Ground-based telescopes must look through Earth's atmosphere, which is opaque in many infrared bands (see figure of atmospheric absorption). Even where the atmosphere is transparent, many of the target chemical compounds, such as water, carbon dioxide, and methane, also exist in the Earth's atmosphere, vastly complicating analysis. Existing space telescopes such as Hubble cannot study these bands since their mirrors are insufficiently cool (the Hubble mirror is maintained at about ) thus the telescope itself radiates strongly in the infrared bands.