A new picture of the composition of comets is emerging with the help of 21st century technology available at Diamond, the UKs national synchrotron light source, in Oxfordshire. We already know that comets played a significant role in ensuring that conditions were right for life on Earth. Most of the icy, small planetary bodies that otherwise became comets went into forming the gas giant planets in the outer Solar System but some were ejected from the vicinity of the largest planets. Of these, a fraction ended up in the inner Solar System bringing water and biogenic elements of interest to Earth. Without this cometary transport, life on Earth may never have had a chance to start.
An asteroid cruising through the solar system six years ago seemed just another silent ship sailing in the eternal darkness, until it flared up with the startling brightness of a comet's halo. Just like that, the space rock known as NEO 2001 OG108 was re-classified as C/2001 OG108 in 2002, from asteroid to comet. Scientists now suspect that 5 to 10 percent of other Near Earth Objects (NEOs) may also be comets lurking in disguise as asteroids.