Earlier this summer, it seemed that NASA’s Europa Clipper mission, aimed at exploring Jupiter’s icy moon Europa, might miss its launch window. In May, engineers flagged concerns about transistors embedded throughout the spacecraft, potentially vulnerable to Jupiter’s intense radiation. These transistors are crucial to about 200 functions, many critical for the spacecraft’s operation as it orbits Jupiter and conducts multiple flybys of Europa using nine science instruments.
Since the transistors were already installed, removing them for inspections or replacements would delay the mission’s launch until late next year. The mission has a tight 21-day launch window starting October 10, 2024, to begin its journey to the outer solar system.
After four months of testing similar transistors on Earth, engineers concluded that the transistors onboard Europa Clipper can withstand the harsh radiation environment around Jupiter without altering the flight plan or mission trajectory.
“One major challenge was analyzing how those transistors would cope with Jupiter’s radiation,” said Jordan Evans, Europa Clipper’s project manager at NASA’s Jet Propulsion Laboratory (JPL). “After extensive testing, I’m confident we can complete the mission as planned.”
NASA’s leadership has agreed with the findings, giving the green light for launch. “We’re thrilled to say the Europa Clipper mission passed a key milestone review,” said Nicky Fox, associate administrator of NASA’s science mission directorate.
With the final approval in place, teams at Kennedy Space Center in Florida will soon load 3 metric tons of propellant into the spacecraft, accounting for nearly half of Europa Clipper’s total weight. The spacecraft will then be enclosed in its launch fairing and mounted on a SpaceX Falcon Heavy rocket for an October liftoff.
“I’m excited to say that our spacecraft and team are ready for launch,” said Laurie Leshin, JPL’s center director.
After launching from Florida, Europa Clipper will reach Mars in February 2025 for a gravity-assist flyby, then swing past Earth in December 2026 to set its course for Jupiter. By April 2030, the spacecraft will enter Jupiter’s orbit and begin its primary mission, flying by Europa 49 times over four years, coming as close as 16 miles from the moon’s surface.
Europa Clipper’s instruments will map the icy crust of Europa and search for signs of habitability in the moon’s subsurface ocean. The spacecraft might even pass through plumes erupting from Europa’s surface, allowing scientists to study pristine material from its ocean.
“This is an epic mission,” said Curt Niebur, Europa Clipper’s program scientist at NASA. “We’re exploring a world that might be habitable today, not just billions of years ago.”
Europa orbits within Jupiter’s radiation belts, where charged particles can damage spacecraft electronics. To mitigate this, Europa Clipper’s most sensitive electronics are shielded inside a vault with aluminum-zinc walls. However, some transistors are exposed in instruments outside the vault. Fortunately, these transistors can self-heal, a process called annealing, which helps them recover from radiation exposure. Engineers will adjust heater settings around vulnerable transistors to enhance this self-healing process.
The spacecraft’s metal oxide field effect transistors function as electronic switches. “We carefully analyzed each circuit and determined we have enough margin to confidently complete the mission,” Evans said.
