Congress officially ordered NASA to monitor all possible "killer" asteroids in 2005, but no additional funds were given to the U.S. space agency.  Congress wants at least 90 percent of all deadly rocks that could threaten Earth to be tracked. Despite this request, NASA hasn't been given the necessary funds -- NASA officials say they've already tracked around one-third of the floating threats.

The United States remains just one of the few governments attempting to monitor threats to Earth.  Between now and 2020, according to NASA, more than $800 million must be set aside to help track asteroids.

It appears there are around 20,000 asteroids and comets that are threats to Earth, with each one at least 460 feet in diameter.  NASA only knows the locations of around 6,000 of these near-Earth objects, and wants to continue locating all threats.

It's possible floating objects that are 460 feet to 3,280 feet in diameter would be able to cause devastation on Earth, but will not destroy the entire planet.

Just five near-Earth objects have a 1-in-a-million risk or better to strike Earth leading to major damage, NASA said.  The Apophis asteroid, almost 900-feet in diameter poses a one-in-43,000 chance of hitting Earth in 2036, 2037 or 2069.

By 2020, Congress wants NASA to use ground-based telescopes -- which can be used by other researchers and space agencies for different tasks -- including the Pan-STARRS telescope in Hawaii.

Along with tracking possible threats, scientists and researchers are developing ideas on how to destroy any asteroids that could impact Earth.