C Confirmed by ISO & Galileo measurements

15. HD: ISO/SWS Feuchtgruber et al., 1999 Lellouch et al., 2001 Deuterium in the Solar System

16. What to do with Herschel? New measurement of HD at 56 and 112  m on the four giant planets with PACS Questions: –Is (D/H) S > (D/H) J ? –Are (D/H) in protoneptunian ices different from cometary values? –Is D/H in Oort-cloud comets the same as in Kuiper-Belt comets?

17. Giant planets: evolution He/H: a tracer of giant planets ’ evolution –In Jupiter and (even more) in Saturn: He is expected to be depleted vs the protosolar value due to condensation in liquid hydrogen during the cooling phase –In Uranus and Neptune: no liquid hydrogen expected but H partly linked in ices -> He/H might be enriched in the gas phase –Present determination are still uncertain (except Jupiter) –Future: Cassini CIRS (Saturn), Herschel/PACS (Uranus,Neptune), from the far-IR continuum

18. He/H in the giant planets Jupiter: Galileo mass spectrometer Saturn, Uranus, Neptune: Voyager (IRIS)

19. The oxygen source in the giant planets and Titan H 2 O and CO 2 emissions detected by ISO-SWS + SWAS/ODIN (Jupiter, Saturn) Comparable H 2 O input fluxes: 10 5 -10 7 cm -2 s -1 Possible sources: –interplanetary flux (U, N), –local source (rings, satellites)(S, T?), –cometary impacts (J?) Important implications on: –Dust production and water content at large Rh (collisions in the Kuiper Belt?) –Rate of cometary impacts

20. Bergin et al. 2000 Observation of the H 2 O vertical distribution in Jupiter with SWAS

21. Oxygen source: What to do with Herschel and ALMA? NB: For Saturn: complementarity Herschel/Cassini-CIRS Herschel: –H 2 O abundance and variability Possible role of cometary impacts –H 2 O vertical distribution (HIFI) Constrains on transport models –Low-resolution mapping of J and S (PACS) Possible trapping in aurorae ALMA: HDO high-resolution mapping Determination of D/H in external source?

22. Why are Uranus and Neptune so different? Strong internal source in Neptune, not in Uranus CO and HCN abundant in Neptune ’s stratosphere (CO N = 10 -6, CO U = 3 10 -8 ) CO mostly internal in Neptune, probably external in Uranus Uranus is much more sluggish (eddy diffusion coefficient 10 3 times less than in Neptune)

23. What to do with Herschel and ALMA? Search for tropospheric CO and PH 3 (tracer of vertical motions in Jupiter and Saturn ’s tropospheres) –PH 3 expected to be abundant in Neptune, apparently absent in Uranus (convection inhibited?) Search for CH 4 emission lines –oversaturation observed in Neptune, not in Uranus Search for photochemical products in Neptune (nitriles)

24. Detectability of stratospheric CH 4 in Uranus and Neptune with Herschel/PACS

25. Satellites & Pluto with ALMA Io –Search for minor species (H 2 S, S 2 O, KCl, SiO…) –SO 2 low-res. Mapping (-> volcanism monitoring) Titan (complementarity with Cassini/CIRS) –Mapping of CH 3 CN, HC 3 N at z = 500 km -> dynamics, photochemistry –HCN: winds (low-res.map), D/H Triton and Pluto –Search for CO, HCN…

26. Distant asteroids and TNOs Interest of far-IR/submm measurements: determination of diameter + Ts (in the visible: aD 2 is measured) Spitzer program (GTO): 114 TNOs, 14 Centaurs With Herschel: possible to reach D=300 km at 40 AU With ALMA: 300 km at 80 UA

27. Sensitivity (1  - 1h) = 0.6 mJy HERSCHEL/SPIRE 250 micron Detectability of TNOs with Herschel/SPIRE

28. Observations of comets with Herschel and ALMA (1) Water-rich objects ->Study with Herschel –Activity monitoring – D/H -> origin –T initial from ortho/para ratio -> origin –T coma from H 2 O line intensities -> thermodynamics –Doppler shifts -> velocity fields -> thermodynamics, study of jets...

30. Many complex parent molecules -> study with ALMA –Search for new species (possible candidates: all ISM molecules!) –Chemical diversity among comets –Relative abundances -> link with ISM –Isotopic ratios (D/H in HCN, HNC, H 2 CO…) -> link with ISM –Velocity fields -> thermodynamics, origin of outgassing (nucleus, grains), structure (jets) Observations of comets with Herschel and ALMA (2)

31. The heritage from ISO: high-resolution spectroscopy of rovibrational bands Crovisier et al., 1997

32. The heritage from SWAS: the 557 GHz line in comet C 1999 H I (Lee) About 12 comets observed with SWAS and/or ODIN

33. The heritage from ground-based observations: Evolution of production rates with heliocentric distances Biver et al., 2002

34. Parent molecules observed in comets In the far-IR/radio range: –H 2 O, CO, CH 3 OH, H 2 CO, HCN, H 2 S –NH 3, HNCO,CH 3 CN,HNC, OCS (Hyakutake) –HCOOH, CH 3 CHO, HCOOCH 3, NH 2 CHO, HC 3 N, H 2 CS, SO, SO 2 (Hale-Bopp) In the near-IR range: –H 2 O, CO, CO 2, H 2 CO, OCS, saturated & unsaturated hydrocarbons –CH 4, C 2 H 2, C 2 H 6, OCS, NH 3 (Hyakutake, Hale- Bopp)

35. Water in comets (Herschel) H 2 O in a sample of weak comets (down to Q=10 26 s -1 )-> prod. rates (HIFI, 557 GHz) H 2 O monitoring as a function of R h (HIFI, 557 GHz) Search for H 2 O in distant weakly active objects (link with asteroids) Measurement of D/H in H 2 O

36. D/H in comets D/H in water: a stringent clue to the formation of comets (T, R h ) D/H is known for only 3 Oort-cloud comets, not for Kuiper-belt comets HDO lines will be searched for with HIFI for bright comets (Q > 2 10 28 s -1 ) D/H in other species (HCN, HNC…) will be searched for with ALMA

37. 8P/Tuttle January 2008, Q[H 2 O] = 3. 10 28 s -1  = 0.25 AU 46P/Wirtanen February 2008, Q[H 2 O] = 1. 10 28 s -1 85P/Boethin December 2008, Q[H 2 O] = 3. 10 28 s -1 67P/Churyu.-G December 2008, Q[H 2 O] = 5. 10 27 s -1 22P/Kopff May 2009, Q[H 2 O] = 2.5 10 28 s -1 81P/Wild 2 February 2010, Q[H 2 O] = 1.3 10 28 s -1 103P/Hartley 2 October 2010, Q[H 2 O] = 1.2 10 28 s -1  = 0.12 AU A few good targets for Herschel + possible brighter targets as Targets of Opportunity

38. ALMA Instantaneous 3-D maps of gaseous and dust (thermal) emissions Coma morphology, spiral gaseous jets, nucleus outgassing, rotation properties, dust/gas links Gas temperature and velocity maps Nucleus thermal emission on long baselines: size, albedo CO 230 GHz/Hale-Bopp with IRAM PdB Mapping cometary atmospheres Henry,2003

39. In summary... Herschel/ALMA observations of solar-system objects will be precious in addition to space missions (MEx, VEx, Rosetta) D/H in the solar system-> origins Search for minor species in comets-> link with the ISM Observation of many samples (KB comets, TNOs) High-resolution mapping of planets and satellites A major program with Herschel: H 2 O in the solar system Formation of planets and comets Activity of outer small bodies and water content in outer planetesimals