Dodging stormy weather ahead of Hurricane Milton, SpaceX launched the European Space Agency’s $398 million Hera probe Monday on a follow-up flight to find out precisely how a moonlet orbiting a small asteroid was affected by the high-speed impact of NASA’s DART probe in 2022.

The launching was in doubt until the last moment, with thick clouds and rain across Florida’s Space Coast, fueled by moisture pulled in by the intensifying hurricane to the west.

But as the launch time approached, conditions improved enough to satisfy launch safety rules and NASA managers cleared the rocket for takeoff. Right on time, at 10:52 a.m. EDT, the Falcon 9’s first stage engines ignited with a burst of flame and the booster climbed smoothly away from the Cape Canaveral Space Force Station.

Liftoff came in the nick of time for several hundred European Space Agency managers, scientists, engineers and journalists who flew to Florida to watch the launch.

Hurricane Milton is expected to bring extreme winds and torrential rain to Florida’s Space Coast by Wednesday, a forecast that prompted NASA to stand down on plans to launch the agency’s $5.2 billion Europa mission to Jupiter and its ice-covered moon Europa on Thursday.

Instead, NASA announced late Sunday the rocket and it costly payload will remain in a SpaceX hangar at the base of launch pad 39A at the Kennedy Space Center until Milton passes by and safety personnel have a chance to inspect spaceport facilities for signs of damage.

The weather also has thrown a wrench into NASA’s plans to bring three NASA astronauts and a Russian cosmonaut back to Earth after a 217-day stay aboard the International Space Station.

Crew 8 commander Matthew Dominick, Mike Barratt, Jeanette Epps and cosmonaut Alexander Grebenkin had planned to undock Monday.

But NASA announced Sunday their departure would be delayed to at least Thursday because of the expected bad weather. Crew Dragon ferry ships require calm winds and seas in the Gulf of Mexico or the Atlantic Ocean to permit a safe splashdown.

Mission to an asteroid and its moon

In the meantime, despite an initially grim forecast, SpaceX was able to take advantage of a break in the weather to kick off Hera’s two-year voyage to the asteroid Didymos and its small moon Dimorphos.

The DART impact altered the 11-hour 55-minute orbit of the 495-foot-wide Dimorphos, shaving 31 minutes off the time needed to complete one trip around the parent asteroid Didymos. The test confirmed the feasibility of someday nudging a threatening asteroid off course before a possibly devastating Earth impact.

But a successful deflection would depend on a variety of factors, including when the threat was detected — the farther out, the better — and the asteroid’s composition.

ESA’s Hera probe will orbit the Didymos system and study both asteroids in detail with 11 high-tech cameras and other instruments, deploying two small “cubesat” satellites to study the interior structure of Dimorphos, assess the DART impact crater, the moon’s internal structure and composition.

The goal of the Asteroid Impact and Deflection Assessment, or AIDA, is to better understand the techniques that might be needed to prevent an Earth impact.

“The good news is no dinosaur killer is on its way to Earth during the next 100 years,” said 
Richard Moissl, director of ESA’s Planetary Defense Office. “We are safe from that scenario, but there are smaller ones, especially in this dangerous size, 50 meters and upwards, where it really threatens human life on the ground.”

The first step in planetary defense is detection, he said, followed by detailed observations to pin down the asteroid’s orbit and determine whether a collision with Earth is a possibility.

“For small objects, civil protection is the way to go,” he said. “But 50 meters (160 feet across) and larger, you really want this thing not to hit Earth, not to threaten population centers. And then step three comes into play, deflection.

“But again, it’s always good to know what you’re up against. And this is where Hera and DART come into play.”

Unlike most Falcon 9 flights, there were no plans to recover the rocket’s first stage. To give Hera the velocity need to break free of Earth gravity, the Falcon 9’s two stages were programmed to use up all of their propellants, leaving none in reserve for a powered first stage landing.

The flight plan called for two firings of the upper stage engine before Hera’s release to fly on its own one hour and 16 minutes after liftoff.

To reach Didymos and Dimorphos, Hera will have to execute a deep space thruster firing in November to set up a gravity-assist flyby of Mars in March, sailing within about 3,700 miles of the red planet. Along the way, the spacecraft will pass within 620 miles of the small martian moon Deimos.

“By swinging through the gravitational field of Mars in its direction of movement, the spacecraft gains added velocity for its onward journey,” Michael Kueppers, ESA’s project scientist, said on the agency’s website.

“This close encounter is not part of Hera’s core mission, but we will have several of our science instruments activated anyway. It gives us another chance to calibrate our instruments and potentially to make some scientific discoveries.”

After another deep space maneuver in February 2026, Hera will finally be on course to slip into orbit around Didymos the following October. The mission is expected to last about six months.

After an exhaustive review of suspect transistors in NASA’s Europa Clipper spacecraft, NASA managers have cleared the probe for launch next month as planned on a $5.2 billion mission to find out if a suspected sub-surface ocean on Jupiter’s icy moon Europa is a habitable environment.

The transistor issue cropped up in May, raising fears the scope of the Clipper’s mission might have to be reduced or the flight delayed for costly repairs.

But the review showed the transistors in question will, in effect, heal themselves during the 20 days between the high radiation doses the probe will receive during each of 49 close flybys of Europa, all of them deep in Jupiter’s powerful magnetic field and radiation environment.

In addition, onboard heaters can be used as needed to raise the temperature of affected transistors, improving the recovery process.

“After extensive testing and analysis of the transistors, the Europa Clipper project and I personally have high confidence we can complete the original mission for exploring Europa as planned,” said Jordan Evans, Europa Clipper project manager at NASA’s Jet Propulsion Laboratory.

The solar-powered Europa Clipper, one of NASA’s most ambitious planetary probes, is a “flagship” mission designed to make multiple close flybys of Europa to learn whether a subsurface salt water ocean beneath the frozen world’s icy crust could host a habitable environment.

If habitability can be confirmed, “just think of what that means, that there are two places in one solar system that have all the ingredients for life that are habitable right now at the same time,” said Curt Niebur, Europa Clipper program scientist at NASA Headquarters.

“Think of what that means when you extend that result to the billions and billions of other solar systems in this galaxy. Setting aside the ‘is there life?’ question on Europa, just the habitability question in and of itself opens up a huge new paradigm for searching for life in the galaxy.”

Discovered in 1610 by Galileo, Europa has been studied by NASA’s Voyager probes and, much more extensively, by the agency’s aptly-named Galileo orbiter in the 1990s, which made a dozen close flybys.

The spacecraft discovered that Jupiter’s magnetic field was disrupted around Europa, implying an electrically conductive fluid deep within the moon. Given Europa’s frozen crust, the most likely explanation is a sub-surface salt water ocean, kept warm by tidal flexing, the repetitive squeezing by Jupiter’s enormous gravity as the moon swings through its orbit.

The Europa Clipper is not designed to search for signs of life on or below Europa’s crust. But confirming the presence of a hidden sea and determining its habitability would be a major step forward in the search for places in the solar system and beyond where life, as currently defined, could exist.

“This is an epic mission,” Niebur said. “It’s a chance for us to explore not a world that might have been habitable billions of years ago, but a world that might be habitable today, right now,”

“A chance to do the first exploration of this new kind of world that we’ve discovered very recently called an ocean world, that is just totally immersed and covered in a liquid water ocean, completely unlike anything we’ve seen before. That’s what Europa Clipper and her team are going to unveil for us.”

Scheduled for launch from the Kennedy Space Center on Oct. 10 atop a SpaceX Falcon Heavy rocket, the spacecraft will first fly past Mars in February, using the red planet’s gravity to send it toward another velocity-boosting flyby of Earth in December 2026.

Only then will the Europa Clipper be traveling fast enough to head out into deep space on a trajectory to Jupiter. Even so, the probe won’t reach its target until April 2030, using its thrusters to brake into an initial orbit around the giant planet.

Five months later, the first in a series of close flybys of several moons will be needed to set up the first close encounter with Europa in the spring of 2031. During two science campaigns running through 2034, at least 49 close flybys of Europa are planned, including passes as low as 16 miles above the moon’s frozen surface.

The mission was progressing toward launch when engineers were alerted in May to a potentially serious problem with transistors used throughout the spacecraft. Similar components were found to fail at lower radiation doses than expected.

The radiation environment around Jupiter is powered by the planet’s titanic magnetic field, which traps and accelerates electrically charged particles from the solar wind and the volcanic moon Io. The radiation environment in the vicinity of Europa would kill an unprotected astronaut in a matter of hours.

As a result, Europa’s flight computer and other key components are protected in a radiation-resistant “vault.” Radiation “hardened” components are used throughout the spacecraft. But test data from the manufacturer showed similar components were failing at lower radiation levels than the Europa Clipper will experience.

But after months of testing, engineers concluded the spacecraft can complete its mission with no major modifications.

“We completed extensive testing to validate the transistors on the spacecraft,” Evans said. “We ran tests 24 hours a day over the last four months at multiple locations. We simulated flight-like conditions to illuminate any issues that the transistors might have over our four-year science mission across the variety of applications we have on the spacecraft.

“We put these representative transistors into these environments, irradiated entire circuits to see how the system behaves. … We replicated that transistor self-healing, or annealing as it’s called, that occurs by heating them to room temperature while they, essentially, (are out of) that intense radiation environment as we go around each orbit.”

Based on the results, he said, “we’re ready for our final launch preparations and reviews. We are ready for Europa.”