Cassini spacecraft's Saturn mission ends after 20 years
Iran Press TV
Fri Sep 15, 2017 04:26PM
NASA's famous Cassini spacecraft, after traveling through space since 1997, has reached its final destination.
The US space agency said Cassini disintegrated on Friday at 7:55 a.m. EDT (1155 GMT) shortly after it lost contact with Earth as it entered Saturn's crushing atmosphere in a meteor-like plunge at a speed of about 113,000 kilometers per hour.
"The signal from the spacecraft is gone," said Cassini program manager Earl Maize of NASA's Jet Propulsion Laboratory.
The end of Cassini was met with applause, hugs and tears from NASA officials after its final transmission was received, according to video footage on the space agency's website.
"I hope you are all as deeply proud of this amazing accomplishment," he told colleagues at mission control. "This has been an incredible mission, an incredible spacecraft and you are all an incredible team."
Cassini's plunge into the ringed gas giant, the furthest planet visible from Earth with the naked eye, came after the spacecraft ran out of rocket fuel after a journey of some 7.9 billion kilometers.
Its well-planned ending was a way to prevent any damage to Saturn's ocean-bearing moons Titan and Enceladus, which scientists want to keep pristine for future exploration because they may contain some form of life.
"There are international treaties that require that we can't just leave a derelict spacecraft in orbit around a planet like Saturn, which has prebiotic moons," said Maize.
Three other spacecraft have flown by Saturn, Pioneer 11 in 1979, followed by Voyager 1 and 2 in the 1980s.
But none have studied Saturn in such detail as Cassini, named after the French-Italian astronomer Giovanni Domenico Cassini, who discovered in the 17th century that Saturn had several moons and a gap between its rings.
'Cassini changed the way we think about life'
Cassini was launched from Cape Canaveral, Florida, in 1997. It took the spacecraft seven years to reach Saturn. Then it orbited Saturn for 13 years.
During this time, the spacecraft produced 450,000 images and 635 gigabytes of data on Saturn and its 62 known moons.
The 6.7 by 4 meter spacecraft is also credited with discovering icy geysers erupting from Saturn's moon Enceladus, and eerie hydrocarbon lakes made of ethane and methane on Saturn's largest moon, Titan.
In 2005, the Cassini orbiter released a lander called Huygens on Titan, marking the first and only such landing in the outer solar system, on a celestial body beyond the asteroid belt.
Huygens was a joint project of the European Space Agency, Italian Space Agency and NASA.
"The mission has changed the way we think of where life may have developed beyond our Earth," said Andrew Coates, head of the Planetary Science Group at Mullard Space Science Laboratory at University College London.
"As well as Mars, outer planet moons like Enceladus, Europa and even Titan are now top contenders for life elsewhere," he added. "We've completely rewritten the textbooks about Saturn."
Cassini's final transmissions are expected to include unprecedented data from the atmosphere's upper fringe, about 1,915 km above Saturn's cloud tops. The data took 86 minutes to reach NASA antennas in Canberra, Australia.
Linda Spilker, Cassini project scientist, likened Cassini's mission to a marathon.
"For 13 years we have been running a marathon of scientific discovery, and we are on the last lap," she said early Friday.
Eight of the spacecraft 12 scientific instruments were on, capturing data, in Cassini's last moments, before it disintegrates like a meteor, she said.
"We are flying more deeply into Saturn than we have ever flown before," she said. "Who knows how many PhD theses might be in just those final seconds of data?"
Already, some 4,000 scientific papers have been based on data from the mission, said Mathew Owens, professor of space physics at the University of Reading.
"No doubt scientists will be analyzing the information from its final, one-way trip into Saturn's atmosphere for years to come," Owens said.
The international project between NASA, the European Space Agency and the Italian Space Agency cost $3.9 billion and included scientists from 27 nations.
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