Houston - Nasa's Cassini spacecraft has found propylene, a chemical used to make household plastic containers, on Saturn's moon Titan, the space agency said."This is the first definitive detection of the plastic ingredient on any moon or planet, other than Earth," Nasa said.A small amount of propylene was identified in Titan's lower atmosphere by Cassini's composite infrared spectrometer, which measures heat radiation, the agency reported in Monday's edition of the Astrophysical Journal Letters.By isolating the same signal at various altitudes within the lower atmosphere, researchers identified the chemical's unique thermal fingerprint with a high degree of confidence, Nasa said."This chemical is all around us in everyday life, strung together in long chains to form a plastic called polypropylene," said Conor Nixon, a scientist at Nasa's Goddard Space Flight Center in Greenbelt, Maryland, and lead author of the paper."That plastic container at the grocery store with the recycling code 5 on the bottom - that's polypropylene."The chemical is also used to make car bumpers and other consumer products.The discovery could help scientists understand the "chemical zoo" that makes up Titan's hazy brownish atmosphere, said Scott Edgington, Cassini's deputy project scientist at Nasa's Jet Propulsion Laboratory in Pasadena, California.The Cassini-Huygens mission is a co-operative project of Nasa, the European Space Agency and the Italian Space Agency.