23 Jan 2008
The first images have been taken of Mercury by Messenger's wide angle camera with enough spatial and spectral resolution to allow astronomers to determine its surface composition.
High-resolution images have been returned by the Messenger spacecraft as part of its mission to investigate Mercury. Thanks to the spacecraft's imaging system, which is equipped with 11 narrow-band color filters, astronomers are able to see Mercury's surface in a variety of high-resolution color views not previously possible.
Until now, the last images of Mercury from a spacecraft were taken during the Mariner 10 flyby missions 30 years ago, using the spacecraft's one UV and two color filters. The latest images taken using Messenger's 11 color filters are the first high-resolution spectra of Mercury's surface taken in UV, visible and near-IR light.
The range of filters allows astronomers to distinguish subtle color variation indicative of different rock types. Scientists hope that by analyzing color differences across all 11 filters, they can investigate the variety of mineral and rock types present on Mercury's surface. This will help determine how Mercury formed and evolved.
In a bid to accentuate color differences on Mercury's surface, astronomers have combined three separate images taken through filters that transmit light at 1000, 700 and 430 nm (infrared, far red and violet) in the red, green and blue channels respectively. Mercury's spectrum shows the degree to which different wavelengths of sunlight are absorbed or reflected by its surface materials. The size and color of the absorption band indicate the minerals within the surface rocks.
The Messenger spacecraft, launched in 2004, has so far conducted flybys of Earth and Venus and will start a yearlong study of its target planet Mercury in March 2011.