Table 2.
Scientific goals of the Philae lander mission to 67P/Churyumov–Gerasimenko (as defined by the Philae Steering Committee). The goal achievement is evaluated in the last column of the table.
| no. | science goal | achieved? |
|---|---|---|
| (1) | Study of the composition and structure of the cometary nucleus, reflecting growth processes in the early Solar System | partly achieved |
| (2) | Determination of the composition of the cometary surface and subsurface matter: bulk elemental abundances, isotopic ratios, minerals, ices, carbonaceous compounds, organics, volatiles—also dependence on time and insulation | partly achieved |
| (3) | Investigation of the structure and physical properties of the cometary surface: topography, texture, roughness, regolith scales, mechanical, optical and thermal properties, temperatures | achieved |
| (4) | Investigation of the global internal structure by radio wave sounding, seismometer and magnetometer | partly achieved |
| (5) | Characterization of the near-surface plasma environment and investigation of the comet–plasma interaction | partly achieved |
| (6) | Investigation of dynamic processes leading to changes in cometary activity | not achieved |
| (7) | Study of the physical and thermal properties of the near-surface material, the thermal behaviour as well as the heat and mass transport over many insulation cycles and over a significant variation of insulation intensity (i.e. heliocentric distance) yields information about fractionation processes, i.e. the most volatile components have retreated to the cold interior, while refractory materials are concentrated near the surface. Knowledge about fractionation and ageing processes that occur in the upper surface layers is necessary to draw conclusions on the original cometary material from the measured chemical composition of the present aged surface material | partly achieved |
| (8) | Long-term in situ observations on the surface reveal local erosion of the surface by sublimating ices, modifications of texture and chemical composition of near-surface materials, changes in dust precipitation and heat flux through the surface as well as transient activity phenomena as a function of distance to the Sun | not achieved |
| (9) | Provision of ground-truth data for orbiter instruments. Close-up panoramic observations can calibrate albedo and topographical features observed by OSIRIS. In situ analysis of chemical and mineralogical composition can calibrate brightness at various infrared wavelengths observed by VIRTIS. Measurements of the surface structure on small scale can be compared to the respective findings from orbiter dust experiments. Structural stability of solid-state particles as well as possible alteration processes can be analysed | partly achieved |
| (10) | Public relations and public outreach tasks | achieved |