The truth about asteroids and comets: There’s good news and bad

Most asteroids and comets are thought to be remnant collisional fragments of the building blocks from which planets in our solar system formed around 4.5 billion years ago. Asteroids and comets from diverse regions of the solar system probably enriched the early Earth and other planets in minerals, water, and organic materials essential for the development of life. In later epochs, impacts of asteroids and comets on the Earth may have abruptly altered the course of evolution and paved the way for mankind. However, mankind should now be aware that this natural process has not ceased. In particular, the current population of so-called near-Earth asteroids contains many objects that are considered potentially hazardous. On the positive side, near-Earth asteroids may prove to be valuable sources of raw materials (metals, water, rocket propellant, etc.) for future generations. I will illustrate the significance of asteroids and comets for life on Earth and describe current research into the relevant characteristics of these bodies. This research is helping us to better understand the risk of a devastating asteroid impact on our planet: that such an impact will occur one day is beyond question, unless we develop techniques to modify the orbits of hazardous asteroids