The risk history can be accessed via the "Risk history" button in the "Scan results" screen.
it shows the main results of scans against the same system. The idea behind this graph is to show how the risk levels of a single satellite system change over time, for example due to a mitigation project (less Very High and High risks) or a system upgrade.
The risk history is very useful to provide as "evidence" of the effect of a mitigation project.
The table below the graph shows the different scans that took place on that satellite system. By changing the lead selection on that table, the risk distribution from the selected scan will be shown.