samples, which are then brought back via helicopter and further processed in
laboratories close to the launch site.
Biology using rockets, the International Space Station, satellites and parabolic
plane flights appears to be a mismatch at a first glance but provides unique and
almost stimulus-free high-tech environments for gravitational biologists. Here they
can study the impact of gravity on fundamental biological processes and on mechanisms almost all organisms on Earth have invented to make use of the only constant
environmental cue, the gravity vector, for orientation. Changing and, most importantly, switching off the parameter of interest and studying its impact on biological
processes and responses of organisms is the usual way to characterize the nature of
biosensors and to unravel the molecular and cellular basis of sensing mechanisms,
signaling pathways and responses. Unlike photobiologists who modify and switch
off light to investigate photosynthetic processes, photoreceptors or light-induced
pathways, gravitational biologists cannot simply switch off gravity on Earth. However, the influence of gravity can be randomized and strongly reduced with the aid of
clinostats, 2D and 3D random positioning machines. Furthermore, the gravitational
acceleration can be increased by using centrifuges; but investigations in the absence
of gravity can only be achieved in so-called free-fall situations provided by drop
towers, parabolic flights, sounding rockets flights, shuttles, satellites and the International Space Station in the low-Earth orbit.
The following chapters provide a comprehensive overview of the wealth of
information that has been collected over the last 30 years in the areas of gravity
sensing and gravity orientation found in microorganisms, lower and higher plants.
The knowledge is of fundamental importance for understanding life on Earth and
has significance for regenerative life support and energy systems for Earth applications and as critical components of future long-term spaceflight missions and human
exploration of other planets and the universe.
1.2 Gravity and the Evolution of Life on Earth
About a century ago Albert Einstein showed the equivalence of mass and energy in
the “world’s most famous equation” E ¼ mc
2 (Bodanis 2005). His theory of special
relativity combined the electrical and magnetic forces. Modern quantum theory deals
with weak and strong intermolecular forces as well as electromagnetic interactions
(Margenau and Kestner 1969) but fails, 100 years after Albert Einstein, to include
gravity, which is the fourth elementary force in our universe described by the theory
of general relativity, in a generalized ‘weltformel’ (theory of everything; Hawking
2006).
The difficulty of including gravity in this theory is annoying since it rules our
universe, holds planetary systems and galaxies together and traps the masses of
hundreds of millions to billions of stars in the space less than our solar system in
black holes which are believed to linger in the center of perhaps every of the several
2
1 Gravity Sensing, Graviorientation and Microgravity
laboratories close to the launch site.
Biology using rockets, the International Space Station, satellites and parabolic
plane flights appears to be a mismatch at a first glance but provides unique and
almost stimulus-free high-tech environments for gravitational biologists. Here they
can study the impact of gravity on fundamental biological processes and on mechanisms almost all organisms on Earth have invented to make use of the only constant
environmental cue, the gravity vector, for orientation. Changing and, most importantly, switching off the parameter of interest and studying its impact on biological
processes and responses of organisms is the usual way to characterize the nature of
biosensors and to unravel the molecular and cellular basis of sensing mechanisms,
signaling pathways and responses. Unlike photobiologists who modify and switch
off light to investigate photosynthetic processes, photoreceptors or light-induced
pathways, gravitational biologists cannot simply switch off gravity on Earth. However, the influence of gravity can be randomized and strongly reduced with the aid of
clinostats, 2D and 3D random positioning machines. Furthermore, the gravitational
acceleration can be increased by using centrifuges; but investigations in the absence
of gravity can only be achieved in so-called free-fall situations provided by drop
towers, parabolic flights, sounding rockets flights, shuttles, satellites and the International Space Station in the low-Earth orbit.
The following chapters provide a comprehensive overview of the wealth of
information that has been collected over the last 30 years in the areas of gravity
sensing and gravity orientation found in microorganisms, lower and higher plants.
The knowledge is of fundamental importance for understanding life on Earth and
has significance for regenerative life support and energy systems for Earth applications and as critical components of future long-term spaceflight missions and human
exploration of other planets and the universe.
1.2 Gravity and the Evolution of Life on Earth
About a century ago Albert Einstein showed the equivalence of mass and energy in
the “world’s most famous equation” E ¼ mc
2 (Bodanis 2005). His theory of special
relativity combined the electrical and magnetic forces. Modern quantum theory deals
with weak and strong intermolecular forces as well as electromagnetic interactions
(Margenau and Kestner 1969) but fails, 100 years after Albert Einstein, to include
gravity, which is the fourth elementary force in our universe described by the theory
of general relativity, in a generalized ‘weltformel’ (theory of everything; Hawking
2006).
The difficulty of including gravity in this theory is annoying since it rules our
universe, holds planetary systems and galaxies together and traps the masses of
hundreds of millions to billions of stars in the space less than our solar system in
black holes which are believed to linger in the center of perhaps every of the several
2
1 Gravity Sensing, Graviorientation and Microgravity