Researchers believe it is likely that there is liquid water underground on Pluto after discovering frozen ammonia on the dwarf planet’s surface.
An enormous crack discovered on Pluto as a result of the fly-by from the New Horizons space probe in 2015 is now believed to have been created by volcanic activity.
Unlike the volcanic activity on Earth, which is driven by the planet’s hot core and magma, a cryovolcano doesn’t erupt with molten rock but with other material – such as water and ammonia – which has a low boiling point.
Researchers examined the region the crack was discovered in, known as Virgil Fossa, which they suspected could have been covered in ammonia due to its reddish-brown colour.
This would have been a rare find if confirmed because ammonia is easily broken down when exposed to ultraviolet light and charged particles in solar wind.
But the New Horizons data, which also showed frozen water on Pluto’s surface, confirmed that the reddish-brown areas were covered in ammonia.
According to the researchers, this means that it is likely that Pluto harbours liquid water beneath its surface.
Because ammonia doesn’t last very long when exposed to the vacuum of space, the researchers believe it could not have been on the surface for very long.
Their research suggests that it erupted onto the surface within the last few million years due to cryovolcanism on the dwarf planet.
Cryovolcanic activity has also been detected on Saturn’s moon Enceladus, which is among the main candidates for liquid water and thus extra-terrestrial life in our solar system.
Pluto’s extreme distance from the sun means the existence of liquid water on the surface of the planet – which has a temperature of -230C – is impossible.
But beneath the surface there could be liquid water warmed by the heat of the dwarf planet’s nuclear core.
The researchers from a range of institutions in the US and one in France published their work in the journal Science Advances.