• mission planning,monitoring and control of the spacecraft and its payload
• determination and control of the spacecraft trajectory
• distribution of the scientific data received from the spacecraft to the Rosetta scientific community and the Principal Investigators

Lander operations will be coordinated through the German Aerospace Research Centre (DLR) control centre in Cologne, and the scientific control centre of CNES, the French Space Agency, in Toulouse.
 
 
Quite a Dish
 
Radio communications between Rosetta and the ground will use a newly developed deepspace antenna,which is being built by ESA at New Norcia, near Perth in Western Australia. This 35 metre-diameter parabolic antenna concentrates the energy of the radio signal into a narrow beam, allowing it to reach distances of more than 1 million kilometres from Earth. Signals are transmitted and received in two radio frequency bands: S-band (2 GHz) and X-band (8 GHz). The radio signals, travelling at the speed of light, will take up to 50 minutes to cover the distance between the spacecraft and Earth!
 
 
What a Memory!
 
During the mission, the rate at which data can be sent from Rosetta to Earth will vary from 10 to 22 000 bits per second. However, the rotation of the Earth means that real-time communication will not always be possible. The spacecraft will be visible from the New Norcia antenna for an average of 12 hours per day. In addition, there will be several communicationblackout periods when the spacecraft passes behind the Sun. To overcome these breaks in communication, Rosetta's solidstate memory of 25 Gbits capacity is able to store all scientific data and then transmit it to Earth at the next opportunity.