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Cruikshank DP, Materese CK, Pendleton YJ, Boston PJ, Grundy WM, Schmitt B, Lisse CM, Runyon KD, Keane JT, Beyer RA, Summers ME, Scipioni F, Stern SA, Dalle Ore CM, Olkin CB, Young LA, Ennico K, Weaver HA, Bray VJ. Prebiotic Chemistry of Pluto. Astrobiology 2019; 19:831-848. [PMID: 30907634 DOI: 10.1089/ast.2018.1927] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
We present the case for the presence of complex organic molecules, such as amino acids and nucleobases, formed by abiotic processes on the surface and in near-subsurface regions of Pluto. Pluto's surface is tinted with a range of non-ice substances with colors ranging from light yellow to red to dark brown; the colors match those of laboratory organic residues called tholins. Tholins are broadly characterized as complex, macromolecular organic solids consisting of a network of aromatic structures connected by aliphatic bridging units (e.g., Imanaka et al., 2004; Materese et al., 2014, 2015). The synthesis of tholins in planetary atmospheres and in surface ices has been explored in numerous laboratory experiments, and both gas- and solid-phase varieties are found on Pluto. A third variety of tholins, exposed at a site of tectonic surface fracturing called Virgil Fossae, appears to have come from a reservoir in the subsurface. Eruptions of tholin-laden liquid H2O from a subsurface aqueous repository appear to have covered portions of Virgil Fossae and its surroundings with a uniquely colored deposit (D.P. Cruikshank, personal communication) that is geographically correlated with an exposure of H2O ice that includes spectroscopically detected NH3 (C.M. Dalle Ore, personal communication). The subsurface organic material could have been derived from presolar or solar nebula processes, or might have formed in situ. Photolysis and radiolysis of a mixture of ices relevant to Pluto's surface composition (N2, CH4, CO) have produced strongly colored, complex organics with a significant aromatic content having a high degree of nitrogen substitution similar to the aromatic heterocycles pyrimidine and purine (Materese et al., 2014, 2015; Cruikshank et al., 2016). Experiments with pyrimidines and purines frozen in H2O-NH3 ice resulted in the formation of numerous nucleobases, including the biologically relevant guanine, cytosine, adenine, uracil, and thymine (Materese et al., 2017). The red material associated with the H2O ice may contain nucleobases resulting from energetic processing on Pluto's surface or in the interior. Some other Kuiper Belt objects also exhibit red colors similar to those found on Pluto and may therefore carry similar inventories of complex organic materials. The widespread and ubiquitous nature of similarly complex organic materials observed in a variety of astronomical settings drives the need for additional laboratory and modeling efforts to explain the origin and evolution of organic molecules. Pluto observations reveal complex organics on a small body that remains close to its place of origin in the outermost regions of the Solar System.
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Affiliation(s)
- D P Cruikshank
- 1NASA Ames Research Center, Moffett Field, California, USA
| | - C K Materese
- 2Goddard Space Flight Center, Greenbelt, Maryland, USA
| | - Y J Pendleton
- 1NASA Ames Research Center, Moffett Field, California, USA
| | - P J Boston
- 1NASA Ames Research Center, Moffett Field, California, USA
| | - W M Grundy
- 3Lowell Observatory, Flagstaff, Arizona, USA
| | - B Schmitt
- 4Université Grenoble Alpes, CNRS, IPAG, Grenoble, France
| | - C M Lisse
- 5Applied Physics Laboratory, Johns Hopkins University, Laurel, Maryland, USA
| | - K D Runyon
- 5Applied Physics Laboratory, Johns Hopkins University, Laurel, Maryland, USA
| | - J T Keane
- 6California Institute of Technology, Pasadena, California, USA
| | - R A Beyer
- 1NASA Ames Research Center, Moffett Field, California, USA
| | - M E Summers
- 7Department of Physics and Astronomy, George Mason University, Fairfax, Virginia, USA
| | - F Scipioni
- 1NASA Ames Research Center, Moffett Field, California, USA
| | - S A Stern
- 8Southwest Research Institute, Boulder, Colorado, USA
| | - C M Dalle Ore
- 1NASA Ames Research Center, Moffett Field, California, USA
| | - C B Olkin
- 8Southwest Research Institute, Boulder, Colorado, USA
| | - L A Young
- 8Southwest Research Institute, Boulder, Colorado, USA
| | - K Ennico
- 1NASA Ames Research Center, Moffett Field, California, USA
| | - H A Weaver
- 5Applied Physics Laboratory, Johns Hopkins University, Laurel, Maryland, USA
| | - V J Bray
- 9Lunar and Planetary Laboratory, University of Arizona, Tucson, Arizona, USA
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Abstract
Data from the New Horizons mission to Pluto show no craters on Sputnik Planum down to the detection limit (2 km for low resolution data, 625 m for high resolution data). The number of small Kuiper Belt Objects that should be impacting Pluto is known to some degree from various astronomical surveys. We combine these geological and telescopic observations to make an order of magnitude estimate that the surface age of Sputnik Planum must be less than 10 million years. This maximum surface age is surprisingly young and implies that this area of Pluto must be undergoing active resurfacing, presumably through some cryo-geophysical process. We discuss three possible resurfacing mechanisms and the implications of each one for Pluto’s physical properties.
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Affiliation(s)
- David E. Trilling
- Department of Physics and Astronomy, Northern Arizona University, Flagstaff, AZ, United States of America
- Lowell Observatory, Flagstaff, AZ, United States of America
- * E-mail:
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Zachar P, Kendler KS. The removal of Pluto from the class of planets and homosexuality from the class of psychiatric disorders: a comparison. Philos Ethics Humanit Med 2012; 7:4. [PMID: 22244039 PMCID: PMC3283463 DOI: 10.1186/1747-5341-7-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2011] [Accepted: 01/13/2012] [Indexed: 05/12/2023] Open
Abstract
We compare astronomers' removal of Pluto from the listing of planets and psychiatrists' removal of homosexuality from the listing of mental disorders. Although the political maneuverings that emerged in both controversies are less than scientifically ideal, we argue that competition for "scientific authority" among competing groups is a normal part of scientific progress. In both cases, a complicated relationship between abstract constructs and evidence made the classification problem thorny.
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Affiliation(s)
- Peter Zachar
- Department of Psychology, Auburn University Montgomery, 7061 Senators Drive, Montgomery, AL, 36117, USA
| | - Kenneth S Kendler
- Virginia Institute for Psychiatry and Behavioral Genetics and Departments of Psychiatry and Human Genetics, Medical College of Virginia of Virginia Commonwealth University, Virginia Commonwealth University Medical School, Box 980126, 800 E. Leigh Street, Room 1-123, Richmond, VA, USA 23298-0126
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Mervis J. 2003 U.S. budget. NSF gets big lift; Pluto mission backed. Science 2002; 297:755. [PMID: 12161625 DOI: 10.1126/science.297.5582.755a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
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7
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Abstract
Observations have resolved the satellite Charon from its parent planet Pluto, giving separate spectra of the two objects from 1.0 to 2.5 micrometers. The spectrum of Charon is found to be different from that of Pluto, with water ice in crystalline form covering most of the surface of the satellite. In addition, an absorption feature in Charon's spectrum suggests the presence of ammonia ices. Ammonia ice-water ice mixtures have been proposed as the cause of flowlike features observed on the surfaces of many icy satellites. The existence of such ices on Charon may indicate geological activity in the satellite's past.
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Affiliation(s)
- M E Brown
- Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125, USA
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Affiliation(s)
- E Young
- Southwestern Research Institute, Boulder, CO 80302, USA.
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9
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Ethane on Pluto? Science 1999; 285:1355. [PMID: 11536920] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/21/2023]
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10
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Sincell M. Telling Pluto and its partner apart. Science 1999; 285:649-50. [PMID: 11536918 DOI: 10.1126/science.285.5428.649a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
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11
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Abstract
Ion irradiation of carbon containing ices produces several effects among which the formation of complex molecules and even refractory organic materials whose spectral color and molecular complexity both depend on the amount of deposited energy. Here results from laboratory experiments are summarized. Their relevance for the formation and evolution of simple molecules and complex organic materials on planetary bodies in the external Solar System is outlined.
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Affiliation(s)
- G Strazzulla
- Osservatorio Astrofisico, Citta Universitaria, Catania, Italy
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12
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Galeev AA. Russian program of planetary missions. Acta Astronaut 1996; 39:9-14. [PMID: 11540765 DOI: 10.1016/s0094-5765(96)00117-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
In the area of Solar System Exploration most of recently proposed mission oriented to the studies of Mars. Except MARS-96 and possibly MARS SAMPLE RETURN missions other Mars missions use Molnija class launchers. All Russian missions heavily involve international partners.
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Affiliation(s)
- A A Galeev
- Space Research Institute of Russian Academy of Sciences, Moscow, Russia
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Abstract
In the context of prebiotic chemistry in space, some of the outer planetary objects display H, C, N and O rich chemistry similar to the one in the biosphere of Earth. Of particular interest are Saturn's moon, Titan; Neptune's moon, Triton; and Pluto where extreme cold conditions prevail. Identifications of chemical species on these objects (surfaces and atmospheres) is essential to a better understanding of the radiation induced chemical reactions occurring thereon. There have been several ground based observations of these planetary objects in the infrared windows from 1 to 2.5 micrometers. Voyager also provided spectra in the thermal infrared (6 to 50 micrometers) region. Interpretation of these data require laboratory infrared spectra of relevant species under the temperature conditions appropriate to these objects. The results of some of these studies carried out in our laboratory and elsewhere and their impact on the analyses of the observed data will be summarized.
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Affiliation(s)
- R K Khanna
- Department of Chemistry and Biochemistry, University of Maryland, College Park 20742, USA
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Bohn RB, Sandford SA, Allamandola LJ, Cruikshank DP. Infrared spectroscopy of Triton and Pluto ice analogs: the case for saturated hydrocarbons. Icarus 1994; 111:151-173. [PMID: 11539177 DOI: 10.1006/icar.1994.1138] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The infrared transmission spectra and photochemical behavior of various organic compounds isolated in solid N2 ices, appropriate for applications to Triton and Pluto, are presented. It is shown that excess absorption in the surface spectra of Triton and Pluto, i.e., absorption not explained by present models incorporating molecules already identified on these bodies (N2, CH4, CO, and CO2), that starts near 4450 cm-1 (2.25 micrometers) and extends to lower frequencies, may be due to alkanes (C(n)H2n+2) and related molecules frozen in the nitrogen. Branched and linear alkanes may be responsible. Experiments in which the photochemistry of N2:CH4 and N(2):CH4:CO ices was explored demonstrate that the surface ices of Triton and Pluto may contain a wide variety of additional species containing H, C, O, and N. Of these, the reactive molecule diazomethane, CH2N2, is particularly important since it may be largely responsible for the synthesis of larger alkanes from CH4 and other small alkanes. Diazomethane would also be expected to drive chemical reactions involving organics in the surface ices of Triton and Pluto toward saturation, i.e., to reduce multiple CC bonds. The positions and intrinsic strengths (A values) of many of the infrared absorption bands of N2 matrix-isolated molecules of relevance to Triton and Pluto have also been determined. These can be used to aid in their search and to place constraints on their abundances. For example, using these A values the abundance ratios CH4/N2 approximately 1.3 x 10(-3), C2H4/N2 < or = 9.5 x 10(-7) and H2CO/N2 < or = 7.8 x 10(-7) are deduced for Triton and CH4/N2 approximately 3.1 x 10(-3), C2H4/N2 < or = 4.1 x 10(-6), and H2CO/N2 < or = 5.2 x 10(-6) deduced for Pluto. The small amounts of C2H4 and H2CO in the surface ices of these bodies are in disagreement with the large abundances expected from many theoretical models.
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Affiliation(s)
- R B Bohn
- NASA-Ames Research Center, Moffett Field, California 94035, USA
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Tryka KA, Brown RH, Cruikshank DP, Owen TC, Geballe TR, DeBergh C. Temperature of nitrogen ice on Pluto and its implications for flux measurements. Icarus 1994; 112:513-527. [PMID: 11538596 DOI: 10.1006/icar.1994.1202] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Previous work by K.A. Tryka et al. (Science 261, 751-754, 1993) has shown that the profile of the 2.148-micrometers band of solid nitrogen can be used as a "thermometer" and determined the temperature of nitrogen ice on Triton to be 38(+2)-1 K. Here we reevaluate that data and refine the temperature value to 38 +/- 1 K. Applying the same technique to Pluto we determine that the temperature of the N2 ice on that body is 40 +/- 2 K. Using this result we have created a nonisothermal flux model of the Pluto-Charon system. The model treats Pluto as a body with symmetric N2 polar caps and an equatorial region devoid of N2. Comparison with the infrared and millimeter flux measurements shows that the published fluxes are consistent with models incorporating extensive N2 polar caps (down to +/- 15 degrees or +/- 20 degrees latitude) and an equatorial region with a bolometric albedo < or = 0.2.
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Affiliation(s)
- K A Tryka
- Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena 91125, USA
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Abstract
The competition between impact erosion and impact supply of volatiles to planetary atmospheres can determine whether a planet or satellite accumulates an atmosphere. In the absence of other processes (e.g., outgassing), we find either that a planetary atmosphere should be thick, or that there should be no atmosphere at all. The boundary between the two extreme cases is set by the mass and velocity distributions and intrinsic volatile content of the impactors. We apply our model specifically to Titan, Callisto, and Ganymede. The impacting population is identified with comets, either in the form of stray Uranus-Neptune planetesimals or as dislodged Kuiper belt comets. Systematically lower impact velocities on Titan allow it to retain a thick atmosphere, while Callisto and Ganymede get nothing. Titan's atmosphere may therefore be an expression of a late-accreting, volatile-rich veneer. An impact origin for Titan's atmosphere naturally accounts for the high D/H ratio it shares with Earth, the carbonaceous meteorites, and Halley. It also accounts for the general similarity of Titan's atmosphere to those of Triton and Pluto, which is otherwise puzzling in view of the radically different histories and bulk compositions of these objects.
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Affiliation(s)
- K Zahnle
- NASA Ames Research Center, Moffett Field, California 94035, USA
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17
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Abstract
Detailed models of the internal structures of Pluto and Charon, assuming rock and water ice as the only constituents, indicate that the mean silicate mass fraction of this two-body system is on the order of 0.7; thus the Pluto/Charon system is significantly "rockier" than the satellites of the giant planets (silicate mass fraction approximately 0.55). This compositional contrast reflects different formation mechanisms: it is likely that Pluto and Charon formed directly from the solar nebula, while the circumplanetary nebulae that produced the giant planet satellites were derived from envelopes that surrounded the forming giant planets (envelopes in which icy planetesimals dissolved more readily than rocky planetesimals). Simple cosmic abundance calculations, and the assumption that the Pluto/Charon system formed directly from solar nebula condensates, strongly suggest that the majority of the carbon in the outer solar nebula was in the form of carbon monoxide; these results are consistent with (1) inheritance from the dense molecular clouds in the interstellar medium (where CH4/CO < 10(-2) in the gas phase) and/or (2) of the Lewis and Prinn kinetic inhibition model of solar nebula chemistry. Theoretical predictions of the C/H enhancements in the atmospheres of the giant planets, when compared to the actual observed enhancements, suggest that 10%, or slightly more, of the carbon in the outer solar nebula was in the form of condensed materials (although the amount of condensed C may have dropped slightly with increasing heliocentric distance). Strict compositional limits computed for the Pluto/Charon system using the densities of CH4 and CO ices indicate that these pure ices are at best minor components in the interiors of these bodies, and imply that CH4 and CO ices were not the dominant C-bearing solids in the outer nebula. Clathrate-hydrates could not have appropriated enough CH4 or CO to be the major form of condensed carbon, although such clathrates may be necessary to explain the presence of methane on Pluto after its formation from a CO-rich nebula. Laboratory studies of carbonaceous chondrites, and spacecraft observations of Comet Halley, strongly suggest that of the remaining possibilities, organic material, rather than elemental carbon, is the most likely candidate for the dominant C-bearing solid in the outer solar nebula. We conclude that the majority of the carbon in the outer solar nebula was in gaseous CO; 10% to a few tens of percent of the C was in condensed organic materials; and at least a trace amount of carbon was in methane gas.
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Affiliation(s)
- D P Simonelli
- Space Science Division, NASA Ames Research Center, Moffett Field, California 94035, USA
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STRUGHOLD H, RITTER OL. Solar irradiance from Mercury to Pluto. Proj Rep USAF Sch Aviat Med 1960; 60:1-5. [PMID: 24546283] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
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STRUGHOLD H, RITTER OL. Solar irradiance from Mercury to Pluto. Aerosp Med 1960; 31:127-30. [PMID: 13835316] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 04/24/2023]
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ROHEIM G. Charon and the obolos. Psychiatr Q Suppl 1946; 20:160-196. [PMID: 20291866] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
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