Reviewed by Lexie CornerApr 22 2025
Researchers from NASA's Jet Propulsion Laboratory in Southern California, along with academic institutions and private businesses, are developing the first space-based quantum gravity sensor. Supported by NASA's Earth Science Technology Office, this mission will be the first to utilize quantum sensing, enabling new observations of various global resources, including freshwater supplies and petroleum reserves.
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. Image Credit: NASA
Earth's gravitational field fluctuates daily as mass redistributes across the planet's surface due to geologic processes, with gravitational force increasing with mass.
While these small variations in gravity are imperceptible to humans, scientists can use gravity gradiometers to map Earth's gravitational field and relate it to underground features such as mineral deposits and aquifers. These gravity maps play a critical role in navigation, resource management, and national security.
“We could determine the mass of the Himalayas using atoms,” said Jason Hyon, Chief Technologist for Earth Science at JPL and Director of JPL’s Quantum Space Innovation Center.
Hyon and colleagues introduced the principles behind their Quantum Gravity Gradiometer Pathfinder (QGGPf) instrument.
Gravity gradiometers measure the difference in the rate at which two objects fall at different locations. These objects, referred to as test masses, experience different accelerations that correlate with variations in gravitational strength. In regions of stronger gravity, test masses fall more quickly.
For the QGGPf, two clouds of extremely cold rubidium atoms will serve as test masses. When cooled to nearly absolute zero, the particles in these clouds behave like waves. The quantum gravity gradiometer will measure the difference in acceleration between these matter waves to detect gravitational anomalies.
Sheng-wey Chiow, an Experimental Physicist at JPL, explained that using ultra-cold atom clouds as test masses ensures accurate space-based gravity measurements over extended periods.
With atoms, I can guarantee that every measurement will be the same. We are less sensitive to environmental effects.
Sheng-wey Chiow, Experimental Physicist, Jet Propulsion Laboratory
It is also possible to measure gravity using a small instrument on a single spacecraft with atoms as test masses. Compared to conventional space-based gravity instruments, the QGGPf will be more compact and lighter, with a volume of about 0.3 yd3 (0.25 m3) and a weight of only about 275 pounds (125 kg).
Quantum sensors may also offer enhanced sensitivity. Some estimates suggest that a science-grade quantum gravity gradiometer could be up to ten times more sensitive than traditional sensors in measuring gravity.
This technology validation mission is planned for launch at the end of the decade. Its primary objective is to test a set of new technologies for atomic-scale manipulation of light-matter interactions.
No one has tried to fly one of these instruments yet. We need to fly it so that we can figure out how well it will operate, and that will allow us to not only advance the quantum gravity gradiometer, but also quantum technology in general.
Ben Stray, Postdoctoral Researcher, Jet Propulsion Laboratory
This technology development project involves key partnerships between small businesses and NASA. NASA's Goddard Space Flight Center in Greenbelt, Maryland, is working with Vector Atomic to advance the laser optical system, while the JPL team is collaborating with AOSense and Infleqtion to develop the sensor head technology.
Ultimately, the advancements made during this pathfinder mission may enhance understanding of Earth, distant planets, and how gravity influences the universe.
The QGGPf instrument will lead to planetary science applications and fundamental physics applications.
Jason Hyon, Chief Technologist, Jet Propulsion Laboratory
Journal Reference:
Stray, B., et al. (2025). Quantum gravity gradiometry for future mass change science. EPJ Quantum Technology. doi.org/10.1140/epjqt/s40507-025-00338-1.