After an extensive investigation into a suspect transistor on NASA’s Europa Clipper spacecraft, NASA administrators have approved the launch of the probe next month as planned for a $5.2 billion mission to determine whether a possible subsurface ocean on Jupiter’s icy moon Europa is habitable.
The transistor problems first emerged in May, raising concerns that the scope of Clipper’s missions might have to be curtailed or flights postponed because of costly repairs.
But tests showed that the problem transistors would essentially repair themselves during the 20 days between the high radiation doses the probe would receive during each of its 49 flybys of Europa, all deep within Jupiter’s strong magnetic field and radiation environment.
National Aeronautics and Space Administration (NASA)
Additionally, an on-board heater can be used if desired to increase the temperature of the affected transistors to improve the recovery process.
“Following extensive testing and analysis of the transistor, the Europa Clipper project and I have high confidence that we will be able to complete the original Europa exploration mission as planned,” said Jordan Evans, Europa Clipper project manager at NASA’s Jet Propulsion Laboratory.
One of NASA’s most ambitious planetary probes, the solar-powered Europa Clipper is a “flagship” mission designed to make multiple close flybys of Europa to determine whether the salty ocean beneath the frozen world’s icy crust could support a habitable environment.
If habitability is confirmed, “think about what that would mean: We now have two places in the solar system that have all the ingredients for life to exist, at the same time,” said Kurt Niebuhr, Europa Clipper mission scientist at NASA Headquarters.
“Consider what this means when you extend it to the billions of other solar systems in our galaxy. Setting aside the question of ‘is there life’ on Europa, the question of habitability itself opens up a major new paradigm for the search for life in the galaxy.”
Discovered by Galileo in 1610, Europa has been studied by NASA’s Voyager spacecraft and more extensively by the agency’s Galileo spacecraft in the 1990s, which flew close by Europa 12 times.
The probe found that Jupiter’s magnetic field is disrupted around Europa, suggesting the presence of electrically conductive fluids deep inside the planet. Given Europa’s frozen crust, the most likely explanation is a subsurface saltwater ocean kept warm by tidal forces repeatedly compressed by Jupiter’s enormous gravity as the moon moves in its orbit.
National Aeronautics and Space Administration (NASA)
Europa Clipper is not designed to search for signs of life on or beneath Europa’s crust, but confirming the existence of a hidden ocean and determining whether it might be habitable would be a major step forward in the search for potential sites for life, as currently defined, both within and outside the solar system.
“This is an epic mission,” Niebuhr said, “a chance to explore not just a world that might have been habitable billions of years ago, but a world that might be habitable right now.”
“This is our chance to be the first to explore a new kind of world that has only recently been discovered, called an ocean world. This world is completely immersed and covered by an ocean of liquid water, and it’s something we’ve never seen before. And that’s exactly what Europa Clipper and its team are going to reveal to us.”
The spacecraft, scheduled to launch on a SpaceX Falcon Heavy rocket from the Kennedy Space Center on October 10, will first fly by Mars in February before speeding past Earth again in December 2026, using the Red Planet’s gravity to do so.
Only then will the Europa Clipper be able to travel fast enough to set off into deep space on a trajectory to Jupiter, though the probe won’t reach its destination until April 2030, when it will have to use its thrusters to brake its orbit around the giant planet.
Five months later, the first in a series of multi-moon flybys will be conducted to set up the first close encounter with Europa in the spring of 2031. At least 49 flybys of Europa are planned over two science campaigns running through 2034, including flights that will pass as low as 10 miles above Europa’s icy surface.
As the mission was heading for launch, engineers were warned in May that there might be a serious problem with transistors used throughout the spacecraft, after similar components were found to fail at lower than expected levels of radiation.
The radiation environment around Jupiter is driven by the planet’s enormous magnetic field, which traps and accelerates electrically charged particles from the solar wind and its volcanic moon Io. The radiation environment near Europa would kill an unprotected astronaut within a few hours.
As a result, Europa’s flight computers and other key components are protected in a radiation-resistant “vault.” Radiation-hardened “components” are used throughout the spacecraft, but manufacturers’ test data shows that similar components fail at lower radiation levels than the Europa Clipper is exposed to.
But after months of testing, engineers determined the spacecraft could complete the mission without any major modifications.
“We have completed extensive testing to validate the transistors on the spacecraft,” Evans said, “We have performed tests 24 hours a day for the past four months in multiple locations, simulating flight-like conditions in a variety of applications aboard the spacecraft to uncover any issues that may arise with the transistors during the four-year science mission.”
“We put these representative transistors in these environments and exposed the entire circuit to radiation to see how the system behaves. … We replicated the self-healing of the transistors, what’s called annealing, which occurs by basically (taking) the transistor out of that intense radiation environment and heating it up to room temperature between each orbit.”
Based on the results, he said, “We are ready for final launch preparations and considerations. We are ready for Europa.”
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