Rosetta is the European Space Agency (ESA) space probe launched on 2 March 2004, now conducting a detailed study of comet Churyumov–Gerasimenko (67P). The spacecraft reached the comet’s orbit and on 12 November its lander module successfully descended on 67P. It was the first time in history that a spaceship landed on a comet.

Rosetta NAVCAM image taken on 28 October 2014
Rosetta navigation camera (NAVCAM) image taken on 28 October 2014 at 7.7 km above the surface and 9.7 km from the center of comet 67P/Churyumov–Gerasimenko.
Image by ESA/Rosetta/NAVCAM. CC BY-SA IGO 3.0

“This is the first unambiguous detection of glycine at a comet.” <...> “At the same time, we also detected certain other organic molecules that can be precursors to glycine, hinting at the possible ways in which it may have formed.”

Kathrin Altwegg (Principal Rosinna investigator) 27 May ESA report.

ESA’s Rosetta spacecraft has been probing the comet for almost two years. The scientific conclusions are that critical ingredients for life have an origin in comets. Among those ingredients are amino acids that were brought by asteroids and comets to the recently cooled Earth following its early development phase.
One of those amino acids is Glycine, which is commonly found in proteins and is an essential component of DNA and cell membranes.

“The importance of comets for the origin of life on Earth has been advocated for many decades. Amino acids are key ingredients in chemistry, leading to life as we know it. Many primitive meteorites contain amino acids, and it is generally believed that these are formed by aqueous alterations.” <...> “We report the presence of volatile glycine accompanied by methylamine and ethylamine in the coma [atmosphere] of 67P/Churyumov-Gerasimenko measured by the ROSINA (Rosetta Orbiter Spectrometer for Ion and Neutral Analysis) mass spectrometer, confirming the Stardust results. Together with the detection of phosphorus and a multitude of organic molecules, this result demonstrates that comets could have played a crucial role in the emergence of life on Earth.”

Research article published by the American Association for the Advancement of Science.