NASA is advancing research on autonomous underwater robots designed to search for signs of life in the ocean worlds of the Solar System, specifically targeting Jupiter's moon Europa and Saturn's moon Enceladus.
These icy moons are considered prime candidates for extraterrestrial life due to the vast oceans of liquid water lying beneath their thick ice crusts.
In October 2024, NASA launched the Europa Clipper spacecraft, which aims to gather data on the surface conditions of Europa. Concurrently, several projects are underway to directly investigate the internal oceans of these moons.
One notable initiative, named SWIM (Sensing With Independent Micro-swimmers), is led by NASA's Jet Propulsion Laboratory. This program plans to deploy palm-sized autonomous underwater robots into the internal oceans of Europa and Enceladus.
Europa has a diameter of approximately 3,120 kilometers, about a quarter of Earth's diameter, and is covered by a thick ice shell, which scientists estimate to be between 3 to 30 kilometers in thickness. The moon's orbit is elliptical, and its shape is influenced by Jupiter's gravity, creating tidal heating that generates substantial internal heat, keeping its ocean in a liquid state.
The internal ocean of Europa is salty and is estimated to average around 100 kilometers in depth. Despite being smaller than Earth, the total volume of water in Europa’s ocean is roughly double that of Earth’s.
Researchers also believe that similar internal oceans may exist on Jupiter's moons Ganymede and Callisto, as well as Saturn's moons Titan and Enceladus.
The SWIM project envisions extremely small autonomous research robots, each measuring only 12 centimeters in length. A device known as a 'cryobot' will transport these robots through the ice to the ocean below, utilizing nuclear energy to melt the ice.
One advantage of deploying a large number of research robots is the ability to cover more extensive areas. Additionally, the robots are designed to operate in teams, allowing multiple units to explore the same region from overlapping directions, thus reducing observational errors.
Each robot will be equipped with sensors to measure temperature, pressure, acidity, conductivity, and the chemical composition of the water. These sensors will be integrated onto chips measuring just a few square millimeters.
According to Ethan Schaller, the SWIM project lead, 'People may wonder why NASA is developing an underwater robot for space exploration. Because there are places in the Solar System where we want to search for life, and we believe that liquid water is essential for life.'
It is also worth noting that scientists do not rule out the possibility of a new planet being captured by the Solar System in the future due to the Sun's gravity affecting wandering planets.