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Europa, Jupiter‘s fourth-largest moon, has been hailed as one of the most likely locations for aliens to exist in our solar system.
Now, NASA may have the chance to find out, as its ambitious Europa Clipper mission is set to launch on an ambitious five-and-a-half-year journey to investigate.
After a delay caused by Hurricane Milton, Clipper will launch from NASA’s Kennedy Space Center in Florida at 12:06 ET (17:06 BST) today.
Following an approximately 1.8-billion-mile trip, the $5.2 billion (£4 billion) spacecraft will finally start orbiting Jupiter in April 2030.
Over more than 40 flybys, Clipper will conduct a detailed survey of Europa to determine whether the icy world ‘could have conditions suitable for life’.
Beyond Earth, Jupiter’s moon Europa is considered one of the solar system’s most promising potentially habitable environments. Clipper will enter orbit around Jupiter in 2030 to probe Europa, the fourth-largest of Jupiter’s 95 moons
Europa is comprised of an icy shell, estimated to be about 15 miles thick and a very thin atmosphere. It’s pictured here, as imaged by the Juno spacecraft, September 2022
Slightly smaller than Earth’s moon, Jupiter’s moon Europa is considered one of the solar system’s most promising potentially habitable environments.
Along with Earth and Saturn’s moon Enceladus, Europa is one of the very few locations in our solar system with liquid water.
Live coverage of today’s launch will stream on NASA+ and NASA’s YouTube channel.
‘There is very strong evidence that the ingredients for life exist on Europa, but we have to go there to find out,’ said Dr Bonnie Buratti at NASA’s Jet Propulsion Laboratory, the mission’s deputy project scientist.
Dr Buratti said exploratory missions like this one always uncover something ‘that we could not have imagined’.
‘There is going to be something there – the unknown – that is going to be so wonderful that we can’t conceive of it right now,’ she said.
‘That’s the thing that excites me most.’
One of Jupiter’s 95 known moons, Europa is encased in an ice sheet estimated to be 10 to 15 miles or more (15 kilometers to 24 kilometers) thick.
Scientists believe this outer frozen crust hides a saltwater liquid ocean that could be 80 miles (120 kilometers) or more deep.
Europa’s ocean could hold about twice as much water as Earth’s global ocean, scientists think – and could possibly harbor life.
Clipper is the biggest spacecraft NASA has ever built for a planetary mission, measuring about 100 feet (30.5 meters) with its solar arrays deployed – bigger than a basketball court.
Clipper’s sizable solar arrays will gather sunlight for powering scientific instruments, electronics and its other systems – around 500 million miles from the sun where sunlight is weaker compared with on Earth.
Clipper’s key mission objectives are producing high-resolution images of Europa’s surface, determining its composition and looking for signs of recent or ongoing geological activity.
The mission will also measure the thickness of the moon’s icy shell, search for subsurface lakes and determine the depth and salinity of Europa’s ocean.
Scientists are almost certain that hidden beneath the icy surface of Europa is a saltwater ocean with about twice as much water as Earth’s global ocean. Illustration depicts possible model of Europa
The mission aims to find out if Europa (pictured) contains the ingredients that would allow life to be present
Clipper is as large as an SUV with solar arrays long enough to span a basketball court. It is seen here being built and tested at Jet Propulsion Laboratory during a media tour, in Pasadena, California, April 11, 2024
Elon Musk’s firm SpaceX will launch its Falcon Heavy rocket carrying Europa Clipper from LC-39A, Kennedy Space Center, Florida. Pictured, prior to launch on Sunday, October 13
In this animation, Clipper (pink) departs Earth (blue). It swings past Mars (brown) early next year and then Earth in late 2026. Finally, after an approximately 1.8-billion-mile journey, Europa Clipper enters orbit around Jupiter (green) in April 2030
Dr Buratti notes that there are three main requirements for life to form in our solar system – liquid water, certain chemistry (so organic compounds that could serve as food for any primitive organisms) and an energy source.
In Europa’s case, an energy source could be thermal vents on the ocean floor.
Experts think there could be microbes deep down in this potentially nutrient-rich liquid ocean, which could be a lot warmer than the outer shell thanks to the thermal vents.
Alternatively, the lifeforms may be adapted to survive in extremely frigid temperatures.
These lifeforms could be tiny, such as ‘extremophile’ microbes that would be invisible to the naked human eye.
A hugely promising finding by the James Webb space telescope last year was the presence of carbon dioxide (CO2) on Europa.
The ‘biologically essential’ compound could be produced by lifeforms much like humans produce CO2 on Earth.
Last year, scientists found there’s less oxygen on Europa’s surface than previously thought, which is crucial for cells to be able to function.
Although it didn’t completely rule out the possibility of life on Europa, the study said there’s a ‘narrower range to support habitability’ than we realised.
Clipper will not enter orbit around Europa, but will instead orbit Jupiter. This illustration provided by NASA depicts the Europa Clipper spacecraft above the surface of the moon Europa, foreground, and Jupiter behind
The main body of the spacecraft is a giant 10-foot-tall propulsion module, designed and constructed by Johns Hopkins Applied Physics Laboratory (APL) in Laurel, Maryland
Dr Buratti thinks any life on Europa would be primitive like the bacterial life that originated in Earth’s deep ocean vents.
However, she stresses than Clipper will not look directly for signs of life but will instead determine if the moon contains the ‘ingredients’ that would allow life to be present.
If it does, another mission would then have to make the journey to try and detect it – for example by drilling down through the icy shell.
‘We will not know from this mission because we can’t see that deep,’ Dr Buratti said.
This look at the complex, ice-covered surface of Jupiter’s moon Europa came from NASA’s Juno mission during a close pass on September 29, 2022
When it completes its journey more than five years from now, Clipper will not enter orbit around Europa, but will instead orbit Jupiter.
As it’s orbiting Jupiter, it will conduct 44 flybys of Europa, each at altitudes ranging from 16 miles to 1,678 miles (25 km to 2,700 km) during its 3.5-year mission.
In September 2022, another NASA probe called Juno within 220 miles (355 kilometers) of the moon’s frozen surface.
But Clipper will sneak within 16 miles (25 kilometers) of Europa’s surface – closer than any other spacecraft.
When its work is done in 2034, the mission will end with a planned crash into Ganymede – Jupiter the solar system’s biggest moon.