Enceladus's Hidden Mysteries, by Dr Rachael Hamp

Moon’s the Word - Is There Life Out There?

The evening opened with a talk on the Moon from Manish Patel, returning to a theme he had also spoken on last year and giving it something of an annual-event feel. He looked at the success of Artemis II, launched on 1st April 2026, 54 years after humans had previously left Earth’s orbit. A flyby mission to the Moon, its objective was to help decide ‘which post codes to move into’. He revealed the European dimension of this first crewed mission of the Artemis programme, including the total success of the European Service Module and the important role played by the satellite Earth station at Goonhilly in tracking the mission.

Richard was our host for the evening, and Manish Patel gave a talk about Artemis II. Pictures by Bobby Manoo and Amy Scammell.

In Enceladus’s Hidden Mysteries, Dr Rachael Hamp of the Open University explained that her background in chemistry gives a different view from the geoscience perspective. However, you did not need a knowledge of chemistry to be able to enjoy the tour Rachael took us on, exploring the hidden mysteries of the big planets’ icy moons, and Enceladus in particular, which was discovered by William Herschel in 1789. The initial assumption was that Enceladus consisted of solid ice. Rachael’s enthusiasm was infectious.

Dr Rachael Hamp, at the start of her talk to the Flamsteed. Picture by Mike Meynell.

Icy moons live in the outer Solar System, away from the Sun, and are made of water ice. Europa is one of the larger moons, the same size as Earth’s Moon, but possessing two to three times more water than Earth, orbiting around Jupiter. Enceladus, on the other hand, circling around Saturn, is a mere five hundred kilometres in diameter and reaches surface temperatures of minus 200°C. Yet both have the potential for life because, under their icy crusts, they have an internal structure which contains subsurface oceans that are in touch with a rocky central core. This can lead to chemical reactions and life.

The 1997 Cassini mission, arriving at Saturn in 2004, discovered the plumes of Enceladus almost by accident. Located at the moon’s south pole, the plumes emerge out of surface vents at 2 km per second, reaching high above the surface. It was then determined that Enceladus must have liquid water to feed the plumes. The existence of the moon’s global ocean was established when it was observed that the surface of Enceladus wobbles as it orbits Saturn.

Dr Rachael Hamp. Pictures by Mike Meynell, Bobby Manoo and Amy Scammell.

Rachael explained how the discovery of carbonaceous chondrite material from the asteroid Bennu, along with the presence of amino acids, has led to the belief that these could also be present in the centre of Enceladus. The existence of living creatures in and around hydrothermal vents on Earth points to the possibility of life elsewhere. Rachael’s own experiments with rapid hyper-freezing of sodium chloride have led to the creation of other minerals not found on Earth. A colleague is studying the processes of plume geysers in Iceland.

Lots of questions at the end of Rachael's talk, with the lecture theatre almost packed to capacity. Pictures by Bobby Manoo.

While Cassini led to an improved knowledge of Enceladus, it had not been set up to fly through the plumes of Enceladus or identify the organic materials of this icy moon. Rachael revealed that she is part of the European Space Agency team working on its largest planned mission focused on the moons of the giant planets, planned to launch in the mid-2040s. She hopes to remain closely involved with the project as it develops towards its expected arrival in the mid-2050s. The mission will include an orbiter and lander, which could enable a possible landing on Enceladus and the exciting possibility of finding life out there too.