An asteroid with dimensions equivalent to a cruise ship will make one of the largest predicted encounters between Earth and an asteroid by science, scheduled for April 13, 2029. This event will occur in a region near the planet but does not pose a collision danger.
With an estimated diameter of about 375 meters, the asteroid Apophis will pass at a distance of approximately 32 thousand kilometers from the Earth's surface, a proximity smaller than the orbit of many geostationary satellites. It is estimated that about 90% of the world's population may witness this phenomenon in the sky, depending on atmospheric conditions.
Projections regarding Apophis's passage were detailed during the workshop 'Apophis T-3 Years: Knowledge Opportunities for the Science of Planetary Defense,' held in June at the University of Padua, Italy. Researchers presented maps indicating the global areas where the object's trajectory can be seen. The apparent route of the asteroid should be observed for about seven hours, starting in Australia and Asia, reaching maximum brightness over Africa, and ending over the North Atlantic.
North America will be the only region where climatic conditions will not be favorable for observation. For those in appropriate locations, Apophis will not appear as a fast meteor, but rather as a luminous point moving slowly among the stars.
Despite the notable proximity, NASA confirmed that there is no risk of impact during the 2029 approach or in the next hundred years. The great scientific interest lies precisely in the short distance between the asteroid and Earth, since a body of this size typically makes such a close pass only every five to ten thousand years, constituting a rare opportunity for the current generation.
Richard Binzel, an astronomer at the Massachusetts Institute of Technology (MIT), emphasized the historical value of the observation, stating that 'This is the first time we have been able to predict, in human history, the visible passage of an asteroid by Earth.' For him, following the movement of Apophis is a collective experience of spatial contemplation and an opportunity to understand Earth's position in the universe.
The approach will also serve to expand knowledge about these celestial bodies. The European Space Agency is preparing the Ramses mission, which will approach the asteroid before the passage and monitor it during the close flyby. The purpose of this mission is to investigate possible modifications caused by Earth's gravity on the asteroid, covering changes in its shape, rotation, surface, and internal structure.
Additionally, NASA has reassigned the OSIRIS-APEX spacecraft, formerly known as OSIRIS-REx, to study Apophis after the approach. This probe had been responsible for collecting samples from the asteroid Bennu before taking on the new task. According to ESA, gravitational influence can cause transformations, such as the displacement of surface materials and the exposure of elements preserved since the formation of the Solar System, more than four billion years ago.
Patrick Michel, research director at the CNRS in the Observatoire de la Côte d’Azur, highlighted the scientific uniqueness of the moment in an ESA statement, affirming: 'For the first time, nature is bringing one of them to us and conducting the experiment on its own. All we need to do is observe.' The findings from these missions may support future planetary defense studies, providing data on asteroid composition, structure, and behavior to aid international strategies against objects on collision courses.
The European Space Agency (ESA) has completed a crucial phase of the Hera mission by updating the spacecraft's software intended for the study of the asteroids Dimorphos and Didymos. This procedure was conducted remotely, as the craft was already on a trajectory in deep space.
The mission control team, based at the European Space Operations Centre (ESOC) in Darmstadt, Germany, executed the update by sending commands via space communication. This achievement was made despite the challenge of managing a vehicle located approximately 140 million kilometers from Earth.
With the new system, the Hera spacecraft will be able to utilize its autonomous navigation capabilities, test its remaining instruments, and establish contact with two small satellites that will be released during the mission. This update prepares the craft for the approach and analysis phase of the targets.
Implementing the new software required a series of meticulously planned tests and procedures. Since Hera was already traveling at over 12 kilometers per second, the personnel did not have physical access to the equipment, necessitating remote instruction via 35-meter communication antennas.
After sending the commands, the team performed two reboots of the onboard computer. The system uses parallel processors designed to ensure redundancy, allowing for the isolated evaluation of each component before resuming full operations.
Anna Schiavo, Hera operations engineer, clarified that this update marks the final preparation of the craft for the asteroid phase, as the software will enable the activation of pending instruments and autonomous systems essential for the exploration of celestial bodies.
Before launch, the program underwent an extensive validation campaign at ESOC, which lasted about a year and a half. This campaign included 50 days of ground activities and navigation simulations around the asteroids, as well as interaction with the CubeSats that will accompany the mission.
Sylvain Lodiot, responsible for ESA's planetary defense and outer solar system operations, reported that the tests were conducted using a functional replica of Hera at the company OHB, located in Bremen, Germany. This equipment simulated flight scenarios, asteroid models, and communication between the main spacecraft and the small satellites.
Caglayan Guerbuez, spacecraft operations manager, noted that Hera was launched in October 2024 without the final software version due to dependence on a specific window to take advantage of a close pass near Mars. A delay in the launch could extend the arrival at the destination by several years.
Hera is ESA's first planetary defense mission and focuses on the asteroid Dimorphos, which orbits the larger body known as Didymos. Scientific interest in this system arose after an unprecedented human intervention in space.
In September 2022, the DART spacecraft, belonging to NASA, collided with Dimorphos, resulting in an alteration of its orbit. Although this event was monitored by ground telescopes, the detailed impacts of the collision on the asteroid's surface and structure are still unknown.
The Hera mission will conduct a detailed inspection of the affected area to investigate the consequences of the impact, thereby transforming the kinetic impact experiment into a clearer model of planetary defense. The ultimate goal is to increase knowledge about possible response methods should a space object pose a future threat to Earth.
