Researchers believe it is likely that there is liquid water underground on Pluto after discovering frozen ammonia on the dwarf planet’s surface.
Astronomers have detected the presence of ammonia mixed in with the rusty colouration of Pluto’s surface. This could have fascinating implications for the icy dwarf planet, as researchers have detailed in two new studies. Firstly, that ammonia-tainted ice hints at a salty, organic-rich ocean hiding beneath Pluto’s surface – one that may contain the right ingredients for life. It also hints at the presence of elusive ice volcanoes, drawing the water and ammonia from underground and spewing it all over the surface.
The data comes from New Horizons, the spacecraft that flew by the dwarf planet in 2015. As it made its closest encounter, the probe’s instrumentation was furiously collecting data – including a near-infrared spectrum of the Virgil Fossa, a region deeply tinted a rich brownish red. 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. The presence of ammonia is another piece of the puzzle. It’s a natural antifreeze that can lower the freezing point of water by up to 100 degrees Celsius. It’s long been thought that icy bodies such as Pluto might have cryovolcanoes, so finding supporting evidence for that theory is deeply rewarding, as well as support for the hypothesised subsurface oceans. But the presence of ammonia could have other implications. It’s thought Pluto’s redness comes from molecules known as tholins, organic compounds that form when ultraviolet or cosmic radiation cooks compounds that contain carbon, such as methane or carbon dioxide.
“The red material associated with the H2O ice may contain nucleobases resulting from energetic processing on Pluto’s surface or in the interior,”
Does that mean there’s life on Pluto? Probably not. It’s -230 degrees Celsius! But as we get pieces of evidence for subsurface oceans that are potentially rich in organics, it now seems at least slightly possible. We have no way of knowing if there are life-giving hydrothermal vents down there on Pluto’s alien seafloor, but with all that ammonia in the water, any life that did emerge – if it could – would have to have some pretty extreme adaptations.