Kelvin (1824–1907), due to the strong believe that viruses and other microorganisms
would be deactivated or destroyed by cosmic radiation (Davies 1988). However,
some sceptics still support the theory that a molecular cloud generated by meteorite
force from the soil microbiome of a planet that sustains life can become a lifebearing ejectum transferred to other planets within a planetary system or even to the
universe as a whole (Napier 2004; Wickramasinghe et al. 2010; Wickramasinghe
and Smith, 2014). These ideas are supported by the facts that seeds of life can be
protected from cosmic rays in asteroids, comets, and meteors (Lithopanspermia) and
that viruses which lack a fragile phospholipid envelope might be able to survive
unprotected in interplanetary space (Radiopanspermia). The carbon isotope ratio
(
13 C/
12 C) of ancient rocks revealed that life on Earth developed between 3.82 and
4 billion years ago during active meteorite bombardment of our planet (Mojzsis et al.
1996), indicating that life on Earth developed early in a hostile environment, referred
to as the Hadean epoch, where life as we know it today, would not be able to survive
with the exception of some extremophilic prokaryotes and their viral parasites.
Furthermore, amino acids were discovered in the Murchison meteorite that landed
on Earth in 1969 (Schmitt-Kopplin et al. 2010). Due to radioactive decay, comets
might also carry liquid water deep within protected from the À800
C degrees of
outer space to support fragile molecules or primitive life (Wickramasinghe et al.
2010). In fact, it has been shown that bacterial endospores, endolithic cyanobacteria,
as well as lichens and dormant forms of primitive microeukaryotic species, such as
Tardigrada, are able to survive outer space environments which include the full
spectrum of solar extraterrestrial electromagnetic radiation. However, damage to
outer layers of microbial colonies was observed, and these microorganisms did not
survive the re-entry process to Earth in these so-called Lithopanspermia experiments
(De La Torre et al. 2010; Persson et al. 2011; Horneck et al. 2012; Kawaguchi et al.
2016). If protected from harmful radiation that could damage the microbe’s genetic
information, re-germination is possible even after millions of years, as it was shown
to be true for some spore forming bacterial species retrieved from ancient soils,
sediments, glacial ice, or from within amber, and with them their viral parasites
(Cano and Borucki, 1995; Ma et al. 1999; Willerslev et al. 2004; Nicholson 2009).
The ability of many viruses to incorporate themselves into the genome of their host
in form of a provirus allows them to survive adverse conditions together with their
host. Recently, a spin-off of the Panspermia theory received new attention, the
Nebula-Relay theory, that tries to explain life on Earth seeded by primitive life
forms that may exist in the nebulae and in the celestial bodies of solar systems and
which could be carried to our planet via meteorites that came in contact with them
(Feng 2019). The lithopanspermia hypothesis is difficult or even impossible to
prove, because some factors that were proposed in an equation to test the probability
of this theory cannot be determined, and consequently different researchers who
applied this equation came to opposite results (Nicholson 2009).
Nevertheless, scientists agree that viruses comprise the most abundant entities on
the planet by far and have discovered that uncountable numbers of viruses that have
been swept upward into Earth’s atmosphere and higher by sea spray. Also dust
storms can travel large distances, raining down onto Earth in high numbers each day,
616
A. Lauer
would be deactivated or destroyed by cosmic radiation (Davies 1988). However,
some sceptics still support the theory that a molecular cloud generated by meteorite
force from the soil microbiome of a planet that sustains life can become a lifebearing ejectum transferred to other planets within a planetary system or even to the
universe as a whole (Napier 2004; Wickramasinghe et al. 2010; Wickramasinghe
and Smith, 2014). These ideas are supported by the facts that seeds of life can be
protected from cosmic rays in asteroids, comets, and meteors (Lithopanspermia) and
that viruses which lack a fragile phospholipid envelope might be able to survive
unprotected in interplanetary space (Radiopanspermia). The carbon isotope ratio
(
13 C/
12 C) of ancient rocks revealed that life on Earth developed between 3.82 and
4 billion years ago during active meteorite bombardment of our planet (Mojzsis et al.
1996), indicating that life on Earth developed early in a hostile environment, referred
to as the Hadean epoch, where life as we know it today, would not be able to survive
with the exception of some extremophilic prokaryotes and their viral parasites.
Furthermore, amino acids were discovered in the Murchison meteorite that landed
on Earth in 1969 (Schmitt-Kopplin et al. 2010). Due to radioactive decay, comets
might also carry liquid water deep within protected from the À800
C degrees of
outer space to support fragile molecules or primitive life (Wickramasinghe et al.
2010). In fact, it has been shown that bacterial endospores, endolithic cyanobacteria,
as well as lichens and dormant forms of primitive microeukaryotic species, such as
Tardigrada, are able to survive outer space environments which include the full
spectrum of solar extraterrestrial electromagnetic radiation. However, damage to
outer layers of microbial colonies was observed, and these microorganisms did not
survive the re-entry process to Earth in these so-called Lithopanspermia experiments
(De La Torre et al. 2010; Persson et al. 2011; Horneck et al. 2012; Kawaguchi et al.
2016). If protected from harmful radiation that could damage the microbe’s genetic
information, re-germination is possible even after millions of years, as it was shown
to be true for some spore forming bacterial species retrieved from ancient soils,
sediments, glacial ice, or from within amber, and with them their viral parasites
(Cano and Borucki, 1995; Ma et al. 1999; Willerslev et al. 2004; Nicholson 2009).
The ability of many viruses to incorporate themselves into the genome of their host
in form of a provirus allows them to survive adverse conditions together with their
host. Recently, a spin-off of the Panspermia theory received new attention, the
Nebula-Relay theory, that tries to explain life on Earth seeded by primitive life
forms that may exist in the nebulae and in the celestial bodies of solar systems and
which could be carried to our planet via meteorites that came in contact with them
(Feng 2019). The lithopanspermia hypothesis is difficult or even impossible to
prove, because some factors that were proposed in an equation to test the probability
of this theory cannot be determined, and consequently different researchers who
applied this equation came to opposite results (Nicholson 2009).
Nevertheless, scientists agree that viruses comprise the most abundant entities on
the planet by far and have discovered that uncountable numbers of viruses that have
been swept upward into Earth’s atmosphere and higher by sea spray. Also dust
storms can travel large distances, raining down onto Earth in high numbers each day,
616
A. Lauer