Europa’s Eruptive Plume Hints At Habitability

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Aviation Week.com/space/Europa's eruptive plume hints at habitability?

Mark Carreau | Aerospace Daily & Defense Report May 14, 2018

HOUSTON—During a 1997 close flyby of Europa, the ice- and ocean-covered moon of Jupiter, NASA’s long-concluded Galileo spacecraft appears to have flown through an eruptive watery plume more than 600 mi. (1,000 km) long, according to a new study that adds to evidence of an internal heat source and potential habitability.

The findings, published May 14 in the journal Nature Astronomy, adds merit to further scrutiny of Europa by NASA’s planned Europa Clipper multiple flyby mission, the study team says.

The effort also supports the notion that Europa’s potential habitability can be further assessed by flying through the geyser sprays without engineering a much more costly lander mission in the near term. Such a mission would drill through a global surface ice layer estimated at 10 to 15 mi. (15-25 km) thick to submerge into an ocean layer 40 to 100 mi. (60-150 km) deep or attempt a touchdown near one of the many fractures in the ice layer amid a blocky, chaotic terrain. Both mission concepts have an influential supporter, Rep. John Culberson (R-Texas), who chairs the House Appropriations Committee’s commerce, justice and science subcommittee.

The findings also back up multiple Hubble Space Telescope observations dating back to 2012. Those observations revealed evidence of vapor plumes rising 125 mi. (200 km) above Europa’s south pole region, which first fueled speculation of an internal heat source and a moisture cloud that might be able to be analyzed in situ by an orbiter/flyby mission for evidence of habitability.

About 2,000 mi. in diameter, smaller than the Earth’s Moon, Europa speeds around Jupiter every 3 1/2 days. Like the Earth’s Moon, Europa is tidally locked, presenting just one face to its host planet. Europa played key roles in a pair of science fiction film classics about U.S., Russian and Chinese efforts to seek intelligent extraterrestrial life: 1968’s 2001: A Space Odyssey and a 1984 sequel, 2010: The Year We Make Contact, adding to a longstanding scientific fascination with the Jovian moon.

During the Dec. 16, 1997 flyby, Galileo sped within 100 mi. (150 km) of Europa’s surface, the closest of 11 low-altitude swings near the moon by Galileo overall. Data from two instruments, Galileo’s planet wave spectrometer and magnetometer, suggest the probe made a 3-min. pass through a disrupted region above the moon’ surface.

The Hubble observations, coupled with science gathering early last year to prepare for the Clipper mission in which the Galileo findings were summarized, prompted Xianzhe Jia, a University of Michigan space physicist, and his team to computer model the probe’s late-1997 Europa encounter using magnetometer and plasma wave data as well as Hubble. The findings became the basis of the Nature Astronomy report.

“Combining the two independent pieces of evidence—that really strengthens the case that Europa seems to have plumes, and that, I think, provides a great opportunity for the future exploration of Europa,” Jia told a May 14 NASA-hosted Web briefing and discussion of the research paper.

Jia’s team was also inspired by the recently concluded Cassini mission to Saturn. The NASA-led collaboration with the European and Italian space agencies flew through eruptive material coming from Enceladus, another ice-covered ocean world in the outer Solar System that hints at a habitable environment.

The Clipper mission will attempt to advance an understanding of Europa’s potential habitability without attempting a direct detection of biological activity, Lori Glaze, the acting director of NASA’s planetary science division, told the Web session. As planned, Clipper will be able to make an in situ assessment of the chemistry and particle composition of the plumes.

“Clipper’s ultimate aim is to determine whether Europa is habitable, possessing the ingredients we believe are necessary for life as we know it: liquid water, chemical ingredients and an energy source,” said Thomas Zurbuchen, NASA’s associate administrator for science. “Europa’s ocean is one of the most promising places that could potentially harbor life in the Solar System.”

NASA is in the preliminary design phase of the Clipper mission with a runout cost estimate of $1.78 billion through 2023, according to 2019 budget documents. It would launch possibly in 2025 on a commercial launch vehicle. After a long journey, Clipper would steer into orbit around Jupiter and maneuver for more than 40 close Europa flybys, some dipping as close as 16 mi. (25 km) from the moon’s surface.

But a May 9 markup by the Culberson-chaired appropriations subcommittee of NASA’s 2019 budget would advance Clipper’s launch to 2022 using a NASA Space Launch System (SLS) rocket at an estimated mission cost of $2.55 billion.

The 2019 House CJS markup includes $585 million for Clipper, plus $195 million for a follow-on Europa lander mission, which would launch in 2024, also using an SLS rocket.

The White House has rejected a Europa lander mission, characterizing its “multi-billion” dollar price tag as disruptive to other NASA science initiatives and slated for launch much too soon to take advantage of Clipper data needed for landing site selection.

Like Mars, Europa is considered a high priority by the National Academy of Sciences in the search for life beyond Earth.

Launched aboard a space shuttle in 1989 and maneuvered into orbit around Jupiter in December 1995, Galileo’s mission to Jupiter was slated to end in December 1997. But the investigations were extended into September 2003, allowing a total of 11 close Europa passes. As its mission concluded, Galileo was commanded to plunge into Jupiter to avoid possible terrestrial contamination of Europa.

The European Space Agency is also pursuing further exploration of Europa and other Jovian moons with its Jupiter Icy Moon Explorer (Juice) mission, slated for launch in 2022. After reaching its destination in October 2029, Juice would orbit Jupiter for four years for closeup observations of the icy moons Callisto and Ganymede as well as Europa

NASA has signed up for $114.4 million in contributions to Juice science instruments with Swedish and Italian collaborators, including an ultraviolet spectrometer, a plasma mapper and an ice-penetrating radar to investigate below the ice, assessing the presence of a core and possible heat sources.

We all know the next line..... :smirk:

From 3 years ago... :CoW:
https://arstechnica.com/science/2015/11/attempt-no-landing-there-yeah-right-were-going-to-europa/