On Wed, 27 Jun 2001, Rick Baldridge wrote: > Jim King wrote: > > Since the Moon always keeps the same face towards the Earth wouldn't a > > "lunasynch" sat be at the L2 Earth-Moon Lagrange point? > > Not quite. L2 Lagrange point is on a LINE with the Sun and the Earth, > further out than the Earth, with the Moon's orbit well inside. L2 does NOT > follow the Moon, therefore, it does NOT stay in-sync with the "far side" of > the Moon. (Although since L2 is downsteam of the Moon and the Earth, it DOES > see mostly the "dark" side of the Moon with some small phase being possible, > and ALWAYS the dark side of the Earth!) The Moon is only downstream AND > in-line with the Sun and Earth at Full Moon. (For purists, I won't get more > technical than that!) > > > Anybody know the distance from the Moon of the Earth-Moon L2? Would a sat > > Earth-Moon L2 ever be visible from the Earth? > > L2 is 1.5 million kilometers from Earth, away from the Sun side, according But, just as the Sun-Earth system has Lagrangian points, so does the Earth-Moon system! Thus there is a point some distance beyond the moon (as seen from the Earth) at which a spacecraft could "stay put" in the Earth-Moon frame. The spacecraft would be perpetually watching the far (rather than dark!) side of the moon. Communicating with that spacecraft might be a problem; or, what with the moon being in the way, Earth-Moon L2 might be perfect for a radio astronomy mission -- free from this planet's electromagnetic spam ;-) // Magnus ----------------------------------------------------------------- Unsubscribe from SeeSat-L by sending a message with 'unsubscribe' in the SUBJECT to SeeSat-L-request@lists.satellite.eu.org http://www2.satellite.eu.org/seesat/seesatindex.html
This archive was generated by hypermail 2b29 : Wed Jun 27 2001 - 23:54:32 PDT