NASA tests a defence system on simulated Earth-killing Apophis asteroid; Check results

What if a planet-killing asteroid is hurtling rapidly towards Earth? Would we be prepared enough to survive the space rock using planetary defence systems? To answer these basic yet highly important questions, over 100 astronomers including National Aeronautics and Space Administration (NASA) scientists simulated an impact scenario with the actually existing Apophis asteroid. This test was carried out last year out to determine our defence readiness against such "potentially hazardous" asteroids.

During the simulated scenario, the astronomers removed Apophis from the planetary defense-monitoring database to see whether it could be properly detected again. They also pretended that they found the asteroid, which was discovered in 2014, for the first time in order to practise for a quick response to avoid an impact. Organised by NASA's Planetary Defense Coordination Office and the International Asteroid Warning Network, the exercise and its results have been published in the Planetary Science Journal.

Did they succeed?

To track the path of the approaching asteroid, the experts analysed data of the Apophis asteroid during its recent flyby which occurred in December last year. Vishnu Reddy, associate professor at the University of Arizona said in a statement, "This real-world scientific input stress-tested the entire planetary defense response chain, from initial detection to orbit determination to measuring the asteroid’s physical characteristics and even determining if, and where, it might hit Earth.

Thanks to observations from a number of observatories including the Near-Earth Object Wide-field Infrared Survey Explorer (NEOWISE) telescope, not only the astronomers discovered the asteroid again, its chances of hitting Earth were continually reassessed as it was tracked, and the possibility of impact was ruled out. NASA underscored the role of NEOWISE saying that the timely detection would not have been possible without it. NEOWISE is a space telescope and provides infrared observations that would not have been possible from the ground because moisture in the Earth’s atmosphere absorbs light at these wavelengths.

"NEOWISE was able to confirm Apophis' rediscovery while also rapidly gathering valuable information that could be used in planetary defense assessments, such as its size, shape and even clues as to its composition and surface properties," said Akash Satpathy, another contributor to the study. The study revealed that the astronomers were also able to estimate the impact energy of Apophis and potential impact locations on Earth. Experts say that data collected beforehand could help prepare defence systems and caution disaster agencies about possible evacuation efforts.

Measuring 340 meters across, the Apophis asteroid was initially thought to strike Earth around 2029 or maybe later, however, follow-up observations confirmed later that Earth has no risk from the space rock for at least the next 100 years. However, as far as survival from a giant asteroid is concerned, another study carried out by NASA and the European Space Agency (ESA) claimed that Earth would be defenceless even if the asteroid is discovered six months prior to the impact.

Image: NASA