What happened?
On 26 September, as part of the planetary defence testing method, NASA’s Double Asteroid Redirection Test (DART), a spacecraft designed to smash into an asteroid, collided with an asteroid categorized as a Near-Earth Object. The target of the spacecraft was Dimorphos, which is 11 million kilometres away, orbiting a larger asteroid Didymos, in a binary system. DART spacecraft, weighing around 600 kg and travelling at a speed of 22,000 kilometer per hour, collided with Dimorphos to achieve a kinetic impact as part of humanity’s first-ever planetary defence research. DART managed to alter the orbit of Dimorphos by almost a minute.
 
On 29 September, the Hubble Space Telescope and Webb Space telescope confirmed the alteration by observing plumes of material streaming away from the binary system consisting of Dimorphos. In visible light the impact created collision of DART increased the brightness of the binary system by three times, confirming a successful kinetic impact. NASA Administrator Bill Nelson said: “DART is turning science fiction into science fact and is a testament to NASA’s proactivity and innovation for the benefit of all.”

What is the background?
First, practising planetary defence. Astronomers estimate that there are about 1,000 near-Earth asteroids close to a half-mile wide and larger and big enough to cause a global disaster if they struck the Earth. About 95 per cent of these large asteroids have been identified. In contrast, it is predicted that there are roughly 25,000 near-Earth asteroids that are 500 feet wide or larger, but only about a third of these asteroids have been found. Dimorphos which poses no threat to Earth was used like a test to achieve a desired deflection in the orbit.
 
Second, feeding the computation of space generated kinetic impact from the back end.  The objective for DART was also to be able to observe the post-impact changes and effects in the binary system, and train the computer-generated simulations of similar possible kinetic impacts. All models of sub-solar systems can be observed and predicted mathematically, DART would be the first ever evidence of real-time data on recording and observing the kinetic impact. Mathematics and computer science will now have a real-time template to compute and learn from raw data in post-impact assessment and effects as well.
 
Third, the space mission was a proof and culmination of the most sophisticated technologies. As part of inter-agency planetary defence, it carried, a DRACO Camera, used for optical navigation to determine and measure the geologic context as DART gained on the Dimorphos, SMART Nav (Small-body Maneuvering Autonomous Real-Time Navigation) which took control of DART in the last part of the journey, and NEXT–C (NASA’s Evolutionary Xenon Thruster–Commercial), an ion thruster and lastly, Roll-Out Solar Array (ROSA).

What does it mean?
The success of the mission demonstrates NASA’s ability in low-cost space missions in planetary science. NASA has embarked on planetary science experiments which entail less cost and within scope of time affordability. DART is the first ever humanity’s stray into planetary defence research and looks into the impact of planetary defence in the terrain of gravity of systems. 
 
The history of the mission and coordination showed that the US contributed and led the mission on its part. The efficiency and technology demonstration has placed NASA into domains of research from which space agencies of other nations will pick up. It might seem like a technological (arms) race, but it will likely make the planet more secure.