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S P E C I A L The Cassini Mission

Cassini roars into space


First step in a long journey

October 15, 1997
Web posted at: 5:19 a.m. EDT (0919 GMT)

CAPE CANAVERAL, Florida (CNN) -- In the hours before dawn, the controversial Cassini probe started its 11-year, 2.2 billion mile journey, the engines of its Titan/Centaur rocket booster lighting the skies over Central Florida.

After a two-day delay due to weather problems and technical glitches, there were no delays in the second attempt. The launch went off as scheduled Wednesday, at 4:43 a.m. EDT (0843 GMT).

Night launch of Cassini
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Cassini will again pass by Earth in 1999, on the way to a 2004 rendezvous with Saturn. If all goes as planned, it will orbit Saturn and its moons for four years and deposit the European Space Agency's Huygens probe on the surface of Titan, Saturn's largest moon.


Wednesday's launch, originally planned for Monday, was rescheduled due to problems with testing equipment on the ground, minor computer problems and high winds that could have blown debris into populated areas in the event of an explosion during liftoff.

The Cassini mission has been controversial because the probe carries energy cells containing about 72 pounds of extremely radioactive plutonium. While NASA officials have downplayed the danger, anti-nuclear activists warned of dire risks if anything went wrong during the launch.

Over the weekend, protesters marched near Cape Canaveral and outside the White House, some carrying signs saying "Halt nuclearization of space: Stop Cassini." Last Saturday, a federal judge in Hawaii rejected a request to block the launch.

Last of blockbuster planetary probes


Cassini is the largest, most expensive interplanetary probe in NASA's history. Its $3.4 billion, 11-year mission was planned before NASA's recent commitment to "faster, better, cheaper" missions like Mars Pathfinder and Mars Global Surveyor. Cassini will be the first spacecraft to visit Saturn since the Voyager 2 probe in the early 1980s.

The Cassini orbiter is a do-everything machine, with 18 on-board experiments and the Titan probe. Scientists are interested in Titan because they believe its conditions are similar to the conditions that preceded the development of life on Earth.

Because Saturn is so far from the sun -- 9.5 times as far as the Earth -- Cassini cannot use the solar panels found on many other spacecraft. According to project manager Richard Spehalski, it would take solar panels the size of two tennis courts to power Cassini at that distance.

Odds of crash on Earth one in a million, NASA says


The probe will make two passes by Venus before passing Earth in August 1999. It will use the planets' gravity to "sling-shot" itself toward Saturn, so it will travel far faster than is possible with rockets alone.

Though the launch was uneventful, Cassini opponents worry that the craft may still re-enter the Earth's atmosphere on its return. NASA says the odds of Cassini falling to Earth are 1 in 1 million, but opponents aren't so sure.

"I find that NASA bureaucrats in some sense are living in Fantasyland," says Michio Kaku, a physics professor at City University of New York. "Pure guesswork has replaced rigorous physics. Many of these numbers are simply made up."

The plutonium aboard Cassini is in Radioisotope Thermal Generators (RTGs), "batteries" that draw power from the natural decay of the element. It is not, NASA officials stress, in a nuclear reactor. RTGs have been used in two dozen other space missions without incident, they said.

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