Italian astronomer Galileo Galilei was the first one to look at Europa, Jupiter’s fourth largest moon, through his telescope in 1610. Interest has only grown through time and visiting spacecraft have been studying Europa for over 50 years.
Its icy water oceans are one of the most promising places to find habitable environments in our Solar System. Through previous missions, scientists now know enough information to ask well-defined and specific questions about Europa’s geology, composition and conditions below the water ice sheets on its surface.
On 14 October, The Clipper spacecraft from NASA launched towards Europa, tasked with three main science missions: understanding the nature of Europa’s ice shell and the ocean beneath, its composition and geological features. The spacecraft will be looking for evidence of the ingredients of life such as potential water plumes, chemical sources of energy, stability of conditions and the ocean’s geological makeup.
Water plumes are giant columns of vapour, ice particles and organic molecules spraying through the icy surface, caused by a geologically active ocean floor; this heat and movement could potentially be circulating life’s chemical building blocks, such as oxygen, hydrogen and carbon, on the moon’s seafloor.
Research on Earth’s extremophile organisms, which live in habitats like volcanic vents in the deep ocean and below arctic sea ice, has given hope to scientists that similar conditions on icy Europa could be habitable for life. Recent findings on fractures and ridges in Greenland’s ice sheets, which are comparable to Europa’s, have also boosted scientists’ curiosity.
The Europa Clipper craft is named after graceful and speedy Clipper ships which sailed across Earth’s oceans in the 1800s. It has been developed over more than a decade and is the largest spacecraft ever built for a planetary mission. Clipper is packed with scientific instruments which are the most advanced and sensitive to ever explore our Solar System. These are housed in a thick-walled radiation vault, shielding sensitive electronics against Jupiter’s strong magnetic field which is 20,000 times stronger than Earth’s.
After launching from the Kennedy Space Center in Florida, the mission will take the spacecraft to Mars and then back to Earth, using ‘gravity assists’ from each planet to provide enough velocity for the Clipper to reach Europa by 2030.
These gravity assists enable the Clipper flyby to be close enough to use Mars and Earth’s gravity to accelerate towards Jupiter. The spacecraft will then spend 3 years conducting almost 50 flybys of the moon while in Jupiter’s orbit, as close as 16 miles from the surface and sending data back to Earth.
These flybys will be packed with data-gathering. Europa will be photographed and mapped by UV and Infrared spectrometers to better understand the distribution of ice, and any warm hotspots, organic chemicals and atmospheric gases.
Its surface will be investigated via ice-penetrating radar to study the water ocean below, while scientists are hoping an analysis of its surface dust and atmosphere might reveal evidence of water plumes. Europa will have its gravity and magnetic field measured, and its ice analysed by thermal instruments with the aim of assessing the potential for microbial life beyond our planet.
But the craft does not only contain scientific instruments; it will also take an intriguing collection of creative responses to the exploration of Europa and the mission’s hope to find more about the ‘water world’, as Robert Pappalardo, Project Scientist at NASA’s Jet Propulsion Laboratory, names Europa.
Engraved on a plate will be a poem by Ada Limón, US Poet Laureate; a portrait of scientist Ron Greeley, who laid the foundations of the Europa mission; 2.6 million names submitted by the public, engraved on a tiny microchip via electron beam; a representation of sound waves and the word ‘water’ written in 103 languages including sign language.
The Drake equation, the mathematical formula used to estimate the possibility of finding life beyond earth; and radio frequencies used by scientists to listen for messages beyond the cosmos are also included. These frequencies are known by astronomers as ‘the water hole’ as they match the radio waves emitted by water components in space.
But for a spacecraft where every bit of space, mass and budget must be justified, why include art, poetry and millions of engraved names? It speaks to NASA’s aim to bring the public along on these missions and to raise awareness of the exciting science it is doing. But it also demonstrates humanity’s enduring and hopeful desire to reach out to other worlds, and the deep artistic, as well as scientific, responses to the possibility of life beyond earth.
The Europa Clipper launched this week with an important scientific mission – and also full of hope.