Observations have already confirmed the existence of an underground ocean on Europe and there has been fierce speculation as to whether they might contain life. Although there have been preliminary plans to send a submersible spaceship into this ocean, we are still a long way from uncovering what lies at these depths.
This is a big reason why the geysers that occasionally shoot out of Europe's ice sheet have attracted so much interest. The scientists hoped that some of the expelled water could come from this ocean. It could then be scanned using a simple flyby mission like Europa Clipper instead of a submersible. However, a new paper published in Geophysical Research Letters suggests a much more mundane source of geysers – local liquid water buried in the moon's thick ice shelf.
The paper, written by an interdisciplinary team from Stanford, the University of Arizona, the University of Texas, and NASA's JPL, used data from the Galileo spacecraft, which made multiple lunar flyby. The data focused on Manannán, a crater that formed millions of years ago when the moon collided with an object the size of a comet or asteroid.
NASA video describing the feathers found on Europe.
Photo credit: NASA Goddard Youtube Channel
The team modeled how the extreme heat released by the impact could affect the local ice shelf. In particular, they found that some of the local ice would have melted, although most were refrozen in the later stages of the impact, some may have absorbed enough salt to remain liquid after the impact itself.
Some of the water might not only have remained liquid after impact, but could also have moved within the ice sheet itself. Part of the team model demonstrates the ability of this isolated pocket to melt adjacent ice surfaces due to its increased salinity. These liquid spots can then move within the ice sheet and when they hit a particularly loose piece of ice sheet that covers the surface of Europe, they can explode into the geysers for which the moon is so famous. Unfortunately, this means that these geysers are less likely to have come from the subterranean ocean, and therefore less likely that we will find biological signatures in them.
Space-time video about the probability of life in Europe.
Photo credit: PBS Space Time
Admittedly, the work so far is based on preliminary data from Galileo. As with almost all science, more data is needed and the team is hoping to get some data from the Europe Assessment and Probing Radar: Ocean to Shallow Ground (REASON) tool for the Europa Clipper mission. One of the co-authors of this new paper, Dr. Don Blankenship, from the University of Texas Department of Geophysics, is also REASON's lead researcher and is focused on ensuring that his instrument can collect data that can test the hypothesis developed in this paper.
You will have to wait a while to collect this data as the Europa Clipper mission is expected to arrive on the moon around 2030. By then, there are plenty of other data sets from Galileo that could use a second look, this team has already proven.
Stanford: Stanford researchers model the source of the Eurption on Jupiter's moon Europa
Geophysical Research Letters: Brine Migration and Shock Induced Cryovolcanism on Europe
UT: Even more evidence that Europe has geysers
Lead Image Credit: Justice Blaine Wainwright