  Recently, we presented the detection of carbon monoxide in the transmission
spectrum of extrasolar planet HD209458b, using CRIRES, the Cryogenic
high-resolution Infrared Echelle Spectrograph at ESO's Very Large Telescope
(VLT). The high spectral resolution observations (R=100,000) provide a wealth
of information on the planet's orbit, mass, composition, and even on its
atmospheric dynamics. The new observational strategy and data analysis
techniques open up a whole world of opportunities. We therefore started an ESO
large program using CRIRES to explore these, targeting both transiting and
non-transiting planets in carbon monoxide, water vapour, and methane.
Observations of the latter molecule will also serve as a test-bed for METIS,
the proposed mid-infrared imager and spectrograph for the European Extremely
Large Telescope.
