Many Worlds

Tag: Europa (page 1 of 2)

Where Might Plumes of Water Vapor Come From on Icy Moons?

October 12, 2022 / / 0 Comments

This illustration depicts a plume of water vapor that could potentially be emitted from the icy surface of Jupiter’s moon Europa. New research sheds light on what plumes, if they do exist, could reveal about lakes that may be inside the moon’s crust. (NASA/ESA/K. Retherford/SWRI)

It’s been some years since Europa scientists agreed that the Jovian moon has a large global ocean beneath miles of ice.  More recently, scientists have identified what they view as pockets of water surrounded by ice but much nearer the surface than the ocean below.  And there has been research as well into what may be salty, slushy pocket of water further down in the ice covering.

With NASA’s mission to Europa scheduled to launch in about two years, modeling of these all potential collections of liquid water has picked up to prepare for the Europa Clipper arrival to come.

The latest research into what the subsurface lakes on Europa may look like and how they may behave comes in a recently published paper in Planetary Science Journal.

A key finding supports the idea that water could potentially erupt above the surface of Europa either as plumes of vapor or as cryovolcanic activity —  flowing, slushy ice rather than molten lava.

Computer modeling in the paper goes further, showing that if there are eruptions on Europa, they likely come from shallow, wide lakes embedded in the ice and not from the global ocean far below.

“We demonstrated that plumes or cryolava flows could mean there are shallow liquid reservoirs below, which Europa Clipper would be able to detect,” said Elodie Lesage, Europa scientist at NASA’s Jet Propulsion Laboratory and lead author of the research.

“Our results give new insights into how deep the water might be that’s driving surface activity, including plumes. And the water should be shallow enough that it can be detected by multiple Europa Clipper instruments.”

A minimally processed version of this image was captured by JunoCam, the public engagement camera aboard NASA’s Juno spacecraft. It was taken during the mission’s close flyby earlier this fall, almost 950 miles above the moon’s surface. The raw image was processed by “citizen scientist” Navaneeth Krishnan to add enhanced color contrast that allow larger surface features to stand out more.

The question of whether or not Europa has plumes is not settled.  While the plumes coming from Saturn’s moon Enceladus have been well studied and even had a spacecraft fly through one, Europa has only some fuzzy Hubble Space Telescope, Galileo mission and ground-based telescope images that suggest a plume.… Read more

The Juno Spacecraft Images Jupiter’s Moon Europa as it Speeds Past

September 30, 2022 / / 0 Comments

The first image from NASA’s Juno spacecraft as it passed close by Europa as part of its extended mission.  (NASA)

For NASA to extend its space science missions well past their original lifetime in space has become such a commonplace that it is barely noticed.

The Curiosity rover was scheduled to last on Mars for two years but now it has been going for a decade — following the pace set by earlier, smaller Mars rovers.  The Cassini mission to Saturn was extended seven years beyond it’s original end date and nobody expected that Voyager 1, launched in 1977,  would still flying out into deep space and sending back data 45 years later.

The newest addition to this virtuous collection of over-achievers is the Juno spacecraft, which arrived at Jupiter in 2016.  Its prime mission in and around Jupiter ended last year and then was extended until 2025, or beyond.

And now we have some new and intriguing images of Jupiter’s moon Europa thanks to Juno and its extension.

Traveling at a brisk 14.7 miles per second, Juno passed within 219 miles of the surface of the icy moon on Thursday and images from the flyby were released today (Friday.)  That gave the spacecraft only a two-hour window to collect data and images, but scientists are excited.

“It’s very early in the process, but by all indications Juno’s flyby of Europa was a great success,” said Scott Bolton, Juno principal investigator from Southwest Research Institute in San Antonio, in a NASA release.

“This first picture is just a glimpse of the remarkable new science to come from Juno’s entire suite of instruments and sensors that acquired data as we skimmed over the moon’s icy crust.”

Candy Hansen, a Juno co-investigator who leads planning for the Juno camera at the Planetary Science Institute in Tucson, called the released images “stunning.”

“The science team will be comparing the full set of images obtained by Juno with images from previous missions, looking to see if Europa’s surface features have changed over the past two decades,” she said.

An image of Europa taken by the Galileo spacecraft as it passed the moon in 1998. (NASA/JPL-Caltech)

During the flyby, the mission collected what will be some of the highest-resolution images of the moon (0.6 miles per pixel) taken so far and obtained valuable data on Europa’s ice shell structure, interior, surface composition, and ionosphere, in addition to the moon’s interaction with Jupiter’s magnetosphere.… Read more

Icy Moons, And Exploring The Secrets They Hold

August 18, 2022 / / 0 Comments

Voyager 2’s flew by the Uranian moon Miranda in 1986 and the spacecraft spent 17 minutes taking  photos to make this high-resolution portrait.  Miranda has three oval and trapezoid coronae, tectonic features whose origins remain debated. (NASA / JPL / Ted Stryk)

When it come to habitable environments in our solar system, there’s Earth, perhaps Mars billions of years ago and then a slew of ice-covered moons that are likely to have global oceans under their crusts.  Many of you are familiar with Europa (a moon of Jupiter) and Enceladus (a moon of Saturn) — which have either been explored by NASA or will be in the years ahead.

But there quite a few others icy moons that scientists find intriguing and just possibly habitable.  There is Ganymede,  the largest moon of Jupiter and larger than Mercury but only 40 percent as dense, strongly suggesting a vast supply of water inside rather than rock.

There’s Saturn’s moon Titan, which is known for its methane lakes and seas on the surface but which has a subterranean ocean as well.  There is Callisto, the second largest moon of Jupiter and an subsurface-ocean candidates and even Pluto and Ceres, now called dwarf planets that show signs of having interior oceans.

And of increasing interest are several of the icy moons of Uranus, particularly Ariel and Miranda.  Each has features consistent with a subsurface ocean and even geological activity.  Although Uranus is a distant planet, well past Jupiter and Saturn and would take more than a decade to just get there, the possibility of a future Uranus mission is becoming increasingly real.

The National Academy of Sciences (NAS) Decadal Survey for planetary science rated a Uranus mission as the highest priority in the field, and just today (Aug. 18) NASA embraced the concept.

At a NASA Planetary Science Division town hall meeting, Director Lori Glaze said the agency was “very excited” about the Uranus mission recommendation from the National Academy and that she hoped and expected some studies could be funded and begun in fiscal 2024.

If a Uranus mission is fully embraced,  it would be the first ever specifically to an ice giant system — exploring the planet and its moons.  This heightened interest reflects the fact that many in the exoplanet field now hold that ice giant systems are the most common in the galaxy and that icy moons may well be common as well.… Read more

A Clue Into The Makeup of Jupiter’s Moon Europa Provided by the Greenland Ice Sheet

April 25, 2022 / / 0 Comments

Double ridge ice formations seen on Europa are similar to formations detected on the Greenland Ice Sheet. This artist’s rendering shows how double ridges on the surface of Jupiter’s moon Europa may form over shallow, refreezing water pockets within the ice shell. This mechanism is based on the study of an analogous double ridge feature found on Earth’s Greenland Ice Sheet. (Justice Blaine Wainwright)

Europa’s ice crust is crossed by thousands of double ridges, pairs of long parallel raised lines with a small valleys in between, sometimes as much as hundreds of miles long and skyscraper-height tall rims. While these double ridges are ubiquitous on Europa’s surface, how they form remains something of a mystery to scientists.

Dustin Schroeder, an associate professor of geophysics at Stanford University’s School of Earth, Energy & Environmental Sciences, was working on an issue related to climate change when he saw double ridges similar to those seen on Europa here on Earth.  The ridges, in Northwest Greenland, were tiny when compared with those on Europa, but the found the same “M”-shaped crest as found everywhere on that Jovian moon.

“We were working on something totally different related to climate change and its impact on the surface of Greenland when we saw these tiny double ridges – and we were able to see the ridges go from ‘not formed’ to ‘formed,’ ” Schroeder said.

Could the double ridges be forming as a result of processes similar to those that form the double ridges on Europa?

If so, then Greenland would provide a possibly important new window into a central question about Europa:  Is that thick ice shell surrounding the subsurface ocean completely solid, or does it have what are called “water sills” within the shell?

This is important because, as the Nature Communications paper concludes, “If the same process is responsible for Europa’s double ridges, our results suggest that shallow liquid water is spatially and temporally ubiquitous across Europa’s ice shell.”

Or as Schroeder put it, “If the mechanism we see in Greenland is how these things happen on Europa, it suggests there’s water everywhere,” he said in a release.

They can make this inference because the double ridges formed in Greenland are the known, and detectable, result of the dynamics of subsurface water surrounded by the ice sheet.

Surface imagery comparison of a double ridge on Europa (a) and on Earth (b), on the Northwest Greenland Ice Sheet.

… Read more

Frigid Europa Holds a Huge and Maybe Habitable Ocean Beneath Its Thick Ice Covering. How is That Possible?

September 29, 2021 / / 1 Comment

Europa has one of the smoothest surface of any body in the solar system.  A moon as old as Europa that did not have an ice cover — and a likely ocean inside — would be pocked with asteroid craters.  On Europa, these craters appear to be absorbed into the icy surface via geologic and thermal processes.  Giant lakes trapped in Europa’s crust also bust up the icy surface. (NASA)

Jupiter’s moon Europa is almost five times as far away from the sun as Earth is, with surface temperatures that don’t rise above minus 260 degrees Fahrenheit.  It’s slightly smaller than our moon and orbits but 400,000 miles from the solar system’s largest planet, which it takes but 3.5 Earth days to orbit.  As a result it is tidally locked, always showing the same face to Jupiter.

When it comes to potentially habitable objects in our solar system, Europa would not seem to be a terribly likely possibility.

But, of course, it is.  And in three years NASA’s Europa Clipper mission will launch to explore what would appear to be one of the most unlikely yet possible places in our solar system to find potential signs of life.

The reason why is that scientists are almost certain that under Europa ‘s 10-to 15 mile ice covering is a deep, global ocean of salty water.

The size of the ocean has not been well determined yet, with estimates of between 40 and 100 miles of depth.  But a  consensus has been reached that the ocean is likely to be global, and contains two to three times as much liquid water as found on Earth.

This then raises a question with great significance for Europa, other moons in the solar system and quite likely planets and moons well beyond us:  How can there be so much liquid water inside such frigid places?

The spot toward the lower left is one Europa, against the backdrop of Jupiter.  Images from Voyager in 1979 bolster the modern hypothesis that Europa has an underground ocean and is therefore a good place to look for extraterrestrial life. The dark spot on the upper right is a shadow of another of Jupiter’s large moons. Sixteen frames from Voyager 1’s 1979 Jupiter flyby were recently reprocessed and merged to create this image.  (NASA, Voyager 1, JPL, Caltech; Processing & License: Alexis Tranchandon / Solaris)

There are numerous possible answers to that question, and it’s likely that all or most played some role.… Read more

Icy Moons and Their Plumes

December 5, 2019 / / 2 Comments

The existence of water or water vapor plumes on Europa has been studied for years, with a consensus view that they do indeed exist.  Now NASA scientists have their best evidence so far that the moon does sporadically send water vapor into its atmosphere.  (NASA/ESA/K. Retherford/SWRI)

Just about everything that scientists see as essential for extraterrestrial life — carbon, hydrogen, oxygen, nitrogen, phosphorus, sulfur and sources of energy — is now known to be pretty common in our solar system and beyond.  It’s basically there for the taking  by untold potential forms of life.

But what is not at all common is liquid water.  Without liquid water Earth might well be uninhabited and today’s Mars, which was long ago significantly wetter, warmer and demonstrably habitable,  is widely believed to be uninhabited because of the apparent absence of surface water (and all that deadly radiation, too.)

This is a major reason why the discovery of regular plumes of water vapor coming out of the southern pole of Saturn’s moon Enceladus has been hailed as such a promising scientific development.  The moon is pretty small, but most scientists are convinced it does have an under-ice global ocean that feeds the plume and just might support biology that could be collected during a flyby.

But the moon of greatest scientific interest is Europa, one of the largest that orbits Jupiter.  It is now confidently described as having a sub-surface ocean below its crust of ice and — going back to science fiction writer extraordinaire Arthur C. Clarke — has often been rated the most likely body in our solar system to harbor extraterrestrial life.

That is why it is so important that years of studying Europa for watery plumes has now paid off.   While earlier observations strongly suggested that sporadic plumes of water vapor were in the atmosphere, only last month was the finding nailed, as reported in the journal Nature Astronomy.

“While scientists have not yet detected liquid water directly, we’ve found the next best thing: water in vapor form,” said Lucas Paganini, a NASA planetary scientist who led the water detection investigation.

 

As this cutaway shows, vents in Europa’s icy crust could allow plumes of water vapor to escape from a sub-surface ocean. If observed up close, the chemical components of the plumes would be identified and could help explain the nature and history of the ocean below. ( NASA) 

The amount of water vapor found in the European atmosphere wasn’t great — about an Olympic-sized pool worth of H2O.  … Read more

A Reprieve for Space Science?

March 23, 2018 / / 0 Comments

View of WFIRST focusing on supernova SN1995E in NGC 2441. The high-priority but embattled space telescope would, if congressional support continues, add greatly to knowledge about dark energy and dark matter, supernovae, and exoplanets.  (NASA)

 

A quick update on a recent column about whether our “golden age” of space science and discovery was in peril because of cost overruns and Trump administration budget priorities that emphasized human space travel over science.

The 2018 omnibus spending bill that was passed Wednesday night by the House of Representatives and Thursday night by the Senate represents a major push back against the administration’s earlier NASA budget proposals.  Not only would the agency receive $1.6 billion more funding than proposed by the administration, but numerous projects that had been specifically eliminated in that proposal are back among the living.

They include four Earth science satellites, a lander to accompany the Europa Clipper mission to that potentially habitable moon and, perhaps most important, the Wide Field Infrared Survey Telescope (WFIRST) space telescope.

Funding for that mission, which was the top priority of the space science community and the National Academy of Sciences for the 2020s, was eliminated in the proposed 2019 Trump budget, but WFIRST received $150 million in the just-passed omnibus bill.

A report accompanying the omnibus bill is silent about the proposed cancellation and instructs NASA to provide to Congress in 60 days a cost estimate for the full life cycle of the mission, including any additions that might be needed.  So there appears to be a strong congressional desire to see WFIRST launch and operate.

Still hanging fire is the fate of the James Webb Space Telescope, which has fallen behind schedule again and is in danger of crossing the $8 billion cap put into place by Congress in 2011.  NASA officials said this week that they will soon announce their determination about whether a breach of the program’s cost cap will occur as a result of further delays.

NASA has a fleet of 18 Earth science missions in space, supported by aircraft, ships and ground observations. Together they have revolutionized understanding of the planet’s atmosphere, the oceans, the climate and weather. The Obama administration emphasized Earth studies, but the Trump administration has sought to eliminate future Earth missions. This visualization shows the NASA fleet in 2017, from low Earth orbit all the way out to the DSCOVR satellite taking in the million-mile view.

… Read more

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

July 6, 2017 / / 0 Comments

 

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

Planetary Protection is a "Wicked" Problem

May 15, 2017 / / 0 Comments

The Viking landers were baked for 30 hours after assembly, a dry heat sterilization that is considered the gold standard for planetary protection.  Before the baking, the landers were given a preliminary cleaning to reduce the number of potential microbial spores.  The levels achieved with that preliminary cleaning are similar to what is now required for a mission to Mars unless the destination is an area known to be suitable for Martian life.  In that case, a sterilizing equivalent to the Viking baking is required.  (NASA)

The only time that a formally designated NASA “life detection” mission was flown to another planet or moon was when the two Viking landers headed to Mars forty years ago.

The odds of finding some kind of Martian life seemed so promising at the time that there was little dispute about how much energy, money and care should be allocated to making sure the capsule would not be carrying any Earth life to the planet.  And so after the two landers had been assembled, they were baked at more than 250 °F for three days to sterilize any parts that would come into contact with Mars.

Although the two landers successfully touched down on the Martian surface and did some impressive science, the life detection portion of the mission was something of a fiasco — with conflict, controversy and ultimately quite a bit of confusion.

Clearly, scientists did not yet know enough about how to search for life beyond Earth and the confounding results pretty much eliminated life-detection from NASA’s missions for decades.

But scientific and technological advances of the last ten years have put life detection squarely back on the agenda — in terms of future searches for fossil biosignatures on Mars and for potential life surviving in the oceans of Europa and Enceladus.  What’s more, both NASA and private space companies talk seriously of sending humans to Mars in the not-too-distant future.

With so many missions being planned, developed and proposed for solar system planets and moons, the issue of planetary protection has also gained a higher profile.  It seems to have become more contentious and to some seems far less straight-forward as it used to be.

A broad consensus appears to remain that bringing Earth life to another planet or moon, especially if it is potentially habitable, is a real possibility that is both scientifically and ethically fraught. But there are rumblings about just how much time, money and attention needs to be brought to satisfying the requirements of “planetary protection.”… Read more

NASA Panel Supports Life-Detecting Lander for Europa; Updated

April 20, 2017 / / 0 Comments

Artist conception of water vapor plumes coming from beneath the thick ice of Jupiter’s moon Europa. The plumes have not been definitively detected, but Hubble Space Telescope images make public earlier this month appear to show plume activity in an area where it was detected once before.  How will this finding affect decision-making about a potential NASA Europa lander mission? (NASA)

As I prepare for the Astrobiology Science Conference (Abscicon) next week in Arizona, I’m struck by how many speakers will be discussing Europa missions, Europa science, ocean worlds and habitability under ice.  NASA’s Europa Clipper mission to orbit that moon, scheduled for launch to the Jupiter system in the mid 2020s, explains part of the interest, but so too does the unsettled fate of the Europa lander concept.

The NASA Science Definition Team that studied the Europa lander project will both give a science talk at the conference and hold an afternoon-long science community meeting on their conclusions.  The team argued that landing on Europa holds enormous scientific promise, most especially in the search for life beyond Earth.

But since the Europa lander SDT wrote its report and took its conclusions public early this year, the landscape has changed substantially.  First, in March, the Trump Administration 2018 budget eliminated funding for the lander project.  More than half a billion dollars have been spent on Europa lander research and development, but the full project was considered to be too expensive by the White House.

Administration budget proposals and what ultimately become budget reality can be quite different, and as soon as the Europa lander was cancelled supporters in Congress pushed back.  Rep. John Culberson (R-Tex.) and chair of the House subcommittee that oversees the NASA budget, replied to the proposed cancellation by saying “NASA is a strategic national asset and I have no doubt NASA will receive sufficient funding to complete the most important missions identified by the science community, including seeking out life in the oceans of Europa.”

More recently, researchers announced additional detections of plumes of water vapor apparently coming out of Europa — plumes in the same location as a previous apparent detection.  The observing team said they were confident the difficult observation was indeed water vapor, but remained less than 100 percent certain.  (Unlike for the detection of a water plume on Saturn’s moon Enceladeus, which the Cassini spacecraft photographed, measured and flew through.)

So while suffering a serious blow in the budgeting process, the case for a Europa lander has gotten considerably stronger from a science and logistics perspective. 

… Read more
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