Enceladus up close: Cassini sends back first images after diving through icy plumes in search for life on Saturn’s moon
- Nasa confirmed its Cassini spacecraft is healthy after its close encounter
- First pictures reveal the icy plumes up close
- Spacecraft dived through the icy plume at speeds of more than 19,000 mph
- The plumes are thrown out from a giant ocean buried beneath the crust
- It is hoped data from the flyby will reveal whether this ocean is habitable
A spacecraft has successfully completed its closest ever dive through the icy spray ejected into space from an ocean buried beneath the frozen crust of Saturn’s moon Enceladus.
Nasa confirmed its Cassini space probe had survived the close encounter with the plumes of ice and water vapour thrown out from the alien world’s south pole, sending back the first images.
The dive, which took the spacecraft to within 30 miles of the surface at speeds of more than 19,000mph, was aimed at analysing the content of the giant plumes seen in the first image.
The spacecraft will continue transmitting its data from the encounter for the next several days.
‘Cassini’s stunning images are providing us a quick look at Enceladus from this ultra-close flyby, but some of the most exciting science is yet to come,’ said Linda Spilker, the mission’s project scientist at Nasa’s Jet Propulsion Laboratory in Pasadena, California.
Researchers will soon begin studying data from Cassini’s gas analyzer and dust detector instruments, which directly sampled the moon’s plume of gas and dust-sized icy particles during the flyby.
Those analyses are likely to take several weeks, but should provide important insights about the composition of the global ocean beneath Enceladus’ surface and any hydrothermal activity occurring on the ocean floor.
Enceladus is thought to have a global ocean of liquid water beneath a thick crust of ice and is one of the best candidates in the solar system for harbouring life.
It is hoped the flyby will have brought the probe close enough to detect large organic molecules in the spray, which may be an indicator that life exists on the moon.
The potential for such activity in this small ocean world has also made Enceladus a prime target for future exploration in search of habitable environments in the solar system beyond Earth.
Scientists confirmed they had already started receiving data from the flyby and have now begun to analyse it, although the entire job could take several months.
Images taken by the Cassini spacecraft while flying through the immense plumes are also expected to be received within the next 48 hours.
The plumes are fed by icy geysers which blast water vapour, ice grains and volatile chemicals up to 50 miles into space at speeds of 1,360 mph (2,188km/h).
A statement released by Nasa confirmed that Cassini had performed the flyby of Enceladus successfully and checks on the spacecraft had confirmed it was unscathed.
It said: ‘Nasa’s Cassini spacecraft successfully completed its close flyby of Saturn’s moon Enceladus today, passing 30 miles above the moon’s south polar region at approximately 8:22 a.m. PDT (11:22 am GMT).’
Enceladus is Saturn’s sixth-largest moon – one of 62 – discovered in 1789 by William Herschel. In the early 1980s Nasa sent two Voyager spacecraft to the Saturnian system to capture the first close-up images of the moon.
Voyager 1 made its flyby on 12 November 1980 but captured only poor resolution shots that revealed a highly reflective surface that didn’t appear to have any craters on it.
Voyager 2 made its closest approach on 26 August 1981 during which its higher-resolution images instead revealed the surface to be heavily cratered in the north and lightly cratered around the equator.
Nasa’s Cassini craft began multiple flybys of Enceladus in 2005 and was able to identify cryovolcanoes near the south pole that shoot geyser-like jets of water vapour, and last month Cassini spotted evidence for a large ocean beneath Enceladus’ surface.
The icy moon is known to be highly geologically active with features on the surface that are less than 100 million years old.
Saturn’s moon is also thought to have an internal heat supply, possibly caused by the movement in its core, which may be responsible for the liquid water on the distant world.
Scientists believe this source of heat could make the ocean on Enceladus an ideal place to look for signs of alien life.
As well as measuring the content of the ice plumes from the moon’s south pole, it is also hoped it may help reveal more about the levels of hydrothermal activity is there.
Scientists also hope the flyby will help solve the mystery of whether the plume is comprised of column-like, individual jets, or sinuous, icy curtain eruptions – or a combination of both.
Speaking before the flyby, Brent Buffington, mission designer at Nasa’s Jet Propulsion Laboratory, said: ‘We are flying deep – the deepest we have ever been through this plume.
‘We will be sensing the gases and looking at the particles that make up these plumes.’
The plumes at the south pole were first spotted by Cassini in 2005, a year after it arrived in the Saturnian system.
Around 100 geysers erupting from surface features known as ‘tiger stripes’ were identified as its source.
The four 1.2-mile wide (1.9km-wide) aligned cracks are believed to be sites of heightened volcanic activity on Enceladus.
The $3.26 billion Cassini space mission is a joint project by the US space agency, European space agency and Italian space agency.
Cassini is the first spacecraft to orbit Saturn, and it has been circling the planet since 2004.
Morgan Cable, a science system engineer at Nasa’s Jet Propulsion Laboratory, said: ‘Cassini was never designed to look for life in the Enceladus ocean but it does have powerful instruments that can look for habitability.
‘So we are looking for the conditions suitable for life.’
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