ESA Approves 5 Science Missions

The European Space Agency's (ESA) Science Directorate announced the selection of five future space missions under the Horizon 2000+ program proposed by the Space Science Advisory Committee. The missions are to be launched between 2008-2013. The missions which were approved are:  Bepi-Colombo, Global Astrometric Interferometer for Astrophysics (GAIA), Laser Interferometer Space Antenna (LISA), Next Generation Space Telescope (NGST), and Solar Orbiter. If more funds become available, ESA could also launch Eddington.

Bepi-Colombo is a 2272 kg orbiter to be launched by an Ariane 5 in 2009 to explore the planet Mercury. Bepi-Colombo’s science objectives are: to map and image Mercury’s surface; sample the surface geochemistry; study Mercury’s gravity and magnetic fields; study the planet’s rotational state and models of the planet's interior; study particles and waves in near Mercury space and in the solar wind close to the sun (0.3 - 0.5 AU); and test gravitation theory using radio science. It will take the mission 2.5 years to reach Mercury, at which point it will be inserted into a 400 x 1 500 km polar orbit. There will be a “lander” element to be deployed at 85° latitude. The mission is planned to last for 3.5 years, nominal (2.5 year cruise plus 1 year on orbit). This project will be done in collaboration with Japan. The Bepi Colombo mission is named after the late Italian scientist, Giuseppe Colombo of Italy’s University of Padua.

GAIA will be a 3,000-kg astrometric observatory, scheduled for launch on an Ariane 5 in 2011 (no later than 2012). GAIA will study the composition, formation and evolution of the Galaxy by mapping 1 billion stars. GAIA is planned for operation in a Lissajous-type, eclipse free orbit, around the L2 point of the Sun-Earth system. (L2 is 1.5 million km from the Earth.) An operational lifetime of 5 years is planned.

ESA will take a 50% participation role in NASA's LISA mission, which is scheduled for launch in 2009 atop a Delta 2 7925H (or equivalent) vehicle, to study gravity waves. The Laser Interferometer Space Antenna (LISA) consists of three spacecraft flying 5 million km apart in the shape of an equilateral triangle. The center of the triangle formation will be in the ecliptic plane 1 AU from the Sun and 20 degrees behind the Earth. The main objective of the LISA mission is to observe gravitational waves from galactic and extra-galactic binary systems, including gravitational waves generated in the vicinity of the very massive black holes found in the centers of many galaxies.

ESA will make a 15% contribution to the NASA-led Next Generation Space Telescope (NGST), scheduled for launch in 2009. NGST will replace the Hubble Space Telescope (HST) when it is retired near the end of the decade. The 2700 kg telescope will carry cameras and spectrographs sensitive to infrared radiation and have an expected 5-10 year lifetime. NGST would be placed in a Lissajous-type, eclipse free orbit, around the L2 point of the Sun-Earth system. The launch vehicle for NGST has not yet been selected.

The Solar Orbiter, a successor to SOHO and Ulysses, missions that are currently studying the Sun, will be launched from Baikonur on a Soyuz-Fregat rocket. The spacecraft will provide high spatial and temporal resolution, remote-sensing observations of the solar atmosphere from near-Sun and out-of-ecliptic vantage points as well as in-situ measurements of the unexplored inner heliosphere. It will take the Solar Orbiter two years, using solar slectric propulsion (SEP) to reach a perihelion of 45 Rs with an orbital period of 149 days. For the nominal 5-year mission phase, the Solar Orbiter will perform several swing-by manoeuvres at Venus, in order to increase the inclination of the orbital plane to 24° with respect to the ecliptic plane, i.e. 30° with respect to the solar equator (heliographic latitude). During an extended mission phase of about two years the inclination will be further increased, up to maximum heliographic latitude of 38.3°. The maximum angular velocity at perihelion is 13.1°/day, enabling near-synchronous observations (sidereal rotation rate of the Sun: 14.4°/day).

Eddington is a reserve mission which could be implemented depending on the NGST and LISA schedules or the availability of further resources. It’s mission would be to map stellar evolution and find habitable planets. The lift-off mass is planned at about 1200 kg. The operational orbit, of the Lissajous type, which is an eclipse-free orbit around the lagrangian point L2 of the Sun-Earth system, would be reached in about 100 days with direct injection by a Soyuz-Fregat launcher from Baikonur.

Bepi-Colombo and GAIA are “Cornerstone missions”, which are not to exceed US$500 million (excluding instrument costs). The other missions are Flexi-missions. 
  

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