Greek mythology in popular culture elements tantalum and niobium are always found together in nature, and have been named after the King Tantalus and his daughter Niobe. The element promethium also draws its name from Greek mythology, as does titanium, which was named after the titans who in mythology were locked away far underground, which reflected the difficulty of extracting titanium from ore. The U.S. Apollo Space Program to take astronauts to the moon, was named after Apollo, based the god's ability as an archer to hit his target and being the god of light and knowledge. Oceanographer Jacques-Yves Cousteau named his research ship, a
Greek mythology in popular culture of the god of medicine, Asclepius. Today's medical professionals hold a similarly honored position as did the healer-priests of Asclepius. The American colonial revolutionary, Thomas Greenleaf, subtitled his newspaper ""The Argus"" after the mythological watchman and took the slogan "We Guard the Rights of Man." The Pegasus appears frequently on stamps, particularly for air mail. In 1906, Greece issued a series of stamps featuring the stories from Hercules' life. Australia commemorated the laying of an underwater cable linking it to the island of Tasmania through a stamp featuring an image of Amphitrite. The United States military has used Greek mythology