One of planetary defense‘s biggest opportunities will come as the asteroid Apophis makes its tight flyby of our planet on April 13, 2029, allowing international space missions to interact with the near-Earth object. Asteroids this size only approach this close to Earth about once every 7,500 years, making the event a rare opportunity for real-world planetary defense research.
In a new paper published in the journal Space: Science & Technology, a team of researchers analyzes the many opportunities the Apophis flyby will offer for science and planetary defense.
The closest distance between Earth and Apophis during the flyby will be a mere 38,000 kilometers, about one-tenth of the distance from the Earth to the Moon. Coordinating these planetary defense efforts among the Earth’s nations may be one of the biggest challenges as the object comes uncomfortably close.
Apophis Explained
As soon as astronomers first discovered Apophis in 2004, the asteroid’s 340-meter-wide diameter and close pass by Earth immediately made it a concern for scientists. Fortunately, it is expected that on April 13, 2029, it will safely pass our planet at a distance of close to 20,000 miles—closer than some of our weather and communication satellites, but still with no risk of an impact.
Yet the near-Earth asteroid still holds mysteries for scientists. Models of the object depend heavily on assumptions, not hard data, to predict not just its tidal effects but also its composition, size, internal structure, and spin state.
With so many open questions about the asteroid and the unique opportunity to collect data and test processes for future planetary defense operations, many countries are planning missions to Apophis, but in this new paper, the researchers note that some of these activities require increased international coordination to avoid interference.
Part of the paper synthesizes known data on Apophis, including radar observations, light-curve, and spectral data. From this data, the team then developed new predictions for the asteroid’s dust ejection, orbital and spin changes, internal structural response, and surface material displacement. These projections were crucial in the researchers’ evaluations of the feasibility of various currently proposed or authorized missions and their likely scientific value.
Apophis Missions are Gearing Up
Future Apophis missions fit into four primary categories: rendezvous, flyby sample return, and impactor experiments.
In the recent research, the team found that flyby missions should capture data at very fine scales, down to the centimeter or decimeter for surface changes and hours for changes in spin period. Additionally, these space-borne instruments should be able to measure dust ejection phenomena. Together, this data stream alone could provide important direct evidence for how such rubble-pile asteroids evolve structurally. Relatively low-cost sample return missions could push this even further.
The activities coordinated under the International Asteroid Warning Network constitute the largest multinational asteroid detection and observation effort ever assembled and are its first global joint exercise. The network will build experience responding to potentially deadly space threats in the future.
Earth Interactions
On the other hand, the asteroid’s close approach to Earth will affect Apophis as well. Our planet’s gravity is expected to alter Apophis’s orbit from an Aten-type to an Apollo-type, changing the object’s spin period and orbital uncertainty.
Additionally, roughly 1% of Apophis may experience a surface material disruption, potentially altering the object’s spectral properties by exposing fresh material.
The asteroid’s extremely low gravity may also cause it to lose surface dust to Earth’s magnetosphere, posing an electromagnetic disturbance hazard to spacecraft. Space agencies will need to monitor the situation to protect our increasingly essential space-based communications infrastructure during the event.
While there is no immediate danger to our planet, the researchers say this event is shaping up to be a pivotal moment in international space cooperation and a turning point for organized space defense.
The paper, “The Apophis Encounter in 2029: A Rare Opportunity for Planetary Science and Defense,” appeared in Space: Science & Technology on August 22, 2026.
Ryan Whalen covers science and technology for The Debrief. He holds an MA in History and a Master of Library and Information Science with a certificate in Data Science. He can be contacted at ryan@thedebrief.org.