In July 2009 it was announced that traces of ammonia had been found in the plumes during flybys in July and October 2008. Reducing the freezing point of water with ammonia would also allow for outgassing and higher gas pressure, and less heat required to power the water plumes. The subsurface layer heating the surface water ice could be an ammonia–water slurry at temperatures as low as , and thus less energy is required to produce the plume activity. However, the observed 4.7 gigawatts heat flux is enough to power the cryovolcanism without the presence of ammonia.