Watch: How NASA’s Cassini will dive into Saturn’s atmosphere, burn like a meteor to meet its end
NASA’s Cassini probe is counting its final hours before one last plunge into Saturn on Friday.science Updated: Sep 15, 2017 11:02 IST
NASA’s Cassini probe is counting its final hours before plunging into Saturn on Friday that will cap a fruitful mission that greatly expanded knowledge about the gas giant.
Cassini flew by Titan one last time on Tuesday before transmitting images and scientific data from the flight.
Mission engineers will use the information gathered from the encounter which they dubbed “the goodbye kiss” to make sure the vessel is following the right path to plunge into the gas giant’s atmosphere.
When Cassini ends its 13-year tour of the Saturn system with an intentional plunge into the planet on Friday, the spacecraft’s speed will be approximately 1,13,000 km per hour, NASA said.
The mission’s final calculations predict loss of contact with the Cassini spacecraft will take place on Friday at 7:55am EDT (5.25pm IST).
Cassini will enter Saturn’s atmosphere approximately one minute earlier, at an altitude of about 1,915 kilometres above the planet’s estimated cloud tops.
When Cassini first begins to encounter Saturn’s atmosphere, the spacecraft’s attitude control thrusters will begin firing in short bursts to work against the thin gas and keep Cassini’s saucer-shaped high-gain antenna pointed at Earth to relay the mission’s precious final data.
As the atmosphere thickens, the thrusters will be forced to ramp up their activity, going from 10% of their capacity to 100% in the span of about a minute.
Once they are firing at full capacity, the thrusters can do no more to keep Cassini stable and pointed, and the spacecraft will begin to tumble.
When the antenna points just a few fractions of a degree away from Earth, communications will be severed permanently, NASA said.
The predicted altitude for loss of signal is approximately 1,500 kilometres above Saturn’s cloud tops.
From that point, the spacecraft will begin to burn up like a meteor. Within about 30 seconds following loss of signal, the spacecraft will begin to come apart. Within a couple of minutes, all remnants of the spacecraft are expected to be completely consumed in the atmosphere of Saturn.
Due to the travel time for radio signals from Saturn, which changes as both Earth and the ringed planet travel around the Sun, events currently take place there 83 minutes before they are observed on Earth.
This means that, although the spacecraft will begin to tumble and go out of communication at 6:31am EDTat Saturn, the signal from that event will not be received at Earth until 83 minutes later.
“The spacecraft’s final signal will be like an echo. It will radiate across the solar system for nearly an hour and a half after Cassini itself has gone,”said Earl Maize, Cassini project manager at NASA’s Jet Propulsion Laboratory in Pasadena, California.
“Even though we’ll know that, at Saturn, Cassini has already met its fate, its mission isn’t truly over for us on Earth as long as we’re still receiving its signal,” Maize added.
By safely disposing of the spacecraft in Saturn’s atmosphere, we avoid any possibility Cassini could impact one of Saturn’s moons somewhere down the road, keeping them pristine for future exploration
Where can you watch the plunge
Live mission commentary and video from Jet Propulsion Laboratory Mission Control will air on NASA TV and the agency’s website from 7 to 8:30am EDT (4.30 to 6 pm India time)on Friday.
Launched in 1997, Cassini arrived in orbit around Saturn in 2004 on a mission to study the giant planet, its rings, moons and magnetosphere.
First Published: Sep 14, 2017 22:36 IST