Chapter 1
Gravity Sensing, Graviorientation
and Microgravity
Donat-Peter Häder, Markus Braun, and Ruth Hemmersbach
Abstract Gravity has constantly governed the evolution of life on Earth over the
last 3.5 billion years while the magnetic field of the Earth has fluctuated over the
eons, temperatures constantly change, and the light intensity undergoes seasonal and
daily cycles. All forms of life are permanently exposed to gravity and it can be
assumed that almost all organisms have developed sensors and respond in one way
or the other to the unidirectional acceleration force. Here we summarize what is
currently known about gravity sensing and response mechanisms in microorganisms, lower and higher plants starting from the historical eye-opening experiments
from the nineteenth century up to today’s extremely rapidly advancing cellular,
molecular and biotechnological research. In addition to high-tech methods, in
particular experimentation in the microgravity environment of parabolic flights and
in the low Earth orbit as well as in “microgravity simulators” have considerably
improved our knowledge of the fascinating sensing and response mechanisms which
enable organisms to explore and exploit the environment on, above and below the
surface of the Earth and which was fundamental for evolution of life on Earth.
Keywords Gravitaxis · Gravitropism · Gravireceptor · Statolith · Microgravity
platforms
1.1 Introduction
“. . .3. . .2. . .1. . .Lift off!” Esrange near Kiruna in Northern Sweden—a remote
European satellite station. A TEXUS sounding rocket roars out of the launch
tower into the blue early morning sky. Teams of gravitational biologists and
engineers follow anxiously on the video screens the separation of the first rocket
stage, the ignition and burn-out of the second stage. After separation from the rocket
motor 74 s after launch, the payload with its biological samples weightlessly follows
a parabolic flight path up to an altitude of about 350 km before it falls back towards
Earth. The 6-min microgravity phase is abruptly terminated by the reentry of the
payload into the Earth’ atmosphere. A parachute guarantees the safe landing of the
© The Author(s), under exclusive licence to Springer International Publishing AG,
part of Springer Nature 2018
M. Braun et al., Gravitational Biology I, SpringerBriefs in Space Life Sciences,
https://doi.org/10.1007/978-3-319-93894-3_1
1
Gravity Sensing, Graviorientation
and Microgravity
Donat-Peter Häder, Markus Braun, and Ruth Hemmersbach
Abstract Gravity has constantly governed the evolution of life on Earth over the
last 3.5 billion years while the magnetic field of the Earth has fluctuated over the
eons, temperatures constantly change, and the light intensity undergoes seasonal and
daily cycles. All forms of life are permanently exposed to gravity and it can be
assumed that almost all organisms have developed sensors and respond in one way
or the other to the unidirectional acceleration force. Here we summarize what is
currently known about gravity sensing and response mechanisms in microorganisms, lower and higher plants starting from the historical eye-opening experiments
from the nineteenth century up to today’s extremely rapidly advancing cellular,
molecular and biotechnological research. In addition to high-tech methods, in
particular experimentation in the microgravity environment of parabolic flights and
in the low Earth orbit as well as in “microgravity simulators” have considerably
improved our knowledge of the fascinating sensing and response mechanisms which
enable organisms to explore and exploit the environment on, above and below the
surface of the Earth and which was fundamental for evolution of life on Earth.
Keywords Gravitaxis · Gravitropism · Gravireceptor · Statolith · Microgravity
platforms
1.1 Introduction
“. . .3. . .2. . .1. . .Lift off!” Esrange near Kiruna in Northern Sweden—a remote
European satellite station. A TEXUS sounding rocket roars out of the launch
tower into the blue early morning sky. Teams of gravitational biologists and
engineers follow anxiously on the video screens the separation of the first rocket
stage, the ignition and burn-out of the second stage. After separation from the rocket
motor 74 s after launch, the payload with its biological samples weightlessly follows
a parabolic flight path up to an altitude of about 350 km before it falls back towards
Earth. The 6-min microgravity phase is abruptly terminated by the reentry of the
payload into the Earth’ atmosphere. A parachute guarantees the safe landing of the
© The Author(s), under exclusive licence to Springer International Publishing AG,
part of Springer Nature 2018
M. Braun et al., Gravitational Biology I, SpringerBriefs in Space Life Sciences,
https://doi.org/10.1007/978-3-319-93894-3_1
1