Planetary Interchange of Bioactive Material: Probability Factors and Implications
It is now well-accepted that both lunar andmartian materials are represented in the meteoritecollections. Early suggestions that viable organismsmight survive natural transport between planets havenot yet been thoroughly examined. The concept ofPlanetary Interchange of Bioactive Material (PIBM) ispotentially relevant to the conditions under whichlife originated. PIBM has been also invoked to inferthat the potential danger to Earth from martianmaterials is non-existent, an inference with, however,many pitfalls. Numerous impediments to efficienttransfer of viable organisms exist. In this work, thelethality of space radiation during long transientsand the biasing of launched objects toward materialsunlikely to host abundant organisms are examined andshown to reduce the likelihood of successful transferby orders of magnitude. It is also shown that martianmeteorites studied to date assuredly have beensubjected to sterilizing levels of ionizing radiationin space. PIBM considerations apply to both the solarsystem locale(s) of the origin of life and to theapplicability of planetary protection protocols topreserve the biospheres of planetary bodies, including our own.