October 20, 2021

I, Science

The science magazine of Imperial College

What we know (or perhaps more accurately what we think we know) about our universe is constantly changing – in a relatively tiny amount of time, our scientific research has progressed from a simplistic geocentric solar system model to one in which there are hundreds upon thousands of galaxies, each containing countless stars with orbiting extrasolar planets. In a similar fashion, our view of our solar system is equally changeable as new research constantly unearths new boundaries and theories involving planetary formation, evolution and habitability.

It is no great surprise, then, that new work conducted by Pryscilla Maria Pires dos Santos at UNESP-São Paulo State University in Brazil and her research team have explored the idea that Pluto may be eligible to join the ranks of Jupiter, Saturn, Uranus and Neptune in boasting a ring of dust, ice and various other interstellar particles.

They come to the conclusion that, despite the lack of evidence in the highest quality Hubble images, Pluto should in fact have such a ring – although it may be much too faint for Hubble to detect.

Dust and particles that make up such planetary rings often come from impacts on orbiting satellites, which release cascades of material that can subsequently be captured in the host planet’s orbit. Pires dos Santos focused on the possibility of micrometeorite impacts on Pluto’s satellites, Nix and Hydra, in sending sufficient material into Pluto’s orbit to sustain such a ring.

Rings were previously suspected to be unsustainable around dwarf planets due to their interaction with the solar wind, which removes material and debris that becomes trapped in orbit around planets or other solar system objects – a ring can be sustained if dust is supplied to the orbit by collisions and impacts faster than it is removed by the solar wind.

Although this solar wind interaction is strong, Pires dos Santos and co’s calculations demonstrate that it is not strong enough to completely remove Pluto’s ring. They estimate an initially-formed dust ring of around 16,000 km wide (a radius that encompasses the orbits of both satellites). To counter this, they place the rate of dust depletion due to solar wind at 50% within 1 year.

Therefore, “[a] tenuous ring…can be maintained by the dust particles released from the surfaces of Nix and Hydra,” say Pires dos Santos and team. Hubble (with a viewing capability of transparency 10-5) has thus far been unable to see this predicted ring, although the team responds to this issue by calculating Pluto’s ring to have a transparency of 10-11.

Without observational evidence the research may struggle to gain mainstream acceptance, but there isn’t long to wait; in summer 2015 the already-launched New Horizons spacecraft will approach the dwarf planet, equipped with a dust counter capable of either proving or discrediting this research.

The full work can be found here: “Small Particles In Pluto’s Environment: Effects Of The Solar Radiation Pressure”.