Panspermia - "Seeds Everywhere"
A theory that life arose elsewhere in the Universe, but can travel across galaxies as "life spores" protected in comets from U.V. Radiation and seed the planets with life.
Chemical Panspermia - interstellar dust and comets, even space itself, contains organic compounds, that may be the ingredients of life.
Panspermia - bacterial life exists throughout the Universe and can traverse long interstellar distances in a protected cometary state to eventually seed life throughout the Universe.
Earliest recorded advocates of a Panspermic philosophy was Greek philosopher Anaxagoras, but Aristotle's ideas on spontaneous generation came to be preferred for the next 2,000 years. In 1864 Pasteur disproved spontaneous generation and by 1870 Lord Kelvin and Hermann vov Helmholtz revived arguments that life could come from space. Nobel chemist, Svante Arrhenius (1903 Nobel) formalized the theory that microbe spores were propelled through space by radiation emitted by stars and were the seeds of life on Earth.
These ideas of Panspermy were also supported by Francis Crick.
In 1920's Alexander Oparin and J.B.S. Haldane revived ideas of spontaneous generation suggesting the Earth's reducing atmosphere was conducive to self-organization of chemically reactive molecules. Supporting this idea, Stanley Miller and Harold Urey in 1953 showed that some amino acids can be chemically produced from ammonia and methane in the lab (see next lecture section for the Miller/Urey Experiments).
In the early 1970's there was a rekindling of interest in Panspermia by Fred Hoyle and Chandra Wickramasinghe, who with spectroscopic analysis of light from stars, found traces of the molecules of life in the intervening space dust. They proposed that comets, made mostly of water & ice, could carry bacterial life across the galaxies protecting it from U.V. radiation on its traverse.
To experimentally test the possibility of space microbes 2 recent experiments have been done...
1) BALLOON CAPTURE EXPERIMENTS... The first unequivocal recovery of any culturable microorganisms from 41 km up in the stratosphere using modern aseptic collection protocols and molecular identification has been accomplished. N.C. Wickramasinghe, F. Hoyle, & J.V. Narlikar. On December 11, 2000 a launch a high altitude balloon from Hyderabad, India to collect air samples from heights of 10 to 35 km and bring them back eight hours later in sixteen super-cooled sterilized containers. Large volumes of air from the stratosphere at heights ranging from 20 to 41km were collected on 21 January 2001. By March 2002, supposed microbes from these atmospheric samples tested positive for bacteria. In fact, DNA sequences from these microbe samples were not similar to Earthly microbes weakened the argument that the bacteria could be earthly contaminants. Testing the bacteria for unearthly isotope ratios (C, ), H, & N) is planned for this October of 2002 at the Earth Sciences Dept at the ANU in Canberra.
By December 2002 the microbes from the balloon experiment had been isolated cultured in the lab by Milton Wainwright. Two bacteria (Bacillus simplex and Staphylococcus pasteuri) and a single fungus, Engyodontium album (Limber) de Hoog were isolated and cultured from the samples. M. Wainwright et al., "Microorganisms cultured from stratospheric air samples obtained at 41 km," [abstract], p 161-165 v 218 n 1, Federation of European Microbiological Societies Microbiology Letters, 2003.
SEM images of the stratospheric particles have also been published.
If instrumental and laboratory contamination can be excluded at all stages of the experiment two options remain. Firstly, one might think that these microbe were carried from the ground in a volcanic eruption or in an exceptional meteorological event. The other is that they arrive from space. A volcanic origin is ruled out for the simple reason that there was no volcanic eruption recorded in a two-year run-up to the balloon launch date on January 20, 2001. A similar objection applies to rare meteorological events. Assuming our collections on January 20, 2001 gave us representative stratospheric samples at 41km no process that is purely terrestrial can sustain the high densities of bacterial clusters as are implied.
The alternative extraterrestrial origin (Hoyle and Wickramasinghe, 1981, 2000), although controversial, is more attractive as an explanation of our findings. The bacterial material, cultured in the present experiment, and detected earlier through fluorescence microscopy, can be regarded as forming part of the 100 ton/day input of cometary material known to reach the Earth.
2) STARDUST MISSION (NASA)... On Saturday, February 7, 1999 NASA will launch StarDust, a spacecraft designed to sample and return material from the comet Wild 2 (below). Comet Wold-2 travels a path from just outside Jupiter's orbit to just inside the orbit of Mars. StarDust will sweep through the comet's coma, the ball of gas surrounding the nucleus of the comet, at 136,000 miles per hour. NASA will use an aerogel "catcher's mitt" designed by Dr. Peter Tsou and his colleagues at the Jet Propulsion Laboratory in Pasadena, Calif. to catch particles coming off the comet during January 2, 2004. After a 7-year journey, StarDust returned to Earth (January 15, 2006 @ 5:12am) NASA Stardust, dropping its newly obtained cargo onto the Utah desert.
aerogel collectors will be used to trap the samples of coma and interstellar
dust. This material will provide our first sample of pristine cometary material,
and increase our understanding of interstellar dust. Stardust will then return
to Earth with these samples for scientific study. The mission will also analyze
the cometary coma in situ, examine the composition of the samples in-flight
using a mass spectrometer, and take images of the comet.