The 2900 kg (6391 lbm) Rosetta spacecraft will be launched singly-manifested into an Earth-escape orbit using an Ariane 5 heavy-lift rocket. The mission includes flybys of asteroids (4979) Otawara and (140) Siwa and measurements of the trailing dust of Comet 46P/Wirtanen. A 100 kg (220 lbm) lander will separate from the satellite and land, in November 2011, on a comet named 46P/Wirtanen. The spacecraft will fly by Earth and Mars in 2005, asteroid Otawara in 2006, Earth again in 2007 and Siwa in 2008 prior to its rendezvous with comet 46P/Wirtanen in 2011 for a 2-year observation mission.

The Rosetta Science Instruments will be made up of an Imager, IR and UV spectrometers, plasma package, radio sounder to investigate subsurface layering of materials, magnetometer, particle analysis instruments. The lander package will include an imager, magnetometer, and an alpha/proton/x-ray spectrometer to determine the chemical composition of the surface materials. Ground operations will acquire the down-link in S-band using the ESA network and control the spacecraft to a fine pointing attitude with the HGA Earth pointing using X-band telemetry.

The Rosetta spacecraft design is based on a box-type central structure, 2.8 m x 2.1 m x 2.0 m, on which all subsystems and payload equipments are mounted. Two solar panels, each of 32 square meters, extend outwards, giving a total span of about 32 m tip to tip. The Lander is attached to the face opposite the two-axes steerable high-gain antenna. The instrument panel will almost always point towards the comet, while the antennas and solar arrays will be oriented towards the Sun and Earth. The spacecraft is built around a vertical thrust tube, whose diameter corresponds to the 1194 mm Ariane-5 interface. This tube contains two large, equally sized, propellant tanks, the upper one containing fuel, and the lower one the oxidizer. At least 1578 kg (3478 lbm) propellant will be accommodated.

The total program budget, including satellite design, construction and launch, is 540 million euros, not including the individual experiments provided by national space agencies. Rosetta is an ESA Cornerstone science mission. The Rosetta Mission was approved in November 1993.

Rosetta is being built by Astrium GmbH of Friedrichshafen, Germany. The French and Italian space agencies are collaborating on the construction of the lander.