Abstract: The next decade will witness a dramatic expansion in the known population of small exoplanets, as missions such as TESS, and China's upcoming ET mission are expected to reveal thousands of new transiting planets, including more than one hundred potentially habitable terrestrial worlds. Yet despite this rapid progress, no planned facility—ground or space—will be capable of obtaining the comprehensive atmospheric characterization or biosignature assessments required to address whether any nearby Earth-sized planets are truly habitable or inhabited. To bridge this critical gap, China is currently supporting a concept study for Tianlin, a 6+ meter class space telescope covering the UV–NIR range, with operations envisioned to begin around 2035+ and a mission lifetime exceeding 10 years. Tianlin is designed with a primary science goal of directly characterizing rocky planets in the habitable zones of nearby stars, enabling the detection of key atmospheric species and potential biosignatures. Our preliminary simulations indicate that Tianlin would substantially advance the detection of water on a statistical sample of nearby terrestrial planets.Beyond its exoplanet focus, Tianlin will also deliver transformative science in galaxy formation, nearby galaxy archaeology, and early-universe astrophysics, enabled by its wide wavelength coverage and large collecting area. In this paper, we will present an overview of the Tianlin mission, including the baseline telescope and instrument requirements derived from our first-generation simulations. We will also focus on NASA's Habitable Worlds Observatory (HWO), the ESA-led Large Interferometer for Exoplanets (LIFE) mission employing mid-infrared nulling interferometry, as well as China's interferometry-based Miyin Program and the Nearby Habitable Exoplanet Survey (CHES), which utilizes high-precision astrometry. We will discuss the advantages, limitations, and scientific potential of direct imaging, nulling interferometry, and astrometry methods.

Key words: space telescope, spectrograph, coronagraph, habitable zones, terrestrial planet