Author(s)

Werner Schmidt^1,2*

¹Fachbereich Biologie, Philipps-Universität Marburg, Marburg, Germany.
²Fachbereich Biologie, Universität Konstanz, Konstanz, Germany.

Under parabolic flight conditions microgravity is not lower than 3 to 5 times 10^-2 g. In contrast to parabolic flights, sounding rocket flights are virtually vibrational-free allowing microgravity as low as 10^-5 g. Thus, a rotating platform serving as centrifuge allows the precise generation of gravitational forces ranging from 5 to 100 mg (not possible during parabolic flights). On this basis we determined the threshold¹ for optical reflection/absorption changes in Phycomyces to be lower than 25 × 10^-3 g. This compares well with the threshold determination of gravitropism in Phycomyces on a clinostat centrifuge. Kinetics of gravity-induced absorption changes and gravity as generated by the on-board centrifuge do not coincide but show a distinctive hysteresis with a latency of 4 s (75 mg-ramp, pull-up).

MDWS (Micro-Dual Wavelength Spectrophotometer), Δ GIAC (Differential Gravity-Induced Absorption Change), Phycomyces blakesleeanus, Sporangiophore, Micro- and Hypergravity, Texus 50, Sounding Rocket, Gravireception

Schmidt, W. (2015) Gravireception in Phycomyces: Threshold Determination on the Sounding Rocket TEXUS 50. Journal of Modern Physics, 6, 1381-1389. doi: 10.4236/jmp.2015.610143.