Cassini’s Swan Song: How Saturn Probe Will Spend Its Final Day

NASA’s Cassini spacecraft will work tough to a really end.

Cassini will plummet into Saturn’s atmosphere early Friday morning (Sept. 15), finale a epic 13-year army during a ringed world with a bang. But before that happens, a examine will snap a failing design — a sketch of a accurate mark where Cassini will accommodate a predestine — send home any stored information remaining in a memory, stagger a scholarship instruments toward Saturn’s onrushing atmosphere and a receiver toward Earth, and start streaming real-time information behind home.

Cassini’s final section began with a final Titan flyby on Saturday (Sept. 11), that gave a examine a poke it indispensable to conduct toward Saturn. [Cassini’s Saturn Crash 2017: How to Watch Its ‘Grand Finale’]

“The Titan flyby was only tighten adequate and only a right march to sign Cassini’s fate,” Cassini module manager Earl Maize, of NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, California, pronounced during a news discussion on Wednesday (Sept. 13).

Milestones in Cassini's final dive toward Saturn in Sep 2017.
Credit: NASA/JPL-Caltech

Cassini is being driven into Saturn’s atmosphere to safeguard that a examine doesn’t pervert a moons Titan and Enceladus — both of that might be means of ancillary life — with microbes from Earth. The booster is scarcely out of fuel, so goal managers wanted to dispose of Cassini safely while they still had control of it.

While a bulk of a commands for Cassini’s final hours were sent 10 weeks ago, a few last-minute tweaks were uploaded on Wednesday during 6:53 a.m. EDT (1053 GMT; 3:53 a.m. PDT), JPL’s Michael Staab told As “Cassini Ace,” or chairman on point, Staab is one of a engineers who monitors and communicates with a booster from a goal control room during JPL.

Today (Sept. 14) during 3:58 p.m. EDT (1958 GMT; 12:58 p.m. PDT), Cassini will snap a final photo, targeting a patch of atmosphere where it will accommodate a burning fate. (Cassini won’t be holding photos during a tangible genocide dive on Friday; information will be during a premium, and images would sow too most bandwidth, goal group members said.)

After holding that picture, a examine will solemnly rotate, aiming a Ion and Neutral Mass Spectrometer (INMS) instrument toward a world and a receiver on a tail toward Earth.

If all goes well, Cassini will shortly start promulgation home a final of a information stored in a memory — a extensive routine that will start during 5:45 p.m. EDT (2145 GMT; 2:45 p.m. PDT) currently and finish during 4:37 a.m. EDT (0837 GMT; 1:37 a.m. PDT) Friday morning.

“We will afterwards reconfigure Cassini for a final transmissions,” Maize said.

With a solid-state information recorder empty, Cassini will change into what Maize called “bent-pipe” mode — all of a information issuing into a orbiter will be relayed to Earth roughly immediately.

“It’s radically now a real-time instrument,” Maize said. (It will still take any “packet” of transmitted information about an hour and 23 mins to transport from Saturn to Earth, however.)

With INMS leading, Cassini will pierce Saturn’s atmosphere, an area a booster wasn’t creatively designed to explore.

“Cassini is not built for a atmosphere,” Maize said. “We’re a deep-vacuum kind of probe.”

Though a booster has skimmed a aspect of Titan’s thick atmosphere and done a few dips into Saturn’s atmosphere on a final 5 orbits, Cassini’s thrusters weren’t done for a complicated drag it will confront on a planet, Maize said.

“The thrusters will be fighting intensely tough to keep a receiver forked during Earth,” he said. “It’s going to do that for as prolonged as it presumably can.”

As it dives — transitioning from a Saturn orbiter to a really initial Saturn atmosphere examine — Cassini will lamp home information, that will be perceived by a belligerent stations of NASA’s Deep Space Network. Most of this information will arrive in Australia, yet some will come in by a DSN receiver in Spain. [NASA’s Deep Space Network: 50 years of Interplanetary WiFi (Video)]

Cassini’s incursion into a atmosphere will be really short-lived.

“Cassini will be vaporized in maybe dual minutes,” Maize said.

Atmospheric models advise that a spacecraft’s final vigilance will be perceived behind on Earth during 7:55:06 a.m. EDT (1155:06 GMT; 4:55:06 a.m. PDT). Most likely, that final vigilance will be data-only, Staab said.

“It won’t know that something bad has happened to it until it’s already over,” he said.

But Staab combined that it’s probable that, in a final moments, a booster will send out a trouble summary as it tumbles by a atmosphere. Not suggestive that a genocide has been delicately scripted, Cassini might try to warning goal control that something has left horribly wrong.

Mission controllers wouldn’t be means to respond to that putative vigilance in any suggestive approach even if they wanted to; Cassini will die scarcely an hour and a half before such a vigilance reaches a planet.

“You can’t meddle on a booster that doesn’t exist anymore,” Staab said.

Cassini is resolutely set on a pile-up march into Saturn, so it shouldn’t need any assistance reaching a final destination. But that doesn’t meant zero can go wrong.

According to Cassini method planner Jan Berkeley, a singular feeble placed eventuality in space could means a problem. For instance, a cosmic ray flung from a inlet of space could impact a moody hardware, causing a complement to go into protected mode and no longer broadcast toward Earth. Berkeley and her group have spent a final few weeks programming solutions to forestall such probable problems.

“We have a whole set of commands that we have prepared to go,” Berkeley said.

According to Staab, a commands — if indispensable — would be sent to a moody operations server before being transmitted to a Cassini hire during goal control. The behaving Ace would afterwards send them on to a spacecraft.

The engineers would work tough to get a booster behind on a feet, yet Staab pronounced a routine would take 10 to 12 hours. “You’re racing opposite a time during that point,” he said.

Once Cassini came behind online, Staab pronounced a information could tide alongside a real-time observations, yet a routine would devour some-more bandwidth.

Still, he voiced certainty that a goal will float by a final hours though a problem, interjection to a Cassini team’s preparation.

“You devise for a misfortune yet design a best,” he said.

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