Tag: Enceledus

Certain Big, Charged Molecules Are Universal to Life on Earth. Can They Help Detect It In The Far Solar System?

 

This article of mine, slightly tweaked for Many Worlds, first appeared today (July 6)  in Astrobiology Magazine,  http://www.astrobio.net

NASA’s Cassini spacecraft completed its deepest-ever dive through the icy plume of Enceladus on Oct. 28, 2015. The spacecraft did not have instruments that could detect life, but missions competing for NASA New Frontiers funding will — raising the thorny question of how life might be detected. (NASA/JPL-Caltech)

As NASA inches closer to launching new missions to the Solar System’s outer moons in search of life, scientists are renewing their focus on developing a set of universal characteristics of life that can be measured.

There is much debate about what might be considered a clear sign of life, in part, because there are so many definitions separating the animate from the inanimate.

NASA’s prospective missions to promising spots on Europa, Enceladus and Titan have their individual approaches to detecting life, but one respected voice in the field says there is a better way that’s far less prone to false positives.

Noted chemist and astrobiologist Steven Benner says life’s signature is not necessarily found in the presence of particular elements and compounds, nor in its effects on the surrounding environment, and is certainly not something visible to the naked eye (or even a sophisticated camera).

Rather, life can be viewed as a structure, a molecular backbone that Benner and his group, Foundation for Applied Molecular Evolution (FfAME), have identified as the common inheritance of all living things. Its central function is to enable what origin-of-life scientists generally see as an essential dynamic in the onset of life and its increased complexity and spread: Darwinian evolution via transfer of information, mutation and the transfer of those mutations.

“What we’re looking for is a universal molecular bio-signature, and it does exist in water,” says Benner. “You want a genetic molecule that can change physical conditions without changing physical properties — like DNA and RNA can do.”

Steven Benner, director of the Foundation for Applied Molecular Evolution or FfAME. (SETI)

Looking for DNA or RNA on an icy moon, or elsewhere would presuppose life like our own — and life that has already done quite a bit of evolving.

A more general approach is to find a linear polymer (a large molecule, or macromolecule, composed of many repeated subunits, of which DNA and RNA are types) with an electrical charge. That, he said, is a structure that is universal to life, and it can be detected.… Read more

More Evidence of Water Plumes On Europa Increases Confidence That They’re For Real

 Figure 2: This composite image shows suspected plumes of water vapor erupting at the 7 o’clock position off the limb of Jupiter’s moon Europa. The Hubble data were taken on January 26, 2014. The image of Europa, superimposed on the Hubble data, is assembled from data from the Galileo and Voyager missions. Credits: NASA/ESA/W. Sparks (STScI)/USGS Astrogeology Science Center Image comparison of 2014 transit and 2012 Europa aurora observations


This composite image shows suspected plumes of water vapor erupting at the 7 o’clock position off the limb of Jupiter’s moon Europa. The Hubble data were taken on January 2014, and appear to show plumes that spit out as much as 125 miles.  The image of Europa, superimposed on the Hubble data, is assembled from data from the Galileo and Voyager missions. (NASA/ESA/W. Sparks (STScI)/USGS Astrogeology Science Center)

Europa is a moon no bigger than our own and is covered by deep layers of ice, but it brings with it a world of promise.  Science fiction master and sometimes space visionary Arthur C. Clarke, after all,  named it as the most likely spot in our solar system to harbor life, and wrote a “2001: A Space Odyssey”  follow-up based in part on that premise.

Many in the planetary science and astrobiology communities are similarly inclined and have supported a specifically Europa mission geared to learning more about what is generally considered to be a large ocean beneath that ice.

Along the way, Europa became the only object deemed by Congress to be an obligatory NASA destination, and formal plans for such a voyage have been under way — however slowly — for several years.  Formal development of the “Europa Clipper” flyby project began last year, after a half decade of conceptual work.

The logic for the flyby got a major boost on Monday when a team using the Hubble Space Telescope reported that they had most likely detected plumes of water erupting out of Europa on three separate occasions.

Because of the difficulty of the observation — and the fact that plumes were found on 3 out of 10 passes — nobody was willing to claim that the finding was definitive.  But coupled with an earlier identification of a Europa plume by a different team using a different technique, the probability that the plumes are real is getting pretty high.

And if there really are plumes of water vapor or ice crystals being pushed through Europa’s thick surface of ice, then the implications for the search for signs of habitability and of life on Europa are enormous.

“Europa is surely one of the most compelling astrobiological targets in solar system with its apparent saline oceans,” said William Sparks, an astronomer with Space Telescope Science Institute in Baltimore and lead author of the Europa paper, to be published in The Astrophysical Journal.… Read more

© 2021 Many Worlds

Theme by Anders NorenUp ↑