TCS Main Page SAS Store Resources SAS Home Page Author's Guidelines Meet the StaffAbout TCS Contact Us 02 November 2007 Poorman's Space Program Paul Verhage What and Where is Near Space? If you've never launched a BalloonSat before, then the term “near space” is probably new to you. What you're about to do is very exciting. However, before you start, you need to become familiar with some terms. Airplanes, Satellites, and their Altitudes There's a range of altitudes in which airplanes and satellites fly. Most aircraft fly at altitudes below 15 km (50,000 feet). Military spy planes, the U-2 (not the rock band) and SR-71 for instance, can fly at altitudes between 24 and 30.4 km (80,000 and 100,000 feet). Rockets and spacecraft like the X-15 and Space Shuttle reach higher altitudes still. Controlled air space tops out at 18 km (60,000 feet). In other words, the FAA doesn't control any flights above 60,000 feet. The international body governing the standards for awards in aviation is the International Aeronautical Federation (abbreviated FAI after its French name). According to the FAI, (outer) space begins at an altitude of 100 kilometer (62.5 miles or 328,000 feet). Between controlled air space and outer space is a region called near space. In most ways near space is closer to a space environment that a sea level environment. And so far, there's only one inexpensive way to fly experiments into near space, the we ather balloon. Climbing to Near Space As a balloon climbs into near space, several interesting e nvironmental changes take place. First, as the balloon ascends, the cosmic ray flux climbs higher and the air tempe rature gets colder. The lowest air temperature occurs between 12 and 15 km (40,000 and 50,000 feet). Air temperatures in this atmospheric region will be as cold as -60 degrees Fahrenheit in the summer and may drop to -90 degrees in the winter. At an altitude of 15 km (50,000 feet), 90% of the atmosphere lies below the balloon. Above 15 km, the balloon has left behind the troposphere, where most weather occurs, and has entered the stratosphere.
