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How would humanity respond if an asteroid headed for Earth? NASA answers
NASA is actively working on planetary defence against asteroids that could threaten Earth. Their new documentary highlights efforts being made.
Asteroids are unpredictable and can cause massive damage if they collide with Earth. NASA is taking this threat seriously and is working to mitigate - and even deflect - asteroids that may pose a danger. This effort is highlighted in NASA’s new documentary Planetary Defenders, which focuses on the Planetary Defense Coordination Office. The office is responsible for detecting, tracking, and, if necessary, deflecting asteroids and comets that could come dangerously close to Earth.
The urgency of planetary defense was underscored in 1994 when the comet Shoemaker-Levy 9 collided with Jupiter, dramatically demonstrating the potential impact of such objects. In response, Congress tasked NASA with identifying 90% of all near-Earth objects (NEOs).
“We've discovered more than 30,000 near-Earth objects so far, and we're discovering hundreds more every year,” says Vishnu Reddy, professor of planetary science at the University of Arizona.
Planetary defence
The process begins with wide-field telescopes that scan the night sky. NASA-funded facilities take multiple images over time and use software to detect moving objects. These survey telescopes then send their measurements to the Minor Planet Center at Harvard, which consolidates data from global observatories into a public catalog.
The Jet Propulsion Laboratory’s Center for Near-Earth Object Studies (CNEOS) then evaluates the potential impact risk of these objects, calculating their orbits over a 100-year period and issuing alerts as needed.
NASA also uses radar systems like the Goldstone Solar System Radar to estimate an asteroid’s size, shape, rotation, and trajectory. High-powered radar waves are bounced off the asteroid’s surface, providing detailed information about its characteristics.
“The race is to figure out how we can get more data so that we can determine which way it's actually going,” says Dr Federica Spoto, project scientist at the Minor Planet Center.
Mission that proved asteroids can be deflected
The Double Asteroid Redirection Test (DART) marked a historic milestone in planetary defense, serving as the first real-world test of asteroid deflection via kinetic impact. The spacecraft intentionally crashed into the moonlet of the asteroid Didymos and successfully altered its orbit by 32 minutes. This proved that, given sufficient time, an asteroid’s trajectory can indeed be changed.
Beyond technological capabilities, the mission emphasized the importance of timing. Early detection remains crucial for effective mitigation. This includes conducting what are known as reconnaissance missions to better understand an asteroid’s composition.
