As with previous mission phases, there is no clear transition between SDP and routine operations. As each project received its SDP data, if no significant problems were revealed, the Principal Investigator (PI) was invited to have a release telecon with the Project Scientist and HSC staff to discuss the data and any problems or issues that had arisen. If no serious issues were identified, the PI was invited to release all, or part of the observations in his or her programme for scheduling, in which case, the observations would be made available to the HSC Mission Planners. The first routine observations were observed on 18 October 2009 and, by December, the immense majority of scheduled observations came from released routine programmes. Over the course of the mission Herschel will produce hundreds, or thousands of spectacular images like these Figure 1.9, Figure 1.10.

Figure 1.9. M31's once and future stars. A combined Herschel and XMM image of M31 showing dusty start-forming regions (Herschel) and the point-sources that represent highly evolved stars (XMM). The Herschel data were taken at 250 microns with SPIRE between 17 and 21 December 2010. In the XMM RGB image, red sources are low-mass x-ray binaries, while the blue sources are compact binaries with a neutron star or black hole secondary.

Figure 1.10. Galaxies spread like grains of sand on a beach. Every source in this GOODS-N field, which is about the size of the Full Moon, is a distant galaxy. The insert to the left shows the indivdual frames in each of the SPIRE bands while the main image combines them as an RGB. The colour of the galaxy gives an indication of its red shift and, hence, distance: the reddest galaxies are the most distant and may be as much as 12 000 million light years away; blue objects are relatively nearby and may be as close as 8000 million light years.

Herschel will carry out routine science operations phase for a minimum of 3 years. Early on, mainly Guaranteed Time and "Key Project" observing programmes have received priority. Key Projects were performed early in the mission to permit follow-up and to give the Guaranteed Time holders at the HSC the opportunity to obtain real data to work with, in preparation for supplying community support to the open time observers with the benefit of a thorough knowledge of the entire observing chain from proposal submission to access and reduction of data. Almost all Key Programme observations are expected to be completed by May 2011, at which point OT1 observing programmes will start to be heavily scheduled, although some OT1 observations have been scheduled since December 2010 where they help to improve efficiency by filling inconvenient gaps in the telescope schedule.

All observers can track the state of their proposals from the (password protected) proposal handling pages of the HSC Web page and are notified when the resulting data has been passed through the Quality Control process; this may take from 2-3 weeks to complete, although data is available for retrieval from the HSC usually within 48 hours of the observations being executed. Observers can also check both what observations are scheduled for observation and have been delivered to MOC (http://herschel.esac.esa.int/observing/ScheduleReport.html) and the observing log (http://herschel.esac.esa.int/observing/LogReport.html) from the HSC. Observations marked "Failed" are automatically cloned and released for re-scheduling by HSC.

There is considerable uncertainty about when boil off will happen. This is unlikely to be reduced much in the future. Current best estimates place the most likely date for helium exhaustion around the end of 2012, but with an uncertainty of several months. It is possible that in the last few weeks of the mission it may be difficult or impossible to re-cycle the instrument coolers after the helium level has dropped below a certain point and that, as a result, only spectroscopy will be schedulable, but this is still uncertain at this time as we do not know what the helium behaviour will be at very low levels.

Once boil off has occurred Herschel's instruments will no longer operate. There is still considerable discussion about what will happen to Herschel finally post-helium. MOC will continue to operate Herschel for a time even after boil off has occurred for routine spacecraft housekeeping operations. As the radiation monitors will continue to function indefinitely there is a suggestion that Herschel could continue to function after MOC operations have ended as a space weather station. Alternatively, it could be allowed to escape into solar orbit, or even crash into the Moon.

The Herschel post-operations phase will consist of the rundown monitoring phase (starting at the moment of helium boil-off), mission consolidation phase, active archive phase, and the archive consolidation phase (at which point the transfer to the subsequent historical archive phase takes place), which is the final formal phase of the mission. Herschel is currently fully funded for 5 years of post-operations.

The goal of this phase is, within the constraints of time and available resources, to maximise the scientific return from the Herschel mission by facilitating continuing widespread effective and extensive exploitation of the Herschel data. This will continue after the conclusion of this phase (i.e. in the historical archive phase). Documentation will be extensively revised during this phase to provide a legacy and the Herschel Interactive Processing Environment (HIPE) will continue to be updated and refined in line with the state of knowledge of instrument behaviour and calibration.

The ultimate legacy of Herschel will be the historical archive, plus the sum of all the knowledge, both scientific and technical, derived from implementing and operating Herschel.

The historical archive phase is outside the funded Herschel mission. This phase commences after the end of the post-operations phase.

The historical archive will provide access to all Herschel observations and derived products. The products will all be derived in the archive consolidation phase during the post-operations phase in a consistent manner and to consistent standards using the best knowledge of Herschel instrument calibration and data processing. In addition, the software, documentation - manuals, etc.- and tools will be available from the historical archive.