Of the ten orbit correction manoeuvres (OCMs) that began on 7 May, there remains just one to complete: the last one is dubbed ‘CATI’ for ‘Close Approach Trajectory – Insertion’ and will take place today.
Orbit entry will be triggered by a small but crucial thruster firing lasting just 6 min: 26 sec, starting at 09:00 GMT (11:00 CEST). The commands were uploaded during the night of 4 August. The burn will be monitored closely by the Rosetta Flight Control Team at ESOC.
There are more details including a timeline in the main ESA website.
This burn will tip Rosetta into the first leg of a series of three-legged triangular paths about the comet. The legs will be about 100 km long and it will take Rosetta between three and four days to complete each one.
Orbit insertion means that Rosetta will in fact begin following a series of triangular arcs, each about 100-km long, and it will conduct a small thruster burn at each apex to swing onto the next arc and stay near the comet. The height of the arcs above the surface will be steadily lowered, until 67P/C-G’s gravity does capture the spacecraft.
Tracking coverage will be provided by ESA’s 35m deep-space station at New Norcia, Australia, and the event will be covered in a live webcast via https://www.esa.int/rosetta.