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Ocean-like water in the Jupiter-family comet 103P/Hartley 2


For decades, the source of Earth's volatiles, especially water with a deuterium-to-hydrogen ratio (D/H) of (1.558 ± 0.001) × 10−4, has been a subject of debate. The similarity of Earth’s bulk composition to that of meteorites known as enstatite chondrites1 suggests a dry proto-Earth2 with subsequent delivery of volatiles3 by local accretion4 or impacts of asteroids or comets5,6. Previous measurements in six comets from the Oort cloud yielded a mean D/H ratio of (2.96 ± 0.25) × 10−4. The D/H value in carbonaceous chondrites, (1.4 ± 0.1) × 10−4, together with dynamical simulations, led to models in which asteroids were the main source of Earth's water7, with ≤10 per cent being delivered by comets. Here we report that the D/H ratio in the Jupiter-family comet 103P/Hartley 2, which originated in the Kuiper belt, is (1.61 ± 0.24) × 10−4. This result substantially expands the reservoir of Earth ocean-like water to include some comets, and is consistent with the emerging picture of a complex dynamical evolution of the early Solar System8,9.

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Figure 1: Submillimetre water emission lines from comet 103P/Hartley 2.
Figure 2: D/H ratios in the Solar System.


  1. Javoy, M. et al. The chemical composition of the Earth: enstatite chondrite models. Earth Planet. Sci. Lett. 293, 259–268 (2010)

    Article  ADS  CAS  Google Scholar 

  2. Wänke, H. Constitution of terrestrial planets. Phil. Trans. R. Roc. Lond. 303, 287–302 (1981)

    Article  ADS  Google Scholar 

  3. Robert, F. A distinct source of lunar water? Nature Geosci. 4, 74–75 (2011)

    Article  ADS  CAS  Google Scholar 

  4. Drake, M. J. & Righter, K. Determining the composition of the Earth. Nature 416, 39–44 (2002)

    Article  ADS  CAS  Google Scholar 

  5. Oró, J. Comets and the formation of biochemical compounds on the primitive Earth. Nature 190, 389–390 (1961)

    Article  ADS  Google Scholar 

  6. Owen, T., Bar-Nun, A. & Kleinfeld, I. Possible cometary origin of heavy noble gases in the atmospheres of Venus, Earth and Mars. Nature 358, 43–46 (1992)

    Article  ADS  CAS  Google Scholar 

  7. Morbidelli, A. et al. Source regions and time scales for the delivery of water to Earth. Meteorit. Planet. Sci. 35, 1309–1320 (2000)

    Article  ADS  CAS  Google Scholar 

  8. Tsiganis, K., Gomes, R., Morbidelli, A. & Levison, H. F. Origin of the orbital architecture of the giant planets of the Solar System. Nature 435, 459–461 (2005)

    Article  ADS  CAS  Google Scholar 

  9. Gomes, R., Levison, H. F., Tsiganis, K. & Morbidelli, A. Origin of the cataclysmic Late Heavy Bombardment period of the terrestrial planets. Nature 435, 466–469 (2005)

    Article  ADS  CAS  Google Scholar 

  10. Levison, H. F. & Duncan, M. J. From the Kuiper belt to Jupiter-family comets: the spatial distribution of ecliptic comets. Icarus 127, 13–32 (1997)

    Article  ADS  Google Scholar 

  11. Dones, L., Weissman, P. R., Levison, H. F. & Duncan, M. J. in Comets II (eds Festou, M. C., Keller, H. U. & Weaver, H. A. ) 153–174 (Univ. Arizona Press, 2005)

    Google Scholar 

  12. Hartogh, P. et al. Water and related chemistry in the solar system: a guaranteed time key programme for Herschel. Planet. Space Sci. 57, 1596–1606 (2009)

    Article  ADS  CAS  Google Scholar 

  13. Meech, K. et al. EPOXI: 103P/Hartley 2 observations from a worldwide campaign. Astrophys. J. 734, L1 (2011)

    Article  ADS  Google Scholar 

  14. Biver, N. et al. Submillimetre observations of comets with Odin: 2001–2005. Planet. Space Sci. 55, 1058–1068 (2007)

    Article  ADS  CAS  Google Scholar 

  15. Linsky, J. L. et al. What is the total deuterium abundance in the local galactic disk? Astrophys. J. 647, 1106–1124 (2006)

    Article  ADS  CAS  Google Scholar 

  16. Butner, H. M. et al. Discovery of interstellar heavy water. Astrophys. J. 659, L137–L140 (2007)

    Article  ADS  CAS  Google Scholar 

  17. Watson, W. D. Ion-molecule reactions, molecule formation, and hydrogen-isotope exchange in dense interstellar clouds. Astrophys. J. 188, 35–42 (1974)

    Article  ADS  CAS  Google Scholar 

  18. Geiss, J. & Reeves, H. Cosmic and solar system abundances of deuterium and helium-3. Astron. Astrophys. 18, 126–132 (1972)

    ADS  CAS  Google Scholar 

  19. Drouart, A., Dubrulle, B., Gautier, D. & Robert, F. Structure and transport in the solar nebula from constraints on deuterium enrichment and giant plant formation. Icarus 140, 129–155 (1999)

    Article  ADS  CAS  Google Scholar 

  20. Mousis, O. et al. Constraints on the formation of comets from D/H ratios measured in H2O and HCN. Icarus 148, 513–525 (2000)

    Article  ADS  CAS  Google Scholar 

  21. Aikawa, Y. & Herbst, E. Two-dimensional distributions and column densities of gaseous models in protoplanetary disks II. Deuterated species and UV shielding by ambient clouds. Astron. Astrophys. 371, 1107–1117 (2001)

    Article  ADS  CAS  Google Scholar 

  22. Emel’yanenko, V. V., Asher, D. J. & Bailey, M. E. Centaurs from the Oort cloud and the origin of Jupiter-family comets. Mon. Not. R. Astron. Soc. 361, 1345–1351 (2005)

    Article  ADS  Google Scholar 

  23. Marzari, F., Farinella, P. & Vanzani, V. Are Trojan collisional families a source for short-period comets? Astron. Astrophys. 299, 267–276 (1995)

    ADS  Google Scholar 

  24. Thi, W.-F., Woitke, P. & Kamp, I. Warm non-equilibrium gas phase chemistry as a possible origin of high HDO/H2O ratios in hot and dense gases: application to inner protoplanetary discs. Mon. Not. R. Astron. Soc. 407, 232–246 (2010)

    Article  ADS  CAS  Google Scholar 

  25. Walsh, K. J. & Morbidelli, A. The effect of an early planetesimal-driven migration of the giant planets on terrestrial planet formation. Astron. Astrophys. 526, A126 (2011)

    Article  ADS  Google Scholar 

  26. Delsemme, A. H. The deuterium enrichment observed in recent comets is consistent with the cometary origin of seawater. Planet. Space Sci. 47, 125–131 (1998)

    Article  ADS  Google Scholar 

  27. Greenwood, J. P. et al. Hydrogen isotope ratios in lunar rocks indicate delivery of cometary water to the Moon. Nature Geosci. 4, 79–82 (2011)

    Article  ADS  CAS  Google Scholar 

  28. Jørgensen, U. G. et al. The Earth-Moon system during the late heavy bombardment period — geochemical support for impacts dominated by comets. Icarus 204, 368–380 (2009)

    Article  ADS  Google Scholar 

  29. Zakharov, V., Bockelée-Morvan, D., Biver, N., Crovisier, J. & Lecacheux, A. Radiative transfer simulation of water rotational excitation in comets. Comparison of the Monte Carlo and escape probability methods. Astron. Astrophys. 473, 303–310 (2007)

    Article  ADS  CAS  Google Scholar 

  30. Bensch, F. & Bergin, E. A. The pure rotational line emission of ortho-water in comets. I. Radiative transfer model. Astrophys. J. 615, 531–544 (2004)

    Article  ADS  CAS  Google Scholar 

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Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation by NASA. The Heterodyne Instrument for the Far Infrared (HIFI) has been designed and built by a consortium of institutes and university departments from across Europe, Canada and the United States under the leadership of SRON, the Netherlands Institute for Space Research, and with major contributions from Germany, France and the USA. This development has been supported by national funding agencies: CEA, CNES, CNRS (France); ASI (Italy); and DLR (Germany). Additional funding support for some instrument activities has been provided by ESA. Support for this work was also provided by NASA through an award issued by JPL/Caltech. D.C.L. is supported by an NSF award to the Caltech Submillimeter Observatory. We thank R. Lorente, P. García-Lario, M. Kidger and G. Pilbratt for helping with the scheduling of these observations, and I. Avruch for the assistance with HIFI specific software issues.

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This paper represents the combined work of the HssO (the Herschel guaranteed time key programme “Water and related chemistry in the solar system”) team members listed as authors. P.H. is the coordinator of this programme. All authors contributed to this work, including observation planning, data analysis and writing of the manuscript. N.B., D.B.-M., M.R., R.M, M.d.V.-B. and M.E. carried out the data reduction and contributed to the modelling efforts. All authors were collectively involved in the discussion and interpretation of the results.

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Correspondence to Paul Hartogh.

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Hartogh, P., Lis, D., Bockelée-Morvan, D. et al. Ocean-like water in the Jupiter-family comet 103P/Hartley 2. Nature 478, 218–220 (2011).

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