A model of a tiny, wedge-shaped robot designed to explore subsurface oceans of icy moons, right, sits beside a large waterproof capsule containing electronics and sensors for testing below glacial ice at the Juneau Icefield in Alaska in July 2023. The model, about 5 inches (12 centimeters) long, was 3D-printed to show the final envisioned size of a futuristic NASA mission concept called SWIM, short for Sensing With Independent Micro-swimmers.

Led by NASA's Jet Propulsion Laboratory from spring 2021 to fall 2024, SWIM envisions a swarm of dozens of self-propelled, cellphone-size robots exploring the waters of icy moons like Jupiter's Europa and Saturn's Enceladus. Delivered to the subsurface ocean by an ice-melting cryobot, the tiny robots would zoom away to look for chemical and temperature signals that could point to life.

The capsule shown here contains the first generation of an ocean composition sensor built for the SWIM robots by a team at Georgia Tech. The final version of the sensor would enable each robot to simultaneously measure temperature, pressure, acidity or alkalinity, conductivity, and chemical makeup. During the Alaska field test, the team lowered the capsule through a borehole in the ice and measured pressure and conductivity down to a depth of 164 feet (50 meters).

This field test was conducted as part of a JPL-managed project called ORCAA (Ocean Worlds Reconnaissance and Characterization of Astrobiological Analogs). Known as an analog mission, ORCAA is working to answer science questions and test technology in preparation for a potential future mission to explore the surface or subsurface of icy moons. ORCAA is funded by NASA's Planetary Science and Technology from Analog Research program.

SWIM was supported by Phase I and II funding from NASA's Innovative Advanced Concepts program under the agency's Space Technology Mission Directorate. JPL is managed for NASA by Caltech in Pasadena, California.