Old data from NASA's Galileo spacecraft shows that it may have traveled through a plume of water on the moon of Europa in 1997 without scientists realizing what had happened. Scientists have been looking for proof of suspected water plumes emerging from Europa but haven't been able to prove it.
Previous images showed what scientists think is Europa spewing water in 2012 and 2016.
Water On Europa
The Hubble Space Telescope was able to capture images of water escaping from Europa but couldn't be considered definitive proof because of the quality of the images. Old data from the Galileo mission provides scientists with the strongest proof of water on Europa. Researchers published their findings in Nature Astronomy.
Researchers believe that Europa contains a global salt water ocean under its crust. They believe that this may also point to evidence of life on the moon. To study the makeup of the water on Europa, scientists would only need to perform flybys with spacecraft going through the plumes instead of landing on the moon.
Scientists thought that they may have been able to find data about water plume in Galileo's data. They found that Galileo had flown about 250 miles (400 kilometers) above the surface of Europa on December 16, 1997. Galileo measured a spike in the magnetic field strength along with a spike in the energy particles. Scientists think that this spike in energy particles may have been the probe flying through a water plume.
Galileo went offline in 2003 when it plunged into the atmosphere of Jupiter and was vaporized.
Europa is set to be explored by two different spacecraft in the next decade. The European Space Agency will be sending JUICE (Jupiter ICy moons Explorer), while NASA will be sending the Europa Clipper, which will be focusing on Europa to see if it has the right conditions to be able to host life.
The Europa Clipper mission will study Europa for two years, spending time orbiting Jupiter and making at least 40 close flybys of Europa. Each time the orbiter will be gathering data on different parts of the moon.
To study the plumes, the probe will not need to pass directly through them. The particles that are spread by the plumes will be found in the atmosphere of Europa. Instruments on the Europa Clipper will have to be sensitive enough to capture the particles from the water plume.
Nine instruments have been chosen for the mission. They would study the moon's icy shell, another would measure its magnetic field, the salinity of the ocean on the moon, and another to capture high-resolution images of the surface of the moon.