[X] My Assistant

[Guest_PhilCo126_*]

The Lagrange points (there are 5 for any restricted three-body problem) are positions where a satellite/spacecraft or even small celestial body (asteroid) can theoretically be stationary relative to two larger objects (such as Sun and the Earth-Moon system). Therefore the Sun-Earth L2 point was chosen for several observatories as it faces away from the Sun and the Earth-Moon system. It sits at a distance of 1.5 million kilometers.
L2 based missions include: WMAP, Planck, Herschel, JWST, PLATO, etc…
The above short list of missions (to be) placed at the L2 point immediately points out it might get crowded out there. We all know there’s a lot of space out there but these spacecraft are situated in stable periodic orbits around the L2 point itself.
So what’s the risk on interference or even collisions of L2 based observatories?
Moreover, the problem gets worse in time as these spacecraft become inoperative and start to buildup as “space junk” at L2…

[dmuller]

www.dmuller.net/planck gives the current distance between Planck and Herschel. Currently 390,000km ... that's like from the Earth to the Moon, so plenty of space to share.
EDIT: BTW, the Planck orbit is somewhere in the magnitude of 800,000km IIRC