The Envisat mission was launched in March 2002 for 5-year nominal lifetime. Consequently the on-board hydrazine capacity was designed for a 5-year duration operation. Careful management of the satellite orbital manoeuvres allowed saving enough hydrazine for operating nominally Envisat for an additional 3.5 years, i.e. until end 2010.
The operations of the Envisat satellite beyond end 2010 require modifying the orbital characteristics of the mission. Careful trading between all possible options led to the selection a new orbit, called the “Envisat Extension Orbit“, which allows:
1) operating the mission for an additional 3 years, with a minimum amount of hydrazine,
2) ensuring the continuity of the maximum number of Envisat applications, with the exception of ASAR interferometry which will be degraded.
The Envisat extension orbit will be implemented through an altitude decrease of 17.4 km which will be reached through different orbital manoeuvres starting on 22 October 2010.
Consequently, the Envisat data flow will be suspended during the period 22 October to 01 November 2010. The data flow will resume on 02 November 2010.
The Envisat mission represents an important goal in the field of Earth Observation. Chelys will follow the entire operation attentively, as we are also the real time image generation software (Miravi) provider for the Meris sensor. This post will be updated in the next few days in order to provide a preview of the Envisat images at the end of the maneuver as soon as its sensors are reactivated.
The last OCM (Orbit Control Manoeuvre) finished in time without problems on October 26th. The satellite instruments are gradually resuming their nominal condition and the dissemination to the users is started. However the ESA disclaimer is clear: users are invited to discard such data until November 2nd, 2010 as they are destined only for the ESA internal verification.
We started generating the first images using the “new” data, and the results, despite some geolocation problems, are very promising. Here below are some images generated after the completion of the manoeuvre.