Tetrahedral multi-satellite continuous-coverage constellation

• Main Author: DRAIM, JOHN E
• Format: Patent
• Language: English; French; German
• Published: 11.03.1987
• Edition: 4
• Subjects: AIRCRAFT; AVIATION; COSMONAUTICS; ELECTRIC COMMUNICATION TECHNIQUE; ELECTRICITY; PERFORMING OPERATIONS; TRANSMISSION; TRANSPORTING; VEHICLES OR EQUIPMENT THEREFOR

An improved, optimized, four-satellite tetrahedral constellation (S₁ to S₄) using common period elliptic orbits is disclosed which provides continuous global coverage (i.e., any point on the earth can always maintain line-of-sight visibility with at least one of the four satellites). The constellation consists of two satellites having perigees in one hemisphere, and two satellites having perigees in the other hemisphere. All satellites have a common period, and positive visibility angles can be maintained down to a constellation (or satellite) period of 27 hours. At higher altitudes (longer periods) both the minimum visibility angles and the mean visibility angles will tend to increase. Replication may be provided by overlaying arrays with convenient offset. The invention is aplicable to any celestial body wherein two satellites have two periapses in one hemisphere and the other two satellites have periapses in the other hemisphere.