Destination Europa! –“Will a Future NASA Mission Discover Life at Jupiter’s ‘Ocean Moon’?” (Tuesday’s Most Popular)





“Landing on the surface of Europa would be a key step in the astrobiological investigation of that world,” said Chris McKay, a senior editor of the journal Astrobiology, who is based at NASA Ames Research Center, Moffett Field, Calif. “The hope would be that surface materials, possibly near the linear crack features, include biomarkers carried up from the ocean.”

Most of what scientists know of Jupiter’s moon Europa they have gleaned from a dozen or so close flybys from NASA’s Voyager 2 spacecraft in 1979 and NASA’s Galileo spacecraft in the mid-to-late 1990s. Even in these fleeting, paparazzi-like encounters, scientists have seen a fractured, ice-covered world with tantalizing signs of a liquid water ocean under its surface.


Such an environment could potentially be a hospitable home for microbial life. But what if we got to land on Europa’s surface and conduct something along the lines of a more in-depth interview? What would scientists ask? A study in the journal Astrobiology authored by a NASA-appointed science definition team in August of 2013, laid out their consensus on the most important questions to address.




“If one day humans send a robotic lander to the surface of Europa, we need to know what to look for and what tools it should carry,” said Robert Pappalardo, based at NASA’s Jet Propulsion Laboratory. “There is still a lot of preparation that is needed before we could land on Europa, but studies like these will help us focus on the technologies required to get us there, and on the data needed to help us scout out possible landing locations. Europa is the most likely place in our solar system beyond Earth to have life today, and a landed mission would be the best way to search for signs of life.”

The 2013 study was authored by scientists from a number of other NASA centers and universities. The team found the most important questions clustered around composition: what makes up the reddish “freckles” and reddish cracks that stain the icy surface? What kind of chemistry is occurring there? Are there organic molecules, which are among the building blocks of life?

Additional probe priorities of the 2013 involved improving our images of Europa – getting a look around at features on a human scale to provide context for the compositional measurements. Also among the top priorities were questions related to geological activity and the presence of liquid water: how active is the surface? How much rumbling is there from the periodic gravitational squeezes from its planetary host, the giant planet Jupiter? What do these detections tell us about the characteristics of liquid water below the icy surface?

The follow-up to the 2013 NASA study, NASA’s fiscal year 2016 budget request included $30 million to formulate a mission to Europa. The solar-powered spacecraft would be placed in a long, looping orbit around the gas giant Jupiter – the largest planet in the solar system – performing repeated flybys of Europa as close as 16 miles (25 kilometers) over a three-year period. While previous Presidential budget proposals have called for this mission to launch in the mid to late 2020s, the February 2016 budget proposal seems to call for a possible delay in that vague schedule by suggesting a “launch as early as the late 2020s”.

This NASA flagship mission would honor Arthur C. Clark’s dire admonition about Europa to “attempt no landing there,” by placing a spacecraft in orbit around Jupiter to perform close flybys. NASA has selected nine instruments for the mission, including cameras and spectrometers, an ice-penetrating radar, a thermal instrument, a magnetometer, and in-situ mass spectrometers. LASP will provide the Surface Dust Analyzer (SUDA), an instrument to investigate the chemical makeup of Europa’s surface, which may hold the fundamental clues for understanding its potential to develop and sustain life, because materials embedded in the ice matrix on Europa’s surface carry a treasure trove of information about the moon’s interior.

The epic NASA mission would explore whether Jupiter’s moon Europa could harbor conditions suitable for life. Previous missions have provided compelling evidence for such conditions on Europa: The moon most likely harbors a global ocean underneath its icy crust; the conditions within the ocean are acceptable for extant terrestrial life; and the chemical inventory of the ocean provides the range of elements essential for Earth-like organisms.

The view of Europa below features several regional-resolution mosaics overlaid on a lower resolution global view for context. The regional views were obtained during several different flybys of the moon by NASA’s Galileo mission, and they stretch from high northern to high southern latitudes. Prominent here are the long, arcuate (or arc-shaped) and linear markings called lineae (Latin for strings or threads), which are a signature feature of Europa’s surface. Color saturation has been enhanced to bring out the subtle red coloration present along many of the lineae. The color data extends into the infrared, showing bluish ice (indicating larger ice grains) in the polar regions.

The SUrface Dust Mass Analyzer (SUDA), which has been under development for about 10 years, will be used to measure the composition of solid particles released from Europa’s surface due to meteoroid bombardment. The instrument also will be able to measure the properties of small, solid particles believed to be spewing from the hidden ocean within the moon.

“This instrument will be used to support the overarching goal of the Europa mission, which is to understand the prerequisites of life in the solar system,” said Sascha Kempf of the University of Colorado’s Laboratory for Atmospheric and Space Physics, principal investigator on the project.

There is evidence from both NASA’s Galileo mission to Jupiter and from Hubble Space Telescope images that plumes of water and ice particles are shooting out from Europa’s surface, according to NASA officials.

Europa is one of four large Jovian moons and is about the size of Earth’s moon. Scientists believe there is a frozen crust about 40 miles (70 kilometers) thick separating the ocean from the surface, said Kempf. The ocean, which may be heated by Europa’s interior, could harbor more than twice as much water as Earth’s oceans, according to NASA officials.

“There appears to be an exchange of material occurring between Europa’s surface and its subsurface ocean,” said Kempf. “We are building a very powerful instrument that will provide us with information about the moon’s interior structure and the repository of material in the water under the ice crust.”

The Daily Galaxy via NASA’s Science Mission Directorate, Washington, D.C.; JPL a division of the California Institute of Technology, Pasadena; and the University of Colorado, Boulder.

Image credit: Top of page image from the movie Europa Report, with thanks to thecinemamonster




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