The first of 22 weekly dives between Saturn's rings has been completed
It marks the first time a man-made object has explored this region of space
NASA’s Cassini spacecraft has begun an unprecedented series of space dives that will see it plunge through the icy rings of Saturn, in the final phase of its 20-year mission.
Controllers operating the Deep Space Network antenna in Goldstone, California confirmed data collected during its passage was being received from the probe just after 8:00 a.m. GMT (3:00 a.m. ET) on Thursday.
“In the grandest tradition of exploration, NASA’s Cassini spacecraft has once again blazed a trail, showing us new wonders and demonstrating where our curiosity can take us if we dare,” said Jim Green, director of the NASA’s Planetary Science Division in a statement.
Plunging through the ring plane on Monday morning, scientists had taken precautions to protect the spacecraft from unexpected collisions with tiny smoke particles by using its dish-shaped antenna as a shield.
This meant repositioning Cassini’s antenna away from Earth, which caused controllers to temporarily lose signal with the unmanned probe.
“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,” said Earl Maize, Cassini project manager at NASA’s Jet Propulsion Laboratory.
“I am delighted to report that Cassini shot through the gap just as we planned and has come out the other side in excellent shape.”
A roaring success
The unprecedented gap-run was the first of 22 weekly dives Cassini will undertake between April and September, traveling at a top speed of more than 76,800 mph (120,000 kph).
As it zipped through the gap, the probe traveled to within 1,900 miles (3,000 kilometers) of Saturn’s cloud tops (where air pressure is similar to the atmospheric pressure of Earth at sea level), and within about 200 miles (300 kilometers) of the innermost visible edge of the rings, NASA said.
Now that engineers have reacquired the probe’s signal, they will evaluate data from this first dive and make tweaks to the orbit and trajectory to ensure the craft is protected ahead of future dives.
During these final revolutions around Saturn – which take around seven days – Cassini will return pioneering scientific data which scientists hope will help them decipher how giant planets evolve.
It will also collect a wealth of information including detailed maps of Saturn’s gravity and magnetic fields, which could answer questions surrounding the speed of Saturn’s rotations.
The closing plunges of the mission could also reveal the makeup and origin of the rings, as well as providing intriguing glimpses of the gas giant from closer than ever before.
Countdown to collision
Cassini has been orbiting Saturn for the last 13 years and is now entering the final phase of its 20-year mission, which NASA has dubbed “the grand finale.”
It is now locked into a terminal collision course with the atmosphere of the planet, where it is expected to burn up like a meteor on September 15 at 9:45 a.m. GMT (6:45 a.m. ET).
“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 September 15, no matter what,” said Earl Maize, Cassini project manager at NASA’s Jet Propulsion Laboratory (JPL), in a statement.
Shortly before impact, Cassini will emit a final signal which will be received on Earth just over an hour later.
Why destroy Cassini?
Cassini’s mission has twice been extended – in 2008 and 2010 – but the probe is now running low on rocket fuel.
Deliberately allowing the craft to burn up in Saturn’s atmosphere cuts the risk of it damaging one of Saturn’s moons if scientists lost the ability to control it enough to prevent a collision.
This way, Cassini should not contaminate future scientific work.
Before Cassini’s mission, little was known about the planet. Previous missions, including Pioneer 11 and Voyagers 1 and 2, all undertook flybys providing glimpses of Saturn and yielding ground-breaking discoveries.
But it was Cassini’s first close-up survey of the planet and its system of rings and moons in 2004 that changed scientists’ understanding of the planet and altered our approach to future planetary exploration.
Cassini’s next ring-run is scheduled for May 2.