Using NASA’s Spitzer Space Telescope (an infrared space observatory launched in 2003) Michael Momment and his team re-examined images of Don Quixote taken in 2009 when he was at his closest orbit to the sun and surprise! This asteroid had a coma and a faint tail. So Don Quixote now was given more attention.
It was determined that the surface is composed of silicate dust, which is similar to comet dust. Its size and low reflectivity is very comet-like. Apparently this discovery leads scientists to believe that this near-Earth object contains a lot of ice, CO2/CO and further implies that CO2 and water may be present in other near-Earth asteroids as well. Oh, another thing, seems that while there are number of times that Don Quixote’s coma or tail were not evident, comets actually need to be near the sun as it is the Sun’s radiation that cause the tail to form. “They” are even saying that Don Quixote holds implications for the water that exists here on earth. Apparently it hold 100 billion tons of water (around the same amount held in Lake Tahoe). So the mighty Asteroid that would be a comet has gained some powerful friends.
What are the near-Earth objects for the most part? 5% of these objects are believed to be ‘dead’ comets. (comets that have shed all their water and CO2) This is just an educated guess but these near-Earth objects that are assumed to be dead, will probably get checked out again!