1. There are many different definitions of the location of the top of the atmosphere – the near edge of outer space. • Until around 1600, it was believed that the Earth’s atmosphere extended throughout space (recall that the Earth was also considered to be the center of the Universe until around then). • In the BOREALIS ballooning program, we claim we fly student payloads to the edge of space, since we reach altitudes of around 110,000 feet (approximately 30 km). • The X-prize competition awarded Burt Rutan on October 4, 2004, $10,000,000 for the first spaceship to carry three people to an altitude of greater than 100 km twice within two weeks. Look up the radius of the Earth and atmospheric pressure at sea level, and estimate the height, H, of the atmosphere, assuming the following: • At sea level, the weight of an object of mass m is mg, where g = 9.80665m/s^2 is the acceleration due to gravity. Atmospheric pressure is the weight of the air above us per unit area. • The density of air at sea level is 1.3 kg/m^3, about 1000 times less than the density of water. • Take the atmosphere to be a spherical shell of constant density up to H after which the density rapidly falls to zero. (In reality, the density of the atmosphere decreases smoothly with height.) This is a Fermi Estimate, and it should be quite easy, as all the other homework problems were. I think I am just missing something. The diameter of the Earth is 6,378km The pressure at sea level is 101.325kPa I am not sure where to start, and I don't see why it matters that the density of air at sea level is about 1000 times less than the density of water. If you can help me get started, then thanks a lot!