Linda Moulton Howe reports that the Principal Investigator for the Dawn space probe mission sent to the asteroid Ceres, Christopher Russell, Professor of Geophysics and Space Physics at UCLA cannot discuss the new high resolution images from Ceres because they have been embargoed by the science journal Nature. He may not discuss the images until after the journal publishes its article about them.
Professor Russell was able to discuss the issue of Ceres’ strange bright spots, appearing prominently in both the large crater known as ‘Occator’, of which is 60 miles (90 km) across and 2 miles (4 km) deep, and on the slopes of an extremely strange, pyramid-shaped mountain that is 4 miles (6 km) tall. These spots, as described by professor Russell, appear to be a powdery substance that is deposited on the surface of the crater. The substance has an albedo, which is the fraction of the light being reflected from it, of about 50%. This is extremely bright, in contrast to Ceres’ extremely dark surface albedo of only approximately 4-8%.
Infrared spectroscopy readings of the substance have been taken, but due to an apparent malfunction, he is unable to positively identify what the powder is made of. He suspects it is a form of salt, possibly from a sub-surface water source, that has come to the surface, and following the evaporation of it’s host water, fell back to the surface of the crater, in a manner similar to snow. He has, for the time being, ruled out the probability that the substance is water-ice, due to it’s apparent persistence on the surface: comparisons with images taken of the same feature by the Hubble Space Telescope in 2004 indicates that there has been no change in it’s appearance, and water-ice would have sublimated in the eleven years since.
Professor Russell has been given no publication date for the article in Nature, as it is still under review. The Dawn spacecraft will also settle into an even lower orbit around Ceres in December of this year, of which will allow it to take even higher-resolution images, of which will hopefully shed more light on the enigma this dark planetoid presents.
Whether or not a journal has the right to embargo images taken by a publicly funded NASA project is an open question. Denying the public its right to view these images is a direct violation of the NASA Charter, and so probably could not survive a legal challenge.