NASA Cassini Saturn probe's last journey: Why is US space agency killing its spacecraft? All you need to know

NASA’s Cassini spacecraft, which began its grand finale by making a daring encounter with the Saturn’s rings by diving between the planet and its rings, has beamed back closest-ever images.

The NASA Cassini probe re-established contact with Earth on Thursday morning, a day after its signals faded during the first plunge. Cassini’s risky dive turned out to be successful and it began beaming back data collected during the manoeuvre back to NASA.

NASA's Cassini spacecraft sent the closest-ever images of Saturn on Thursday after surviving its first plunge inside the planet's rings, the US space agency said.

The latest pictures sent by Cassini reveal the swirling clouds, massive hurricane and odd six-sided vortex weather system of Saturn.

First of the 22 Cassini dives:

Cassini made the dive at the innermost ring of the planet, where no spacecraft has ever dared to go before. NASA has planned total 22 close encounters in the last phase and Wednesday’s dive was the first of these.

"Cassini spacecraft has once again blazed a trail, showing us new wonders and demonstrating where our curiosity can take us if we dare," National Aeronautics and Space Administration planetary sciences chief Jim Green said in a statement.

What Cassini is supposed to do in Grand Finale?

During the last phase, Cassini is expected to capture several small inner moons and observe Saturn’s winds, clouds, auroras and gravity.

In its last phase, the Cassini will perform a long string of historic firsts and Wednesday’s successful manoeuvre was the latest one. However, Cassini is soon going to die after its almost 20-year space odyssey.

Why NASA is killing Cassini probe?

In October 1997, NASA had launched Cassini probe to study Saturn and its moons. Cassini arrived at the orbit of Saturn in July 2004. After years of observations and data collection, Cassini is now ageing and is running low on fuel. Hence, NASA has decided to kill Cassini, which will meet its death after plunging into the atmosphere of Saturn.

" reason for this ending to the Cassini mission is something that NASA is very worried about – contamination of our life forms on planets and moons that may harbor other forms of life," says Nicholas Suntzeff, a professor of Observational Astronomy at Texas A&M University, tells the Monitor via email. "The moons of Saturn – Enceladus and Titan – could have life or complex organic molecules that are the soup out of which life forms."

What NASA scientists say about Cassini?

"NASA and the Cassini team's devotion to the mission are an example for all of us," Harold C. Connolly Jr., chair of the department of geology at Rowan University in New Jersey, tells The Christian Science Monitor in an email. "I remember as a child living in southern New Jersey being glued to the TV when the Voyager images came back to Earth, and now I am an upper manager of a NASA space mission – I hope Cassini-Huygens has motivated a new generation of future scientists and explorers."

Dr. Connolly is currently working on the OSIRIS-REx program, NASA's first mission to collect an asteroid sample and return it to Earth for analysis. 

"Cassini has provided a better understanding of Saturn's ring system, why it exists, the weather conditions on Saturn, and the mysteries of its largest moon, Titan: A truly primitive world potentially similar to what Earth was like in the earliest days of its life," Connolly adds. "From an engineering point, we as humans have learned how to navigate and fly around the massive planet of Saturn, which provides key information on how to fly to and around other planets. We have also learned the extent of the lifetime of various payload instruments, those critical to meet science objectives and those needed for navigation."

"No spacecraft has ever been this close to Saturn before," said Cassini project manager Earl Maize in a NASA statement. "We could only rely on predictions, based on our experience with Saturn's other rings, of what we thought this gap between the rings and Saturn would be like."

ALSO READ | Death of NASA's Cassini: Spacecraft makes daring encounters with Saturn rings, communications with probe blurred

When will NASA Cassini spacecraft meet death:

NASA officials are not sure whether Cassini will survive all its ring dives. The gap between Saturn and the rings is about 1,500 miles (2,400 km) wide and likely littered with ice particles.

Cassini is travelling through the gap at a relative speed of about some 77,000 mph (124,000 kph) so even small particles striking the spacecraft can be deadly.

The Cassini spacecraft will perform similar manoeuvres during its subsequent dives, the second of which is scheduled for Tuesday.
On its final dive on September 15, Cassini will explode like a meteor and destroy itself by flying directly into Saturn's crushing atmosphere.

NASA plans to crash the spacecraft into Saturn to avoid any chance Cassini could someday collide with any ocean-bearing moons that have the potential to support indigenous microbial life.