30, 2012, particle detection instruments aboard NASA's twin Van Allen Probes revealed to scientists the existence of a new, transient, third radiation belt around Earth, shown in this image.Ĭredits: NASA's Goddard Space Flight Center/Johns Hopkins University, Applied Physics LaboratoryĪbove right: Cropped from NASA's Press Kit for Radiation Belt Storm Probes Launch (click for larger).Ībove: From the NASA Page for Van Allen Probes.įIREBIRD II and NASA Mission Locate Whistling Space Electrons' Origins.Īnd just in case you are wondering what Roadster was really doing in orbit for six hours experiencing the Van Allen belts: This early schematic of the Van Allen Belts' structure was created after the first American satellite discovered their existence in 1958.Ĭredits: NASA's Goddard Space Flight Center/Historic image of Van Allen Belts courtesy of NASA’s Langley Research CenterĪbove left: Newer. link However, there is still no international legal definition of the demarcation between a country's air space and outer space link.Ībove: 'Retro' or how I remember it when I was growing up. An international committee recommended the 100 km line to the FAI, and upon adoption, it became widely accepted as the boundary to space for many purposes. According to Wikipedia:Īlthough the calculated altitude was not exactly 100 km, Kármán proposed that 100 km be the designated boundary to space, because the round number is more memorable, and the calculated altitude varies minutely as certain parameters are varied. The Kármán line on the other hand now has an (fairly) exact definition of 100 kilometers altitude, and I am guessing that altitude is a line perpendicular to the local geoid surface.

However, there are two (or maybe even three!), and they are fuzzy, and they are moving all the time. Answer is probably just what you are looking for, the distance from the Kármán line to the beginning of the intense part of the lower Van Allen belt.

Where I Fly by K.M. Allen