March 2 — ESA's Rosetta mission is launched at 07:17 GMT (08:17 Central European Time). The launcher placed its upper stage and payload into an eccentric coast orbit (200 x 4000 km). About two hours later, at 09:14 GMT, the upper stage ignited its own engine to reach an escape velocity in order to leave the Earth’s gravity field and enter heliocentric orbit. The Rosetta probe was released 18 minutes later. ESA’s Operations Centre (ESOC) in Darmstadt, Germany, established contact with the probe shortly after that.
March 3 — S Band communication commenced with Rosetta, using both low- and high-gain antenna configurations. Also, all reaction wheels were in operation, compensating for large disturbances due to outgassing from the space craft, which was expected to last for a few days in the vacuum of space.
March 4 — The power subsystem of Rosetta was tested and commissioned.
March 5 — RosettaX band communications were commissioned.
March 10 — The first three instruments (Cosima, CONSERT(Orbiter part) and Osiris) were activated and completed their initial commissioning activities in the last three days. The CONSERT Orbiter antenna was also deployed.
March 11 — The Rosetta Science Working Team announces that accuracy of launch made it possible to select two asteroids as targets for a rendezvous fly-by of the probe. "Comets and asteroids are the building blocks of our Earth and the other planets in the Solar System. Rosetta will conduct the most thorough analysis so far of three of these objects," said Prof. David Southwood, Director of ESA’s Science Programme in a press release.
March 17 — Over the last five days, starting on March 12, the lander was commissioned. Only one step was rescheduled due to early release of the launch locks during the first mission day.
March 19 — The Rosetta Plasma Consortium (RPC) instruments were commissioned during the previous two days. A redundant power supply seem to have failed during a repeat check of the RPC instruments. Further investigation is under way. The spacecraft booms, carrying the RPC MIP (Mutual Impedance Probe) and LAP (Langmuir Probe) instruments were deployed by using the primary systems.
March 26 — Checked out three instruments: ROSINA, ALICE, and VIRTIS, during commissioning activities. Each activity took two days and was within or ahead of schedule. The High Gain Antenna (HGA) emission pattern was calibrated by performing spiral maneuvers. The radio station at New Norcia was used to measure antenna gain.
March 30 — The RSI (Radio Science Instrument) completed five days of commissioning.
April 3 — The MIRO instrument checked out well after three commissioning passes through more spiral maneuvers, during which the planet Venus was scanned.
April 4 — The Rosetta spacecraft was pointed into its attitude towards Earth, which is to be kept for the remainder of the year. Slight adjustments are planned to avoid having the sunlight hit Rosetta head-on. (Also called "+X" axis). The GIADA instrument was activated and commissioned.
April 9 — The last instrument on board Rosetta (MIDAS) was turned on during April 4 and 5 days of commissioning concluded. At this point all science and engineering subsystems have been activated at least once.
Use of the radio station at New Norcia was reduced from 11 hours to 7 hours, to allow more time for the Mars Express mission.
April 15 — Five days of checkout procedures for the lander concluded successfully. This second lander activity was focussing on the lander's payload. The ALICE instrument was activated again and high voltage operations were executed. Other activities performed as planned, including an adjustment of the internal heater system due to decreasing distance to the Sun.
April 17 — Rosetta commissioning hit a snag, today. A pyro, designed to open the ALICE detector, did not fire.
April 21 — After some investigation, a backup pyro was fired to release the ALICE detector door.
April 25 — During a test sequence using an Earth pointing attitude, the thruster temperature (heated by the sun) caused an unplanned "slew" to occur. This mechanism is used to prevent the thrusters from overheating. Due to this maneuver, a planned imaging activity of the Earth-Moon system was cancelled, but the remaining commissioning activities were completed satisfactorily.
May 1 — The first scientific observations were performed at this date. The instruments were pointed towards the comet C/2002 T7 (LINEAR), at that time close to the sun.
May 6 — In preparation for the first deep space maneuver of Rosetta a total of 12 pyro valves were fired, and the pressure in the reaction control system started to build up as expected.
May 10 — The most critical deep space maneuver was successfully executed. The four thrusters on board of Rosetta were fired for about 3.5 hours, and a velocity change (delta v) of 152.8 metre per second was imparted to the spacecraft.
May 16 — A planned "touch-up" deep space maneuver was successfully executed. A burn of just under 17 minutes was performed with high accuracy. Then Rosetta pointed its instruments again towards Comet LINEAR for observation.
May 28 — ESA released the first pictures taken with the OSIRIS camera during the April 30 observation tests pointed at comet LINEAR. The camera produced high-resolution images of the comet from a distance of about 95 million kilometres.
March 4 — The first planned flyby of Earth was executed successfully. ESA asks amateur astronomers that took pictures of the spacecraft to submit them. Also, tests with the Moon as target standing in for a comet or asteroid, produced pictures and other data as expected.
March 24 — Rosetta transitioned back into "cruise mode".
April 15 — A test of the Near Sun Hibernation Mode (NSHM) was successfully concluded. It started on April 11 and tested a special low activity mode of Rosetta. In this state the gyroscopes and reaction wheels are inactive, and the craft is using the star tracker and the thrusters to control its attitude, only.
July 18 — ESA reported that the observation of the Deep Impact encounter with comet Tempel 1 was very successful. Science data was recorded and down-linked to Earth during the period from June 28 until July 14, and the data is currently being analysed.
August 8 — Mission members performed an unplanned monitor pass to investigate anomalies in the spacecraft's dynamic behavior. On mission day 213 and 216 a total of 20 grams of fuel were spent and a delta-v of 2.5 mm per second were added unexpectedly.
January 20 — At 10:00 CET the spacecraft woke up and started post-hibernation procedures. Rosetta restored communications with ESA's Operations Centre through NASA’s Goldstone ground station at 18:17 CET. Greets the Earth with a "Hello World" message. The message was received on a very low bit level. Over the next months ESA's job will be to raise communication speed through a software update. 
May 7 — First of ten Orbital Correction Manoeuvres (OCMs) (1 h 33 min 13 s) to align the trajectories of Rosetta and 67P/C-G, delta-v of 20 m/s (66 ft/s) (approximate distance to 67P/C-G - 1,900,000 km (1,200,000 mi))
May 21 — OCM 2 of 10, longest burn (7 h 16 min) with largest delta-v (291 m/s (950 ft/s)) using approximately 218 kg (481 lb) of fuel (approximate distance to 67P/C-G - 1,000,000 km (620,000 mi))
June 4 — OCM 3 of 10, 6 h 39 min burn time with a delta-v of 269.5 m/s (884 ft/s) using approximately 190 kg (420 lb) of fuel (approximate distance to 67P/C-G - 425,000 km (264,000 mi))
June 18 — OCM 4 of 10, 2 h 20 min burn time with a delta-v of 88.7 m/s (291 ft/s), this was an over performance of 5%, the first notable deviation from expected performance. (approximate distance to 67P/C-G - 195,000 km)
September 4 — The first science data from Rosetta 's ALICE instrument was reported, showing that the comet is unusually dark in ultraviolet wavelengths, hydrogen and oxygen are present in the coma, and no significant areas of water-ice have been found on the comet's surface. Water-ice was expected to be found as the comet is too far from the Sun to turn water into vapor.
September 10 — Rosetta enters the Global Mapping Phase, orbiting 67/C-G at an altitude of 29 km (18 mi).
November 12 — Philae successfully landed after touching down three times, on the surface of 67P/G-C without firing its harpoons. Touchdown 16:08 GMT.
November 15 — Philae battery exhausted after insufficient collection of solar energy. It is possible that the conditions may change as the comet moves closer to the Sun, making it possible to charge the battery.
10 December — The Rosetta's Rosina mass spectrometers report that the ratio of heavy water to normal water on comet 67P is more than three times that on Earth. The ratio is regarded as a distinctive signature and the discovery means that Earth's water is unlikely to have originated from comets like 67P.