The New Horizons spacecraft might have detected an atmosphere on Pluto that’s brimming with nitrogen, but how this gaseous planetary cover is continually being replenished – since it’s seeping into space at an alarming rate – has puzzled the scientists behind the mission.
The dwarf planet’s atmosphere has a pressure that’s 10,000 times lower than that found on Earth and every hour, hundreds of tons of nitrogen is being stripped by the Sun. Despite such a loss, Pluto’s atmosphere remains at a constant 98 per cent nitrogen, but how the planet is managing to replace such a large proportion of its atmosphere as quickly as it’s losing it, is uncertain. “New nitrogen has to come from somewhere to resupply both the nitrogen ice that is moving around Pluto’s surface in seasonal cycles and the nitrogen that is escaping off the top of the atmosphere as the result of heating by ultraviolet light from the Sun,” says New Horizons team member Kelsi Singer of the Southwest Research Institute.
Singer and her team, which includes the spacecraft’s principal investigator Alan Stern, have ruled out the possibility of extra nitrogen hailing from comets, which have impacted the dwarf planet’s surface. What they do suspect though, is some geological process that’s pulling nitrogen up and out of Pluto’s interior. “Our pre-flyby prediction is that it’s most likely that Pluto is actively resupplying nitrogen from its interior to its surface, possibly meaning the presence of ongoing geysers or cryovolcanism [ice volcanoes],” explains Stern.
Other features on Pluto’s surface captured by the New Horizons flyby in July seem to support the processes that Stern suggests since they reveal landforms suggestive of heat rising up through the dwarf planet’s surface. “We currently have only a tiny fraction of the data back from the New Horizons flyby, but the fact that there are young-looking areas on Pluto hints at relatively recent geological activity,” adds Singer.
With the New Horizons spacecraft sending back more detailed information, which was collected during its flyby of the dwarf planet, we’ll be learning much more about Pluto’s possible internal activity and its atmosphere.