NASA’s Hubble Space Telescope has reportedly discovered evidence of complex organic compounds on the surface of Pluto.
“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,” said study leader Alan Stern, of the Southwest Research Institute in Boulder, Colorado.
Using the Cosmic Origins Spectrograph, which was installed aboard the Hubble Space Telescope in 2009, the researchers said Wednesday that they have discovered a strong ultraviolet-wavelength absorber on the distant dwarf planet. NASA researchers said the discovery is the latest evidence to point to the possibility of complex hydrocarbon molecules lying on the surface.
The compounds in question may well be organics, possibly complex hydrocarbons or nitrogen-containing molecules, researchers said. The dwarf planet Pluto is known to harbor ices of methane, carbon monoxide and nitrogen on its surface. The ultraviolet-absorbing chemical species may have been produced when sunlight or super-speedy subatomic particles known as cosmic rays interacted with these ices, researchers said.
The team also discovered evidence of changes in Pluto’s ultraviolet spectrum compared to Hubble measurements from the 1990s. The changes may be related to differing terrains seen now versus in the 1990s, or to 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.
While the dwarf planet may hold evidence of organic compounds, it does not mean that life is present. Pluto is composed primarily of rock and ice and is relatively small: approximately a fifth the mass of the Earth’s Moon and a third its volume. The planet’s orbit equates to 248 Earth years, and it remains 5.9 billion km from the sun. The team suggested that the chemicals could be produced as weak sunlight or cosmic rays bombard Pluto and break apart methane and carbon monoxide ice on the dwarf planet.
The team noted that the discovery was made possible with the assistance of the Hubble Space Telescope, adding that the latest discovery should be a sign that the telescope remains a key feature for understanding planets and the outer reaches of the solar system.
“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.
The discovery comes as NASA has set its sights on Pluto. The space agency has launched New Horizons, a mission designed to fly by Pluto and its moon Charon and transmit images and data back to Earth. The primary objectives are to characterize the global geology and morphology and map the surface composition of Pluto and Charon and characterize the neutral atmosphere of Pluto and its escape rate.
The probe will also study the time variability of Pluto’s surface and atmosphere, imaging Pluto and Charon in stereo, mapping the terminators and composition of selected areas of Pluto and Charon at high-resolution, characterizing Pluto’s upper atmosphere, ionosphere, energetic particle environment, and solar wind interaction, searching for an atmosphere around Charon and characterizing its energetic particle environment, refining bulk parameters, orbits, and bolometric Bond albedos of Pluto and Charon, searching for additional satellites and rings, and characterizing one or more Kuiper Belt Objects.