  The quest for other habitable worlds and the search for life among them are
major goals of modern astronomy. One way to make progress towards these goals
is to obtain high-quality spectra of a large number of exoplanets over a broad
range of wavelengths. While concepts currently investigated in the United
States are focused on visible/NIR wavelengths, where the planets are probed in
reflected light, a compelling alternative to characterize planetary atmospheres
is the mid-infrared waveband (5-20~$\mu$m). Indeed, mid-infrared observations
provide key information on the presence of an atmosphere, the surface
conditions (e.g., temperature, pressure, habitability), and the atmospheric
composition in important species such as H$_2$O, CO$_2$, O$_3$, CH$_4$, and
N$_2$O. This information is essential to investigate the potential habitability
of exoplanets and to make progress towards the search for life in the universe.
Obtaining high-quality mid-infrared spectra of exoplanets from the ground is
however extremely challenging due to the overwhelming brightness and turbulence
of Earth's atmosphere. In this paper, we present a concept of space-based
mid-infrared interferometer that can tackle this observing challenge and
discuss the main technological developments required to launch such a
sophisticated instrument.
