On Thursday afternoon, NASA’s $3.3 billion Cassini spacecraft will capture one final image: A close-up of its eventual killer, the gas giant Saturn.
Roughly 14 hours later, the spacecraft will fly into the planet’s atmosphere at 76,000 mph, lighting up like a meteor.
It’ll take 1 1/2 minutes, by NASA’s estimates, before Cassini is ripped apart, but up until the final moments, the craft’s thrusters will burn up the remaining propellant in a struggle to keep the antenna pointed toward Earth long enough to send back unprecedented new data about Saturn’s atmosphere.
• Photos: Planning for destruction
“It will fight, it will fight and it will fight,” said Earl Maize, Cassini’s project manager at the Jet Propulsion Laboratory in La Cañada Flintridge. “It’s going to do this as long as it can.”
Within seconds, the spacecraft will heat up, melting its aluminum, carbon fiber and mylar parts first. Then, the temperatures will overcome the iridium-casing for its plutonium power supply, creating a flare just before the last evidence of Cassini is erased.
“It will be completely vaporized,” Maize said.
The explosion may even create enough light for telescopes to observe Cassini’s demise from Earth, according to NASA.
By 3:30 a.m., Cassini will be gone.
The spacecraft’s final transmissions will reach Earth approximately 86 minutes later with the last expected by 4:55 a.m.
NASA sealed the then 20-year-old mission’s fate when Cassini flew by Saturn’s moon, Titan, on Monday, by using the world’s gravity to shift Cassini’s trajectory toward an inevitable destruction.
With low fuel, there is no way to abort the final maneuver.
The team decided to destroy Cassini out of fear it could crash into Enceladus or Titan, two of the most likely candidates for life elsewhere in our solar system. Enceladus has oceans beneath its ice and the presence of some of the necessary elements for life. Titan is the only known world with liquid on the surface in the form of methane lakes and seas. These discoveries made by Cassini challenged NASA’s understanding of the solar system and made Cassini’s continued operation a risk, officials said.
By destroying Cassini, NASA ensures that spacecraft doesn’t inadvertently contaminate either moon with microbes carried billions of miles from Earth. Such contamination could harm or create potential life.
Cassini’s team is reconfiguring the spacecraft to send back scientific data in “near real time.” Gas analyzed by the Ion and Neutral Mass Spectrometer, one of eight instruments running until the bitter end, is expected to collect new information about the atmosphere’s chemical and elemental composition.
“In these very final seconds, we’ll be plunging deeper into Saturn than we ever have before,” said Linda Spilker, Cassini’s project scientist. “In fact, you can think of Cassini becoming the first Saturn probe.”
NASA’s Deep Space Network complex in Canberra, Australia will receive the last transmissions, barring a torrential rainfall in the region.
Like most of Cassini’s discoveries, the science team expects that data collected will overturn existing theories about Saturn and fuel debate for decades.
“Who knows how many Ph.D. theses will be made into the next decade with Cassini’s data,” Spilker said.
Hundreds of scientists, engineers and support staff have worked on the mission from around the world, Maize said. The team is sad, but proud of accomplishing their goals, he said.
“We set out to do something at Saturn, we did it, we did it extremely well and we delivered more and more and we left the world informed, but still wondering,” Maize said. “I couldn’t ask for more. We’ve got to go back, I know it.”
Cassini was launched in 1997 and arrived at Saturn seven years later. The lessons learned from the last 13 years will carry forward to the Europa Clipper, a planned mission to Jupiter’s icy moon in the 2020s.
But, a return to Saturn could happen in the near future, too, according to Jim Green, the director of NASA’s planetary science division. Proposals submitted and now under review through NASA’s New Frontier program include potential missions to Titan and Enceladus, Green said.
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