Earth Science: Geology, the Environment, and the Universe

Chapter 29: Our Solar System

Problem of the Week

Near Earth Objects

Are hurtling chunks of rock and ice—the leftovers from the creation of the solar system—dangerous? Are comets and asteroids a part of these "leftovers" from the solar system’s formation? They are ice and rock (comets) and rock (asteroids), they do hurtle through space, and they are believed to be remnants from the formation of the solar system. As for being dangerous, that’s a matter of opinion. However, there are several scientists who are studying the asteroids and comets whose orbits cross Earth’s orbit. These objects, periodic comets and asteroids, are referred to as Near-Earth-Objects, or NEOs. They are studied to identify those that may pose an impact threat to Earth.

Earth’s atmosphere is constantly bombarded by particles, and the larger the particle, the greater the effect. Examples of these bombardments are meteors streaking through the night sky. The remnants of large, but ancient impacts can be seen in places like the Barringer Meteor Crater in Arizona. In recent history, an example of a "small" impact of an asteroid took place in the Tunguska wilderness of Siberia in June 1908. Though the chance of being hit by one of these objects seems small, if one were to hit, the effect could be catastrophic. A comparable event would be a massive nuclear attack. The United States government has funded the Spaceguard Survey Program to identify and track Near Earth Objects.

Problem:

The Spaceguard Survey Project was officially funded and began operation in 1998. The objective of the survey is to discover and track 90% of the Near Earth Asteroids (NEAs) with a diameter greater than 1 kilometer within ten years, or by 2008. To date, the Massachusetts Institute of Technology-Lincoln Lab LINEAR (Lincoln Near Earth Asteroid Research) group has discovered most of the known NEAs.

• Estimated number of NEAs larger than 1 kilomter—900
• Number discovered through end of 2000—430
• Discovery rate—approximately 5/month
• Estimated completion—2012

1. Given this information, is it possible for the program to attain its goals?
2. With the goal of 90% by 2008, why is it logical that the project completion date is 2012?

*To read more about NEOs and what NASA and other groups are doing about them check out the following Web site: Asteroid and Comet Impact Hazards - http://impact.arc.nasa.gov/