LVLH (Local Vertical/Local Horizontal)

LVLH (Local Vertical/Local Horizontal)
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LVLH (Local vertical/local horizontal) is a frame of reference that is relative to a line drawn from the spacecraft to the centre of the body it is orbiting, or whose sphere of influence it is in.

Local Vertical / Local Horizontal

Imagine the point where this line intersects the planet's surface. We can further imagine a flat plane at this point parallel to the horizontal. Obviously, as the spacecraft moves across the planet, the absolute orientation of this plane keeps changing but it provides a useful reference for orbital velocity computation. In this arrangement, the plus-Z axis is along the vertical line towards the planetary centre, the plus-X axis is in the direction of orbital motion parallel to the local horizontal and the plus-Y axis is perpendicular to the orbital plane.(ap15fj)

    This article is based on material extracted, with permission, from the [Apollo Flight Journal] by David Woods and Frank O'Brien. The NASA Apollo Flight Journal files are copyright © 1998 - 2004. W. David Woods and Frank O'Brien.(more...)
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