Abstract: The exploration of habitable planets and the detection of potential biosignature are hot topics in the field of exoplanetary science, and represent frontier domains in astronomy and space science. The challenges of current research in this area include how to quantitatively assess planetary habitability and how to identify observational signals representing the presence of life. To address these challenges, an observation variable framework for habitable planets and its elements is introduced. A method is introduced to accurately estimate the habitability of exoplanets with limited understanding. To further validate the completeness of observation variable framework, a specific focus is directed towards investigating the mapping of observational parameters to habitable planets characteristics. By simulating atmospheric spectra of habitable planets, and analyzing the requirement to combine real observational data to verify the accuracy and effectiveness of models, it is underscored that the Earth is an excellent observational template for proxy habitable exoplanets. Additionally, studies which use the Earth as a proxy habitable exoplanet are analyzed by summarizing their observational methods, results, strengths and weaknesses. Building upon this foundation, a mission for spectroscopic observations of the Earth from deep space is proposed. This mission aims to acquire empirical data to validate the completeness of the observation variable framework and the mapping of observational parameters. Such validation serves as essential support for future endeavors in the detection of habitable exoplanets.

Key words: exoplanet detection, observation variable framework, integral spectroscopy, forward model and retrieval