A classified U.S. military satellite recently launched into an orbital inclination of 123 degrees. What makes this trajectory so unique? Pondering the answer affords the opportunity to learn some deceptively tricky concepts about the nature of all spacecraft orbits.
Before automated space observatories like SDO could send pictures and videos of solar phenomenon in real-time, humans had to do it manually, as in the case of the groundbreaking Skylab space station missions, which featured the Apollo Telescope Mount.
As of November 2011, the Earth Observing Handbook counts 109 active missions to study the Earth as a planet, with 112 more approved and planned for the future. Jason Davis provides an overview of key current and upcoming earth-observing missions.