Today, I saw for the first time a person suspended from a set of jet-powered wings in free flight. Reuters provides footage of this stunning performance that took place yesterday near Bex,VD, Switzerland, on May 14, 2008.
Alas, observing the audacious aviator looping at break-neck speed high in the sky gave me pause. The breath-taking footage rendered a vivid picture of the fragility of the human body. I was reminded of our modern day frontiers and the yet unknown limitations they may impose upon us.
Multiple nations help maintain a permanently-inhabited space station in orbit around Earth. According to the National Air and Space Agency, the U.S. president is firm in the Federal Government's continued commitment to manned interplanetary space flight. The BBC reports that the Peoples Republic of China aims to establish a human presence on the moon in the next decade. Reuters reports that the Russian and the European Space Agencies may join in the development of a spacecraft capable of transporting personnel to the moon. In the face of such ambitions, it is important to understand that we actually know little about the effects that extended tours in weightlessness may have on our body.
As John Steinbeck aptly described in his book The Log from the Sea of Cortez (chapter 4), all organisms on Earth develop and live under the influence of the planet's gravity and its tidal changes imposed by the lunar pull. I have not found a study yet that sheds a light on the question whether a mammalian brain develops normally in the absence of these forces.
Animal models are available to answer this fundamental question. For example, in layer IV of the mouse's somatic sensory cortex cell aggregates known as barrels topographically represent the whiskers on the face.
The picture on the right (courtesy of H. Van der Loos) shows a micrograph of an 80 micrometer-thick section cut tangentially through the left cerebral hemisphere of a Swiss Webster mouse cortex embedded in celluloidine. The left side is up. The nose is right. The section was stained for cell bodies with a blue dye. The barrels are clearly visible as nerve cell-dense rings surrounding cell-sparse centers. The large barrels are arrayed in five oblique rows representing the five rows of long whiskers on the snout. The whiskers on the face are sensory hairs with thousands of touch receptors embedded in their roots. The nerve cells in a cortical barrel respond most vigorously to deflections of the whisker the barrel represents. The barrels develop during the first week after birth. If a whisker is damaged at birth, the corresponding barrel will not develop, suggesting a strong influence of the sensory periphery on cortical development.
Examining the brains of mice taken to the space station shortly after birth for a week would inform us immediately whether microgravity gravely disrupts brain development.
In this grasping adventure story for kids, Brian Greene explains in most insightful and easy-to-understand fashion the relationship between gravity, speed and time.