Ptolemy is the first example of a new concept in space instrumentation, which has been devised at PSSRI to tackle the analytical challenge of making in situ isotopic measurements of solar system bodies. The concept is termed "MODULUS" which is taken to mean Methods Of Determining and Understanding Light elements from Unequivocal Stable isotope compositions. MODULUS was named in honour of Thomas Young, the initial translator of the Rosetta stone, whose name is immortalised by the measure of elasticity known as Young's Modulus. The philosophical approach of MODULUS was originally selected for ESA's Rosetta mission in two guises, with instruments known as Ptolemy (located on the lander) and Berenice (located on the orbiter).
The scientific goal of using Ptolemy is to understand the geochemistry of light elements, such as hydrogen, carbon, nitrogen and oxygen, by determining their nature, distribution and stable isotopic compositions. The picture on the right shows the lander instrument, Ptolemy, which was designed and developed in conjunction with the Rutherford Appleton Laboratory. The size of a shoebox and weighing just 4.5 kg, Ptolemy will use gas chromatography / mass spectrometry (GCMS) techniques to investigate the comet surface and subsurface.
For more information on the Ptolemy experiment contact
Dr Simeon Barber.
