Orbits and mechanics
两行轨道根数
Two-line element set (TLE)
A 69-character-per-line format that encodes an orbit.
TLEs age: a week-old set can be minutes off for a pass.
Related terms
- Earth's shadow — The stretch where a satellite passes behind Earth and loses sunlight.
- Delta-v — The velocity change needed to alter an orbit.
- Escape velocity — The minimum speed needed to leave a body's gravity.
- Atmospheric reentry — A spacecraft coming back into the atmosphere.