GIADA analyses the comet's dust
The probe Rosetta continues on its mission to explore the comet 67P Churyumov-Gerasimenko, which at the moment finds itself just 277 million kilometres from the Sun.
Following the historic landing on the 12th November 2014, the lander Philae went into “hibernation” to wait for new energy from the Sun as soon as the trajectories of the comet permits. In the meantime, the analysis activities using the instruments aboard the probe continue.
A great deal of data has already been gathered, like for example that the nucleus of comet 67P does not have a magnetic field. While waiting for Philae to come out of hibernation, the star of the scientific mission at this time is GIADA – the Grain Impact Analyser and Dust Accumulator – designed and built by Selex ES.
This is a sophisticated instrument that has the task of analysing the dust and particles in the comet’s coma, which is beginning to form around the nucleus of the comet as it draws closer to the Sun. In reality, GIADA has already be working for several months and by August 2014 had already collected more than 70 grains of this dust, with sizes ranging from one thousandth to one tenth of a millimetre, and analysed their physical and dynamic properties, the relationships between the gas and granular material as well as the velocity of the particles themselves.
In January 2015 the instrument had counted around 850 particles and identified two types of dust: one type made up of compact grains and the other consisting of extremely low density fragments. Thanks to the analysis conducted by GIADA, this second type of comet dust offers an explanation of the phenomenon of fragmentation of the particles and revealed the presence of a type of dust whose origins could lie in the very distant past of our Solar System.
GIADA will keep on providing this type of information and results up until December 2015 when, after the comet reaches its minimum distance from the Sun in August, Rosetta’s principal mission will have been completed.
Selex ES technology has accompanied the Rosetta mission throughout every phase, helping to understand the mysteries of comets, thanks also to the measurements provided by the other instruments installed both on the probe and on the lander, Philae.
Over recent weeks the navigation camera, or NAV-CAM – has been taking high definition images as the probe orbits around the comet, sending spectacular photographs of this extraordinary voyage back the Earth as well as showing the increasing amounts of dust emitted by the comet over the last six months.
VIRTIS – the Visible and Infrared Thermal Imaging Spectrometer – the instrument that observes and determines the composition of the comet’s solid nucleus by analysing its thermal characteristics, has obtained detailed information about the actual composition of the comet’s nucleus, through spectral analysis during the observations conducted between August and December.
Thanks to information obtained about the low reflectivity of 67P, VIRTIS has demonstrated that the presence of frozen water in the shallower layers of the nucleus is extremely limited or absent. This does not necessarily mean that the comet isn’t rich in water, but only that the initial strata (little more than a millimetre thick) have no ice, a detail most likely associated with the recent history of the comet.
And so Rosetta continues on this exciting voyage to discover the secrets of the comet and the origins of the Solar System, of which these heavenly bodies are considered a veritable testimony.