"NASA Plans to Launch Its First Quantum-Based Gravity Measurement Sensor"

A map of Earth’s gravity. Red indicates areas of the world that exert greater gravitational pull, while blue indicates areas that exert less. A science-grade quantum gravity gradiometer could one day make maps like this with unprecedented accuracy. Credit: NASA

Scientists at NASA’s Jet Propulsion Laboratory in Southern California, in collaboration with private industry and academic partners, are working on the development of the first quantum sensor designed to measure gravity from space. Backed by NASA’s Earth Science Technology Office (ESTO), this mission represents a milestone in quantum sensing technology and could revolutionize the way we observe vital Earth systems, including underground oil reserves and freshwater resources.

Earth’s gravity field isn’t static—it shifts daily as geological processes move mass across the planet. Heavier areas exert stronger gravitational forces.

While these minor variations in gravity go unnoticed in daily life, highly sensitive instruments known as gravity gradiometers allow scientists to detect and map them. These detailed gravity maps can reveal underground structures such as aquifers and mineral deposits, and are crucial for activities like navigation, resource monitoring, and national defense.

"Using atoms, we could measure the mass of something as massive as the Himalayas," said Jason Hyon, chief technologist for Earth Science at NASA’s Jet Propulsion Laboratory and director of JPL’s Quantum Space Innovation Center. Hyon and his team recently detailed their work on the Quantum Gravity Gradiometer Pathfinder (QGGPf) in a publication in EPJ Quantum Technology.

Gravity gradiometers work by detecting how the acceleration of a falling object changes over small distances. By comparing how two nearby test masses fall, scientists can identify variations in gravitational force. Essentially, where gravity is stronger, the test masses accelerate more rapidly.

The QGGPf will employ two clouds of ultra-cold rubidium atoms as test masses. When cooled to temperatures near absolute zero, the atoms act like waves. The quantum gravity gradiometer will detect differences in how these matter waves accelerate, helping identify variations in Earth’s gravitational field.

Using ultra-cold atom clouds as test masses offers a key advantage for long-term accuracy in space-based gravity measurements, noted Sheng-wey Chiow, an experimental physicist at JPL. “Atoms allow us to ensure consistent measurements every time. They’re less affected by environmental fluctuations,” he explained.

This atomic approach also allows gravity measurements to be taken with a compact system that fits on a single spacecraft. QGGPf will occupy just about 0.3 cubic yards (0.25 cubic meters) and weigh roughly 275 pounds (125 kilograms)—considerably smaller and lighter than conventional space-based gravity instruments.

Quantum sensors also offer the promise of much higher sensitivity. In fact, some projections suggest that a quantum gravity gradiometer suitable for scientific research could be up to 10 times more sensitive than traditional gravity sensors.

The primary goal of this technology demonstration mission—set to launch toward the end of the decade—is to test a suite of advanced technologies that manipulate the interaction between light and matter at the atomic level.

“This will be the first time such an instrument is flown in space,” said Ben Stray, a postdoctoral researcher at JPL. “We need to test it in orbit to understand how well it performs, which will not only push forward the development of the quantum gravity gradiometer but also advance quantum technologies as a whole.”

The project is a collaborative effort involving NASA and several small businesses. JPL is partnering with AOSense and Infleqtion to refine the sensor head, while NASA’s Goddard Space Flight Center in Maryland is teaming up with Vector Atomic to develop the laser optical system.

In the long term, the technological breakthroughs from this mission could significantly improve how we study Earth, explore other planets, and deepen our understanding of gravity’s role in shaping the universe. “The QGGPf instrument will open doors for applications in planetary science and fundamental physics,” added Jason Hyon.