Clipper to begin 6-year journey to Jupiter
Orbiter will observe Europa, one of its moons, up close; launch set for October
Before approaching the spacecraft, Akemi Hinzer suits up: Hairnet, face mask, head cover tucked into a full body “bunny suit,” covered shoes crammed into protective spats and nitrile gloves taped over sleeves.
She steps into the chamber where holes in the walls blast her with air before she can enter the vast, white “clean room” where NASA's Jet Propulsion Laboratory assembles its fragile spacecraft and rovers before they leave Earth.
As the deputy lead planetary protection scientist for the Europa Clipper mission, this is a typical part of Hinzer's job.
What's atypical about this day is that Hinzer will need to make sure that dozens of visiting journalists don't dirty the multibillion-dollar spacecraft with their germs, hairs and other granular detritus, potentially compromising the mission or annihilating an alien species.
“We can't do things like wear perfume,” Hinzer said. “If you can smell it, then it's volatile, it's in the air and it can settle on the instruments. And that is enough to make an instrument not work.”
On Thursday, JPL invited journalists to suit up and visit the Europa Clipper, an orbiter built to observe one of Jupiter's many moons, Europa, up close.
Europa is covered with an icy crust that, scientists believe, might harbor a salty, sloshing ocean capable of sustaining life. Carrying nine scientific instruments, the Clipper will leave Earth in October, beginning its six-year journey to Jupiter.
Once the spacecraft arrives, it will surrender to Jupiter's gravity, circling the planet and passing Europa once per orbit, around 50 times. During those flybys, the Clipper will direct all nine instruments at Europa's surface, collecting unparalleled observations of the icy moon.
Dr. Cynthia Phillips, science communications lead and a staff scientist for the mission, specializes in studying the surfaces of celestial bodies using images. Gesturing at a crosssection model of Europa's ice sheet, Phillips enthusiastically expressed her anticipation to analyze detailed pictures of the moon.
Previous images had pixel sizes of .87 mile, the smallest visible features being much larger than a house. Phillips explained that the Clipper's cameras have a resolution “down to a couple of meters per pixel. So we're going to be able to see big rocks basically. It's going to be amazing!”
Indications that Europa might harbor a lively ocean came from early images of the moon's surface, showing scientists an icy landscape scarred with long, reddish fissures, indicating a grimy ooze had gushed through the cracked ice shelf. Europa also had an unusually youthful appearance for being 41/2 billion years old.
Phillips explained that, having calculated how often any given moon or planet should be hit by meteors, scientists can calculate their age by counting surface craters.
“But when we try to do that on Europa, we run into trouble,” Phillips said. “And that's because Europa has so few craters,” around 50 or 60.
This indicates that Europa's sloshing ocean may have reformed the surface only 50 million years ago.
Observing Europa's internal ocean is of special interest to the mission's Project Scientist, Dr. Robert Pappalardo, a longtime researcher of icy moons with a philosopher's demeanor. Pappalardo is excited about the Clipper's cutting-edge, ice-penetrating radar that will allow the team “to understand the three-dimensional structure of the icy shell.”
“Where is their liquid water? How thick is the ice? Are there warm blobs of ice rising up through the shell?”
Pappalardo illustrated that “life is like a little battery” requiring “a positive and a negative,” meaning oxidants and reductants.
When charged particles hit Europa's ice, they split the water into oxygen and hydrogen, oxidants. Meanwhile, reductants may be produced on Europa's ocean floor. The 3D model of the ice shelf will let scientists determine whetherthese building blocks of life could meet.
“If we were to find that these worlds could support life that would just change our sense of how abundant life could be throughout the universe,” Pappalardo mused.
“Because ocean worlds might be the most common, habitable environment out there.”
As the mission's project manager, responsible for ensuring the Clipper gets built, launched and operated, Jordan Evans is acutely aware of the risks facing the spacecraft.
Jupiter's powerful magnetic field attracts highenergy radiation particles, creating a deadly particle accelerator orbiting the planet; and Europa sits directly in this accelerator's path. Like a boxer in a clinch, the Clipper will hug close to Jupiter, only venturing into the blows of radiation when passing Europa.
“We're still accumulating the total radiation of the equivalent of 100,000 chest X-rays. But we're accumulating it and then we're not. And so we're able to do a four-year mission before we hit our first design limit,” Evans said, standing in front of the spacecraft he soon would send into this chaos.
There are a number of key events during the mission that Evans will be grateful to pass. Evans refers to one of these as the “six hours of terror”: “when we fire the thrusters to get captured into an orbit around Jupiter. That's a big moment.”
Too far in one direction and the spacecraft will burn up above Jupiter, too far in the other and it could crash into a moon.
At JPL, the mission team exudes fervor, eager to share their passion with the world.
The night before the Clipper launches into space, when Jupiter will fortuitously be visible to the naked eye, a crowd, including members of the Clipper mission, will gather on the beach near Kennedy Space Center. As Jupiter rises above the Earth's ocean, U.S. Poet Laureate Ada Limón will read her poem that is inscribed on a plate borne by the spacecraft, incanting:
“O second moon, We, too, are made
of water, of vast and beckoning seas.
We, too, are made of wonders.”