Complex molecules discovered on Pluto

Posted by Kate Taylor

Scientists have discovered new evidence indicating that there may be complex hydrocarbons on the surface of Pluto.

The new Cosmic Origins Spectrograph on the Hubble Space Telescope has discovered a strong ultraviolet-wavelength absorber on the planet.

This indicates the presence of complex hydrocarbon and/or nitrile molecules lying on the surface, says a team from Southwest Research Institute and Nebraska Wesleyan University.

The chemicals may be produced by the interaction of sunlight or cosmic rays with surface ices known to exist on Pluto, including methane, carbon monoxide and nitrogen.

"This is an exciting finding because complex Plutonian hydrocarbons and other molecules that could be responsible for the ultraviolet spectral features we found with Hubble may, among other things, be responsible for giving Pluto its ruddy color," says Dr Alan Stern of SWRI.

The team also discovered evidence of changes in Pluto's ultraviolet spectrum compared to Hubble measurements dating from the 1990s. The changes could simply be because different terrains are now being seen; alternatively, they could be caused by other effects, such as changes in the surface related to a steep increase in the pressure of Pluto's atmosphere during that same time span.

"The discovery we made with Hubble reminds us that even more exciting discoveries about Pluto's composition and surface evolution are likely to be in store when NASA's New Horizons spacecraft arrives at Pluto in 2015," says Stern.