Various spectroscopic experiments performed on the AIRBUS ZERO G—located in Bordeaux, France—in the years 2002 to 2012 exhibit minute optical reflection/absorption changes (GIACs) as a result of gravitational changes between 0 and 1.8 g in various biological species such as maize, oats, Arabidopsis and particularly Phycomyces sporangiophores. During a flight day, the AIRBUS ZERO G conducts 31 parabolas, each of which lasts about three minutes including a period of 22 s of weightlessness. So far, we participated in 11 parabolic flight campaigns including more than 1000 parabolas performing various kinds of experiments. During our campaigns, we observed an unexplainable variability of the measuring signals (GIACs). Using GPS-positioning systems and three dimensional magnetic field sensors, these finally were traced back to the changing earth’s magnetic field associated with the various flight directions. This is the first time that the interaction of gravity and the Earth’ magnetic field in the primary induction process in living system has been observed.
Working several years on the measurement and analysis of Light Induced Absorption Changes in plants and fungi (LIACs), we expanded this idea to gravisensing, searching for (minute) Gravity Induced Absorption Changes (GIACs). The basic idea is that any stimulus such as light or gravity which is discerned by an organism, consequently causes some kinds of molecular change which could be spectroscopically detectable. For this purpose, we designed a novel, highly sensitive micro dual wavelength spectrophotometer [1,2] and we detected the first GIACs in laboratory bound experiments simply by tilting gravisensitive specimen (Phycomyces, coleoptiles of maize, oat and Arabidopsis [
During our recent PFCs, we observed a till then unexplainable small but significant variability of the measuring signals (GIACs). As discussed here, these discrepancies could be finally traced back to the various flight directions, because these, in turn, are inevitably associated with changes of the earth’s magnetic field. The ability to respond to magnetic fields is ubiquitous among the five kingdoms of organisms. E.g., Palmer [
Using two three-dimensional magnetic sensors, we detected a clear-cut correlation of GIACs and particularly the Hx component of the magnetic field of the earth, i.e. as a function of flight direction, i.e. the azimuth angle. During a flight day, the AIRBUS ZERO G conducts 31 parabolas, each of which lasts about three minutes including a period just under half a minute of weightlessness.
The wild-type strain of Phycomyces blakesleeanus (Burgeff) is NRRL1555 (-) originally obtained from the Northern Regional Research Laboratory, USDA, Peoria, IL, USA. They were grown in glass shell vials (1 cm diameter × 4 cm height; Flachbodengläser, AR Klarglas, Münnerstädter Glaswaren-fabrik, Münnerstadt, Germany) on a synthetic solid medium with glucose. Until the appearance of stage-4b sporangiophores (i.e. with sporangium) of 2.5 cm length the material was kept in transparent plastic boxes at ambient temperature (19˚C - 21˚C) under white incandescent light fluence rate (0.5 Wm−2). One remark remains to be cogent: Even if the samples are grown under well controlled conditions in a cave of Chateaux Sentoux near the airport, depending on the season the transport to the airport and finally into the plane gives rise to harsh strain (change of temperature, air pressure, humidity).
So far, GI-ACs in response to microand hypergravity were monitored during roughly 1000 parabolas and 11 campaigns organized by the DLR and ESA during the years 2002-2012 (