ESA's total budget for science is still only about 12.5 percent of NASA's science spending; but a series of developments in recent months have freed up enough additional funds that ESA is now considering several new programs and projects which will play out over the coming decade. And, ironically, one of these sources of new money is the space science woes of the US

ESA managers have been complaining for several years about decreases in its space science budget. From 1985 to 1995, the science budget increased at an impressive yearly rate of a five percent.

But following a conference of ESA's Ministerial Council at Toulouse in 1995, the budget began to drop again in response to the general budgetary woes of the European nations. Since then, it's dropped by a total of three percent -- at precisely the time when ESA was faced with the problem of replacing two missions.

Its first attempt to launch its four-satellite "Cluster" mission to map the structure of Earth's magnetosphere in detail went up with a bang when, in 1996, ESA foolishly allowed the four probes to fly on the maiden flight of Europe's new flagship booster the Ariane 5, which promptly lost control soon after liftoff due to bad flight software.

This forced ESA to engage in a great deal of fund-juggling to scrape together what would become a highly successful replacement mission launched in 2000. To save money, Cluster 2's program managers decided to launch in two sets using much cheaper Russian Soyuz boosters.

Moreover, the curse of '96 saw more launch failures with Russia's "Mars 96" mission failing to make orbit and taking some $300 million in European scientific experiments to the bottom of the South Pacific.

While the Mars '96 payloads had been provided by individual European nations rather than by ESA as a whole, Europe's response was to have ESA initiate a new, low-cost mission dubbed "Mars Express" to carry a reflight of the half-dozen most important European experiments to Mars in 2003. A small Surjouner-class lander affectionately called "Beagle 2" by its Brit managers would also tag along.

Meanwhile new initiatives for ESA's space science program are marching on -- including the little Moon orbiter SMART-1 in 2002; the very ambitious Rosetta mission which will be launched in 2003 and eight years later become the first spacecraft to rendezvous with a comet nucleus and dispatch a small lander to it; and the 2003 Mars Express orbiter which carries a small Mars lander.

Another highlight of this period will be the launch of three astronomy satellites -- INTEGRAL in 2002, and Herschel and Planck in 2007 -- that will survey the Universe in gamma rays and the far infrared, and map the "Cosmic Microwave Background" radiation left over from the Big Bang itself in unprecedented detail.

Moreover, last October ESA officially picked the new space science projects that it plans to fly between 2008 and 2013. This included two "Cornerstone" missions -- ESA's scientific big-gun missions, which can cost as much as $550 million Euros (about $500 million US dollars).

The first would be "Bepi Colombo" -- a very ambitious 2009 mission to explore the planet Mercury with three different spacecraft: a big orbiter equipped with cameras and other instruments in a low polar orbit around Mercury; a much small spin-stabilized craft in a highly elliptical orbit to study the planet's puzzling magnetic field; and a small lander to touch down near one of Mercury's poles and analyze its surface composition and internal structure directly.

ESA has also done a deal with Japan's space science agency, ISAS -- which is also interested in Mercury exploration -- to provide the little "Mercury Magnetospheric Orbiter".

It now seems increasingly likely that the Bepi Colombo mission will be split into two separate launches, each one using its own solar-powered ion drive module (along with Venus flybys) to spiral in close enough to the Sun to reach Mercury, which requires a complex flight plan to reach.

The first launch would carry the little "MMO" orbiter and the Mercury lander -- which would be carried into orbit bythe MMO and then dropped to its polar landing site, with the MMO serving as its data relay.

The second launch would carry the much bigger main "Mercury Planetary Orbiter". This would allow the mission to be launched on two very cheap Russian Soyuz boosters, rather than a single Ariane 5.

The next Cornerstone science mission, after Bepi Colombo, would be GAIA, an astronomy satellite scheduled to be launched in 2012 to carry out astrometric mapping of the heavens with a staggering degree of accuracy.

GAIA's goal will be to map the positions and motions of over one billion stars and other celestial objects with an accuracy of only ten microarcseconds -- one 360-millionth of a degree! -- as well as their brightness and their red or blue shift.

This will allow direct, accurate measurement of the positions of, and distances to, stars as far away as the center of the galaxy, and measurements of their precise motions.

It will thus allow a huge leap in understanding of the structure and dynamics both of the stars making up our own galaxy and of objects in other galaxies -- and it will discover, each day, hundreds of new quasars, dozens of supernovas exploding in other galaxies, and dozens of new large exo-planets orbiting nearby stars. Moreover, GAIA will allow an entirely new series of tests of the accuracy of Einstein's general relativity theory.

In addition, ESA officially selected three smaller "Flexi"-class missions, which (like Mars Express) would be limited to a maximum cost of only 175 million Euros ($150 million US), with two of these being collaborative efforts with the US.

The first would be Europe's role as a junior partner in the Next Generation Space Telescope. This is the planned successor to Hubble -- originally intended for launch in 2008 -- which would have a cryogenically cooled mirror fully eight-meters wide, allowing it to observe galaxies so distant that they are red-shifted into the infrared, and thus would see how galaxies looked during their formative period after the Big Bang.

And it would do all this with a spacecraft weighing only about 1/4 as much, and costing only 1/3 as much as the Hubble Telescope. This will necessitate the development of new advanced technologies such as a lightweight, precisely unfoldable multi-panel mirror, and very high-powered cooling systems. For this mission, ESA would provide its near-IR camera/spectrometer and collaborate on its other, mid-IR camera/spectrometer.

The second collaboration with NASA would be LISA -- the Laser Interferometer Space Antenna -- another space mission with rather staggering logistics, planned for 2011.

It would consist of three small craft in solar orbit, perpetually hovering million km from each other, each holding a cube-shaped mirror floating in its middle, and exchanging laser beams to make up an interferometer capable of measuring changes in distance between the cubes as tiny as 1/10 the diameter of an atom!

This, in turn -- even given the super-precisely adjustable optical systems on each craft -- will require that the craft themselves must be able to measure and constantly maintain their distances from each other with an accuracy of only 1/100 of a micron, using tiny ion engines with thrust levels of only half a milligram.

This system would be able to detect gravity waves -- those extremely weak ripples in space-time predicted by Einstein but not yet directly observed -- with far greater sensitivity and at much lower frequencies than the already vastly sophisticated Earth-based laser instruments which will soon make the first attempt to detect such waves.

Thus LISA could observe gravity waves given off by binary stars and other binary objects (such as black holes), and also that given off by the gigantic black holes in the center of most, if not all, galaxies.

ESA had originally intended LISA to be an independent Cornerstone mission -- but when it became apparent that NASA was also planning such a mission, the two agencies decided to combine as equal partners, allowing ESA to cut its share of LISA's costs to that of a Flexi mission.

This still means that ESA must build the three spacecraft themselves, as well as flying SMART-2 (a 40-million Euro spacecraft to test LISA's super-precise position control systems) in 2006, while NASA provides many of the subsystems, the launch vehicle and the mission control.