NASA’s Jet Propulsion Laboratory (JPL) in Southern California, along with academic and industry partners, is advancing a groundbreaking quantum sensing technology designed to measure gravity from space for the first time. Supported by NASA’s Earth Science Technology Office (ESTO), this effort aims to pioneer a new era of Earth observation using quantum-based instruments to reveal hidden features beneath the planet’s surface, such as underground aquifers, mineral reserves, and oil deposits.

Unlike static physical properties, Earth’s gravitational field continuously changes in response to the dynamic movement of mass below the surface. Detecting these subtle gravitational variations requires extremely sensitive tools. This is where gravity gradiometers come in—specialized instruments that measure how gravitational force changes over small distances. These changes, while imperceptible in daily life, provide critical insights into subsurface structures and are valuable for fields ranging from environmental science to national security.

At the core of this mission is the Quantum Gravity Gradiometer Pathfinder (QGGPf), a prototype instrument that will use ultra-cold atoms as test masses to detect gravitational differences in space. Instead of relying on conventional test objects, QGGPf will employ two clouds of rubidium atoms, cooled to near absolute zero. At such low temperatures, these atoms behave like waves rather than particles. By tracking how each wave-based test mass accelerates under gravity, the instrument can measure tiny differences in gravitational strength across short distances.

Using atoms offers key advantages. Their physical properties remain identical from one measurement to the next, reducing noise and increasing long-term precision. This approach also makes the entire instrument smaller and more practical for spaceflight. The QGGPf will be compact, measuring roughly 0.25 cubic meters in volume and weighing about 125 kilograms—much smaller than traditional space-based gravity instruments.

Beyond portability and precision, the use of quantum matter waves gives the sensor a potential leap in sensitivity. Early projections suggest quantum gradiometers could be up to ten times more sensitive than classical counterparts. The pathfinder mission, planned for launch later this decade, is primarily a technology demonstration to validate these capabilities in orbit and to refine methods for manipulating light-matter interactions at the atomic scale.

This marks the first time a quantum gravity gradiometer will be flown in space. Demonstrating its performance in orbit will not only validate its design for Earth science applications but could also accelerate broader adoption of quantum sensing technologies in space missions.

The QGGPf effort is highly collaborative. JPL is working closely with small businesses including AOSense and Infleqtion on developing the quantum sensor head, while NASA’s Goddard Space Flight Center is partnering with Vector Atomic to advance the laser optics system critical for controlling and reading the quantum states of the atom clouds.

The implications of this technology go well beyond Earth science. Once demonstrated, the same quantum sensing techniques could be used for planetary exploration, helping scientists investigate gravity fields on other celestial bodies, understand planetary interiors, and explore fundamental questions in physics. The QGGPf mission represents not just a leap in Earth observation, but a bold step into the future of quantum space exploration.

By Impact Lab