Unscientific ambivalence over Panspermia

There is common disregard of panspermia by scientists and science commentators outside astrobiology, which is surely bolstered by shyness within the field, as evidenced by contributions to the Origins2011 conference in July. There several speakers were prepared to envisage life originating on Mars (more conducive early environment) and transferring to Earth borne by a meteorite (well-validated processes of meteorite ejection to space and landing from space).   

  

But why won't they go further and accept that life would similarly have arisen in planetary systems around earlier generations of exostars, say 10 Gyr ago, which similarly generated meteorites bearing spores that could have seeded our nascent solar system?

  

There are indeed questions around probability/frequency of transfer and viability of irradiated spores over the Myr timescales, but no issue of principle. Arguments over the probability and viability are up for debate – so we await responses to our appraisals of likely senarios: Interstellar transfer of planetary microbiota;  a mechanism for interstellar panspermia; comets and the origin of life. 

That's why panspermia has come of age, evolving from a hypothesis into a coherent theory. It’s pretty secure in terms of transfer of life between solar system bodies, though not (yet) for interstellar transfer. The ambivalence among astrobiology scientists appears to be psychological**, a relic of 20^th century focus on Origin of Life on Earth, fuelled by over-confidence in the Urey-Miller approach and by a disproved belief that life could not survive space conditions.

** Why Do Some People Reject Panspermia?  by M  Burchell