Scientists estimate that about 35,000 other object ,too small to detect with redar but detectable to us on the Earth ,but since it is traveling at average relative speeds of six miles per second ,it can severely damage expensive equipment in a collision .This threat was dramatized by a cavity one-eight of an inch in diameter created in a window of a united states space shuttle in1983 .The pit was determind to have been caused by a collision with a speck of paint traveling at a speed of about two to four miles per second .The window had to be replaced