Bacterial morphologies in carbonaceous meteorites and comet dust

1. Bacterial morphologies in carbonaceous meteorites and comet dust Chandra Wickramasinghe1, Max K. Wallis1, Carl H. Gibson2, Jamie Wallis1, Shirwan Al-Mufti1 & Nori Miyake1 1 Cardiff Centre for Astrobiology, Cardiff University, UK. 2 Depts of Mechanical and Aerospace Engineering and Scripps Institution of Oceanography, Center for Astrophysics and Space Sciences,  University of California at San Diego, La Jolla CA 92093-0411, USA

2. Aims • To re-visit evidence for microbial fossils in carbonaceous chondrites, linking with extensive modern evidence of Richard Hoover • Examine progress from Claus and Nagy, via Hans Pflug, to Richard Hoover and colleagues • To examine data for IDP’s in relation to embedded particles and organics • Discuss presence of acritarchs in cryosampler collections of cometary dust • Discuss relevance to cometarypanspermia and cosmology

3. Early History of Microfossils • Early in the 1960’s, Claus and Nagy (1961) identified possible microfossils in carbonaceous chondrites (CCs), supported by chemical bio-markers • These were refuted vigorously on grounds of contamination and the subject fell into disrepute – some ragweed pollen but possibly small component • In the 1980’s the matter was re-opened by Hans Dieter Pflug using modern techniques

4. Pflug prepared ultra-thin sections (< 1mm) of the Murchison meteorite H.D.Pflug • The sections were placed on membrane filters and exposed to hydrofluoric acid vapour. • In situ demineralisation was achieved leaving carbonaceous structures indigenous to the meteorite in tact. • A wealth of morphologies revealed.

7. Structures resembling the influenza virus

8. Laser ion probe showed biomarkers within the microfossils

9. Richard Hoover has found a wealth of microfossil structures with biomarkers + low N that leaves no room for dispute..

10. This is consistent with the distribution of biologically relevant molecules discovered in the Murchison meteorite by Schmidt-Koplin et al (2010)

11. If comets carriers of microbial life, a diversity of organic molecules as rich, or richer the terrestrial set is expected.

12. Water-ice and organics found in Tempel 1 3 areas less than 0.5% of surface, 1.5 & 2µm ice bands Ice? Ice could be surfaces of lakes exposed by impacts – and organics in plenty

13. + Clay - evidence of liquid water in comets

14. Possibility of liquid water predicted theoretically Primordial radiogenic heating, with 26Al decays for comets forming 1My after incorporation of 26Al Heat transfer calculations show melting for comets with radii in excess of 10km, with substantial volume fractions staying melted for periods of a fraction of My at least

15. Conclusions so far... • Carbonaceous meteorites carry microfossils of living organisms • They are most likely relic comets that had liquid interior regions • Cometary pools sites for microbial replication? • Theories of cometarypanspermia strongly supported by this data • Implication is that injection of microbes from comets is an ongoing process

16. Dust from modern comets • The Earth picks up debris from comets in the present day • Collection of comet dust in the atmosphere could provide additional proof of cometary life • Daily arrival rate 60 tonnes

17. Brownlee particles – collected from 1970’sAgglomeration of comet dust 18 micrometres Similar to terrestrial fossil of iron-oxidising bacterium

18. Cyrosampler collections, from 2001 (ISRO) • Aseptic collection • Low relative velocity preserves fragile structures • Searches for viable microbes + fossil microbes possible • Risk of contamination can be minimised/avoided by going to sufficient heights

19. Stratospheric balloon with cryosamplerprobes launched from Hyderabad on 20 January 2001

20. Each probe consists of a fully sterilised, evacuated stainless steel cylinder, of volume 0.35 litre • During flight the cylinders are immersed in liquid Ne, cooled to 25o K, thus producing a powerful cryopump. • Over a hundred STP litres of air (and aerosols) in the height range 25-41 km is sucked in and frozen in situ • When brought to ground level and room temperature, the air pressure ~ 200 bars • Collected air released through filters to trap aerosols

21. A wide range of particles from comets identified • Sizes from 0.1 – 10 µm • Mineral condensate mixed with carbonaceous material – possible nanobacteria, spores and fossil microbes C ~ 20%, O – 36% Fe – 33%, low N + Na + Ca + P

22. Acritarchs on Earth • Organic-walled microfossils found in sedimentary unidentified species • Present in sediments from 3.2Gy ago

23. Acritarchs in meteorites Rossignol-Strick + Barghoorn 1971 – revisited 2005 • acid macerated extract of the Orgueil CC meteorite • spherical hollow microstructures = well-defined walls Sulphur map Murchison SEM – part mineralised Mukhopadhyay, + SPIE 2009

24. Achritarchs in cryoprobe sample2009 About 9~10µm diam. spheres - Carbonaceous, often cracked, with cracks opening under the SEM heating Lower image has fossilised flagella-whiskers The carbon fraction ~ 60% also oxidised (O ~ 12%, N ~1%) Coating is mainly Na and Cl .. also some S, Si and K (< 1%)

25. Pair of 2.5-3 m acritarchs with intriguing coatings. Very high C (58%)

26. Example of ~10m spherical particles + mineral coating • Very high in C (70%) • Consistently low N

27. Possible acritarchs occur abundantly in comet dust collection

28. S3+ +S2 • ‘Grapes’ rich in C, O, Na, Fe and P. • Silicate whisker = 3 μm in length • ‘CHO’ umbrella +S1

29. Cracked shells and whiskers

31. Silica whiskers are abundantFirst thought to be contaminantNow found to be integral to acritarchs

33. Torroidal particles, with cracked shells

37. Diatoms most likely explanation

38. Evidence of diatom silica in astronomical sources go back to work of Hoover et al, 1984 • Here the points are data for IR emission in the Trapezium nebula and the curve is for a mixed culture of diatoms

39. Diatom silica is consistent with comet spectra Comet Hale-Bopp at 2.9 AU observed on 6-10-1996 Mix of olivine at temperature 175K and material resembling biomaterial including diatoms at 200K Only 10% mass from crystalline olivine is required

40. We conclude with the intriguing possibility of living bacteria being included among the acritarchs Samples are treated with carbocyanine dyes showing viable and dead cells. Viable (Green) and dead (Red) fluorescent stained bodies (bacteria) are obtained from air sampled at a height of 30-39km

41. Other bacteria detected by stains

42. Coccoidal forms in SEM – living bacteria

43. New work confirm thqt living bacteria are included in comet dust More recently….

44. Concluding.... • According to our favoured theory of cometarypanspermia, living forms of the shapes we have seen were locked in frozen planets 10 million years after the Big Bang • The mass of each planet has a CNO content estimated to be ~ 1027 g. • The ingress of a single such planet into the pre-solar nebula provides material for 1011Oort-cloud comets

45. Evidence of a disintegrating planet in the Helix Nebula provides striking evidence of such a process in action