A pair of infrared telescopes attached together in space could determine the chemical makeup of alien planet atmospheres at a fraction of the cost of NASA's Terrestrial Planet Finder (TPF), which has been delayed indefinitely, a new study says. TPF would have used a technique called interferometry, combining the light from several space telescopes flying in formation to spot Earth-like planets circling other stars. But the mission's likely cost of several billion dollars, combined with daunting technological challenges, led NASA to postpone it indefinitely in 2006.
Title: Towards a Small Prototype Planet Finding Interferometer: The next step in planet finding and characterisation in the infrared Authors: W.C. Danchi, D. Deming, K. G. Carpenter, R. K. Barry, P. Hinz, K. J. Johnston, P. Lawson, O. Lay, J. D. Monnier, L. J. Richardson, S. Rinehart, W. Traub
During the last few years, considerable effort has been directed towards large-scale (>> $1 Billion US) missions to detect and characterize earth-like planets around nearby stars, such as the Terrestrial Planet Finder Interferometer (TPF-I) and Darwin missions. However, technological and budgetary issues as well as shifting science priorities will likely prevent these missions from entering Phase A until the next decade. The secondary eclipse technique using the Spitzer Space Telescope has been used to directly measure the temperature and emission spectrum of extrasolar planets. However, only a small fraction of known extrasolar planets are in transiting orbits. Thus, a simplified nulling interferometer, which produces an artificial eclipse or occultation, and operates in the near- to mid-infrared (e.g. ~ 3 to 8 or 10 microns), can characterize the atmospheres of this much larger sample of the known but non-transiting exoplanets. Many other scientific problems can be addressed with a system like this, including imaging debris disks, active galactic nuclei, and low mass companions around nearby stars. We discuss the rationale for a probe-scale mission in the $600-800 Million range, which we name here as the Small Prototype Planet Finding Interferometer (SPPFI).