The year of the constellation

This month inaugurates a new era in space physics - the era of satellite
constellation research.

It begins with the activation of the first two constellations of
research satellites ever built, to be use for near earth astrophysics.
In this month's Sky & Scope, the L3/L4 pair of solar observatories,
called Stereo, published two test pictures of a the moon transiting the
sun. (Why was the sun was purple, in those photos?) A four machine
constellation of magnetotail research craft will also coming on-line,
before the end of the year, I think.

I personally think that NASA ought to put a third Stereo spacecraft onto
the L5 point, so that they can record the entire life cycles of sunspots
on film. However, that might be impossible, since L5 is directly
opposite the sun from Earth. You'd have to rout the control signals
through at least one of the other spacecraft, which means that it
wouldn't be allowed to spin about its axis. That might be a deal
breaker, because I don't think tht can be done without a continual
expenditure of fuel.

And note that Stereo is also historical in its use of the Lagrange
points, which space hobbyists have been dreaming about for decades. It
is, indeed a banner year for observational astrophysics.