Pseudo-panspermia explained

Pseudo-panspermia (sometimes called soft panspermia, molecular panspermia or quasi-panspermia) is a well-supported hypothesis for a stage in the origin of life. The theory first asserts that many of the small organic molecules used for life originated in space (for example, being incorporated in the solar nebula, from which the planets condensed). It continues that these organic molecules were distributed to planetary surfaces, where life then emerged on Earth and perhaps on other planets. Pseudo-panspermia differs from the fringe theory of panspermia, which asserts that life arrived on Earth from distant planets.

Background

Theories of the origin of life have been current since the 5th century BC, when the Greek philosopher Anaxagoras proposed an initial version of panspermia: life arrived on earth from the heavens.[1] In modern times, full panspermia has little support amongst mainstream scientists.[2] Pseudo-panspermia, in which molecules are formed and transported through space is however well-supported.

Extraterrestrial creation of organic molecules

Interstellar molecules are formed by chemical reactions within very sparse interstellar or circumstellar clouds of dust and gas. Usually this occurs when a molecule becomes ionised, often as the result of an interaction with cosmic rays. This positively charged molecule then draws in a nearby reactant by electrostatic attraction of the neutral molecule's electrons. Molecules can also be generated by reactions between neutral atoms and molecules, although this process is generally slower.[3] The dust plays a critical role of shielding the molecules from the ionizing effect of ultraviolet radiation emitted by stars.[4] The Murchison meteorite contains the organic molecules uracil and xanthine,[5] [6] which must therefore already have been present in the early Solar System, where they could have played a role in the origin of life.[7]

Nitriles, key molecular precursors of the RNA World scenario, are among the most abundant chemical families in the universe and have been found in molecular clouds in the center of the Milky Way, protostars of different masses, meteorites and comets, and also in the atmosphere of Titan, the largest moon of Saturn.[8] [9]

Evidence for the extraterrestrial creation of organic molecules includes both their discovery in various contexts in space, and their laboratory synthesis under extraterrestrial conditions:

Extraterrestrial organic molecules found in space
Molecule Class Body Notes
NASA, 2009[10]
mixed aromatic-aliphatic compounds 2011[11] [12]
Sugar-related Copenhagen University, 2012[13] [14] Precursor of RNA[15]
Imines Precursors of nucleobase adenine, and of amino acid alanine[16]
polycyclic aromatic hydrocarbons (PAHs) widespread, 20% of carbon in universe NASA, 2014[17]
Amino acid, amines Rosetta Mission, 2016[18]
Uracil, NiacinNucleobase, vitamer162173 RyuguHayabusa2, 2023[19] [20]
Laboratory syntheses under extraterrestrial conditions
Molecule Class Conditions Notes
Precursors of amino acids and nucleotides NASA, 2012, starting from polycyclic aromatic hydrocarbons (PAHs)[21] [22]
Nucleobases Pyrimidine, outer space NASA, 2015[23]
OligoglycinesPeptides Low-temperature areas of outer space Initial materials are CO, C, and NH3, common in molecular clouds of the interstellar medium[24] [25]

Planetary distribution of organic molecules

Organic molecules can then be distributed to planets including Earth both when the planets formed and later. If the materials from which planets formed contained organic molecules, and were not destroyed by heat or other processes, then these would be available for abiogenesis on those planets.

Later distribution is by means of bodies such as comets and asteroids. These may fall to the planetary surface as meteorites, releasing any molecules they are carrying as they vaporise on impact or later as they erode. Findings of organic molecules in meteorites include:

Organic molecules found in meteorites
Molecule Class Notes
NASA, 2011[26] [27]
Sugars In "primitive meteorites"[28]
Nucleobases 2022[29]
Large Asteroids With Ice And Organic Chemicals
Asteroid Location Notes
NASA, Jet Propulsion Laboratory,
Near Earth Objects, life on Earth[30]
NASA, JPL Small-Body Database[31]

Notes and References

  1. Hollinger . Maik . Life from Elsewhere – Early History of the Maverick Theory of Panspermia . Sudhoffs Archiv . 100 . 2 . 2016 . 188–205 . 10.25162/sudhoff-2016-0009 . 24913787 . 29668166 .
  2. Book: May, Andrew . Astrobiology: The Search for Life Elsewhere in the Universe . 2019 . 978-1-78578-342-5 . Icon Books . London . 999440041 . Although they were part of the scientific establishment – Hoyle at Cambridge and Wickramasinghe at the University of Wales – their views on the topic were far from mainstream, and panspermia remains a fringe theory.
  3. 10.1073/pnas.0602117103 . The galactic cosmic ray ionization rate . 2006 . Dalgarno . A. . Proceedings of the National Academy of Sciences . 103 . 33 . 12269–73 . 16894166 . 1567869 . 2006PNAS..10312269D . free .
  4. Book: Brown . Laurie M. . Pais . Abraham . Pippard . A. B. . Twentieth Century Physics . 1765 . The physics of the interstellar medium . 2nd . CRC Press . 1995 . 978-0-7503-0310-1 .
  5. 10.1016/j.epsl.2008.03.026 . Extraterrestrial nucleobases in the Murchison meteorite . 2008 . Martins . Zita . Botta . Oliver . Fogel . Marilyn L. . Marilyn Fogel . Sephton . Mark A. . Glavin . Daniel P. . Watson . Jonathan S. . Dworkin . Jason P. . Schwartz . Alan W. . Ehrenfreund . Pascale . Earth and Planetary Science Letters . 270 . 1–2 . 130–36 . 2008E&PSL.270..130M . 0806.2286 . 14309508 .
  6. Web site: We may all be space aliens: study . 20 August 2009 . https://web.archive.org/web/20080617213441/http://afp.google.com/article/ALeqM5j_QHxWNRNdiW35Qr00L8CkwcXyvw . June 17, 2008 . . 8 November 2014.
  7. 10.1016/j.epsl.2008.03.026 . Extraterrestrial nucleobases in the Murchison meteorite . 2008 . Martins . Zita . Botta . Oliver . Fogel . Marilyn L. . Marilyn Fogel . Sephton . Mark A. . Glavin . Daniel P. . Watson . Jonathan S. . Dworkin . Jason P. . Schwartz . Alan W. . Ehrenfreund . Pascale . 3 . Earth and Planetary Science Letters . 270 . 1–2 . 130–36 . 2008E&PSL.270..130M . 0806.2286 . 14309508 .
  8. Rivilla . Víctor M. . Jiménez-Serra . Izaskun . Martín-Pintado . Jesús . Colzi . Laura . Tercero . Belén . de Vicente . Pablo . Zeng . Shaoshan . Martín . Sergio . García de la Concepción . Juan . Bizzocchi . Luca . Melosso . Mattia . 2022 . Molecular Precursors of the RNA-World in Space: New Nitriles in the G+0.693−0.027 Molecular Cloud . Frontiers in Astronomy and Space Sciences . 9 . 876870 . 10.3389/fspas.2022.876870 . 2206.01053 . 2022FrASS...9.6870R . 2296-987X. free .
  9. Web site: 2022-07-08 . Building blocks for RNA-based life abound at center of our galaxy . 2022-07-11 . EurekAlert! . en.
  10. News: 'Life chemical' detected in comet . 18 August 2009 . BBC News . . 6 March 2010.
  11. News: Chow . Denise . Discovery: Cosmic Dust Contains Organic Matter from Stars . 26 October 2011 . . 26 October 2011.
  12. 10.1038/nature10542 . Mixed aromatic–aliphatic organic nanoparticles as carriers of unidentified infrared emission features . 2011 . Kwok . Sun . Zhang . Yong . Nature . 479 . 7371 . 80–83 . 22031328 . 2011Natur.479...80K . 4419859 .
  13. Sugar Found In Space . National Geographic . Than . Ker . August 29, 2012 . https://web.archive.org/web/20120901013431/http://news.nationalgeographic.com/news/2012/08/120829-sugar-space-planets-science-life . dead . September 1, 2012 . August 31, 2012 .
  14. Web site: Sweet! Astronomers spot sugar molecule near star . August 29, 2012 . . August 31, 2012 .
  15. 10.1088/2041-8205/757/1/L4 . Detection of the Simplest Sugar, Glycolaldehyde, in a Solar-Type Protostar with Alma . 2012 . Jørgensen . Jes K. . 4 . Favre . Cécile . Bisschop . Suzanne E. . Bourke . Tyler L. . Van Dishoeck . Ewine F. . Schmalzl . Markus . The Astrophysical Journal . 757 . 1 . L4 . 2012ApJ...757L...4J . 1208.5498 . 14205612 .
  16. 10.1088/2041-8205/765/1/L9 . The Detection of Interstellar Ethanimine (CH3CHNH) from Observations Taken During the GBT PRIMOS Survey . 2013 . Loomis . Ryan A. . Zaleski . Daniel P. . Steber . Amanda L. . Neill . Justin L. . Muckle . Matthew T. . Harris . Brent J. . Hollis . Jan M. . Jewell . Philip R. . Lattanzi . Valerio . Lovas . Frank J. . Martinez . Oscar . McCarthy . Michael C. . Remijan . Anthony J. . Pate . Brooks H. . Corby . Joanna F. . 3 . The Astrophysical Journal . 765 . 1 . L9 . 2013ApJ...765L...9L . 1302.1121 . 118522676 .
  17. Web site: Hoover . Rachel . Need to Track Organic Nano-Particles Across the Universe? NASA's Got an App for That . February 21, 2014 . . 22 February 2014.
  18. Web site: Prebiotic chemicals – amino acid and phosphorus – in the coma of comet 67P/Churyumov-Gerasimenko.
  19. Web site: Strickland . Ashley . 2023-03-21 . RNA compound and vitamin B3 found in samples from near-Earth asteroid . 2023-03-24 . CNN . en.
  20. Oba . Yasuhiro . Koga . Toshiki . Takano . Yoshinori . Ogawa . Nanako O. . Ohkouchi . Naohiko . Sasaki . Kazunori . Sato . Hajime . Glavin . Daniel P. . Dworkin . Jason P. . Naraoka . Hiroshi . Tachibana . Shogo . Yurimoto . Hisayoshi . Nakamura . Tomoki . Noguchi . Takaaki . Okazaki . Ryuji . 2023-03-21 . Uracil in the carbonaceous asteroid (162173) Ryugu . Nature Communications . en . 14 . 1 . 1292 . 10.1038/s41467-023-36904-3 . 36944653 . 10030641 . 2023NatCo..14.1292O . 2041-1723.
  21. News: NASA Cooks Up Icy Organics to Mimic Life's Origins . September 20, 2012 . . September 22, 2012 .
  22. 10.1088/2041-8205/756/1/L24 . In-Situ Probing of Radiation-Induced Processing of Organics in Astrophysical Ice Analogs – Novel Laser Desorption Laser Ionization Time-Of-Flight Mass Spectroscopic Studies . 2012 . Gudipati . Murthy S. . Yang . Rui . The Astrophysical Journal . 756 . 1 . L24. 2012ApJ...756L..24G. 5541727 .
  23. Web site: Marlaire . Ruth . NASA Ames Reproduces the Building Blocks of Life in Laboratory . 3 March 2015 . . 5 March 2015 .
  24. 10.1038/s41550-021-01577-9 . A pathway to peptides in space through the condensation of atomic carbon . 2022 . Krasnokutski . S. A. . Chuang . K. J. . Jäger . C. . Ueberschaar . N. . Henning . Th. . 3 . Nature Astronomy . 6 . 3 . 381–386 . 2202.12170 . 2022NatAs...6..381K . 246768607 .
  25. Krasnokutski . Serge A. . Jäger . Cornelia . Henning . Thomas . Geffroy . Claude . Remaury . Quentin B. . Poinot . Pauline . 2024-04-19 . Formation of extraterrestrial peptides and their derivatives . Science Advances . en . 10 . 16 . eadj7179 . 10.1126/sciadv.adj7179 . 2375-2548 . 11023503 . 38630826. 2405.00744 . 2024SciA...10J7179K .
  26. 10.1073/pnas.1106493108 . Carbonaceous meteorites contain a wide range of extraterrestrial nucleobases . 2011 . Callahan . M. P. . Smith . K. E. . Cleaves . H. J. . Ruzicka . J. . Stern . J. C. . Glavin . D. P. . House . C. H. . Dworkin . J. P. . 3 . Proceedings of the National Academy of Sciences . 108 . 34 . 13995–98 . 21836052 . 3161613 . 2011PNAS..10813995C . free .
  27. Web site: Steigerwald . John . NASA Researchers: DNA Building Blocks Can Be Made in Space . . 8 August 2011 . 10 August 2011.
  28. Furukawa . Yoshihiro . Chikaraishi . Yoshito . Ohkouchi . Naohiko . Ogawa . Nanako O. . Glavin . Daniel P. . Dworkin . Jason P. . Abe . Chiaki . Nakamura . Tomoki . 3 . 13 November 2019 . Extraterrestrial ribose and other sugars in primitive meteorites . Proceedings of the National Academy of Sciences . 116 . 49 . 24440–45 . 10.1073/pnas.1907169116 . 31740594 . 2019PNAS..11624440F . free . 6900709.
  29. Oba, Yasuhiro . et al . Identifying the wide diversity of extraterrestrial purine and pyrimidine nucleobases in carbonaceous meteorites . 26 April 2022 . . 13 . 2008 . 2008 . 10.1038/s41467-022-29612-x . 35473908 . 9042847 . 2022NatCo..13.2008O .
  30. Web site: Life On Earth . NASA-JPL . JPL . 14 September 2022.
  31. Web site: NASA Open Data Portal . NASA dot gov . NASA . 14 September 2022.

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