Quantum Gravity Gradiometer Pathfinder (QGGPf)
NASA’s Jet Propulsion Laboratory is getting ready to launch the first space-based quantum gravity gradiometer in collaboration with academic and small business partners. In order to map Earth’s gravity field from orbit, a suite of quantum sensing technologies will be tested by NASA’s Earth Science Technology Office as part of the Quantum Gravity Gradiometer Pathfinder (QGGPf).
The project aims to show how quantum sensors, particularly those based on ultra-cold atom interferometry, may be used to detect gravitational anomalies with great precision, according to a NASA news release. Applications ranging from subsurface geology and national security to water resource management depend on these changes in gravity, which are brought about by mass redistribution under the surface of the Earth.
How It Operates: Gravity Gradients and Ultra-Cold Atoms
Clouds of rubidium atoms that have been chilled to almost zero will be used as test masses for QGGPf. Because the atoms act as matter waves at this temperature, it is possible to compare the gravitational acceleration of two points in space with accuracy. Gravity gradiometers detect the gravity gradient, which is the difference in the rates at which two test masses fall over short distances. Greater acceleration brought on by stronger gravitational fields enables scientists to pick up on even the smallest changes in mass distribution.
According to the press release, using ultra-cold atoms in space allows for longer-duration and more accurate measurements than traditional mechanical test masses. “It can assure you that every measurement will be the same with atoms,” Sheng-wey Chiow, a JPL experimental physicist, said. Over time, measurement stability is improved by atom-based sensors’ reduced susceptibility to drift and thermal noise.
The fundamental sensor of QGGPf will be substantially smaller than conventional spaceborne gravity instruments, measuring only 0.25 cubic meters and weighing only 125 kilograms. According to previous predictions, the quantum device is predicted to achieve sensitivity up to ten times higher than current classical sensors, despite its small size. The mission’s main objective is to evaluate the technology in orbit, but the findings may also help guide future planetary exploration and Earth research missions.
Towards Advancing Quantum Technologies in Space
NASA’s efforts to incorporate quantum technologies into its science missions are shown by this initiative. “In order to determine how well it will function, as need to fly it,” JPL postdoctoral researcher Ben Stray stated. “That will enable us to develop quantum technology in general as well as the quantum gravity gradiometer.”
A number of subsystems created through public-private cooperation will be the foundation of the instrument. While NASA’s Goddard Space Flight Center is collaborating with Vector Atomic to create the laser systems required for controlling and measuring the atomic clouds, JPL is collaborating with AOSense and Infleqtion to advance the sensor head based on atom interferometry.
Atom Interferometry and Measurement Precision
The method employed in the QGGPf, atom interferometry, measures phase shifts brought on by gravitational forces by splitting and recombining matter waves. The atomic clouds’ varying rates of acceleration are intimately correlated with these phase shifts. The gradiometer maps gravity gradients with great spatial precision by comparing two such clouds in free-fall.
In a recent publication published in EPJ Quantum Technology, Jason Hyon, the director of the Quantum Space Innovation Center and Chief Technologist for Earth Science at JPL, highlighted the promise of atom-based sensing. Jason Hyon pointed out that quantum instrumentation might eventually be used to measure characteristics like mineral reserves and subterranean water reservoirs from orbit with technologies like QGGPf.
Applications and Future Potential
Tectonic movement, glacier melting, groundwater extraction, and other geophysical activities cause the Earth’s gravitational field to change throughout time. Precisely monitoring these shifts is important for climate model improvement and environmental policy. For gravity measurements, NASA has historically depended on missions like GRACE and GRACE-FO, but QGGPf offers a completely new sensing technology that could someday supplement or possibly replace conventional gravimetry missions.
The QGGPf will mostly be used as a technology pathfinder, but the launch is scheduled for the end of the decade. The accomplishment of this mission could pave the way for the creation of compact, high-precision quantum equipment for planetary science and Earth observation, as well as operational quantum gravity gradiometer.