Thus a local conformational change initiated by the agonist, but not antagonist binding results in a destabilization of the protein structure. This destabilization is not strong enough to denature the protein, but results in a long range effect across the protein affecting its active site several angstrom away from the ligand binding site. This is known as an allosteric mechanism. As a rule, agonists induce structure destabilization, while antagonists merely bind , but do not affect the protein structure (or trigger a conformational change that locks a protein in its inactive position). One way to visualize the action of ligands on receptors is to realize that proteins constantly undergo conformational changes which is best described as an equilibrium between an active and inactive, or even among multiple states, including desensitized states (different types of inactive states). Agonists and antagonists shift this equilibrium towards an active or inactive conformation, respectively.
In 2009, India's Chandrayaan-1 satellite, NASA's Cassini spacecraft and the Deep Impact probe have each detected the presence of water by evidence of hydroxyl fragments on the Moon. As reported by Richard Kerr, "A spectrometer [the Moon Mineralogy Mapper, . "M3"] detected an infrared absorption at a wavelength of micrometers that only water or hydroxyl—a hydrogen and an oxygen bound together—could have created."  NASA also reported in 2009 that the LCROSS probe revealed an ultraviolet emission spectrum consistent with hydroxyl presence.  The Venus Express orbiter sent back Venus science data from April 2006 until December 2014. Results from Venus Express include the detection of hydroxyl in the atmosphere.