From: veritasium
The Europa Clipper mission, set to launch in October 2024, is NASA’s most advanced endeavor to hunt for signs of alien life on Jupiter’s moon, Europa [00:38:00]. This mission builds on decades of scientific suspicion, highlighted in Arthur C. Clarke’s 1982 novel 2010, Odyssey Two, that Europa might offer the best chance of finding alien life in the solar system [00:26:00]. However, the Jovian system presents formidable challenges [00:51:00].
The Perilous Environment of Jupiter
Jupiter poses significant threats to spacecraft due to its powerful magnetic field and the resulting radiation belts [00:51:00].
Jupiter’s Magnetic Field
Deep within Jupiter, immense pressure is believed to transform hydrogen into a metallic liquid. This metallic liquid hydrogen generates an incredibly powerful magnetic field, nearly 20,000 times stronger than Earth’s when measured at the same distance [01:09:00]. If visible from Earth, this field would appear twice as large as the full moon [01:26:00].
Formation of Radiation Belts
While Jupiter’s magnetic field itself is harmless, it interacts with Io, the most volcanically active world in the solar system and another of Jupiter’s moons [01:34:00]. Io’s volcanoes spew tons of sulfur dioxide, with one ton becoming ionized and trapped in Jupiter’s magnetic field every second [01:46:00]. The field accelerates these particles to over 300 kilometers per second, causing them to whiz around Jupiter [01:57:00]. Their inertia stretches the magnetic field, leading to collisions with other moons and the ejection of more particles. This cycle forms massive radiation belts that extend past Europa [02:07:00].
Impact on Electronics
This intense radiation is “kryptonite” for electronics [02:26:00]. In the 1970s, the Pioneer 10 and Voyager missions experienced glitches, false commands, and corrupted data from brief passes through Jupiter’s radiation [02:30:00]. Even with modern shielding, a spacecraft within these belts would only survive for approximately three months [02:42:00]. On Europa’s surface, the radiation exposure is 5,400 milliSieverts per day, 1,800 times the annual dose on Earth, enough to cause death from radiation sickness within hours [03:35:00].
Europa Clipper’s Strategy to Overcome Challenges
To survive for over four years in Jupiter’s system, the Europa Clipper employs a unique orbital strategy [02:49:00]:
- Distant Orbit: The probe will orbit Jupiter from a safe distance, away from the most intense radiation [03:00:00].
- Frequent Flybys: Every few weeks, it will swoop in to quickly fly by Europa and then leave again [03:02:00].
- Data Transmission: During downtime while far from Jupiter, the Clipper will transmit collected data back to Earth before its next swoop [03:07:00].
- Extensive Mapping: In total, it will perform 49 flybys, mapping almost the entire surface of Europa [03:17:00].
The mission’s name, “Clipper,” is inspired by the fast and nimble 19th-century clipper ships that quickly dipped in and out of ports [03:21:00].
Why Europa? The Search for Life
Despite the harsh environment, Europa is considered a prime candidate in the search for alien life due to evidence suggesting a subsurface ocean [03:30:00].
Evidence of a Subsurface Ocean
- Lack of Craters: Images from Voyager 1 in 1979 revealed a surprising lack of craters on Europa’s surface compared to other moons. This suggests a recent resurfacing process, possibly within the last 60 million years [03:56:00].
- Induced Magnetic Field: In the 1990s, the Galileo mission detected a relatively strong induced magnetic field on Europa. This indicates an electrically conductive layer close to the surface, likely tens of kilometers deep, reacting to Jupiter’s wobbling magnetic field [04:42:00].
- Surface Composition: Europa’s white surface is covered in a thick crust of water ice. Reddish-brown regions on the surface, when analyzed by a spectrometer, resemble hydrated salts. Recent experiments at JPL showed that sea salt, when bombarded with intense radiation, turns this same brownish color [05:26:00].
These observations strongly suggest a whole saltwater ocean inside Europa, potentially 100 kilometers deep, containing twice as much water as Earth’s oceans [05:56:00]. This ocean drives geological activity that constantly smooths and renews the moon’s surface [06:08:00].
Tidal Heating
Despite receiving only about 4% of Earth’s sunlight and having a surface temperature below -160 degrees Celsius, Europa’s ocean is believed to remain liquid due to internal heat generated by tidal flexing [06:17:00].
- Orbital Resonance: Europa’s orbit around Jupiter is not perfectly circular because it is in orbital resonance with Io and Ganymede. Io tugs Europa inward, while Ganymede pulls it outward, making its orbit eccentric [06:40:00].
- Stretching and Squeezing: As Europa orbits, Jupiter’s gravitational pull varies, causing the moon to be constantly stretched and squeezed [07:04:00]. This friction generates enough heat to keep the ocean liquid [07:22:00]. An ocean increases the amplitude of flexing from about one meter to 30 meters [08:12:00].
- Geological Features: Features like cycloids on Europa’s surface, which are multiple arc-shaped cracks, are thought to form due to the stresses from this tidal flexing, further supporting the presence of a subsurface ocean [08:31:00].
Potential for Life
The tidal flexing can push magma closer to the seafloor, heating water and causing it to pick up minerals, forming hydrothermal vents [09:07:00]. On Earth, these vents are oases for ocean life, supporting unique bacteria that feed on minerals rather than sunlight [09:23:00]. If Europa’s ocean has existed for billions of years, it could have provided sufficient time for single-celled organisms to evolve, utilizing chemical reactions (e.g., methane, carbon dioxide, sulfur) as fuel for metabolism [09:44:00].
Surprisingly, Jupiter’s radiation, while hazardous, could also contribute to Europa’s potential for life. High-speed particles hitting the surface provide energy for water and carbon dioxide molecules to form new compounds like formaldehyde or hydrogen peroxide, which could serve as food for subsurface life if transported into the ocean through ice shell overturn at “chaos zones” [12:12:00].
Europa Clipper’s Instruments and Future Prospects
The Europa Clipper will not drill through the kilometers-thick ice crust [10:32:00]. Instead, it will use several instruments to gather data:
- Infrared Spectrometer: To identify and map salts and organics on the surface by analyzing chemical fingerprints of light [12:58:00].
- Ultraviolet Spectrograph: To search for and potentially fly through water geysers or plumes erupting from the moon’s surface, similar to those observed on Saturn’s moon Enceladus [13:10:00]. Flying through these plumes could reveal their chemical composition using a mass spectrometer [11:12:00].
- Cameras:
- Wide-Angle Camera: Will take swaths of images of the entire globe at better than 100 meters per pixel resolution [13:26:00].
- Narrow-Angle Camera: Will capture half-meter per pixel images from 50 kilometers altitude, capable of resolving small objects on the surface [13:33:00].
Although Enceladus has confirmed plumes and a subsurface ocean, Europa draws more attention because its ocean is believed to have existed for four billion years, offering more time for life to evolve [11:32:00].
Collaboration and Future Missions
The Europa Clipper mission is not alone. The European Space Agency’s (ESA) JUICE (Jupiter Icy Moons Explorer) mission is already en route to Jupiter, arriving 15 months after Clipper [14:14:00]. JUICE will perform flybys of Europa before orbiting Ganymede, allowing for complementary data collection and scientific collaboration between NASA and ESA collaborative efforts in space exploration [14:21:00].
First distant observations from Europa Clipper are expected in 2030, with high-resolution data following in 2031 [15:25:00]. While Europa Clipper will gather evidence, a future mission, potentially a lander capable of surviving on the surface for a month, would be required to physically scoop up material and directly search for signs of life [14:46:00].
The previous Galileo mission was deliberately crashed into Jupiter in 2003 to prevent any risk of contaminating Europa [10:21:00]. The launch of Europa Clipper, after 26 years of planning, represents a significant step forward in exploring the ocean world of Europa, fulfilling a vision that even Arthur C. Clarke, after seeing the mission plans, metaphorically gave permission for humanity to “land on Europa” [15:39:00].