NASA’s Bold Endeavor to Intercept the “God of Chaos” Asteroid During Its Approach to Earth

The mission OSIRIS-APEX, formerly known as OSIRIS-REx, embarks on an investigative journey targeting asteroid Apophis, capitalizing on its 2029 close flyby of Earth. This venture follows the successful return of a sample from Bennu. OSIRIS-APEX aims to study Apophis, an “S-type” asteroid, offering valuable insights into the origins of the solar system and enhancing planetary defense strategies. The initiative is under the auspices of NASA’s Goddard Space Flight Center.

The rebranded OSIRIS-REx spacecraft is on a new mission to explore asteroid Apophis, utilizing its unprecedented near-Earth flyby in 2029, a phenomenon not witnessed since the inception of recorded history.

Upon completing its epic journey of over seven years and four billion miles to deliver a piece of asteroid Bennu to Earth, OSIRIS-REx (Origins, Spectral Interpretation, Resource Identification and Security – Regolith Explorer), a NASA mission, is already progressing towards its next target under a new moniker.

Departing Bennu in May 2021 with a sample on board, OSIRIS-REx was in excellent condition with ample fuel remaining. Consequently, rather than decommissioning the spacecraft post sample delivery, the team decided to redirect it on an extended mission to asteroid Apophis, anticipating its arrival in April 2029. NASA approved this plan, giving rise to OSIRIS-APEX (Origins, Spectral Interpretation, Resource Identification, and Security – Apophis Explorer).

This image illustrates OSIRIS-REx leaving asteroid Bennu, embarking on its two-year return journey to Earth. Credit: NASA/Goddard/University of Arizona

A Unique Opportunity at Apophis

After evaluating various potential destinations, including Venus and multiple comets, NASA settled on directing the spacecraft to Apophis. This “S-type” asteroid, composed of silicate materials and nickel-iron, contrasts with the carbon-rich “C-type” Bennu.

Apophis presents a unique opportunity due to its extraordinarily close approach to Earth on April 13, 2029. Though it poses no collision risk with Earth for this encounter or in the foreseeable future, its proximity – within 20,000 miles (32,000 kilometers) of Earth’s surface, nearer than some satellites and potentially visible with the naked eye in the Eastern Hemisphere – is a rare event.

Scientists estimate that asteroids of Apophis’ size, approximately 367 yards (about 340 meters) in diameter, approach Earth this closely only once in about 7,500 years.

These images of asteroid Apophis were captured using radio antennas at the Deep Space Network’s Goldstone complex in California and the Green Bank Telescope in West Virginia. The asteroid was then 10.6 million miles (17 million kilometers) away, with each pixel representing a resolution of 127 feet (38.75 meters). Credit: NASA/JPL-Caltech and NSF/AUI/GBO

“Amy Simon, the mission’s project scientist at NASA’s Goddard Space Flight Center in Maryland, stated, “OSIRIS-APEX will investigate Apophis immediately after its close encounter, enabling observation of any surface alterations resulting from Earth’s gravitational influence.”

The close proximity to Earth is expected to modify Apophis’ orbit and the duration of its 30.6-hour day. This encounter may also trigger seismic activities and landslides on the asteroid’s surface, potentially exposing its subsurface layers.

Dani Mendoza DellaGiustina, principal investigator for OSIRIS-APEX at the University of Arizona, Tucson, remarked, “This close approach serves as a natural experiment. Tidal forces and the accumulation of rubble pile material are key processes that may have played a role in planet formation. Understanding them could shed light on the transition from debris in the early solar system to fully-formed planets.”

Apophis is of particular interest not only for its potential to provide insights into solar system and planetary formation but also because most known potentially hazardous asteroids (those whose orbits come within 4.6 million miles of Earth) are S-types. Therefore, findings from the study of Apophis could significantly contribute to planetary defense research, a major focus for NASA.

OSIRIS-APEX: Voyage Agenda

Approximately two weeks prior to Apophis’ close approach to Earth, on April 2, 2029, OSIRIS-APEX’s cameras will commence capturing images of the asteroid. During this period, Apophis will also be under intense scrutiny from Earth-based telescopes. However, shortly after the close encounter, Apophis will be in close proximity to the Sun, making ground-based optical telescope observations challenging. This makes the spacecraft’s observations crucial for detecting any post-encounter changes.

This animation shows the orbital path of asteroid 99942

Frequently Asked Questions (FAQs) about OSIRIS-APEX mission

More about OSIRIS-APEX mission

• NASA’s OSIRIS-REx Mission
• About Asteroid Apophis
• Planetary Defense at NASA
• Understanding S-type Asteroids
• NASA’s New Frontiers Program
• Solar System Exploration Research