The search for life beyond Earth is one of the ultimate goals of planetary science. It significantly motivates the detection and characterization of exoplanets. After decades of astrophysical and chemical characterization of exoplanets, astrobiological characterization is becoming increasingly important. Analysis of the detectability of biosignatures is thus critical. Planet Earth, the only celestial object known to harbor life, provides the single ground truth for biosignatures. Analyzing the light curves of Earth, treated as a proxy exoplanet, can therefore provide the baseline for analyzing the detectability and observation limit of potential biosignatures from exoplanets. In this talk, I will present an analysis of multi-wavelength single-point light curves of Earth, where it plays the role of a proxy exoplanet, using observations obtained by the recent Deep Space Climate ObserVatoRy (DSCOVR) mission. In a preliminary analysis, we found that, between the two dominant principal components (PCs), the second PC contains surface-related features of the planet, while the first PC mainly includes cloud information. The first two-dimensional (2D) surface map of Earth is therefore reconstructed from light curve observations without any assumptions of its spectral properties. This study serves as a baseline for reconstructing the surface features of Earth-like exoplanets in the future.