Space Age dawned on October 4, 1957 with the launch of Sputnik-1. Yuri Gagarin became the first space traveller in space on April 12, 1961. His flight lasting 108 minutes made history. Since then, human beings have stayed in space for even more than a year.

  Over 550 persons have so far flown in space; 12 of them walked on the moon, too. Lately, there has been the emerging business of “space tourism” and some have already flown for fun paying over 100 crores of rupees for a holiday in space! For millions of years, our body has been conditioned by the earth’s gravity that causes the familiar sensation of weight. During the initial ascent phase (8-10 minutes), the crew capsule accelerates (gaining speed) from rest to 29,000 km/hour to settle into an earth orbit. This high acceleration (rate of change of speed) creates a “g-force” producing the sensation of increased weight. Under this condition of increased body weight, our....