Looks like there can be no life in Martian meteorites drifting in space for over 100,000 years. So much for all the Zubrin supporters who have insisted Martian life constantly showers Earth within meteorites. Another one bites the dust!

Life's Rocky Road Between Worlds

A possible mechanism for transfer of life between planets is via rocks ejected by major asteroid or comet impacts. The term "transpermia" was coined by Oliver Morton to describe the transfer of lifeforms by this method and to distinguish it from the more general concept of panspermia.
Davies (1998a-c) discusses several possibilities for transpermia including hypothetical Mars-life reaching Earth; Earth-life reaching Mars, the Earth's Moon and moons of the outer solar system and interstellar transfers via meteoroids.

Melosh (1994) outlines the mechanisms by which such transfers can take place. Mileikowsky and others (2000) build on Melosh's work and provide estimates of transfer rates between Mars and Earth over the past 500 million years.

The transfer mechanism

The analysis by Mileikowsky considers the ejection of surface rocks from Mars during impacts by large asteroids, the proportion of ejected rocks that reach the escape velocity of the planet and go into orbit around the Sun and the proportion (they estimate about 5%) that eventually collide with Earth and reach its surface.

Mileikowsky's Table 2 provides calculations for one scenario. They select conditions that optimise the chances of lifeforms surviving the journey. These "hospitable" conditions are:

The radius of ejected rock is between 0.67 and 1 metre (mainly to provide protection from radiation in deep space). [note 1]
The core temperature within the rock during ejection or re-entry did not exceed 100 C (two of the dozen or so Martian meteorites that have been found on Earth meet this criterion)
The journey time between planets was 100,000 years or less

There do not appear to have been large impacts on Mars (or the Earth for that matter) over the past 100,000 years so it is unlikely that "hospitable" Mars rocks are reaching the Earth at present, or vice versa. [Note 3]

http://www.spacedaily.com/news/life-01r.html

Miller ^o^