GR experiment proposed for ISS

I read an interesting article on a proposed experiment for measuring
deviations in general relativity using two satellites that would both
orbit almost behind the Sun (ie, opposite the Earth) and a third point
on the ISS.

http://science.nasa.gov/headlines/y2...htm?list951985

The idea is that you can measure very precisely the distance between
the three points (a tringle), and using an interferometer on the ISS
would be able to measure very precisely the angle of displacement
between the two distant satellites. Among other things, this
apparently can test some theories because they predict sufficient
nonzero curvature that can be measured by this experiment. The mission
wouldn't fly before 2009 or 2010.

My main question is whether the ISS is a good platform for this kind
of experiment? I've heard that the ISS had some inherent
noise/vibration which hinders certain types of experiments (this
experiment would seem to be sensitive to those effects). Also, I
wonder how much more expensive it would be (using current expensive
launch costs) to launch an interferomenter with a base line of this
length (I forget the scale of the ISS but 50-100 meters seems
reasonable).


Karl Hallowell