Launches and Orbital Operations
2017 Apr 30
Sunday, Day 120
Primary source of unclassified orbital elements
Orbital elements based on amateur observations
1957 - Launches to Orbit and Beyond
Listed are all launches, irrespective of outcome, that were irretrievably committed to flight towards orbit or intended to accelerate the payload to escape velocity.
Launch times are in UTC and are from the launching agency or estimated by 'walking back' along the ground track to the launch site. The PRIME source of orbit data and decay information is SpaceTrack. A minority of orbits is based on amateur observations using visual and radio techniques. Occasionally, early orbit data are published by satellite owners and may cover periods before SpaceTrack lists a new object. In extreme cases, orbits are estimated from public data.
Apogee and perigee are measured against the Earth's mean equatorial radius - 6378.145 km. Care should be exercised when comparing with other published orbits even when the source is shown as SpaceTrack.
Web sites may link to specific launches by pointing to the page URL followed by the three digit launch number, eg - http://www.zarya.info/Diaries/Launches/Launches.php?year=1957#001
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