ROSETTA and FIRST: Two cornerstone missions of ESA long-term space science programme

The paper reviews the objectives and status of definition of ROSETTA (Comet Nucleus Sample Return) and FIRST (Far Infrared Space Telescope), which are two cornerstone missions of the ESA long-term scientific programme. ROSETTA is a joint ESA/NASA programme and it will address problems centered on the origin of planetary material and the pre-biotic evolution of organic matter. The ROSETTA spacecraft will be launched in 2001; it will land into the nucleus of comet Churyumov-Gerasimenko, take about 10 kg of cometary samples (ice, dust, organics) and will return the Earth in 2008. FIRST will explore the 10 μm to 1 mm region of the electromagnetic spectrum, where a large number of very important atomic and molecular spectral lines are hosted. The major scientific objectives are the physics of the interstellar medium of the star formation and cosmological studies. The mission is based on a 4.5 to 8 m telescope equipped with imaging spectrometers and operating as a near-real-time observatory from a high elliptical orbit of 24 h period. Low operating temperatures for the payload will be achieved by using a combination of mechanical coolers and a liquid helium cryostat.