In about five and a half years, an asteroid with a width comparable to the Empire State Building will pass through space at a distance of 32,200 km from Earth.
The OSIRIS-APEX spacecraft, launched by NASA in 2016, is expected to be present to observe and study this rare encounter. The mission, directed by scientists from the University of Arizona, aims to provide insights into planet formation and knowledge for developing defense systems that could help Earth avoid a potential “doomsday” in the future.
The NASA OSIRIS-APEX spacecraft is moving away from Earth to begin its five-year journey towards a rendezvous with the asteroid Apophis in 2029. (Photo: NASA).
When discovered in 2004, the asteroid Apophis, named after the demon serpent embodying evil and chaos in ancient Egyptian mythology, was believed to pose a significant threat to Earth. However, subsequent detailed observations have ruled out any impact risk to Earth for at least another century.
Nevertheless, the position and trajectory of this “super asteroid” in 2029 will still bring it relatively close to Earth—less than one-tenth the distance to the Moon and within the orbit of some geostationary satellites.
Apophis, elongated and somewhat peanut-shaped, is a rocky asteroid believed to be composed mainly of silicate materials along with iron and nickel. Michael Nolan, the deputy principal investigator, stated that Apophis has a width of about 340 meters and will pass over Earth’s surface at a distance of 31,860 km on April 13, 2029, making it visible to the naked eye for several hours.
Nolan said, “It won’t be a spectacular sight, but it will appear as a point of light in the night sky over Africa and Europe.”
It is estimated that an asteroid of this size passes near Earth about once every 7,500 years. The flyby of Apophis is the first such encounter predicted in advance.
The gravitational pull of Earth may cause measurable disruptions to the surface and motion of this asteroid, altering its trajectory and rotation. Gravity may also trigger landslides on Apophis, dislodging rocks and dust particles to create a comet-like tail.
The OSIRIS-APEX spacecraft is set to observe the asteroid’s flyby as it approaches and eventually rendezvous with Apophis. These images and data will be combined with ground-based telescope observations to detect and quantify how Apophis has changed as it passes near Earth.
The OSIRIS-APEX spacecraft is expected to get close to Apophis for up to 18 months—orbiting, maneuvering around it, and even hovering above its surface, using rocket propulsion to push away loose material and reveal what lies beneath.
Like other asteroids, Apophis is a remnant of the early solar system. Its minerals and chemistry have remained largely unchanged for over 4.5 billion years, providing clues about the origins and development of rocky planets like Earth.
Nasa previously crashed a spacecraft into a small asteroid last year in a test aimed at protecting Earth from potentially destructive celestial bodies in the future. This was the first time humanity has altered the natural motion of a celestial body in history.
Apophis is significantly larger than that asteroid, but smaller than the asteroid that struck Earth 66 million years ago, which wiped out the dinosaurs. Nolan noted that while it is not large enough to pose an immediate threat to life on Earth, an asteroid the size of Apophis striking at supersonic speed could still devastate a city or large area, impacting oceans and causing tsunamis.
