Models for Varuna's spectrum suggest that its surface is most likely formed of a mixture of amorphous silicates (25%), complex organic compounds (35%), amorphous carbon (15%) and water ice (25%), with a possibility of up to 10% methane ice. For an object with a size similar to Varuna, the presence of volatile methane could not be primordial as Varuna is not massive enough to retain volatiles on its surface. An event that had occurred subsequently after Varuna's formation–such as an energetic impact–would likely account for the presence of methane on Varuna's surface. Additional near-infrared observations of Varuna's spectra were conducted at the NASA Infrared Telescope Facility in 2017 and have identified absorption features between 2.2 and 2.5 μm that might be associated with ethane and ethylene, based on preliminary analysis. For mid-sized bodies such as Varuna, volatiles such as ethane and ethylene are likely to be retained than lighter volatiles such as methane according to volatile retention theories formulated by astronomers Schaller and Brown in 2007.