Dirk Schulze-Makuch : The cyanobacteria, diatoms etc you analyzed in the meteorites are ideally adapted to life on Earth, to life on a planetary surface. So, assuming you are correct and they indeed come from space, where is the source? An origin of these organisms in a comet would make no sense for me from an evolutionary biology standpoint as life thrives always to be ideally adapted to its environment.
Richard Hoover : There are skeptics who claim that even though many of the remains I have found in these meteorites are recognizable as heterocystous cyanobacteria, diatoms, acritarchs, hystrichospheres and other known extant or extinct life forms, they must be modern bio-contaminants. This argument conveniently neglects the fact that the EDAX data consistently show the remains have nitrogen levels below the instrument detection limit and hence died millions of years ago-long before these meteorites were observed to fall to Earth.
Chandra Wickramasinghe : The reason why fossil microbes and diatoms are similar to their modern terrestrial counterparts is that they all came from space in the first place, and continue to do so. Life on Earth is an expression on the Earth of a Darwinian evolutionary scheme that has taken place over a vast cosmological scale. Not so long ago it would have been thought impossible to find the same species in opposite hemispheres of the Earth. The connected biosphere of the Earth has now to be considered connected to a vast cosmological biosphere within which frequent exchanges of genes have established a unity of all life in the cosmos.
Dirk Schulze-Makuch : I find it very strange that extraterrestrial life would look so similar, or should I say identical to cyanobacteria, diatoms etc as Richard claims. This does not make any sense to me and is in my view so implausible that any contamination such as pointed by John is much more likely. I just discussed this matter with Alberto Fairen and he thinks alike but thought about another possibility: Could Richard’s bugs be terrestrial life that has been for billions of years away from Earth because it was ejected in primitive impacts?
William E. (Bill) Smith : Today the Rosetta Mission approaches COMET 67P now just 100 km away. 67P’s orbit is in the plane of the galaxy and is “part of our solar system” (ie it is a Kuiper belt “comet” ) with an orbit of just 6 years. Contrast this with COMET ISON, which unlike 67P (Rosetta), was a parabolic comet. I.E. ISON’s orbit period is unknown (> 100,000 years). It entered the plane of the galaxy at a steep inclination FYI – approximately the same as the angle of the solar system (the ecliptic) to the galaxy’s plane. It is now accepted mainstream science that the solar system is part of the Sagittarius Dwarf galaxy which is colliding with the Milky Way. I believe (educated by conversations with Chandra ) that “long period” comets like ISON are the REAL source of original life in our Solar System. Ie ISON was “sling shot” in towards the SUN from an adjacent star. Short period comets which includes both Halley’s Comet with its 80 year orbit and Rosetta (67P/C-G) with its 7 year orbit, might well (and likely do) contain dormant viruses, bacteria and even diatoms (as found by Richard Hoover). These “seeds of life” were catapulted into local inner space from major collisions like the asteroid (or comet) which caused the end of the dinosaur era.
But I believe it is the long period comets like ISON which carry the real interesting and original “seeds of life” from other solar systems across what Chandra Wickramasinghe calls the “vast cosmological biosphere”.
And at this moment in time in August 2014, I wonder how rigorous was our sterilizing of the Rosetta Mission back in 2004. The Philae Lander will arrive on Comet 67P/C-G this November (2014) carrying untold numbers of dormant viruses and bacteria from earth, just waiting to be reactivated by the water that is already proven to be on the comet – proven using the remote spectroscopy by the ALMA telescope in Chile.
Chandra Wickramasinghe : Bill – although you may well be right, it is not a time for negative thoughts. NASA ask us to emphasize that the “search for life is a difficult endeavour”. To that we all agree. BUT what we are now expecting to find (on 67P, MARS, Titan and Enceladus) is that life is found “everywhere”. Do we really care “where it came from originally” or even if we inadvertently delivered it.
Time to agree that “Life is indeed a Cosmic Phenomenon”.