OPENSPACE 24: The Future of Space Exploration | Page 32

Interview Marco Micheli, Astronomer and NEO Observer NEOS AND THE RISK OF COLLISION WITH EARTH During the past few years, the discovery of new near-earth objects (NEOs) has grown significantly, with new and more powerful telescopes finding many smaller objects of 10 meters or less hurtling through space. Those objects are obviously not as threatening as the km-sized ones that can cause global A s an astronomer and NEO observer, Marco Micheli has been studying NEOs for over 20 years. He works at the ESA Space Situational Awareness (SSA)-NEO Coordination Centre in Frascati, Italy, where he observes those asteroids and comets that are considered most dangerous to our planet. We spoke with him about NEO research and the risk of collision with Earth. consequences if they impact our planet, but they can still cause significant local damage if they impact a populated area, which is what occurred in Russia in 2013 when an asteroid impact injured about 2000 people. What are the odds of an NEO impact happening in the near future? Among the objects we know, the one with the highest impact probability will come close to Earth in 2095. The risk of this tiny object (10 m in diameter) colliding with Earth is around 10 percent. Even if it were to collide, it would likely disintegrate in the atmosphere and not cause any damage. Among the unknown objects, statistically, we can expect that an object of about 50 m in diameter may hit Earth every few centuries. Larger objects are rarer but can cause large devastation, and it is important to discover them as far in advance as possible. What would be the effect of an NEO hitting the Earth? The actual threat of a NEO hitting the Earth depends mostly on its size. On the smaller end, objects a few meters in diameter often just result in a bright meteor in the sky and sometimes the fall of fragments on the ground. Professor Richard Wainscoat (right) and Marco Micheli (left), astronomer and NEO observer. Credit: University of Hawaii Institute for Astronomy. 32 Larger objects from 10 to 20 meters in diameter can cause significant damage. An object of a few hundred meters in diameter could create a major disaster on a regional scale,