Europe: European scientists have successfully dropped a satellite the size of a car onto the frozen surface of a moon orbiting Saturn.
In an apparently flawless descent, the Huygens satellite bumped safely onto the moon Titan and has sent back streams of valuable data.
European Space Agency (ESA) experts are heralding the seven-year two-billion-mile journey and descent through Titan's chemical atmosphere as a huge engineering and scientific triumph. All of Huygens's onboard instruments worked, including its cameras, and ESA scientific teams yesterday confirmed that the probe had delivered usable data.
The €370-million 705-lb, wok-shaped probe slammed into Titan's heavy nitrogen and methane atmosphere at Mach 4. A heat shield helped slow the craft, then Huygens opened its parachutes at about 10.20 a.m. Irish time yesterday.
The US-built Cassini satellite with which Huygens piggy-backed to Saturn immediately began relaying Huygen's data signals back to earth as it started its two-hour 20-minute fall towards Titan's surface.
The probe's main mission was to analyse the moon's atmosphere, given its possible similarity to that which formed about the earth billions of years ago.
Huygens plunked on to solid ground at approximately 12.45 p.m., according to controllers at ESA's Space Operations Centre in Darmstadt, Germany. It was expected to stream back data and pictures via Cassini for three minutes, but mission controllers later announced Huygens was able to send back more than two hours of data before it finally went dead, its mission complete. The first full data set of information from Huygens was received ahead of schedule by 4.09 p.m. Irish time.
"The morning was good, the afternoon was better," said ESA director general, Mr J.J. Dordain. "This morning we were an engineering success, this afternoon we are a scientific success. The scientific data being reviewed now will reveal the secrets of this new world," he said from a press conference in Darmstadt.
All six instruments on board Huygens appear to have worked flawlessly. He praised the contribution made by scientists and engineers in 19 countries over the 25 years of the Cassini-Huygens mission. "It is a staggering engineering feat," said Mr Kevin Nolan, a solar system specialist from the School of Applied Science at the Institute of Technology, Tallaght. "It is going to give such confidence to the space community. The scientific value is hugely significant, almost incalculable. It will cause a rewrite of what we know about the early earth and the solar system."
The Cassini-Huygens voyage to Saturn is one of the most ambitious unmanned missions yet attempted. Huygens represents the furthest a man-made object has travelled to land on a remote celestial body, and Cassini has provided months of data while in Saturnine orbit.
Planned and executed over a 25-year period and costing about €2.5 billion, the two satellites were launched as a pair seven years ago on a roundabout journey to the ringed planet. Its complex route allowed it to pick up speed by swinging by Venus twice and the Earth and Jupiter on its way.
The two satellites finally went into orbit around Saturn on July 1st and since then Cassini has sent back a wealth of images and data about Saturn, its rings and its more than dozen moons including Titan.
Clearly though the highlight of the mission was going to come as Huygens broke its bonds with Cassini to venture on its own towards Titan's surface. The first step in this complex process occurred on Christmas morning when the two separated and Huygens began its slow, irreversible descent.
Larger than the planet Mercury, Titan is the only moon in our solar system that has its own atmosphere. It is half as dense again as the earth's and produces an impenetrable fog that permanently obscures its surface from Cassini's prying cameras.
Scientists are interested in the moon's atmosphere because of its possible similarities to that which formed around early earth 4.5 billion years ago.
Huygens carried a battery of six experiments and cameras that sampled and analysed as the probe descended on its parachutes. Planners expected that Huygens would be able to monitor its surroundings for just over two hours on its way down. It also carried a surface package in the hope that the satellite would survive its 20 m.p.h. bump on to the surface.
Scientists didn't know whether Huygens would land with a bang onto something solid or splash down into an ocean of liquefied methane and ethane. Those fears proved unfounded as the probe continued to send out a data stream for more than two hours.
