One of the things the Starmus science festival makes possible is travelling all the way to Pluto itself without even getting up from your seat in a conference hall in Tenerife.
That is the journey outlined on Monday by Alan Stern, principal investigator of NASA’s ‚New Horizons‘ mission, as he took the audience on a tour of some of the strangest landscapes discovered on that remote world: snow-capped mountains, glaciers, ice volcanoes, avalanches and a blue sky that, at times, seems surprisingly familiar.
At first glance, some images of Pluto might vaguely resemble Earth, but you only need to look at what those structures are made of to discover a completely different world.
Pluto: New Horizons reveals an unexpectedly diverse world
Alan Stern, who has led the mission exploring that part of the solar system since the late 1990s, has outlined some of the surprises revealed by the flyby of Pluto in July 2015, following a nine-year journey to the outer reaches of the solar system, a journey that continues to this day, beyond the much-debated dwarf planet and its moons.
«Pluto is the best part of the solar system, saved for last,» joked Stern, before setting out a catalogue of geological oddities which, a decade on, continue to raise questions.
One of the most striking is the visual resemblance to landscapes on Earth. Pluto, he explained, has mountain ranges up to around 6,000 metres high and peaks that appear to be snow-capped, as well as a blue sky and an atmosphere whose main component is, as on Earth, nitrogen, but that is where most of the similarities end.
The ’snow‘ on these mountains does not have the same composition as that found on Earth; in some cases it even has a reddish appearance, and ‚New Horizons‘ has also observed vast expanses of nitrogen ice and ridges formed from methane ice, some arranged in parallel structures that Stern has likened to a science-fiction landscape.
«When we reach the outer reaches of our planetary system, we see mountain ranges that are very similar to our own,» he pointed out, although chemically they are radically different worlds.
Young landscapes bear witness to geological activity
Pluto also baffled scientists by displaying, at the same time, very ancient terrain, riddled with craters, and other terrain with virtually no craters, a sign of much more recent geological activity.
In Stern’s view, that is one of the mission’s key lessons: the fact that a small, distant body, which in theory might have exhausted its internal energy long ago and become a geologically dead world, continues to show signs of renewal.
'New Horizons' also found evidence of large avalanches and possible ice volcanoes comparable in size to large volcanic structures on Earth, some of which are young in geological terms, with formations that even resemble a frozen lake.
If that interpretation is correct, it would imply that at some point Pluto may have had an atmosphere much denser than it is today, temporarily allowing liquids to exist on its surface, he noted.
Kuiper Belt: New Horizons is looking for another target
'New Horizons' continued on towards the Kuiper Belt and, in 2019, flew past Arrokoth, a small object whose unusual shape provided clues about the early stages of planetary formation and suggested that gentle accretion processes were at work rather than violent, large-scale collisions.
The spacecraft is now continuing its journey through the Kuiper Belt whilst the team searches for a new, even more distant target.
For Stern, one fundamental idea remains: in that outer region, there are still numerous unexplored worlds, and each one may once again prove, as Pluto did, that nature does not always follow the ‚instruction manual‘ that scientists had imagined.
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