TPF-I SWG Report - Exoplanet Exploration Program - NASA

G ENERAL A STROPHYSICS
3 Transforming Astrophysics with TPF-I
The milli-arcsecond (mas) angular resolution of TPF-I/Darwin in the 5- to 15-μm wavelength regime will
enable transformational science in the era of the Atacama Large Millimeter Array ALMA) and (groundbased
extremely large telescopes (ELTs) in the visual to near-IR wavelength region) on topics ranging
from our home planetary system; star and planet formation, evolution, and death; the formation,
evolution, and growth of black holes; and the birth and evolution of galaxies over cosmic time. TPF-
I/Darwin will provide milli-arcsecond resolution, a gain of about two to three orders of magnitude over
filled aperture telescopes such as the James Webb Space Telescope (JWST). This mission will enable
imaging to at least 20th magnitude around a wavelength of 10 μm, a million-fold improvement over the
best ground-based sensitivity in this wavelength regime. These gains in resolution and sensitivity are
comparable to those attained at visual wavelengths over the last four centuries as astronomy evolved from
the naked-eye era before Galileo to the charged couple device (CCD) era in the latter half of the twentieth
century. The TPF-I/Darwin infrared interferometer will be a pathfinder to ultra-high-resolution imaging
in space.
3.1 Introduction
Infrared interferormetry in space with a constellation of telescopes and an image combiner flying in
formation will be a gateway to milli-arcsecond (mas) angular resolution astronomical imaging and
spectroscopy of the future. The TPF-I from NASA and Darwin from ESA are the first formation-flying
interferometer concepts to be seriously investigated for both technical feasibility and scientific potential.
These missions were conceived for a very specific goal – the detection and characterization of terrestrial
planets in terrestrial orbits around about 150 spectral-type G stars within 30 pc of the Sun. However, the
stringent performance requirements imposed on these missions by planet finding and characterization
makes TPF-I/Darwin a powerful tool for many other astronomical applications. Space enables phasestability
unachievable by Earth-based system that will be limited only by the metrology used in
establishing the flux-collector-combiner separations. TPF-I/Darwin will be a technological pathfinder for
future micro-and nano-arcsecond resolution instruments at infrared and other wavelengths. Here, we
explore the general astrophysics enabled by milli-arcsecond angular resolution and micro-jansky
sensitivity in the 5 to 15 μm wavelength regime with possible extension to wavelengths from 2 to 30 μm.
We start by summarizing the assumed parameters of the TPF-I/Darwin interferometer. Consider the four
science areas where this instrument will provide revolutionary observations, followed by a listing of
additional research areas where high-impact observations could be made.
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