CAPE CANAVERAL, Fla. -- A NASA spacecraft rocketed away Monday on a quest to explore Jupiter's tantalizing moon Europa and reveal whether its vast hidden ocean might hold the keys to life.
It will take Europa Clipper 5½ years to reach Jupiter, where it will slip into orbit around the giant gas planet and sneak close to Europa during dozens of radiation-drenched flybys.
Scientists are almost certain a deep, global ocean exists beneath Europa's icy crust. And where there is water, there could be life, making the moon one of the most promising places out there to hunt for it.
Europa Clipper won't look for life; it has no life detectors. Instead, the spacecraft will zero in on the ingredients necessary to sustain life, searching for organic compounds and other clues as it peers beneath the ice for suitable conditions.
In addition to water, the other essential ingredients of life are thought to be energy and carbon-based molecules.
SpaceX started Clipper on its 1.8 billion-mile journey, launching the spacecraft on a Falcon Heavy rocket from Florida's Kennedy Space Center. An hour later, the spacecraft separated from the upper stage, floated off and called home.
"Please say goodbye to Clipper on its way to Europa," NASA's Jet Propulsion Laboratory's flight director Pranay Mishra announced from Southern California.
"The science on this is really captivating," NASA Associate Administrator Jim Free told The Associated Press back at the launch site. Scientists are still learning about the depths of our own ocean, "and here we are looking that far out."
RADIATION RISKS
The $5.2 billion mission almost got derailed by transistors.
NASA didn't learn until spring that Clipper's transistors might be more vulnerable to Jupiter's intense radiation field than anticipated. Clipper will endure the equivalent of several million chest X-rays during each of the 49 Europa flybys. The space agency spent months reviewing everything before concluding in September that the mission could proceed as planned.
Hurricane Milton added to the anxiety, delaying the launch by several days.
"What a great day. We're so excited," JPL Director Laurie Leshin said after liftoff.
About the size of a basketball court with its solar wings unfurled, Clipper will swing past Mars and then Earth on its way to Jupiter for gravity assists. The nearly 13,000-pound probe should reach the solar system's biggest planet in 2030.
Clipper will circle Jupiter every 21 days. One of those days will bring it close to Europa, among 95 known moons of Jupiter and close to our own moon in size.
The spacecraft will skim as low as 16 miles above Europa -- much closer than the few previous visitors. Onboard radar will attempt to penetrate the moon's ice sheet, believed to be 10 miles to 15 miles or more thick. The ocean below could be 80 miles or more deep.
The spacecraft holds nine instruments, with its sensitive electronics stored in a vault with dense zinc and aluminum walls for protection against radiation. Exploration will last until 2034.
"Ocean worlds like Europa are not only unique because they might be habitable, but they might be habitable today," NASA's Gina DiBraccio said on the eve of launch.
"I think Europa is certainly the most likely place for life beyond Earth in our solar system," said Robert Pappalardo, the project scientist for Europa Clipper. "And that's because it is the most likely to have the ingredients for life in abundance and for there to be enough time for life to get going."
If conditions are found to be favorable for life on Europa, then that opens up the possibility of life at other ocean worlds in our solar system and beyond, according to scientists. With an underground ocean and geysers, Saturn's moon Enceladus is another top candidate.
CHEMICAL REACTIONS
Jupiter's immense gravity squeezes and pulls on Europa's insides, and the heat of friction could power hydrothermal vents on its seafloor. The vents could spew chemicals known as reductants into the ocean.
At the surface, the bombardment of radiation from Jupiter on ice produces oxidants. When oxidants and reductants combine, energy is released -- potentially the chemical reactions that could power life.
But for that to occur, the oxidants sitting on the surface of Europa have to somehow move down through miles of ice into the ocean.
The key is that ice on Europa is not a simple solid shell, just as the Earth's crust is not a simple, solid piece of rock.
Under pressure far below the surface, ice becomes bendable. Warm blobs of ice rise to the surface and cold, denser blobs sink, potentially carrying the oxidants downward -- a pattern of convection similar to how the mantle rises and falls within Earth.
That could be the conveyor belt taking chemicals at the surface to the ocean.
"Very much anticipated to be a lava lamp," said Donald Blankenship, who is a research professor at the University of Texas Institute for Geophysics and the principal investigator for Europa Clipper's ice-penetrating radar instrument.
Pings from the spacecraft's radar will pass almost effortlessly through ice and snow but bounce back off salty water. So Europa Clipper may be able to see all the way through the ice to the ocean.
The radar could also detect lakes embedded within the ice, and cryovolcanoes that erupt water, not molten rock.
A thermal imager onboard will look for warm spots, which could indicate places where the ice is thinner and the ocean is closer to the surface.
A tube-shaped instrument about the length of a baguette will scoop up and identify molecules from the thin atmosphere, including carbon-based molecules that could serve as the building blocks for life.
The Hubble Space Telescope has spotted what could be plumes of water vapor sporadically erupting from Europa's surface. With luck, Europa Clipper could fly through an erupting plume, which could be material from the ocean.
Another instrument, an ultraviolet spectrometer, could also identify molecules within a plume when a distant star passes behind Europa. Stars are expected to be eclipsed by Europa in this way about 100 times during the mission. Looking at how the colors of ultraviolet light from the star dim will tell the density of the gases and what they are made of.
Information for this article was contributed by Marcia Dunn of The Associated Press and Kenneth Chang of The New York Times. The Associated Press Health and Science Department receives support from the Howard Hughes Medical Institute's Science and Educational Media Group. The AP is solely responsible for all content.
A SpaceX Falcon Heavy rocket with a NASA spacecraft bound for Jupiter stands ready for launch on pad 39A at the Kennedy Space Center Monday, Oct. 14, 2024 in Cape Canaveral, Fla. (AP Photo/John Raoux)
A SpaceX Falcon Heavy rocket with a NASA spacecraft bound for Jupiter stands ready for launch today on pad 39A at the Kennedy Space Center Monday, Oct. 14, 2024 in Cape Canaveral, Fla. (AP Photo/John Raoux)
A SpaceX Falcon Heavy rocket with a NASA spacecraft bound for Jupiter stands ready for launch today on pad 39A at the Kennedy Space Center Monday, Oct. 14, 2024 in Cape Canaveral, Fla. (AP Photo/John Raoux)
A SpaceX Falcon Heavy rocket with a NASA spacecraft bound for Jupiter lifts off from pad 39A at the Kennedy Space Center Monday, Oct. 14, 2024 in Cape Canaveral, Fla. (AP Photo/John Raoux)
A SpaceX Falcon Heavy rocket with a NASA spacecraft bound for Jupiter lifts off from pad 39A at the Kennedy Space Center Monday, Oct. 14, 2024 in Cape Canaveral, Fla. (AP Photo/John Raoux)
This illustration provided by NASA depicts the Europa Clipper spacecraft over the moon, Europa, with Jupiter at background left. (NASA/JPL-Caltech via AP)
A SpaceX Falcon Heavy rocket with a NASA spacecraft bound for Jupiter lifts off from pad 39A at the Kennedy Space Center Monday, Oct. 14, 2024 in Cape Canaveral, Fla. (AP Photo/John Raoux)
A SpaceX Falcon Heavy rocket with a NASA spacecraft bound for Jupiter stands ready for launch today on pad 39A at the Kennedy Space Center Monday, Oct. 14, 2024 in Cape Canaveral, Fla. (AP Photo/John Raoux)
This illustration provided by NASA depicts the Europa Clipper spacecraft above the surface of the moon Europa, foreground, and Jupiter behind. (NASA/JPL-Caltech via AP)