What We are venturing into unexplored scientific territory at the dawn of a new era of discovery and characterization of worlds akin to the Earth. We now know that small, rocky worlds are commonly occurring, and we propose to utilize new instruments and design concepts to investigate the atmospheres of these planets as we look ahead to the eventual search for biosignatures beyond the Solar System. We will make a sweeping new push to determine which terrestrial worlds orbiting M dwarfs possess atmospheres, and under what conditions these atmospheres remain intact. In parallel, we will build the spectrograph needed to detect true Earth-analogs orbiting in the habitable zones of Sun-like stars that will be the targets of the next generation of giant telescopes capable of performing biosignature searches in their atmospheres. With these two research ventures we will initiate the next phase of the search for life in the cosmos. Why One of humanity’s oldest questions is: Answer are we alone in the universe? This question has pervaded philosophy, literature, pop culture, and now academia. In the last 30 years, exoplanet science has brought us closer, by leaps and bounds, to answering this question by applying the scientific method: observations, experiments, data analysis, and statistics. As we collect more information, we are making surprising discoveries, asking new questions, and inspiring the next generation of thinkers. With this proposal, the Exoplanet Group at DTU Space is breaking fresh ground in exoplanet science by pushing towards atmospheric characterization of rocky worlds orbiting our closest stellar neighbors, M dwarfs, and developing the instruments needed to make the next great detections: Earth-like planets orbiting in the habitable zones of the closest and brightest Sun-like stars. How We stand on the shoulders of decades of observers, theorists, and instrumentalists, but now we venture boldly into a new era of discovery and characterization. The launch of the James Webb Space Telescope on Christmas Day 2021 marks a turning point for exoplanet science, and especially for terrestrial worlds. Our group is already at the forefront of terrestrial planet observations with JWST, having obtained the first transit of a terrestrial world in July 2022. With JWST and a Seper Ardens Advance grant we can, for the first time, characterize the atmospheres of rocky exoplanets, but we will not be able to probe true Earth-analogs orbiting in the habitable zones of Sun-like stars because we have yet to detect such worlds close enough to study. This is why we are embarking on the next big turning point for exoplanet science: the Second Earth Initiative Spectrograph. This will be an ultra-precise radial velocity spectrograph attached to a 2-meter class telescope in Chile. With eyes on the Southern sky we will detect the true Earth analogs that can be probed with next-generation giant telescopes.