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Carbon dioxide (CO2) is one of the most abundant ices in the solar system. It has been detected in giant planet atmospheres and on their moons, on and around comets, and even in regions of Mercury, the Moon, and Mars. However, despite their formation in the coldest regions of the protoplanetary disk, CO2 was not previously detected on trans-Neptunian objects (TNOs). Carbon monoxide (CO) was only expected to be present in the largest TNOs. Out of 45 total, we report the detection of both CO2 and CO in 42 and 24 TNOs, respectively, observed with the NIRSpec instrument on the JWST by the DiSCo-TNOs project (PID 2418). Our analysis shows that \diox is widespread in the trans-Neptunian region, independent of dynamical class, while CO is a common constituent of the reddest objects in our sample. The abundance and characteristics of \diox suggest that most of it could be primordially accreted. While, CO is probably being produced by ion irradiation of CO2 and other C-bearing species. Our results suggest the prevalence of two compositional groups among TNOs based on the abundance and properties of CO2 and CO. We discuss the implication of these results in the context of solar system formation.

The discovery of trans-Neptunian objects (TNOs) marked an important milestone in the understanding of the outer Solar System. Due to their environmental conditions, these objects could preserve the most pristine materials that were present on the protoplanetary disk. Studies focused on understanding TNOs physical and dynamical properties can be used to probe planetary formation processes and the subsequent solar system dynamical evolution that followed the formation era.Nowadays, above 3,000 TNOs have been detected, including four large ones that receive the official designation of dwarf-planets. Analysis of TNOs revealed a compositionally and dynamically diverse population. However, despite all the progress in the last decades, much is still unknown about the composition of the TNOs.The recently launched James Webb Space Telescope (launched on December 25, 2021) will provide a powerful tool to investigate the TNOs surface composition, where all prior instrumentation has fallen short. The NIRSpec instrument onboard JWST will provide high-quality data that will surpass the quality of the data available by orders of magnitude. DiSCo-TNOs, lead by the Florida Space Institute, is the only large program approved by JWST for the study of the Solar System. With it, we aim to assess the relative ratio of water ice, complex organics, silicates, and volatiles on the surface of a large sample of TNOs. This information is vital to improving models of the formation of our Solar System and other planetary systems. In this talk we present the scope of the DiSCo program, and the tools that are being developed to extract the maximal information from the data. We pay special attention to the compositional modeling technique that uses an implementation of a nested sampling algorithm for Bayesian inference of the abundances and grain sizes distribution of the materials present on TNOs surfaces.