In an urgent and high-stakes endeavour, NASA scientists are in the final stages of their relentless mission to prevent a potentially devastating asteroid collision with Earth, projected to occur in next 159 years.
An asteroid named Bennu will make a close flyby of Earth on September 25, 2135. During this encounter, Earth's gravitational pull will influence Bennu's trajectory, making it challenging to precisely predict its future path. According to NASA, there exists an exceedingly small probability that Bennu might traverse a "gravitational keyhole" during this pass—a region in space that could potentially steer it towards a collision with Earth in the late 22nd century.
Bennu has witnessed over 4.5 billion years of our solar system's history. Its materials date back nearly 10 million years after the formation of our solar system, making it a vital piece of the puzzle in understanding the origins of our rocky planets and the potential for organic molecules crucial to the emergence of life on Earth.
Measuring only about half a kilometre wide at its equator, Bennu appears diminutive in comparison to the planets. It's even slightly narrower than the Empire State Building is tall. In contrast, Mercury, the smallest planet, spans over 3,000 miles in diameter. Bennu orbits the Sun at an average distance of approximately 105 million miles, just slightly farther than Earth's average orbital distance of 93 million miles.
Bennu follows an orbital path that takes it around the Sun every 1.2 years, completing a full rotation on its axis every 4.3 hours. It approaches Earth closely every six years, with its distance from our planet varying during these encounters. Bennu's orbital plane is tilted approximately 5 degrees relative to Earth's.
Bennu likely originated from a much larger carbon-rich asteroid that fragmented about 700 million to 2 billion years ago, a relatively recent event in geological terms. This asteroid family member likely formed within the Main Asteroid Belt between Mars and Jupiter before migrating closer to Earth due to gravitational interactions with giant planets and the long-term Yarkovsky effect.
Bennu's distinctive spinning-top shape remains a scientific enigma. Its composition, resembling carbon-rich meteorites found on Earth, suggests it comprises some of the solar system's oldest materials, originating from massive dying stars and supernova explosions. These materials underwent transformations through heat during the cataclysmic collision that gave birth to Bennu. Meteorites akin to Bennu often contain organic material, though not necessarily of biological origin.
Bennu held surprises for scientists when NASA's OSIRIS-REx spacecraft arrived in December 2018 for a sample collection mission. The expected sandy beach-like surface gave way to a rugged terrain strewn with boulders. Additionally, Bennu proved to be an active asteroid, ejecting particles of rock into space, defying initial expectations based on observations from telescopes both on Earth and in space.
While quantifying the exact likelihood of this occurrence is complex, recent data gathered by NASA's OSIRIS-REx spacecraft has enabled scientists to refine their models of Bennu's orbital evolution, resulting in a calculated 1 in 2,700 (0.037%) chance of Bennu impacting Earth on September 24, 2182. However due to the formation composition and speed of the Asteroid, the collision, if happens, will equivalent to the power and energy released by the explosion 22 atomic bombs.
Seven years ago, NASA embarked on a visionary quest, launching the OSIRIS-REx spacecraft on a daring mission. The objective: gather vital samples from asteroid Bennu to acquire invaluable data to thwart the impending celestial catastrophe.
In a remarkable feat of precision and ingenuity, NASA's OSIRIS-REx spacecraft, in 2020, triumphantly descended upon the treacherous surface of asteroid Bennu, executing a Touch-and-Go manoeuver to procure rocky material from a designated sample site known as Nightingale.
The culmination of this ambitious mission is drawing near. The precious samples collected from asteroid Bennu by OSIRIS-REx are poised to return to Earth next week, scheduled to re-enter the atmosphere at 3.42 pm BST on September 24, 2023. The samples from the asteroid will help scientists to study and identify the deflection points off the space rock from Earth’s trajectory in case it comes on a collision course.
As the critical moment approaches, a refrigerator-sized capsule containing the priceless samples of Bennu will endure a fiery re-entry into Earth's atmosphere, hurtling through space at an astonishing speed of nearly 28,000 mph. During this fiery descent, the capsule will be subjected to temperatures twice as scorching as molten lava.
Beyond the critical task of safeguarding Earth from a potentially catastrophic collision, NASA's mission to Bennu holds the promise of unearthing profound insights into the origins of life on our planet. This epic undertaking resonates with the 1998 cinematic spectacle, "Armageddon," where humanity defied the cosmos to protect its home world.