The Terrestrial Planet Finder (TPF) is a system of powerful telescopes planned by NASA for detecting extrasolar planets with earth-like characteristics. It was postponed several times and finally cancelled in 2007. Each of the Terrestrial Planet Finder project telescope would use a different means to achieve the same goal: to block the light from a parent star in order to see its much smaller, dimmer planets. That technology challenge has been likened to finding a firefly near the beam of a distant searchlight. Additional goals of the mission would include characterizing the surfaces and atmospheres of newfound planets, and looking for the chemical signatures of life. In May 2004, both architectures were approved. Nevertheless, congressional spending limits under House Resolution 20 passed on January 31, 2007, by the United States House of Representatives and February 14 by the U.S. Senate have postponed the program indefinitely.