It’s a thrilling period for astronomy, astrophysics, and cosmology. With innovative observatories, instruments, and methodologies, scientists are nearing the experimental verification of theories that have largely been speculative.
These theories address critical questions about the Universe and the physical laws that govern it, such as the nature of gravity, Dark Matter, and Dark Energy. For decades, the hypothesis has been that additional physics might be at play or that our prevailing cosmological model requires adjustments.
Investigations into the existence and properties of Dark Matter and Dark Energy continue, alongside explorations into potential new physics.
Recently, a NASA research team suggested a method for spacecraft to hunt for signs of new physics within our Solar System. They propose that spacecraft flying in a tetrahedral formation using interferometers could help solve a cosmological mystery that has baffled scientists for over fifty years.
The suggestion comes from Slava G. Turyshev, an adjunct professor of physics and astronomy at UCLA and a research scientist at NASA’s Jet Propulsion Laboratory. He collaborated with Sheng-wey Chiow, an experimental physicist at NASA JPL, and Nan Yu, an adjunct professor at the University of South Carolina and a senior research scientist at NASA JPL. Their research paper has been accepted for publication in Physical Review D.
Turyshev has previously explored how missions to the Sun’s solar gravitational lens (SGL) could transform astronomy, a concept that received a Phase III grant from NASA’s Innovative Advanced Concepts (NIAC) program in 2020. He and SETI astronomer Claudio Maccone also examined how advanced civilizations might use SGLs to transmit power across solar systems.
Gravitational lensing, the bending of spacetime by gravitational fields, was predicted by Einstein in 1916 and confirmed by Arthur Eddington in 1919 through his observations of General Relativity (GR).
However, observations between the 1960s and 1990s of galaxy rotation curves and universal expansion led to new theories on gravity’s nature on larger cosmic scales. Scientists proposed Dark Matter and Dark Energy to align these observations with GR, while others suggested alternate gravity theories, such as Modified Newtonian Dynamics (MOND) and Modified Gravity (MOG).
“We are keen to delve into the enigmas of dark energy and dark matter. Despite discoveries last century, their fundamental causes are still a mystery. These anomalies might stem from new physics not yet observed in laboratories or particle accelerators, potentially manifesting at a solar system scale,” Turyshev explained via email to Universe Today.
In their latest study, Turyshev and his team explored how a fleet of spacecraft arranged in a tetrahedral formation could study the Sun’s gravitational field to detect deviations from general relativity predictions at the Solar System scale.
“These deviations might appear as nonzero elements in the gravity gradient tensor (GGT), essentially solutions to the Poisson equation. Detecting these requires precision far beyond current capabilities—by at least five orders of magnitude. This precision is crucial, as many known effects introduce significant noise,” Turyshev noted.
The mission would use local measurement techniques, including interferometric laser ranging, demonstrated by the GRACE-FO mission, and atom interferometers, which measure phase differences between atomic matter waves. These tools will help detect and negate non-gravitational noise like thruster activity and solar radiation pressure.
“Flying in a tetrahedral formation enhances our ability to compare measurements accurately. Laser ranging provides precise data on distances and relative velocities between spacecraft,” Turyshev added.
“This precision also enables us to measure the rotation of the formation relative to an inertial frame using Sagnac observables, a task impossible by other means. Thus, the tetrahedral formation utilizes a suite of local measurements.”
This mission aims to test GR at the smallest scales, a capability previously unattainable. While studies have mostly used galaxies and galaxy clusters as gravitational lenses, this mission will provide a more precise test of GR and alternative gravitational theories, potentially improving the precision by more than five orders of magnitude.
“We have additional scientific goals, which will be detailed in our upcoming paper. These include testing GR and other gravitational theories, detecting gravitational waves in the micro-Hertz range—unreachable by current or planned instruments—and investigating solar system phenomena like the hypothetical Planet 9,” Turyshev concluded.
