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Mon. Not. R. Astron. Soc. 000, 000{000 (0000) Printed 1 October 2003 (MN L A T E X style le v2.2) A Mechanism for Interstellar Panspermia
 

Summary: Mon. Not. R. Astron. Soc. 000, 000{000 (0000) Printed 1 October 2003 (MN L A T E X style le v2.2)
A Mechanism for Interstellar Panspermia
W.M. Napier ?
Armagh Observatory, College Hill, Armagh, BT61 9DG, Northern Ireland
Last update 2003 September 29; in original form 2003 March 20
ABSTRACT
Metre-sized boulders ejected from the Earth by large impacts are destroyed through
collisions and erosion by impacting zodiacal cloud dust particles. The timescale for such
disintegration in a dense zodiacal cloud may be <
 10 4 yr. Once reduced to a critical
size, the particles are rapidly ejected from the solar system by radiation pressure.
The critical size for ejection is of order a micron, large enough to protect groups of
micro-organisms within them from solar UV irradiation. Such life-bearing particles
are ejected at a mean rate of 10 20 per million years. During passages of the solar
system through or close to dense molecular clouds, a signi cant proportion of the
particles may be incorporated into protoplanetary systems and protected from cosmic
rays within growing planetesimals. The speci c number density of micro-organisms so
deposited is highest in small, dense molecular clouds. On the assumption that this
ejection mechanism is common in other planetary systems environmentally capable of
supporting life, a `chain reaction' may seed the disc of the Galaxy within a few billion

  

Source: Armagh Observatory

 

Collections: Physics