Close encounter with a comet: European Space Agency prepares for lift-off

Date: 19/02/04

THEIR bold attempt to discover if there was ever life on Mars may have ended in glorious failure but, undeterred, European space scientists are forging ahead with an even more ambitious challenge.

At 8.36am (CET) next Thursday (26 February), scientists will launch a spacecraft that, they hope, will land on one of the solar system's most elusive and spectacular objects: a comet. Forget Beagle 2 - the spacecraft that landed on Mars on Christmas Day but is now officially declared lost - this latest mission is the biggest yet, the one which, it is hoped, will unlock the secret of how life began on Earth.

"No one has ever attempted a mission like this," says Professor David Southwood, head of science at the Paris-based European Space Agency (ESA). "It is unique for its scientific implications as well as for its spectacular space manoeuvres."

In seven days, the European space probe Rosetta will leave Europe's Kourou spaceport in French Guyana atop an Ariane 5 Gplus rocket - the start of a ten-year, €890 million journey towards the comet 67P/Churyumov-Gerasimenko.

Rosetta, which weighs three tonnes, has been designed by the ESA to discover if a comet's huge balls of dirt and ice - thought to be leftovers from the solar system's birth four-and-a-half billion years ago - bombarded Earth and provided our planet with its water.

The probe was scheduled for blast-off last year but the mission was aborted after another Ariane 5 rocket blew up four minutes into the flight from Kourou.

Since then, Arianespace, the rocket's operator, believes it has corrected the flaws in its rocket. "We are confident but it will be a relief to get the launch over with," says project scientist Gerhard Schwehm.

André Balogh, professor of space physics at Imperial College, London, has an instrument on Rosetta and is praying all goes well with the launch this time.

"If Rosetta misses this launch window, for whatever reason, it will be very difficult to find another target comet for it using Ariane," he said.

If all goes to plan, Rosetta will reach the comet in 2014. The spaceship will track the comet before going into orbit round it. For several months, it will photograph 67P/Churyumov-Gerasimenko - before detaching a small lander, Philae (approximately the size of a washing machine) to drop onto its surface.

Among the many complex instruments that will then go into action will be a mass spectrometer similar to that carried on the ill-fated Martian lander, Beagle 2.

During its two-year mission, Rosetta's lander will send close-up pictures of the comet's nucleus back to Earth and drill into the heart of the "dirty snowball" to sample its primordial ice and gases. The mission will also analyze the chemicals bound up in the comet's icy coat. These carbon-based materials may have provided the building blocks from which life on Earth evolved.

So, why the interest in comets?

"It's a cornerstone of not just our scientific programme, but also of the scientific approach to understanding the solar system," said David Southwood.

Rosetta, which relies solely on solar cells for its power, was originally designed to track comet Wirtanen, but its launch delay had forced scientists to select a new quarry. The comet is 3.2 kilometres in diameter and sweeps round the Sun, between the orbits of Earth and Jupiter, every 6.6 years. As it heads towards the Sun, ice on its surface evaporates and jets of gas blast into space.

Its orbit is perfect for Rosetta, says Southwood, adding that many difficulties still lie ahead: "The complications involved in sending a small spacecraft halfway across the solar system and making a soft landing on a small comet are immense."

Rosetta is named after the Rosetta Stone discovered in 1799 by a French soldier in Napoleon's army near the town of Rashid on the Nile. It proved the key to finally deciphering Egyptian hieroglyphs. The 2004 version will achieve a few historic firsts of its own - it will be the first spacecraft to orbit a comet's nucleus; the first to fly alongside a comet and the first to examine from close proximity how a frozen heavenly body is transformed by the warmth of the Sun.

The space agency certainly cannot be accused of wasting any time restoring public confidence in its missions to various parts of the solar system following the failure of Beagle 2, part of a €300m expedition to Mars, Europe's first planetary mission.

"Actually, it is worth pointing out that only 10% of the Mars Express mission can be considered a failure," says ESA spokesman Franco Bonacina.

"Mars Express actually detected the presence of water on the Red Planet, so the mission generally was a great success."

Next week's landmark launch comes at a time of rapidly growing interest in "all things space" at an EU level. The Union has committed €1.7 billion over a four-year period up to 2006 to space research but Commissioner Philippe Busquin wants to double that. As the EU executive is set for an internal reshuffle with a new team of 25 commissioners taking office in November, there is speculation that a Space directorate general could be created, along with a new DG Industry.

Busquin's spokesman Fabio Fabbi refused to comment on that, but he reaffirmed the Commission's intent, saying: "Space is certainly one of our main priorities, and we want to boost spending on its research."

On 26 February 2004, the European Space Agency probe Rosetta will set off on a ten year journey through the solar system to meet up with Comet Churyumov-Gerasimenko.

• Primary Source

http://www.esa.int/ESA http://www.esa.int/ESA

http://www.esa.int/export/esaCP/SEMA5Y1PGQD_index_0.html http://www.esa.int/export/esaCP/SEMA5Y1PGQD_index_0.html

http://www.esa.int/Our_Activities/Space_Science/Rosetta http://www.esa.int/Our_Activities/Space_Science/Rosetta

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