In message , Andrew Yee
writes
Bill Steigerwald
NASA Goddard Space Flight Center, Greenbelt, MD
301-286-5017

October 5, 2004

Release 04-056

NASA STUDIES SPACE RAILWAY TO EXPLORE ORIGINS OF PLANETS, STARS, AND GALAXIES

A NASA-led team is studying the construction of a railway in space for
a pair of telescopes that will provide views of planet, star, and
galaxy formation in unprecedented detail. The proposed Space Infrared
Interferometric Telescope (SPIRIT) mission will also examine the
atmospheric chemistry of giant planets around other stars.

SPIRIT will consist of two telescopes at opposite ends of a 120-foot
(40-meter) beam. The telescopes will move along the beam like cars on a
railway, combing their images using the techniques of interferometry to
achieve the resolving power of a single giant telescope 120 feet across.


Don't you need at least three mirrors for imaging?