Cassini makes last flyby of Titan ahead of ‘grand finale’


 NASA‘s Cassini spacecraft has made its final flyby of Saturn’s massive moon Titan, collecting data on the hydrocarbon lakes and haze-enshrouded surface of the alien world. 

On April 22, the spacecraft made its closest approach to Titan at a speed of about 13,000 miles per hour, marking the beginning of its ‘Grand Finale.’

This encounter will cause Titan’s gravity to bend Cassini’s orbit, pulling it slightly in so that it can begin its final set of 22 dives between Saturn and its rings, before plunging into the planet on Sept 15.

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This unprocessed image of Saturn's moon Titan was captured by NASA's Cassini spacecraft during its final close flyby of the hazy, planet-sized moon on April 21, 2017

This unprocessed image of Saturn's moon Titan was captured by NASA's Cassini spacecraft during its final close flyby of the hazy, planet-sized moon on April 21, 2017

This unprocessed image of Saturn’s moon Titan was captured by NASA’s Cassini spacecraft during its final close flyby of the hazy, planet-sized moon on April 21, 2017

CASSINI’S ‘GRAND FINALE’

Cassini has circled Saturn for 13 years since reaching its orbit in 2004, spearheading remarkable discoveries about the ringed planet and its icy moons – but now, it’s running low on fuel.

On April 22, the spacecraft will transition into its grand finale orbits, taking one last close flyby of Saturn’s massive moon Titan.

Then, Titan’s gravity will bend Cassini’s flight path, causing the orbit to shrink until it passes between the planet and the inner edges of its rings.

Then, on April 26, Cassini will make the first of 22 dives through an unexplored gap before it ultimately plunges through the skies of Saturn to end its mission as ‘part of the planet itself.’

Cassini’s mission will officially terminate on September 15, after a planned plummet through Saturn’s atmosphere.

And, all the while, it will transmit data from several instruments until the signal is finally lost.

The spacecraft made its 127th and final close approach to Titan on April 21 at 11:08 p.m. PDT (2:08 a.m. EDT on April 22), passing at an altitude of about 608 miles (979 kilometers) above the moon’s surface.

Cassini transmitted its images and other data to Earth following the encounter.

Scientists with Cassini’s radar investigation will be looking this week at their final set of new radar images of the hydrocarbon seas and lakes that spread across Titan’s north polar region. 

The planned imaging coverage includes a region previously seen by Cassini’s imaging cameras, but not by radar. 

The radar team also plans to use the new data to probe the depths and compositions of some of Titan’s small lakes for the first (and last) time, and look for further evidence of the evolving feature researchers have dubbed the ‘magic island’.

‘Cassini’s up-close exploration of Titan is now behind us, but the rich volume of data the spacecraft has collected will fuel scientific study for decades to come,’ said Linda Spilker, the mission’s project scientist at NASA’s Jet Propulsion Laboratory in Pasadena, California. 

It marks the beginning of the ‘thrilling final chapter’ of Cassini’s life, twenty years after it left Earth.

The craft has circled Saturn for 13 years since reaching its orbit in 2004, spearheading remarkable discoveries about the ringed planet and its icy moons – but now, it’s running low on fuel.

“With this flyby we’re committed to the Grand Finale,” said Earl Maize, Cassini project manager at JPL. 

“The spacecraft is now on a ballistic path, so that even if we were to forgo future small course adjustments using thrusters, we would still enter Saturn’s atmosphere on Sept. 15 no matter what.”

Cassini will dive through the 1,500-mile-wide (2,400-kilometer) gap between Saturn and its rings. NASA/ JPL-Caltech/Space Science Institute

THE CASSINI MISSION 

Since it left earth in 1997 and arrived at Saturn in 2004, Cassini has been touring the system with an up-close study of the planet, its rings and moons. 

During its journey, Cassini has made dramatic discoveries, including a global ocean within Enceladus and liquid methane seas on Titan.

Before Nasa’s Cassini probe captured the most detailed images of Saturn ever seen, it dropped its companion Huygens on the planet’s largest moon, Titan. 

After nearly 20 years in space, the mission is drawing near its end because the spacecraft is running low on fuel.

In a captivating video released earlier this month, the space agency revealed a glimpse at Cassini’s ‘grand finale.’

On April 26, Cassini will make the first of 22 dives through an unexplored gap before it ultimately plunges through the skies of Saturn to end its mission as ‘part of the planet itself.’ 

Cassini’s mission will officially terminate on September 15, after a planned plummet through Saturn’s atmosphere.

And, all the while, it will transmit data from several instruments until the signal is finally lost.

In the months leading up to this dramatic conclusion, though, the craft will carry out a plan that is ‘in many ways, like a whole new mission,’ according to NASA.

Cassini will dive through the 1,500-mile-wide (2,400-kilometer) gap between Saturn and its rings.

‘No spacecraft has ever gone through the unique region that we’ll attempt to boldly cross 22 times,’ said Thomas Zurbuchen, associate administrator for the Science Mission Directorate at NASA Headquarters in Washington.

Twenty years after leaving Earth, NASA¿s Cassini spacecraft is set to embark on the ¿thrilling final chapter¿ of its life. The craft has circled Saturn for 13 years  ¿ but now, it¿s running low on fuel

Twenty years after leaving Earth, NASA¿s Cassini spacecraft is set to embark on the ¿thrilling final chapter¿ of its life. The craft has circled Saturn for 13 years  ¿ but now, it¿s running low on fuel

Twenty years after leaving Earth, NASA’s Cassini spacecraft is set to embark on the ‘thrilling final chapter’ of its life. The craft has circled Saturn for 13 years – but now, it’s running low on fuel

‘What we learn from Cassini’s daring final orbits will further our understanding of how giant planets, and planetary systems everywhere, form and evolve.

‘This is truly discovery in action to the very end.’

Researchers first decided the craft would terminate its mission in this way back in 2010.

In the months leading up this this dramatic conclusion, though, the craft will carry out a plan that is ¿in many ways, like a whole new mission,¿ according to NASA. On April 26, Cassini will make the first of 22 dives through an unexplored gap

In the months leading up this this dramatic conclusion, though, the craft will carry out a plan that is ¿in many ways, like a whole new mission,¿ according to NASA. On April 26, Cassini will make the first of 22 dives through an unexplored gap

In the months leading up this this dramatic conclusion, though, the craft will carry out a plan that is ‘in many ways, like a whole new mission,’ according to NASA. On April 26, Cassini will make the first of 22 dives through an unexplored gap

Its terminal orbits over the next five months will bring it closer to Saturn than ever before.

As the craft ‘repeatedly braves this unexplored region,’ it will investigate the origins of the rings and the nature of the planet’s interior, the video explains.

This weekend, NASA¿s Cassini spacecraft will make a close flyby of Saturn¿s moon Titan, collecting data on the hydrocarbon lakes and haze-enshrouded surface of the alien world. And, this will be its last

This weekend, NASA¿s Cassini spacecraft will make a close flyby of Saturn¿s moon Titan, collecting data on the hydrocarbon lakes and haze-enshrouded surface of the alien world. And, this will be its last

This weekend, NASA’s Cassini spacecraft will make a close flyby of Saturn’s moon Titan, collecting data on the hydrocarbon lakes and haze-enshrouded surface of the alien world. And, this will be its last

‘This planned conclusion for Cassini’s journey was far and away the preferred choice for the mission’s scientists,’ said Linda Spilker, Cassini project scientist at NASA’s Jet Propulsion Laboratory.

‘Cassini will make some of its most extraordinary observations at the end of its long life.’ 

According to NASA, the researchers hope to collect the first-ever samples of Saturn’s atmosphere and particles coming from the main rings.

On top of this, the craft will obtain the closest views yet of Saturn’s clouds and inner rings.

Scientists made the final checks on the space probe’s command list ahead of its finale, and uploaded them on April 11.

‘Based on our best models, we expect the gap to be clear of particles large enough to damage the spacecraft,’ said Earl Maize, Cassini project manager at JPL.

‘But we’re also being cautious by using our large antenna as a shield on the first pass, as we determine whether it’s safe to expose the science instruments to that environment on future passes.

TITAN: EARTH’S ‘TOXIC TWIN’

Aside from Earth, Titan is the only place in the solar system known to have rivers, rainfall and seas – and possibly even waterfalls.

Of course, in the case of Titan these are liquid methane rather than water on Earth.

Regular Earth-water, H2O, would be frozen solid on Titan where the surface temperature is -180°C (-292°F).

With its thick atmosphere and organic-rich chemistry, Titan resembles a frozen version of Earth several billion years ago, before life began pumping oxygen into our atmosphere.

Because Titan is smaller than Earth, its gravity does not hold onto its gaseous envelope as tightly, so the atmosphere extends 370 miles (595km) into space.

With Titan’s low gravity and dense atmosphere, methane raindrops could grow twice as large as Earth’s raindrops. 

‘Certainly there are some unknowns, but that’s one of the reasons we’re doing this kind of daring exploration at the end of the mission.’

On April 22, the spacecraft will transition into its grand finale orbits, taking one last close flyby of Saturn’s massive moon Titan.

Then, Titan’s gravity will bend Cassini’s flight path, causing the orbit to shrink until it passes between the planet and the inner edges of its rings.

As the spacecraft plummets into Saturn’s atmosphere on September 15, it will keep its antennas firing toward Earth as long as possible, sending back important data.

‘Cassini’s grand finale is so much more than a final plunge,’ said Spilker.

‘It’s a thrilling final chapter for our intrepid spacecraft, and so scientifically rich that it was the clear and obvious choice for how to end the mission.’



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