Scientists from Samara University and the Space Research Institute of the Russian Academy of Sciences have developed an elegant and economical plan to study the potentially hazardous asteroid Apophis as it makes its historic flyby of Earth in April 2029—passing just 31,000 kilometers above our planet’s surface, closer than many satellites orbit.
Rather than designing and launching a new spacecraft—a costly and time-consuming endeavor—the team proposes redirecting the already-operational “Spektr-RG” (SRG) X-ray observatory, launched in July 2019 and equipped with two advanced X-ray telescopes. The mission would leverage celestial mechanics to achieve a precise rendezvous with minimal fuel expenditure.
According to detailed orbital calculations published in the prestigious journals Cosmic Research and Solar System Research, a brief engine burn of just 1 meter per second (m/s) on September 13, 2028, would place Spektr-RG onto a trajectory that, seven months later—on April 13, 2029—brings it within 18,000 km of Apophis’ center of mass. This proximity is extraordinary: previous observations were made from a distance of 14 million kilometers.
“We used Spektr-RG’s current orbit around the Sun–Earth L2 Lagrange point as our starting point,” explained Olga Starinova, Head of the Department of Flight Dynamics and Control Systems at Samara University and co-author of the mission concept.
“Its primary astrophysics mission—mapping the universe in X-rays—is scheduled to conclude in 2026. Afterward, the observatory will retain enough propellant to transfer onto an invariant manifold trajectory that naturally leads to Apophis during its closest approach. This approach eliminates the need for a dedicated spacecraft and launch, while delivering unprecedented scientific data. After the flyby and data transmission, the observatory could even return to its original L2 orbit for future tasks.”
The team also modeled a second, ultra-close encounter scenario: by initiating the maneuver earlier—on August 24, 2027—and executing two small burns (0.1 m/s and a follow-up impulse on September 5, 2028)—Spektr-RG could intercept Apophis on April 14, 2029, just one day after its Earth flyby, at a distance of merely a few hundred kilometers.
“This second option offers unparalleled observational detail,” Starinova noted, “but requires multiple engine firings and, critically, a 30 m/s braking maneuver afterward to return the observatory to the L2 region. Still, both scenarios represent highly efficient uses of existing infrastructure.”
Both mission profiles are technically feasible and scientifically compelling, demonstrating how clever orbital design can turn existing assets into powerful tools for planetary defense and exploration. The concept could serve as a blueprint for future low-cost missions to other near-Earth objects.
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The research team includes Nathan Eismont (Lead Scientist, IKI RAS), Olga Starinova (Samara University), Maksim Pupkov (Engineer, IKI RAS, and PhD student at Samara University under Starinova’s supervision), and other specialists.
Asteroid Apophis, named after the ancient Egyptian serpent god Apep (Greek: Apophis)—a symbol of chaos threatening cosmic order—was discovered in 2004 and initially raised alarms due to a potential Earth impact on April 13, 2029. Subsequent observations ruled out collision, but the flyby remains a rare opportunity: at 370–450 meters long and traveling at 30 km/s, Apophis is large enough that an impact would cause global catastrophe.
Spektr-RG, Russia’s flagship X-ray astronomy mission, has been mapping the sky since 2019 from the gravitationally stable Sun–Earth L2 point—one of five Lagrange points where gravitational and centrifugal forces balance, allowing spacecraft to maintain position with minimal fuel. These points, first calculated by Joseph-Louis Lagrange in 1772, are now vital hubs for space science.
With this innovative proposal, Russian scientists aim not only to unlock secrets of a visiting celestial body—but to do so with ingenuity, efficiency, and respect for cosmic dynamics.
