ESA's Cosmic Vision: Europe is narrowing the choices for the next round of space science missions.

The Laplace mission would explore Europa and the Jupiter System. The Jovian System, with Jupiter and its moons, is a small planetary system in its own right. Unique among the moons, Europa is believed to shelter an ocean between its geodynamically active icy crust and its silicate mantle. The proposed mission would answer questions on habitability of Europa and of the Jovian system in relation to the formation of the Jovian satellites and to the workings of the Jovian system itself. The mission will deploy three orbiting platforms to perform coordinated observations of Europa, the Jovian satellites, Jupiter's magnetosphere and its atmosphere and interior. If approved, the mission would be implemented in collaboration with JAXA and NASA.

The Titan AND Enceladus Mission (TANDEM) has been proposed to explore two of Saturn's satellites (Titan and Enceladus) in-situ and from orbit. Building on questions raised by Cassini, the mission would investigate the Titan and Enceladus systems, their origins, interiors and evolution as well as their astrobiological potential. The mission would comprise two spacecraft--an orbiter and a carrier which will deliver a balloon and three probes onto Titan. If finally approved, the mission would be implemented in collaboration with NASA.

It is expected that an initial down-select between Laplace and TANDEM, i.e. a decision in favour of Jupiter or Saturn exploration, will be made in consultation with foreign partners in the coming years.

The primary scientific goal of the Laser Interferometer Space Antenna (LISA) mission is to detect and observe gravitational waves from astronomical sources such as massive black holes (MBHs) and galactic binaries in a frequency range of 10-4 to 10-1 Hz. LISA consists of three spacecraft that act as an interferometer with an arm length of 5 million kilometres. The plane circumscribed by the three spacecraft constitutes a very large gravitational-wave antenna.

LISA's low-frequency range is inaccessible to ground-based interferometers due to local gravitational noise arising from atmospheric effects and seismic activity. Ground-based interferometers are also physically limited in length to a few kilometres, restricting their coverage to a frequency range that includes events such as supernova core collapses and binary neutron star mergers. In the low-frequency band of LISA, sources are well known and signals are stable over long periods (from several months to thousands of years). LISA will detect signals from numerous astronomical sources with signal-to-noise ratios of 501000 for MBHs, which will allow determination of the internal parameters of their source.

Least risky

The interest of LISA science was summarized by one of the conclusions of the assessment of NASA's Beyond Einstein programme, recently completed by the National Reasearch Council. The NRC declared: "On purely scientific grounds LISA is the mission that is most promising and least scientifically risky. Even with pessimistic assumptions about event rates, it should provide unambiguous and clean tests of the theory of general relativity in the strong field dynamical regime and be able to make detailed maps of space time near black holes. Thus, the committee gave LISA its highest scientific ranking."

When LISA-related activity started at ESA following its selection as a cornerstone mission of the Horizons 2000 scientific programme in 1995, it was immediately obvious that several technology challenges were going to face the developers. Although all of LISA's technology existed in some form at the beginning of the development effort and no new "inventions" were required, an incremental performance increase and additional functionality from proven technology was required. This applies to the fields of micropropulsion, drag-free sensing and actuation, interferometric measurement systems, phasemeters, high-precision pointing mechanisms. Additionally, the challenge of LISA really comes in tying all these pieces together at the system level, more than in advancing individual technology items. Several Technology Development Activities were put m place, some are still ongoing and some are planned to start in the near future. Between the start of development and now, technology in the above fields has progressed enormously and much of it will be flight-tested on LISA's technology demonstration mission LISA Pathfinder, to be launched in 2010.

International Collaboration

LISA is an ESA/NASA collaborative project. An initial agreement between ESA and NASA on roles and responsibilities for the Mission Formulation phase was finalized in August 2004. It foresees joint ESA and NASA conduction of the Mission Formulation phase in order to achieve a baseline mission architecture that allows requirement specifications to be derived and interfaces to be clearly defined. It also includes a tentative share of responsibility for deliverables and services, to be reviewed prior to entering later project phases, that shows NASA providing the three spacecraft, the launch vehicle, operations, the use of the Deep Space Network and elements of the payload and ESA being responsible for the delivery of the complete payload and the three propulsion modules. An update of the current agreement is planned to start soon to formalize ESA and NASA roles and responsibilities for the Implementation phase.

The technology demonstration mission LISA Pathfinder is an ESA mission that will fly the US Disturbance Reduction System (DRS) package along with the European LISA Technology Package (LTP).

RELATED ARTICLE: Europe ponders manned spaceflight uncertainties.

An ESA/DLR-sponsored international conference on space exploration in early November in Berlin provided the opportunity to take stock of the situation one year ahead of the next ESA ministerial council meeting. In the manned spaceflight domain, the major unresolved question concerns the operation of the International Space Station. The US wants to withdraw from the facility in 2015, while the other partners wish to continue to operate the ISS through 2020.

Other issues include the European contribution to the US Constellation programme. Collaboration with Russia on an alternative transportation system seems to have come to n halt.

Europe's Aurora programme for manned and robotic exploration of the Moon and Mars actually pre-dates the US decision to return to the Moon. The 2001 ESA Ministerial Countil meeting in Edinburgh voted a budget of 14 million [euro] for the period 2002-2006, to which n further 41.5 million [euro] was subsequently added. The following Ministerial Council in Berlin in 2005 adopted n budget of 724 million [euro] for 2006-2009. This funding was used for the ExoMars mission and a research programme including the investigation of a European contribution to the Russian Clipper system.

ExoMars is now scheduled for 2013. A demonstrator mission to the Moon or Mars, Next, is set for 2014-2016 to clear the way for a sample return mission. The Mars sample return mission is envisaged in the 2020 timeframe. Germany has plans to perform its own lunar exploration programme and is looking for 300-350 million [euro] in funding for an initial orbiter mission. France and Italy are more focused on robotic exploration of Mars. In November the Member States approved phase B2 of Exomars. The preferred scenario is a heavy mission launched by Ariane 5, the cost of which has risen from 650 million [euro] to 1 billion [euro]. Next is expected to cost 300 million [euro], while the Mars sample return is budgeted at around 2 billion [euro], if financing can be shared with NASA.

If Europe wishes to pursue its orbital flight activities after 2015, it will have to launch an autonomous orbital laboratory to take over from the ISS. The cost would be on the order of 10 billion [euro]. A further 1 billion [euro] would be required to upgrade the Guiana launch facilities and the Ariane 5 or Soyuz 2 launchers for manned spaceflight from Kourou. To this list must be added the eventual cost of a European contribution to the US-led Constellation programme (elements of the lunar base).

In other related developments, India has announced that it is studying plans to put a man on the Moon, and Korea says it wants to launch a lunar orbiter by 2020 and achieve a lunar landing five years later using a new 300t launch vehicle due to be ready in 2017.

[ILLUSTRATION OMITTED]