In addition to carbon compounds, all currently known terrestrial life also requires water as a solvent. This has led to discussions about whether water is the only liquid capable of filling that role. The idea that an extraterrestrial life-form might be based on a solvent other than water has been taken seriously in recent scientific literature by the biochemist Steven Benner,[32] and by the astrobiological committee chaired by John A. Baross.[33] Solvents discussed by the Baross committee include ammonia,[34] sulfuric acid,[35] formamide,[36] hydrocarbons,[36] and (at temperatures much lower than Earth's) liquid nitrogen, or hydrogen in the form of a supercritical fluid.[37]