These robots, named RoboSalp after salp (marine creatures that live mainly in the surface waters of the ocean), were designed to work in unknown and extreme conditions, including in such as extraterrestrial oceans.

Although salpas resemble jellyfish with their translucent barrel-shaped bodies, they belong to the Tunicata family and have a complex life cycle. They are characterized by the alternation of sexual and asexual generations, usually associated with the formation of polymorphic colonies.

The developed RoboSalp robots have similar lightweight, tubular bodies and can connect with each other to form "colonies", which gives them new opportunities that can be achieved through their joint work.

Researcher Valentina Lo Gatto from the Bristol Department of Aerospace Engineering is leading the study. She is also a student at the EPSRC Center for Doctoral Studies in the Field of Future Autonomous and Robotic Systems (FARSCOPE CDT).

She says: "RoboSalp is the first modular robot inspired by salp. Each module consists of a very light soft tubular structure and a propeller that allows them to float. These simple modules can be combined into "colonies" that are much more reliable and capable of performing complex tasks. Due to their low weight and strength, they are ideal for extraterrestrial underwater research missions, for example, in the subsurface ocean on Europa, a satellite of Jupiter."

RoboSalp robots are unique in that each individual module can float by itself. This is possible thanks to a small engine, similar in drones, inserted into a soft tubular structure. When the RoboSalps modules float by themselves, they are difficult to control, but after combining them into colonies, they become more stable and demonstrate complex movements.

In addition, by connecting several modules together, scientists automatically get a duplicate system, which makes it more resilient to failures. If one module breaks down, the whole colony can keep moving.

A colony of soft robots is a relatively new concept with a wide range of interesting applications. RoboSalp is soft, potentially quite energy efficient and reliable. This makes them ideal for autonomous missions where direct and immediate human control may not be possible.

Dr. Helmut Hauser from the Bristol Department of Engineering Mathematics explained: "These include the study of remote underwater environments, sewer tunnels and industrial cooling systems. Due to the light weight and softness of the RoboSalp modules, they are also ideal for extraterrestrial missions. They can be easily stored in a reduced volume, which is ideal for reducing the payload in global space missions."

The malleable hull also provides safer interaction with potentially fragile ecosystems, both terrestrial and extraterrestrial, reducing the risk of environmental damage. The ability to detach blocks or segments and rearrange them gives the system adaptability: once the target environment is reached, the colony can be deployed. At some point, it may split into several segments, each of which will explore its own direction, and then reassemble in a new configuration to achieve a different goal, for example, manipulation or sample collection.

Professor Jonathan Rossiter added: "We are also developing control approaches capable of exploiting the malleability of modules in order to achieve energy-efficient movements close to those observed in biological salpas."