Philae leaves traces at contact point two
Philae leaves traces at contact point two
This compilation shows the measurements recorded by Philae's ROMAP instrument – a magnetometer with a boom – during the second touchdown on Comet 67P/Churyumov-Gerasimenko on 12 November 2014, alongside OSIRIS images taken later, which show evidence of the key moments of Philae's contacts with the surface (and the reconstructed positions of Philae projected onto them). Signatures relative to the lander were recorded in the magnetometer data from the ROMAP boom when the boom physically moved by hitting an obstacle on the surface, bending slightly (the boom protrudes 48 centimetres from the lander). This produced a characteristic set of 'peaks' in the ROMAP data, which provided an estimate of the duration of Philae's penetration of the ice. The data could also be used to estimate the acceleration of Philae during these contacts. They show that Philae spent almost two full minutes at touchdown point two and made contact with the surface several times. Philae first moved downwards, sliding down the edge of a cliff (1) and rotating vertically like a windmill to pass between two boulders (2), exposing layers of ice in the crevices with its spider legs. The 'windmill action' created a wall of dust through which Philae pushed itself. The gap is approximately 2.5 metres long, curved, and has a width of 1–1.5 metres. Then Philae pushed a 25-centimetre imprint of the top of the lander into the surface of the comet (3) – a hole created by the top of the SD2 (Sampling, Drilling and Distribution Device) tower. Philae then rose out of the crevice, was pressed down again by an overhang (4a), its upper surface creating an impression in the dust that pressed the 'eye' into the skull (4b).
