Evidence of the presence of ammonia on the surface of Pluto was found by a French and US research group. The article, published in Science Advances, talks about how researchers analyzed the various data sent to Earth by the probe New Horizons, launched by NASA in 2006 and arrived near Pluto in 2015.
In particular, the researchers focused on the data of a particular area of the Virgil Fossae, an area of the surface of the dwarf planet that has large cracks on its surface, cracks that according to the researchers should be the result of volcanic activity. This is an important discovery for two reasons: first, because ammonia is not easy to detect on the planets, especially on their surface, because it does not last long since it is easily destroyed by cosmic rays and light in general.
Furthermore, the discovery would suggest that Pluto has liquid water under the surface. Because of the phenomenon of cryovolcanism, in fact, water mixed with ammonia could have been pushed from the inner parts of the planet until it escaped from these cracks. And precisely because of the nature of ammonia, the very beginning of the presence of this substance on the surface of the dwarf planet should not be sought too far back in time, perhaps until a few million years ago.