NASA Says James Webb Telescope will Study Solar System’s “Ocean Worlds”

The moons of Europa and Enceladus, as imaged by the Galileo and Cassini spacecraft. Credit: NASA/ESA/JPL-Caltech/SETI Institute

In October of 2018, the James Webb Space Telescope (JWST) will be launched into orbit. As part of NASA’s Next Generation Space Telescope program, the JWST will spend the coming years studying every phase of cosmic history. This will involve probing the first light of the Universe (caused by the Big Bang), the first galaxies to form, and extra-solar planets in nearby star systems.

In addition to all of that, the JWST will also be dedicated to studying our Solar System. As NASA recently announced, the telescope will use its infrared capabilities to study two “Ocean Worlds” in our Solar System – Jupiter’s moon Europa and Saturn’s moon Enceladus. In so doing, it will add to observations previously made by NASA’s Galileo and Cassini orbiters and help guide future missions to these icy moons.

The moons were chosen by scientist who helped to develop the telescope (aka. guaranteed time observers) and are therefore given the privilege of being among the first to use it. Europa and Enceladus were added to the telescope’s list of targets since one of the primary goals of the telescope is to study the origins of life in the Universe. In addition to looking for habitable exoplanets, NASA also wants to study objects within our own Solar System.

Artist rendering showing an interior cross-section of the crust of Enceladus, which shows how hydrothermal activity may be causing the plumes of water at the moon’s surface. Credits: NASA-GSFC/SVS, NASA/JPL-Caltech/Southwest Research Institute

One of the main focuses will be on the plumes of water that have been observed breaking through the icy surfaces of Enceladus and Europa. Since 2005, scientists have known that Enceladus has plumes that periodically erupt from its southern polar region, spewing water and organic chemicals that replenish Saturn’s E-Ring. It has since discovered that these plumes reach all the way into the interior ocean that exists beneath Enceladus’ icy surface.

In 2012, astronomers using the Hubble Space Telescope detected similar plumes coming from Europa. These plumes were spotted coming from the moon’s southern hemisphere, and were estimated to reach up to 200 km (125 miles) into space. Subsequent studies indicated that these plumes were intermittent, and presumably rained water and organic materials from the interior back onto the surface.

These observations were especially intriguing since they bolstered the case for Europa and Enceladus having interior, warm-water oceans that could harbor life. These oceans are believed to be the result of geological activity in the interior that is caused by tidal flexing. Based on the evidence gathered by the Galileo and Cassini orbiters, scientists have theorized that these surface plumes are the result of these same geological processes.

The presence of this activity could also means that these moons have hydrothermal vents located at their core-mantle boundaries. On Earth, hydrothermal vents (located on the ocean floor) are believed to have played a major role in the emergence of life. As such, their existence on other bodies within the Solar System is viewed as a possible indication of extra-terrestrial life.

The effort to study these “Ocean Worlds” will be led by Geronimo Villanueva, a planetary scientist at NASA’s Goddard Space Flight Center. As he explained in a recent NASA press statement, he and his team will be addressing certain fundamental questions:

“Are they made of water ice? Is hot water vapor being released? What is the temperature of the active regions and the emitted water? Webb telescope’s measurements will allow us to address these questions with unprecedented accuracy and precision.”

Villanueva’s team is part of a larger effort to study the Solar System, which is being led by Heidi Hammel – the executive VP of the Association of Universities for Research in Astronomy (AURA). As she described the JWST’s “Ocean World” campaign to Universe Today via email:

“We will be seeking signatures of plume activity on these ocean worlds as well as active spots. With the near-infrared camera of NIRCAM, we will have just enough spatial resolution to distinguish general regions of the moons that could be “active” (creating plumes). We will also use spectroscopy (examining specific colors of light) to sense the presence of water, methane and several other organic species in plume material.”

Possible spectroscopy results from one of Europa’s water plumes. This is an example of the data the Webb telescope could return. Credit: NASA-GSFC/SVS/Hubble Space Telescope/Stefanie Milam/Geronimo Villanueva

To study Europa, Villanueva and his colleagues will take high-resolution imagery of Europa using the JWST’s near-infrared camera (NIRCam). These will be used to study the moon’s surface and search for hot spots that are indicative of plumes and geological activity. Once a plume is located, the team will determine its composition using Webb’s near-infrared spectrograph (NIRSpec) and mid-infrared instrument (MIRI).

For Enceladus, the team will be analyze the molecular composition of its plumes and perform a broad analysis of its surface features. Due to its small size, high-resolution of the surface will not be possible, but this should not be a problem since the Cassini orbiter already mapped much of its surface terrain. All told, Cassini has spent the past 13 years studying the Saturn system and will conclude the “Grande Finale” phase of its mission this September 15th.

These surveys, it is hoped, will find evidence of organic signatures in the plumes, such as methane, ethanol and ethane. To be fair, there are no guarantees that the JWST’s observations will coincide with plumes coming from these moons, or that the emissions will have enough organic molecules in them to be detectable. Moreover, these indicators could also be caused by geological processes.

Nevertheless, the JWST is sure to provide evidence that will allow scientists to better characterize the active regions of these moons. It is also anticipated that it will be able to pinpoint locations that will be of interest for future missions, such as NASA’s Europa Clipper mission. Consisting of an orbiter and lander, this mission – which is expected to launch sometime in the 2020s – will attempt to determine if Europa is habitable.

As Dr. Hammel explained, the study of these two “Ocean Moons” is also intended to advance our understanding about the origins of life in the Universe:

“These two ocean moons are thought to provide environments that may harbor water-based life as we know it. At this point, the issue of life elsewhere is completely unknown, though there is much speculation. JWST can move us closer to understanding these potentially habitable environments, complementing robotic spacecraft missions that are currently in development (Europa Clipper) and may be planned for the future. At the same time, JWST will be examining the far more distant potentially habitable environments of planets around other stars. These two lines of exploration – local and distant – allow us to make significant advances in the search for life elsewhere.”

Once deployed, the JWST will be the most powerful space telescope ever built, relying on eighteen segmented mirrors and a suite of instruments to study the infrared Universe. While it is not meant to replace the Hubble Space Telescope, it is in many ways the natural heir to this historic mission. And it is certainly expected to expand on many of Hubble’s greatest discoveries, not the least of which are here in the Solar System.

Be sure to check out this video on the kinds of spectrographic data the JWST will provide in the coming years, courtesy of NASA:

Further Reading: NASA

May 3, 2017 by Matt Williams

Building Rovers That Can Detect Life and Sequence DNA on Other Worlds

An interdisciplinary team from MIT (with support from NASA) is seeking to create an instrument that can performing in-situ test for life. Credit: setg.mit.edu

In 2015, then-NASA Chief Scientist Ellen Stofan stated that, “I believe we are going to have strong indications of life beyond Earth in the next decade and definite evidence in the next 10 to 20 years.” With multiple missions scheduled to search foe evidence of life (past and present) on Mars and in the outer Solar System, this hardly seems like an unrealistic appraisal.

But of course, finding evidence of life is no easy task. In addition to concerns over contamination, there is also the and the hazards the comes with operating in extreme environments – which looking for life in the Solar System will certainly involve. All of these concerns were raised at a new FISO conference titled “Towards In-Situ Sequencing for Life Detection“, hosted by Christopher Carr of MIT.

Carr is a research scientist with MIT’s Department of Earth, Atmospheric and Planetary Sciences (EAPS) and a Research Fellow with the Department of Molecular Biology at Massachusetts General Hospital. For almost 20 years, he has dedicated himself to the study of life and the search for it on other planets. Hence why he is also the science principal investigator (PI) of the Search for Extra-Terrestrial Genomes (SETG) instrument.

*This artist’s rendering shows NASA’s Europa mission spacecraft, which will search for life on Europa beginning sometime in the 2020s. Credit: NASA/JPL-Caltech*

Led by Dr. Maria T. Zuber – the E. A. Griswold Professor of Geophysics at MIT and the head of EAPS – the inter-disciplinary group behind SETG includes researchers and scientists from MIT, Caltech, Brown University, arvard, and Claremont Biosolutions. With support from NASA, the SETG team has been working towards the development of a system that can test for life in-situ.

Introducing the search for extra-terrestrial life, Carr described the basic approach as follows:

“We could look for life as we don’t know it. But I think it’s important to start from life as we know it – to extract both properties of life and features of life, and consider whether we should be looking for life as we know it as well, in the context of searching for life beyond Earth.”

Towards this end, the SETG team seeks to leverage recent developments in in-situ biological testing to create an instrument that can be used by robotic missions. These developments include the creation of portable DNA/RNA testing devices like the MinION, as well as the Biomolecule Sequencer investigation. Performed by astronaut Kate Rubin in 2016, this was first-ever DNA sequencing to take place aboard the International Space Station.

Building on these, and the upcoming Genes in Space program – which will allow ISS crews to sequence and research DNA samples on site – the SETG team is looking to create an instrument that can isolate, detect, and classify any DNA or RNA-based organisms in extra-terrestrial environments. In the process, it will allow scientists to test the hypothesis that life on Mars and other locations in the Solar System (if it exists) is related to life on Earth.

*The theory of Lithopanspermia states that life can be shared between planets within a planetary system. Credit: NASA*

To break this hypothesis down, it is a widely accepted theory that the synthesis of complex organics – which includes nucleobases and ribose precursors – occurred early in the history of the Solar System and took place within the Solar nebula from which the planets all formed. These organics may have then been delivered by comets and meteorites to multiple potentially-habitable zones during the Late Heavy Bombardment period.

Known as lithopansermia, this theory is a slight twist on the idea that life is distributed throughout the cosmos by comets, asteroids and planetoids (aka. panspermia). In the case of Earth and Mars, evidence that life might be related is based in part on meteorite samples that are known to have come to Earth from the Red Planet. These were themselves the product of asteroids striking Mars and kicking up ejecta that was eventually captured by Earth.

By investigating locations like Mars, Europa and Enceladus, scientists will also be able to engage in a more direct approach when it comes to searching for life. As Carr explained:

“There’s a couple main approaches. We can take an indirect approach, looking at some of the recently identified exoplanets. And the hope is that with the James Webb Space Telescope and other ground-based telescopes and space-based telescopes, that we will be in a position to begin imaging the atmospheres of exoplanets in much greater detail than characterization of those exoplanets has [allowed for] to date. And that will give us high-end, it will give the ability to look at many different potential worlds. But it’s not going to allow us to go there. And we will only have indirect evidence through, for example, atmospheric spectra.”

Mars, Europa and Enceladus present a direct opportunity to find life since all have demonstrated conditions that are (or were) conducive to life. Whereas there is ample evidence that Mars once had liquid water on its surface, Europa and Enceladus both have subsurface oceans and have shown evidence of being geologically active. Hence, any mission to these worlds would be tasked with looking in the right locations to spot evidence of life.

On Mars, Carr notes, this will come down to looking in places there there is a water-cycle, and will likely involve some a little spelunking:

“I think our best bet is to access the subsurface. And this is very hard. We need to drill, or otherwise access regions below the reach of space radiation which could destroy organic materiel. And one possibility is to go to fresh impact craters. These impact craters could expose material that wasn’t radiation-processed. And maybe a region where we might want to go would be somewhere where a fresh impact crater could connect to a deeper subsurface network – where we could get access to material perhaps coming out of the subsurface. I think that is probably our best bet for finding life on Mars today at the moment. And one place we could look would be within caves; for example, a lava tube or some other kind of cave system that could offer UV-radiation shielding and maybe also provide some access to deeper regions within the Martian surface.”

As for “ocean worlds” like Enceladus, looking for signs of life would likely involve exploring around its southern polar region where tall plumes of water have been observed and studied in the past. On Europa, it would likely involve seeking out “chaos regions”, the spots where there may be interactions between the surface ice and the interior ocean.

*Exploring Europa’s “chaos terrain”, where the is interaction between the interior ocean and the surface ice, could yield evidence of biological organisms. Credit: NASA/JPL-Caltech*

Exploring these environments naturally presents some serious engineering challenges. For starters, it would require the extensive planetary protections to ensure that contamination was prevented. These protections would also be necessary to ensure that false positives were avoided. Nothing worse than discovering a strain of DNA on another astronomical body, only to realize that it was actually a skin flake that fell into the scanner before launch!

And then there are the difficulties posed by operating a robotic mission in an extreme environment. On Mars, there is always the issue of solar radiation and dust storms. But on Europa, there is the added danger posed by Jupiter’s intense magnetic environment. Exploring water plumes coming from Enceladus is also very challenging for an orbiter that would most likely be speeding past the planet at the time.

But given the potential for scientific breakthroughs, such a mission it is well worth the aches and pains. Not only would it allow astronomers to test theories about the evolution and distribution of life in our Solar System, it could also facilitate the development of crucial space exploration technologies, and result in some serious commercial applications.

Looking to the future, advances in synthetic biology are expected to lead to new treatments for diseases and the ability to 3-D print biological tissues (aka. “bioprinting”). It will also help ensure human health in space by addressing bone density loss, muscle atrophy, and diminished organ and immune-function. And then there’s the ability to grow organisms specially-designed for life on other planets (can you say terraforming?)

Exogenesis — *Is life in our Solar System, and the Universe for that matter, universal in nature? Credit: NASA/Jenny Mottor*

On top of all that, the ability to conduct in-situ searches for life on other Solar planets also presents scientists with the opportunity to answer a burning question, one which they’ve struggled with for decades. In short, is carbon-based life universal? So far, any and all attempts to answer this question have been largely theoretical and have involved the “low hanging fruit variety” – where we have looked for signs of life as we know it, using mainly indirect methods.

By finding examples that come from environments other than Earth, we would be taking some crucial steps towards preparing ourselves for the kinds of “close encounters” that could be happening down the road.

Further Reading: SETG, FISO

April 13, 2017April 28, 2017 by Evan Gough

NASA Bombshell: Key Ingredient For Life Discovered On Enceladus

Scientists recently determined that a certain strain of Earth bacteria could thrive under conditions found on Enceladus. Credit: NASA/JPL/Space Science Institute

NASA has announced the discovery of hydrogen in the plumes on Enceladus. This is huge news, and Cassini scientists have looked forward to this day. What it means is that there is a potential source of energy for microbes in the oceans of Enceladus, and that energy from the Sun is not required to support life.

We’ve known about the plumes on Enceladus for a while now, and Cassini has even flown through those plumes to determine their content. But hydrogen was never discovered until now. What it means is that there is a geochemical source for hydrogen in Enceladus’ ocean, coming from the interaction between warm water and rocks.

“This is the closest we’ve come, so far, to identifying a place with some of the ingredients needed for a habitable environment.” – Thomas Zurbuchen, NASA.

This is a capstone finding, according to NASA. As far as we know, life needs three things to exist: water, energy, and the right chemicals. We know it has the necessary chemicals, we know it has water, and we now know it has a source of energy.

On Earth, hydrothermal vents deep in the ocean floor provide the energy for a web of life reliant on those vents. Bacteria live there, forming the base of a food chain that can include tube worms, shrimp, and other life forms. This discovery points to the possibility that similar communities might exist in the sub-surface ocean of Enceladus.

“This is the closest we’ve come, so far, to identifying a place with some of the ingredients needed for a habitable environment,” said Thomas Zurbuchen, associate administrator for NASA’s Science Mission Directorate at Headquarters in Washington.

Microbes in Enceladus’ ocean could use the hydrogen in a process called methanogenesis. They obtain energy by combining hydrogen with dissolved carbon dioxide in the water. This process produces a methane by-product. Methanogenesis is a bedrock process at the root of life here on Earth.

“Confirmation that the chemical energy for life exists within the ocean of a small moon of Saturn is an important milestone in our search for habitable worlds beyond Earth,” said Linda Spilker, Cassini project scientist at NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, California.

Hubble Confirms Plumes On Europa

NASA has also announced that the Hubble Space Telescope has confirmed the presence of plumes on another of our Solar System’s icy moons, Europa.

These plumes were first seen by the Hubble in 2014, but were never seen again. Since repeatability is key in science, those findings were put on the back burner. But in 2016, NASA announced today, Hubble spotted them again, in the same place. This is the same spot that the Galileo probe noticed a thermal hot spot.

We don’t know if Europa has hydrogen in its oceans, but it’s easy to see where this is going. NASA’s excitement is palpable.

What’s Next?

NASA’s Europa Clipper mission will visit Europa and determine the thickness of its ice layer, as well as the depth and salinity of its ocean. It will also analyze the atmosphere and the composition of the plumes. Europa Clipper will fill in a lot of gaps in our understanding.

Europa Clipper will be launched around 2022, but a mission to Enceladus will have to wait a little longer. One mission under consideration in NASA’s Discovery program is ELF, Enceladus Life Finder. ELF would fly through Enceladus’ plumes 8 or 10 times, taking more detailed samples of their content.

The discovery of hydrogen in the plumes of Enceladus is huge news any way you look at it. But that discovery begs the question: Are we doing it all wrong? Are we looking for life in the wrong places?

The search for life elsewhere in the Universe, so far, has mostly revolved around exoplanets. And then refining that search to identify exoplanets that are in the habitable zones of their stars. We’re searching for other Earths, basically.

But maybe we should be changing our focus. Maybe it’s the ice worlds, including icy exomoons, that are the most likely targets for our search. This new evidence from NASA’s Cassini mission, and from the Hubble Space Telescope, suggests that in our Solar System at least, they are the best place to search.

One Final Ingredient Needed?

There’s a fourth ingredient needed for life. Once there is water, energy, and the necessary chemicals, life needs time to get going. How much time, we’re not exactly certain. But this is where Enceladus and Europa are different.

Europa is about 4 billion years old, or so we think. That’s only half a billion years younger than Earth, and we think life started on Earth about 3.5 billion years ago. This hints that, if conditions on Europa are favorable, life has had a long time to get going. Of course, that doesn’t mean it has.

On the other hand, Enceladus is probably much younger. A study of the orbits of Saturn’s moons suggests that Enceladus may only be 100 million years old. If that’s true, it’s not very much time for life to get going.

The hydrogen discovery is huge news. There are still a lot of questions, of course, and lots to be debated. But confirming a source of energy on Enceladus builds the case for the same type of hydrothermal vent life that we see on Earth.

Now all we need is a mission to Enceladus.

March 17, 2017March 17, 2017 by Fraser Cain

Weekly Space Hangout – Mar 17, 2017: Stuart McNeill of the Intrepid Sea, Air & Space Museum

Host: Fraser Cain (@fcain)

Special Guest:
Stuart McNeill is the the Community Engagement specialist in charge of Family Programs and Demonstrations at the Intrepid Sea, Air & Space Museum. Check out their membership site here.

Guests:
Kimberly Cartier ( KimberlyCartier.org / @AstroKimCartier )
Paul M. Sutter (pmsutter.com / @PaulMattSutter)

Their stories this week:

The original weird star: Przybylski’s Star may contain short-lived isotopes

Enceladus’ sub-surface ocean under thin(ner) ice

Star orbiting black hole at 1% c

We use a tool called Trello to submit and vote on stories we would like to see covered each week, and then Fraser will be selecting the stories from there. Here is the link to the Trello WSH page (http://bit.ly/WSHVote), which you can see without logging in. If you’d like to vote, just create a login and help us decide what to cover!

If you would like to join the Weekly Space Hangout Crew, visit their site here and sign up. They’re a great team who can help you join our online discussions!

If you’d like to join Fraser and Paul Matt Sutter on their tour to Iceland in February, 2018, you can find the information at astrotouring.com.

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We record the Weekly Space Hangout every Friday at 12:00 pm Pacific / 3:00 pm Eastern. You can watch us live on Universe Today, or the Universe Today YouTube page

March 14, 2017April 4, 2017 by Nancy Atkinson

Warm Poles Suggest Enceladus’ Liquid Water Near Surface

Saturn's moon Enceladus could harbor microbial life in the warm salty water thought to exist under its frozen surface. Respondents in the study seemed to like that possibility. Credits: NASA/JPL-Caltech/Space Science Institute

One of the biggest surprises from the Cassini mission to Saturn has been the discovery of active geysers at the south pole of the moon Enceladus. At only about 500 km (310 miles) in diameter, the bright and ice-covered moon should be too small and too far from the Sun to be active. Instead, this little moon is one of the most geothermally active places in the Solar System.

Now, a new study from Cassini data shows that the south polar region of Enceladus is even warmer than expected just a few feet below its icy surface. While previous studies have confirmed an ocean of liquid water inside Enceladus which fuels the geysers, this new study shows the ocean is likely closer to the surface than previously thought. Additionally – and most enticing – there has to be a source of heat inside the moon that is not completely understood.

“These observations provide a unique insight into what is going on beneath the surface,” said Alice Le Gall, who is part of the Cassini RADAR instrument team, from Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), and Université Versailles Saint-Quentin (UVSQ), France. “They show that the first few meters below the surface of the area that we investigated, although at a glacial 50-60 K, are much warmer than we had expected: likely up to 20 K warmer in some places. This cannot be explained only as a result of the Sun’s illumination and, to a lesser extent, Saturn’s heating so there must be an additional source of heat.”

Tiger stripes on the south pole of Enceladus. The region studied is indicated by the coloured band. NASA/JPL-Caltech/Space Science Institute; Acknowledgement: A. Lucas

Microwave data taken during a close flyby in 2011 shows there is excess heat at three fractures in the surface of Enceladus. While similar to the so-called “tiger-stripe” features on this moon that are actively venting ice and water molecules into space, these three fractures don’t appear to be active, at least not in 2011.

Scientists say the seemingly dormant fractures lying above the moon’s warm, underground sea point to the dynamic character of Enceladus’ geology, suggesting the moon might have experienced several episodes of activity, in different places on its surface.

The 2011 flyby provided the first – and unfortunately, the only — high-resolution observations of Enceladus’ south pole at microwave wavelengths.

It looked at a narrow, arc-shaped swathe of the southern polar region, about 25 km (15 miles) wide, and located just 30 km to 50 km (18-30 miles) north of the tiger-stripe fractures.

The heat that was detected appears to be lying under a much colder layer of frost.

Because of operational constraints of the 2011 flyby, it was not possible to obtain microwave observations of the active fractures themselves. But this allowed the scientists to observe that the thermally anomalous terrains of Enceladus extend well beyond the tiger stripes.

Cassini’s view down into a jetting “tiger stripe” in August 2010. Credit: NASA

Their findings show it is likely that the entire south pole region is warm underneath, meaning Enceladus’ ocean could be just 2 km under the moon’s icy surface in that area. The finding agrees with a 2016 study, led by another Cassini team member, Ondrej Cadek, which estimated the thickness of the crust on Enceladus’ south pole to be less than the rest of the moon. That study estimated the depth of the ice shell to be less than 5 km (1.2 miles) at the south pole, while average depth on other areas of Enceladus is between 18–22 km (11-13 miles).

What generates the internal heat at Enceladus? The main source of heat remains a mystery, but scientists think gravitational forces between Enceladus, Saturn, and another moon, Dione pull and flex Enceladus’ interior. Known as tidal forces, the tugging causes the moon’s interior to rub, creating friction and heat. It also creates stress compressions and deformations on the crust, leading to the formation of faults and fractures. This in turn creates more heat in the sub-surface layers. In this scenario, the thinner icy crust in the south pole region is subject to a larger tidal deformation that means more heat being created to help keep the underground water warm.

Dramatic plumes, both large and small, spray water ice out from many locations along the famed “tiger stripes” near the south pole of Saturn’s moon Enceladus. Credit: NASA/JPL/Space Science Institute

Since the geysers weren’t known until Cassini’s arrival at Saturn, the spacecraft didn’t have a specific payload to study them, but scientists used the instruments at their disposal to make the best observations they could, flying the spacecraft to within 49 km (30 miles) of the surface. To fully study the tidal heating — or to determine if there is another source of heat — scientists will continue to study the data already taken by various Cassini instruments. But since the mission will be ending in September 2017, it may require another mission to this intriguing moon to fully figure out this mystery.

“This discovery opens new perspectives to investigate the emergence of habitable conditions on the icy moons of the gas giant planets,” says Nicolas Altobelli, ESA’s Project Scientist for Cassini–Huygens. “If Enceladus’ underground sea is really as close to the surface as this study indicates, then a future mission to this moon carrying an ice-penetrating radar sounding instrument might be able to detect it.”

“Finding temperatures near these three inactive fractures that are unexpectedly higher than those outside them adds to the intrigue of Enceladus,” said Cassini Project Scientist Linda Spilker at the Jet Propulsion Laboratory. “What is the warm underground ocean really like and could life have evolved there? These questions remain to be answered by future missions to this ocean world.”

Feel free to submit your mission proposals in the comment section below…

An artist’s illustration of Cassini entering orbit around Saturn. Credit: NASA/JPL.

Sources: ESA
JPL
Paper: Thermally anomalous features in the subsurface of Enceladus’s south polar terrain” by A. Le Gall et al. (2017), published in Nature Astronomy

March 9, 2017March 10, 2017 by Evan Gough

How Will NASA Find Life On Other Worlds?

Is Earth in the range of normal when it comes to habitable planets? Or is it an outlier, with both large land masses, and large oceans? Image: Reto Stöckli, Nazmi El Saleous, and Marit Jentoft-Nilsen, NASA GSFC

For a long time, the idea of finding life on other worlds was just a science fiction dream. But in our modern times, the search for life is rapidly becoming a practical endeavour. Now, some minds at NASA are looking ahead to the search for life on other worlds, and figuring out how to search more effectively and efficiently. Their approach is centered around two things: nano-satellites and microfluidics.

Life is obvious on Earth. But it’s a different story for the other worlds in our Solar System. Mars is our main target right now, with the work that MSL Curiosity is doing. But Curiosity is investigating Mars to find out if conditions on that planet were ever favorable for life. A more exciting possibility is finding extant life on another world: that is, life that exists right now.

MSL Curiosity is busy investigating the surface of Mars, to see if that planet could have harbored life. Image: NASA/JPL/Cal-Tech

At the Planetary Science Vision 2050 Workshop, experts in Planetary Science and related disciplines gathered to present ideas about the next 50 years of exploration in the Solar System. A team led by Richard Quinn at the NASA Ames Research Center (ARC) presented their ideas on the search for extant life in the next few decades.

Their work is based on the decadal survey “Vision and Voyages for Planetary Science in the Decade 2013-2022.” That source confirms what most of us are already aware of: that our search for life should be focussed on Mars and the so-called “Ocean Worlds” of our Solar System like Enceladus and Europa. The question is, what will that search look like?

The North Polar Region of Saturn’s moon, Enceladus. Could there be an ocean world full of life under its frozen surface? Credit: NASA/JPL/Space Science Institute

Quinn and his team outlined two technologies that we could center our search around.

Nanosatellites

A nanosatellite is classified as something with a mass between 1-10 kg. They offer several advantages over larger designs.

Firstly, their small mass keeps the cost of launching them very low. In many cases, nanosatellites can be piggy-backed onto the launch of a larger payload, just to use up any excess capacity. Nanosatellites can be made cheaply, and multiples of them can be designed and built the same. This would allow a fleet of nanosatellites to be sent to the same destination.

Most of the discussion around the search for life centers around large craft or landers that land in one location, and have limited mobility. The Mars rovers are doing great work, but they can only investigate very specific locations. In a way, this creates kind of a sampling error. It’s difficult to generalize about the conditions for life on other worlds when we’ve only sampled a small handful of locations.

In 2010, NASA successfully deployed the nanosatellite NANO-Sail D from a larger, microsatellite. Image: NASA

On Earth, life is everywhere. But Earth is also the home to extremophiles, organisms that exist only in extreme, hard-to-reach locations. Think of thermal vents on the ocean floor, or deep dark caves. If that is the kind of life that exists on the target worlds in our Solar System, then there’s a strong possibility that we’ll need to sample many locations before we find them. That is something that is beyond the capabilities of our rovers. Nanosatellites could be part of the solution. A fleet of them investigating a world like Enceladus or Europa could speed up our search for extant life.

NASA has designed and built nanosatellites to perform a variety of tasks, like performing biology experiments, and testing advanced propulsion and communications technologies. In 2010 they successfully deployed a nanosatellite from a larger, microsatellite. If you expand on that idea, you can see how a small fleet of nanosatellites could be deployed at another world, after arriving there on another larger craft.

Microfluidics

Microfluidics deals with systems that manipulate very small amounts of fluid, usually on the sub-millimeter scale. The idea is to build microchips which handle very small sample sizes, and test them in-situ. NASA has done work with microfluidics to try to develop ways of monitoring astronauts’ health on long space voyages, where there is no access to a lab. Microfluidic chips can be manufactured which have only one or two functions, and produce only one or two results.

In terms of the search for extant life in our Solar System, microfluidics is a natural fit with nanosatellites. Replace the medical diagnostic capabilities of a microfluidic chip with a biomarker diagnostic, and you have a tiny device that can be mounted on a tiny satellite. Since functioning microfluidic chips can be as small as microprocessors, multiples of them could be mounted.

” Technical constraints will inevitably limit robotic missions that search for evidence of life to a few selected experiments.” – Richard.C.Quinn, et. al.

When combined with nanosatellites, microfluidics offers the possibility of the same few tests for life being repeated over and over in multiple locations. This is obviously very attractive when it comes to the search for life. The team behind the idea stresses that their approach would involve the search for simple building blocks, the complex biomolecules involved in basic biochemistry, and also the structures that cellular life requires in order to exist. Performing these tests in multiple locations would be a boon in the search.

Some of the technologies for the microfluidic search for life have already been developed. The team points out that several of them have already had successful demonstrations in micro-gravity missions like the GeneSat, the PharmaSat, and the SporeSat.

“The combination of microfluidic systems with chemical and biochemical sensors and sensor arrays offer some of the most promising approaches for extant life detection using small-payload platforms.” – Richard.C.Quinn, et. al.

Putting It All Together

We’re a ways away from a mission to Europa or Enceladus. But this paper was about the future vision of the search for extant life. It’s never too soon to start thinking about that.

There are some obvious obstacles to using nanosatellites to search for life on Enceladus or Europa. Those worlds are frozen, and it’s the oceans under those thick ice caps that we need to investigate. Somehow, our tiny nanosatellites would need to get through that ice.

Also, the nanosatellites we have now are just that: satellites. They are designed to be in orbit around a body. How could they be transformed into tiny, ocean-going submersible explorers?
There’s no doubt that somebody, somewhere at NASA, is already thinking about that.

The over-arching vision of a fleet of small craft, each with the ability to repeat basic experiments searching for life in multiple locations, is a sound one. As for how it actually turns out, we’ll have to wait and see.

March 8, 2017 by Fraser Cain

What Did Cassini Teach Us?

Ask me my favorite object in the Solar System, especially to see through a telescope, and my answer is always the same: Saturn.

Saturn is this crazy, ringed world, different than any other place we’ve ever seen. And in a small telescope, you can really see the ball of the planet, you can see its rings. It’s one thing to see a world like this from afar, a tiny jumping image in a telescope. To really appreciate and understand a place like Saturn, you’ve got to visit.

And thanks to NASA’s Cassini spacecraft, that’s just what we’ve been doing for the last 13 years. Take a good close look at this amazing ringed planet and its moons, and studying it from every angle.

Space Probes — Cassini orbiting Saturn. Credit: NASA

Throughout this article, I’m going to regale you with the amazing discoveries made by Cassini at Saturn. What it taught us, and what new mysteries it uncovered.

NASA’s Cassini spacecraft was launched from Earth on October 15, 1997. Instead of taking the direct route, it made multiple flybys of Venus, a flyby of Earth and a flyby of Jupiter. Each one of these close encounters boosted Cassini’s velocity, allowing it to make the journey with less escape velocity from Earth.

It arrived at Saturn on July 1st, 2004 and began its science operations shortly after that. The primary mission lasted 4 years, and then NASA extended its mission two more times. The first ending in 2010, and the second due to end in 2017. But more on that later.

Before Cassini, we only had flybys of Saturn. NASA’s Pioneer 11, and Voyagers 1 and 2 both zipped past the planet and its moons, snapping pictures as they went.

But Cassini was here to stay. To orbit around and around the planet, taking photos, measuring magnetic fields, and studying chemicals.

For Saturn itself, Cassini was able to make regular observations of the planet as it passed through entire seasons. This allowed it to watch how the weather and atmospheric patterns changed over time. The spacecraft watched lightning storms dance through the cloudtops at night.

This series of images from NASA’s Cassini spacecraft shows the development of the largest storm seen on the planet since 1990. These true-color and composite near-true-color views chronicle the storm from its start in late 2010 through mid-2011, showing how the distinct head of the storm quickly grew large but eventually became engulfed by the storm’s tail. Credit: NASA/JPL-Caltech/Space Science Institute

Two highlights. In 2010, Cassini watched a huge storm erupt in the planet’s northern hemisphere. This storm dug deep into Saturn’s lower atmosphere, dredging up ice from a layer 160 kilometers below and mixing it onto the surface. This was the first time that astronomers were able to directly study this water ice on Saturn, which is normally in a layer hidden from view.

Natural color images taken by NASA’s Cassini wide-angle camera, showing the changing appearance of Saturn’s north polar region between 2012 and 2016.. Credit: NASA/JPL-Caltech/Space Science Institute/Hampton University

The second highlight, of course, is the massive hexagonal storm churning away in Saturn’s northern pole. This storm was originally seen by Voyager, but Cassini brought its infrared and visible wavelength instruments to bear.

Why a hexagon? That’s still a little unclear, but it seems like when you rotate fluids of different speeds, you get multi-sided structures like this.

Cassini showed how the hexagonal storm has changed in color as Saturn moved through its seasons.

This is one of my favorite images sent back by Cassini. It’s the polar vortex at the heart of the hexagon. Just look at those swirling clouds.

The polar vortex, in all its glory. Credit: NASA/JPL-Caltech/Space Science Institute

Now, images of Saturn itself are great and all, but there was so much else for Cassini to discover in the region.

Cassini studied Saturn’s rings in great detail, confirming that they’re made up of ice particles, ranging in size as small a piece of dust to as large as a mountain. But the rings themselves are actually quite thin. Just 10 meters thick in some places. Not 10 kilometers, not 10 million kilometers, 10 meters, 30 feet.

The spacecraft helped scientists uncover the source of Saturn’s E-ring, which is made up of fresh icy particles blasting out of its moon Enceladus. More on that in a second too.

Vertical structures, among the tallest seen in Saturn’s main rings, rise abruptly from the edge of Saturn’s B ring to cast long shadows on the ring in this image taken by NASA’s Cassini spacecraft two weeks before the planet’s August 2009 equinox. Credit: NASA/JPL/Space Science Institute

Here’s another one of my favorite images of the mission. You’re looking at strange structures in Saturn’s B-ring. Towering pillars of ring material that rise 3.5 kilometers above the surrounding area and cast long shadows. What is going on here?

They’re waves, generated in the rings and enhanced by nearby moons. They move and change over time in ways we’ve never been able to study anywhere else in the Solar System.

Daphnis, one of Saturn’s ring-embedded moons, is featured in this view, kicking up waves as it orbits within the Keeler gap. Credit: NASA/JPL-Caltech/Space Science Institute

Cassini has showed us that Saturn’s rings are a much more dynamic place than we ever thought. Some moons are creating rings, other moons are absorbing or distorting them. The rings generate bizarre spoke patterns larger than Earth that come and go because of electrostatic charges.

Speaking of moons, I’m getting to the best part. What did Cassini find at Saturn’s moons?

Let’s start with Titan, Saturn’s largest moon. Before Cassini, we only had a few low resolution images of this fascinating world. We knew Titan had a dense atmosphere, filled with nitrogen, but little else.

Cassini was carrying a special payload to assist with its exploration of Titan: the Huygens lander. This tiny probe detached from Cassini just before its arrival at Saturn, and parachuted through the cloudtops on January 14, 2005, analyzing all the way. Huygens returned images of its descent through the atmosphere, and even images of the freezing surface of Titan.

Huygen’s view of Titan. Credit: ESA/NASA/JPL/University of Arizona

But Cassini’s own observations of Titan took the story even further. Instead of a cold, dead world, Cassini showed that it has active weather, as well as lakes, oceans and rivers of hydrocarbons. It has shifting dunes of pulverized rock hard water ice.

If there’s one place that needs exploring even further, it’s Titan. We should return with sailboats, submarines and rovers to better explore this amazing place.

A view of Mimas from the Cassini spacecraft. Credit: NASA/JPL/Space Science Institute

We learned, without a shadow of a doubt, that Mimas absolutely looks like the Death Star. No question. But instead of a megalaser, this moon has a crater a third of its own size.

Saturn’s moon Iapetus. Image credit: NASA/JPL/SSI

Cassini helped scientists understand why Saturn’s moon Iapetus has one light side and one dark side. The moon is tidally locked to Saturn, its dark side always leading the moon in orbit. It’s collecting debris from another Saturnian moon, Phoebe, like bugs hitting the windshield of a car.

Perhaps the most exciting discovery that Cassini made during its mission is the strange behavior of Saturn’s moon Enceladus. The spacecraft discovered that there are jets of water ice blasting out of the moon’s southern pole. An ocean of liquid water, heated up by tidal interactions with Saturn, is spewing out into space.

And as you know, wherever we find water on Earth, we find life. We thought that water in the icy outer Solar System would be hard to reach, but here it is, right at the surface, venting into space, and waiting for us to come back and investigate it further.

Icy water vapor geysers erupting from fissures on Enceladus. Credit: NASA/JPL

On September 15, 2017, the Cassini mission will end. How do we know it’s going to happen on this exact date? Because NASA is going to crash the spacecraft into Saturn, killing it dead.

That seems a little harsh, doesn’t it, especially for a spacecraft which has delivered so many amazing images to us over nearly two decades of space exploration? And as we’ve seen from NASA’s Opportunity rover, still going, 13 years longer than anticipated. Or the Voyagers, out in the depths of the void, helping us explore the boundary between the Solar System and interstellar space. These things are built to last.

The problem is that the Saturnian system contains some of the best environments for life in the Solar System. Saturn’s moon Enceladus, for example, has geysers of water blasting out into space.

Cassini spacecraft is covered in Earth-based bacteria and other microscopic organisms that hitched a ride to Saturn, and would be glad to take a nice hot Enceladian bath. All they need is liquid water and a few organic chemicals to get going, and Enceladus seems to have both.

NASA feels that it’s safer to end Cassini now, when they can still control it, than to wait until they lose communication or run out of propellant in the future. The chances that Cassini will actually crash into an icy moon and infect it with our Earth life are remote, but why take the risk?
For the last few months, Cassini has been taking a series of orbits to prepare itself for its final mission. Starting in April, it’ll actually cross inside the orbit of the rings, getting closer and closer to Saturn. And on September 15th, it’ll briefly become a meteor, flashing through the upper atmosphere of Saturn, gone forever.

This graphic illustrates the Cassini spacecraft’s trajectory, or flight path, during the final two phases of its mission. The view is toward Saturn as seen from Earth. The 20 ring-grazing orbits are shown in gray; the 22 grand finale orbits are shown in blue. The final partial orbit is colored orange. Image credit: NASA/JPL-Caltech/Space Science Institute

Even in its final moments, Cassini is going to be sciencing as hard as it can. We’ll learn more about the density of consistency of the rings close to the planet. We’ll learn more about the planet’s upper atmosphere, storms and clouds with the closest possible photographs you can take.

And then it’ll all be over. The perfect finale to one of the most successful space missions in human history. A mission that revealed as many new mysteries about Saturn as it helped us answer. A mission that showed us not only a distant alien world, but our own planet in perspective in this vast Solar System. I can’t wait to go back.

How have the photos from Cassini impacted your love of astronomy? Let me know your thoughts in the comments.

March 3, 2017April 4, 2017 by Matt Williams

NASA’s Plans to Explore Europa and Other “Ocean Worlds”

The fascinating surface of Jupiter’s icy moon Europa looms large in this newly-reprocessed color view, made from images taken by NASA's Galileo spacecraft in the late 1990s. This is the color view of Europa from Galileo that shows the largest portion of the moon's surface at the highest resolution. Credits: NASA/JPL-Caltech/SETI Institute

Earlier this week, NASA hosted the “Planetary Science Vision 2050 Workshop” at their headquarters in Washington, DC. Running from Monday to Wednesday – February 27th to March 1st – the purpose of this workshop was to present NASA’s plans for the future of space exploration to the international community. In the course of the many presentations, speeches and panel discussions, many interesting proposals were shared.

Among them were two presentations that outlined NASA’s plan for the exploration of Jupiter’s moon Europa and other icy moons. In the coming decades, NASA hopes to send probes to these moons to investigate the oceans that lie beneath theirs surfaces, which many believe could be home to extra-terrestrial life. With missions to the “ocean worlds” of the Solar System, we may finally come to discover life beyond Earth.

The first of the two meetings took place on the morning of Monday, Feb. 27th, and was titled “Exploration Pathways for Europa after initial In-Situ Analyses for Biosignatures“. In the course of the presentation, Kevin Peter Hand – the Deputy Chief Scientist for Solar System Exploration at NASA’s Jet Propulsion Laboratory – shared findings from a report prepared by the 2016 Europa Lander Science Definition Team.

*Artist’s rendering of a potential future mission to land a robotic probe on the surface of Jupiter’s moon Europa. Credits: NASA/JPL-Caltech*

This report was drafted by NASA’s Planetary Science Division (PSD) in response to a congressional directive to begin a pre-Phase A study to assess the scientific value and engineering design of a Europa lander mission. These studies, which are known as Science Definition Team (SDT) reports, are routinely conducted long before missions are mounted in order to gain an understanding of the types of challenges it will face, and what the payoffs will be.

In addition to being the co-chair of the Science Definition Team, Hand also served as head of the project science team, which included members from the JPL and the California Institute of Technology (Caltech). The report he and his colleagues prepared was finalized and issued to NASA on February 7th, 2017, and outlined several objectives for scientific study.

As was indicated during the course of the presentation, these objectives were threefold. The first would involve searching for biosignatures and signs of life through analyses of Europa’s surface and near-subsurface material. The second would be to conduct in-situ analyses to characterize the composition of non-ice near-subsurface material, and determine the proximity of liquid water and recently-erupted material near the lander’s location.

The third and final goal would be to characterize the surface and subsurface properties and what dynamic processes are responsible for shaping them, in support for future exploration missions. As Hand explained, these objectives are closely intertwined:

“Were biosignatures to be found in the surface material, direct access to, and exploration of, Europa’s ocean and liquid water environments would be a high priority goal for the astrobiological investigation of our Solar System. Europa’s ocean would harbor the potential for the study of an extant ecosystem, likely representing a second, independent origin of life in our own solar system. Subsequent exploration would require robotic vehicles and instrumentation capable of accessing the habitable liquid water regions in Europa to enable the study of the ecosystem and organisms.”

*Artist’s impression of a hypothetical ocean cryobot (a robot capable of penetrating water ice) in Europa. Credit: NASA*

In other words, if the lander mission detected signs of life within Europa’s ice sheet, and from material churned up from beneath by resurfacing events, then future missions – most likely involving robotic submarines – would definitely be mounted. The report also states that any finds that are indicative of life would mean that planetary protections would be a major requirement for any future mission, to avoid the possibility of contamination.

But of course, Hand also admitted that there is a chance the lander will find no signs of life. If so, Hand indicated that future missions would be tasked with gaining “a better understanding of the fundamental geological and geophysical process on Europa, and how they modulate exchange of material with Europa’s ocean.” On the other hand, he claimed that even a null-result (i.e. no signs of life anywhere) would still be a major scientific find.

Ever since the Voyager probes first detected possible signs of an interior ocean on Europa, scientists have dreamed of the day when a mission might be possible to explore the interior of this mysterious moon. To be able to determine that life does not exist there could no less significant that finding life, in that both would help us learn more about life in our Solar System.

The Science Definition Team’s report will also be the subject of a townhall meeting at the 2017 Lunar and Planetary Science Conference (LPSC) – which will be taking place from March 20th to 24th in The Woodlands, Texas. The second event will be on April 23rd at the Astrobiology Science Conference (AbSciCon) held in Mesa, Arizona. Click here to read the full report.

The second presentation, titled “Roadmaps to Ocean Worlds” took place later on Monday, Feb. 27th. This presentation was put on by members of the the Roadmaps to Ocean Worlds (ROW) team, which is chaired by Dr. Amandra Hendrix – a senior scientist at the Planetary Science Institute in Tuscon, Arizona – and Dr. Terry Hurford, a research assistant from NASA’s Science and Exploration Directorate (SED).

As a specialist in UV spectroscopy of planetary surfaces, Dr. Hendrix has collaborated with many NASA missions to explore icy bodies in the Solar System – including the Galileo and Cassini probes and the Lunar Reconnaissance Orbiter (LRO). Dr. Hurford, meanwhile, specializes in the geology and geophysics of icy satellites, as well as the effects orbital dynamics and tidal stresses have on their interior structures.

Founded in 2016 by NASA’s Outer Planets Assessment Group (OPAG), ROW was tasked with laying the groundwork for a mission that will explore “ocean worlds” in the search for life elsewhere in the Solar System. During the course of the presentation, Hendrix and Hurford laid out the findings from the ROW report, which was completed in January of 2017.

As they state in this report, “we define an ‘ocean world’ as a body with a current liquid ocean (not necessarily global). All bodies in our solar system that plausibly can have or are known to have an ocean will be considered as part of this document. The Earth is a well-studied ocean world that can be used as a reference (“ground truth”) and point of comparison.”

Dwarf planet Ceres is shown in this false-color renderings, which highlight differences in surface materials. The image is centered on Ceres brightest spots at Occator crater. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

By this definition, bodies like Europa, Ganymede, Callisto, and Enceladus would all be viable targets for exploration. These worlds are all known to have subsurface oceans, and there has been compelling evidence in the past few decades that point towards the presence of organic molecules and prebiotic chemistry there as well. Triton, Pluto, Ceres and Dione are all mentioned as candidate ocean worlds based on what we know of them.

Titan also received special mention in the course of the presentation. In addition to having an interior ocean, it has even been ventured that extremophile methanogenic lifeforms could exist on its surface:

“Although Titan possesses a large subsurface ocean, it also has an abundant supply of a wide range of organic species and surface liquids, which are readily accessible and could harbor more exotic forms of life. Furthermore, Titan may have transient surface liquid water such as impact melt pools and fresh cryovolcanic flows in contact with both solid and liquid surface organics. These environments present unique and important locations for investigating prebiotic chemistry, and potentially, the first steps towards life.”

Ultimately, the ROW’s pursuit of life on “ocean worlds” consists of four main goals. These include identifying ocean worlds in the solar system, which would mean determining which of the worlds and candidate worlds would be well-suited to study. The second is to characterize the nature of these oceans, which would include determining the properties of the ice shell and liquid ocean, and what drives fluid motion in them.

*Artist’s conception of the Titan Aerial Daughtercraft on Saturn’s moon Titan. Credit: NASA*

The third sub-goal involves determining if these oceans have the necessary energy and prebiotic chemistry to support life. And the fourth and final goal would be to determine how life might exist in them – i.e. whether it takes the form of extremophile bacteria and tiny organisms, or more complex creatures. Hendrix and Hurford also covered the kind of technological advances that will be needed for such missions to happen.

Naturally, any such mission would require the development of power sources and energy storage systems that would be suitable for cryogenic environments. Autonomous systems for pinpoint landing and technologies for aerial or landed mobility would also be needed. Planetary protection technologies would be necessary to prevent contamination, and electronic/mechanical systems that can survive in an ocean world environment too,

While these presentations are merely proposals of what could happen in the coming decades, they are still exciting to hear about. If nothing else, they show how NASA and other space agencies are actively collaborating with scientific institutions around the world to push the boundaries of knowledge and exploration. And in the coming decades, they hope to make some substantial leaps.

If all goes well, and exploration missions to Europa and other icy moons are allowed to go forward, the benefits could be immeasurable. In addition to the possibility of finding life beyond Earth, we will come to learn a great deal about our Solar System, and no doubt learn something more about humanity’s place in the cosmos.

Further Reading: NASA, USRA, USRA (2)

December 22, 2016April 4, 2023 by Matt Williams

How Do We Settle on Saturn’s Moons?

A collage of Saturn (bottom left) and some of its moons: Titan, Enceladus, Dione, Rhea and Helene. Credit: NASA/JPL/Space Science Institute

Welcome back to our series on Settling the Solar System! Today, we take a look at the largest of Saturn’s Moons – Titan, Rhea, Iapetus, Dione, Tethys, Enceladus, and Mimas.

From the 17th century onward, astronomers made some profound discoveries around the planet Saturn, which they believed was the most distant planet of the Solar System at the time. Christiaan Huygens and Giovanni Domenico Cassini were the first, spotting the largest moons of Saturn – Titan, Tethys, Dione, Rhea and Iapetus. More discoveries followed; and today, what we recognized as the Saturn system includes 62 confirmed satellites.

What we know of this system has grown considerably in recent decades, thanks to missions like Voyager and Cassini. And with this knowledge has come multiple proposals that claim how Saturn’s moons should someday be colonized. In addition to boasting the only body other than Earth to have a dense, nitrogen-rich atmosphere, there are also abundant resources in this system that could be harnessed.

Much like the idea of colonizing the Moon, Mars, the moons of Jupiter, and other bodies in the Solar System, the idea of establishing colonies on Saturn’s moons has been explored extensively in science fiction. At the same time, scientific proposals have been made that emphasize how colonies would benefit humanity, allowing us to mount missions deeper into space and ushering in an age of abundance!

*A montage of images from Cassini of various moons and the rings around Saturn. Credit: NASA/JPL-Caltech/Space Science Institute*

Examples in Fiction:

The colonization of Saturn has been a recurring theme in science fiction over the decades. For example, in Arthur C. Clarke’s 1976 novel Imperial Earth, Titan is home to a human colony of 250,000 people. The colony plays a vital role in commerce, where hydrogen is taken from the atmosphere of Saturn and used as fuel for interplanetary travel.

In Piers Anthony’s Bio of a Space Tyrant series (1983-2001), Saturn’s moons have been colonized by various nations in a post-diaspora era. In this story, Titan has been colonized by the Japanese, whereas Saturn has been colonized by the Russians, Chinese, and other former Asian nations.

In the novel Titan (1997) by Stephen Baxter, the plot centers on a NASA mission to Titan which must struggle to survive after crash landing on the surface. In the first few chapters of Stanislaw Lem’s Fiasco (1986), a character ends up frozen on the surface of Titan, where they are stuck for several hundred years.

In Kim Stanley Robinson’s Mars Trilogy (1996), nitrogen from Titan is used in the terraforming of Mars. In his novel 2312 (2012), humanity has colonized several of Saturn’s moons, which includes Titan and Iapetus. Several references are made to the “Enceladian biota” in the story as well, which are microscopic alien organisms that some humans ingest because of their assumed medicinal value.

The moons of Saturn, from left to right: Mimas, Enceladus, Tethys, Dione, Rhea; Titan in the background; Iapetus (top) and irregularly shaped Hyperion (bottom). Some small moons are also shown. All to scale. Credit: NASA/JPL/Space Science Institute — The moons of Saturn, from left to right: Mimas, Enceladus, Tethys, Dione, Rhea; Titan in the background; Iapetus (top) and irregularly shaped Hyperion (bottom). Credit: NASA/JPL/Space Science Institute

As part of his Grand Tour Series, Ben Bova’s novels Saturn (2003) and Titan (2006) address the colonization of the Cronian system. In these stories, Titan is being explored by an artificially intelligent rover which mysteriously begins malfunctioning, while a mobile human Space Colony explores the Rings and other moons.

Proposed Methods:

In his book Entering Space: Creating a Spacefaring Civilization (1999), Robert Zubrin advocated colonizing the outer Solar System, a plan which included mining the atmospheres of the outer planets and establishing colonies on their moons. In addition to Uranus and Neptune, Saturn was designated as one of the largest sources of deuterium and helium-3, which could drive the pending fusion economy.

He further identified Saturn as being the most important and most valuable of the three, because of its relative proximity, low radiation, and excellent system of moons. Zubrin claimed that Titan is a prime candidate for colonization because it is the only moon in the Solar System to have a dense atmosphere and is rich in carbon-bearing compounds.

On March 9th, 2006, NASA’s Cassini space probe found possible evidence of liquid water on Enceladus, which was confirmed by NASA in 2014. According to data derived from the probe, this water emerges from jets around Enceladus’ southern pole, and is no more than tens of meters below the surface in certain locations. This would would make collecting water considerably easier than on a moon like Europa, where the ice sheet is several km thick.

Data obtained by Cassini also pointed towards the presence of volatile and organic molecules. And Enceladus also has a higher density than many of Saturn’s moons, which indicates that it has a larger average silicate core. All of these resources would prove very useful for the sake of constructing a colony and providing basic operations.

In October of 2012, Elon Musk unveiled his concept for an Mars Colonial Transporter (MCT), which was central to his long-term goal of colonizing Mars. At the time, Musk stated that the first unmanned flight of the Mars transport spacecraft would take place in 2022, followed by the first manned MCT mission departing in 2024.

In September 2016, during the 2016 International Astronautical Congress, Musk revealed further details of his plan, which included the design for an Interplanetary Transport System (ITS) and estimated costs. This system, which was originally intended to transport settlers to Mars, had evolved in its role to transport human beings to more distant locations in the Solar System – which could include the Jovian and Cronian moons.

Artist's rendering of possible hydrothermal activity that may be taking place on and under the seafloor of Enceladus. Image Credit: NASA/JPL — *Artist’s rendering of possible hydrothermal activity that may be taking place on and under the seafloor of Enceladus. Credit: NASA/JPL*

Potential Benefits:

Compared to other locations in the Solar System – like the Jovian system – Saturn’s largest moons are exposed to considerably less radiation. For instance, Jupiter’s moons of Io, Ganymede and Europa are all subject to intense radiation from Jupiter’s magnetic field – ranging from 3600 to 8 rems day. This amount of exposure would be fatal (or at least very hazardous) to human beings, requiring that significant countermeasures be in place.

In contrast, Saturn’s radiation belts are significantly weaker than Jupiter’s – with an equatorial field strength of 0.2 gauss (20 microtesla) compared to Jupiter’s 4.28 gauss (428 microtesla). This field extends from about 139,000 km from Saturn’s center out to a distance of about 362,000 km – compared to Jupiter’s, which extends to a distance of about 3 million km.

Of Saturn’s largest moons, Mimas and Enceladus fall within this belt, while Dione, Rhea, Titan, and Iapetus all have orbits that place them from just outside of Saturn’s radiation belts to well beyond it. Titan, for example, orbits Saturn at an average distance (semi-major axis) of 1,221,870 km, putting it safely beyond the reach of the gas giant’s energetic particles. And its thick atmosphere may be enough to shield residents from cosmic rays.

In addition, frozen volatiles and methane harvested from Saturn’s moons could be used for the sake of terraforming other locations in the Solar System. In the case of Mars, nitrogen, ammonia and methane have been suggested as a means of thickening the atmosphere and triggering a greenhouse effect to warm the planet. This would cause water ice and frozen CO² at the poles to sublimate – creating a self-sustaining process of ecological change.

Colonies on Saturn’s moons could also serve as bases for harvesting deuterium and helium-3 from Saturn’s atmosphere. The abundant sources of water ice on these moons could also be used to make rocket fuel, thus serving as stopover and refueling points. In this way, a colonizing the Saturn system could fuel Earth’s economy, and the facilitate exploration deeper into the outer Solar System.

Challenges:

Naturally, there are numerous challenges to colonizing Saturn’s moons. These include the distance involved, the necessary resources and infrastructure, and the natural hazards colonies on these moons would have to deal with. For starters, while Saturn may be abundant in resources and closer to Earth than either Uranus or Neptune, it is still very far.

On average, Saturn is approximately 1,429 billion km away from Earth; or ~8.5 AU, the equivalent of eight and a half times the average distance between the Earth and the Sun. To put that in perspective, it took the Voyager 1 probe roughly thirty-eight months to reach the Saturn system from Earth. For crewed spacecraft, carrying colonists and all the equipment needed to colonize the surface, it would take considerably longer to get there.

These ships, in order to avoid being overly large and expensive, would need to rely on cryogenics or hibernation-related technology in order to save room on storage and accommodations. While this sort of technology is being investigated for crewed missions to Mars, it is still very much in the research and development phase.

Artist's concept of a Bimodal Nuclear Thermal Rocket in Low Earth Orbit. Credit: NASA — Artist’s concept of a Bimodal Nuclear Thermal Rocket in Low Earth Orbit. Credit: NASA

Any vessels involved in the colonization efforts, or used to ship resources to and from the Cronian system, would also need to have advanced propulsion systems to ensure that they could make the trips in a realistic amount of time. Given the distances involved, this would likely require rockets that used nuclear-thermal propulsion, or something even more advanced (like anti-matter rockets).

And while the former is technically feasible, no such propulsion systems have been built just yet. Anything more advanced would require many more years of research and development, and a major commitment in resources. All of this, in turn, raises the crucial issue of infrastructure.

Basically, any fleet operating between Earth and Saturn would require a network of bases between here and there to keep them supplied and fueled. So really, any plans to colonize Saturn’s moons would have to wait upon the creation of permanent bases on the Moon, Mars, the Asteroid Belt, and most likely the Jovian moons. This process would be punitively expensive by current standards and (again) would require a fleet of ships with advanced drive systems.

And while radiation is not a major threat in the Cronian system (unlike around Jupiter), the moons have been subject to a great deal of impacts over the course of their history. As a result, any settlements built on the surface would likely need additional protection in orbit, like a string of defensive satellites that could redirect comets and asteroids before they reached orbit.

The huge storm churning through the atmosphere in Saturn's northern hemisphere overtakes itself as it encircles the planet in this true-color view from NASA’s Cassini spacecraft. Image credit: NASA/JPL-Caltech/SSI — The huge storm churning through the atmosphere in Saturn’s northern hemisphere overtakes itself as it encircles the planet in this true-color view from NASA’s Cassini spacecraft. Image credit: NASA/JPL-Caltech/SSI

Given its abundant resources, and the opportunities it would present for exploring deeper into the Solar System (and maybe even beyond), Saturn and its system of moons is nothing short of a major prize. On top of that, the prospect of colonizing there is a lot more appealing than other locations that come with greater hazards (i.e. Jupiter’s moons).

However, such an effort would be daunting and would require a massive multi-generational commitment. And any such effort would most likely have to wait upon the construction of colonies and/or bases in locations closer to Earth first – such as on the Moon, Mars, the Asteroid Belt, and around Jupiter. But we can certainly hold out hope for the long run, can’t we?

We have written many interesting articles on colonization here at Universe Today. Here’s Why Colonize the Moon First?, How Do We Colonize Mercury?, How Do We Colonize Venus?, Colonizing Venus with Floating Cities, Will We Ever Colonize Mars?, How Do We Colonize Jupiter’s Moons?, and The Definitive Guide to Terraforming.

Astronomy Cast also has many interesting episodes on the subject. Check out Episode 59: Saturn, Episode 61: Saturn’s Moons, Episode 95: Humans to Mars, Part 2 – Colonists, Episode 115: The Moon, Part 3 – Return to the Moon, and Episode 381: Hollowing Asteroids in Science Fiction.

Sources:

November 22, 2016November 22, 2016 by Fraser Cain

Is There Life on Mars?

Perhaps the most important question we can possible ask is, “are we alone in the Universe?”.

And so far, the answer has been, “I don’t know”. I mean, it’s a huge Universe, with hundreds of billions of stars in the Milky Way, and now we learn there are trillions of galaxies in the Universe.

Is there life closer to home? What about in the Solar System? There are a few existing places we could look for life close to home. Really any place in the Solar System where there’s liquid water. Wherever we find water on Earth, we find life, so it make sense to search for places with liquid water in the Solar System.

I know, I know, life could take all kinds of wonderful forms. Enlightened beings of pure energy, living among us right now. Or maybe space whales on Titan that swim through lakes of ammonia. Beep boop silicon robot lifeforms that calculate the wasted potential of our lives.

Sure, we could search for those things, and we will. Later. We haven’t even got this basic problem done yet. Earth water life? Check! Other water life? No idea.

It turns out, water’s everywhere in the Solar System. In comets and asteroids, on the icy moons of Jupiter and Saturn, especially Europa or Enceladus. Or you could look for life on Mars.

Sloping buttes and layered outcrops within the "Murray formation" layer of lower Mount Sharp. Credit: NASA — Sloping buttes and layered outcrops within the “Murray formation” layer of lower Mount Sharp. Credit: NASA

Mars is similar to Earth in many ways, however, it’s smaller, has less gravity, a thinner atmosphere. And unfortunately, it’s bone dry. There are vast polar caps of water ice, but they’re frozen solid. There appears to be briny liquid water underneath the surface, and it occasionally spurts out onto the surface. Because it’s close and relatively easy to explore, it’s been the place scientists have gone looking for past or current life.

Researchers tried to answer the question with NASA’s twin Viking Landers, which touched down in 1976. The landers were both equipped with three biology experiments. The researchers weren’t kidding around, they were going to nail this question: is there life on Mars?

In the first experiment, they took soil samples from Mars, mixed in a liquid solution with organic and inorganic compounds, and then measured what chemicals were released. In a second experiment, they put Earth organic compounds into Martian soil, and saw carbon dioxide released. In the third experiment, they heated Martian soil and saw organic material come out of the soil.

The landing site of Viking 1 on Mars in 1977, with trenches dug in the soil for the biology experiments. Credit: NASA/JPL

Three experiments, and stuff happened in all three. Stuff! Pretty exciting, right? Unfortunately, there were equally plausible non-biological explanations for each of the results. The astrobiology community wasn’t convinced, and they still fight in brutal cage matches to this day. It was ambitious, but inconclusive. The worst kind of conclusive.

Researchers found more inconclusive evidence in 1994. Ugh, there’s that word again. They were studying a meteorite that fell in Antarctica, but came from Mars, based on gas samples taken from inside the rock.

They thought they found evidence of fossilized bacterial life inside the meteorite. But again, there were too many explanations for how the life could have gotten in there from here on Earth. Life found a way… to burrow into a rock from Mars.

NASA learned a powerful lesson from this experience. If they were going to prove life on Mars, they had to go about it carefully and conclusively, building up evidence that had no controversy.

Greetings from Mars! I’m Spirit and I was the first of two twin robots to land on Mars. Unlike my twin, Opportunity, I’m known as the hill-climbing robot. Artist Concept, Mars Exploration Rovers. NASA/JPL-Caltech — Artist Concept, Mars Exploration Rovers. NASA/JPL-Caltech

The Spirit and Opportunity Rovers were an example of building up this case cautiously. They were sent to Mars in 2004 to find evidence of water. Not water today, but water in the ancient past. Old water Over the course of several years of exploration, both rovers turned up multiple lines of evidence there was water on the surface of Mars in the ancient past.

They found concretions, tiny pebbles containing iron-rich hematite that forms on Earth in water. They found the mineral gypsum; again, something that’s deposited by water on Earth.

Opportunity's Approach to 'Homestake'. This view from the front hazard-avoidance camera on NASA's Mars Exploration Rover Opportunity shows the rover's arm's shadow falling near a bright mineral vein informally named Homestake. The vein is about the width of a thumb and about 18 inches (45 centimeters) long. Opportunity examined it in November 2011 and found it to be rich in calcium and sulfur, possibly the calcium-sulfate mineral gypsum. Opportunity took this image on Sol 2763 on Mars (Nov. 7, 2011). Credit: NASA/JPL-Caltech — A bright mineral vein informally named Homestake. The vein is about the width of a thumb and about 18 inches (45 centimeters) long. Opportunity examined it in November 2011 (Sol 2763) and found it to be rich in calcium and sulfur, possibly the calcium-sulfate mineral gypsum. Credit: NASA/JPL-Caltech

NASA’s Curiosity Rover took this analysis to the next level, arriving in 2012 and searching for evidence that water was on Mars for vast periods of time; long enough for Martian life to evolve.

Once again, Curiosity found multiple lines of evidence that water acted on the surface of Mars. It found an ancient streambed near its landing site, and drilled into rock that showed the region was habitable for long periods of time.

In 2014, NASA turned the focus of its rovers from looking for evidence of water to searching for past evidence of life.

Curiosity found one of the most interesting targets: a strange strange rock formations while it was passing through an ancient riverbed on Mars. While it was examining the Gillespie Lake outcrop in Yellowknife Bay, it photographed sedimentary rock that looks very similar to deposits we see here on Earth. They’re caused by the fossilized mats of bacteria colonies that lived billions of years ago.

A bright and interestingly shaped tiny pebble shows up among the soil on a rock, called "Gillespie Lake," which was imaged by Curiosity's Mars Hand Lens Imager on Dec. 19, 2012, the 132nd sol, or Martian day of Curiosity's mission on Mars. Credit: NASA / JPL-Caltech / MSSS. — A bright and interestingly shaped tiny pebble shows up among the soil on a rock, called “Gillespie Lake,” which was imaged by Curiosity’s Mars Hand Lens Imager on Dec. 19, 2012, the 132nd sol, or Martian day of Curiosity’s mission on Mars. Credit: NASA / JPL-Caltech / MSSS.

Not life today, but life when Mars was warmer and wetter. Still, fossilized life on Mars is better than no life at all. But there might still be life on Mars, right now, today. The best evidence is not on its surface, but in its atmosphere. Several spacecraft have detected trace amounts of methane in the Martian atmosphere.

Methane is a chemical that breaks down quickly in sunlight. If you farted on Mars, the methane from your farts would dissipate in a few hundred years. If spacecraft have detected this methane in the atmosphere, that means there’s some source replenishing those sneaky squeakers. It could be volcanic activity, but it might also be life. There could be microbes hanging on, in the last few places with liquid water, producing methane as a byproduct.

The European ExoMars orbiter just arrived at Mars, and its main job is sniff the Martian atmosphere and get to the bottom of this question.

Are there trace elements mixed in with the methane that means its volcanic in origin? Or did life create it? And if there’s life, where is it located? ExoMars should help us target a location for future study.

The European/Russian ExoMars Trace Gas Orbiter (TGO) will launch in 2016 and sniff the Martian atmosphere for signs of methane which could originate for either biological or geological mechanisms. Credit: ESA — The European/Russian ExoMars Trace Gas Orbiter (TGO) will sniff the Martian atmosphere for signs of methane which could originate for either biological or geological mechanisms. Credit: ESA

NASA is following up Curiosity with a twin rover designed to search for life. The Mars 2020 Rover will be a mobile astrobiology laboratory, capable of scooping up material from the surface of Mars and digesting it, scientifically speaking. It’ll search for the chemicals and structures produced by past life on Mars. It’ll also collect samples for a future sample return mission.

Even if we do discover if there’s life on Mars, it’s entirely possible that we and Martian life are actually related by a common ancestor, that split off billions of years ago. In fact, some astrobiologists think that Mars is a better place for life to have gotten started.

Not the dry husk of a Red Planet that we know today, but a much wetter, warmer version that we now know existed billions of years ago. When the surface of Mars was warm enough for liquid water to form oceans, lakes and rivers. And we now know it was like this for millions of years.

A conception of an ancient and/or future Mars, flush with oceans, clouds and life. Credit: Kevin Gill. — A conception of an ancient Mars, flush with oceans, clouds and life. Credit: Kevin Gill.

While Earth was still reeling from an early impact by the massive planet that crashed into it, forming the Moon, life on Mars could have gotten started early.

But how could we actually be related? The idea of Panspermia says that life could travel naturally from world to world in the Solar System, purely through the asteroid strikes that were regularly pounding everything in the early days.

Imagine an asteroid smashing into a world like Mars. In the lower gravity of Mars, debris from the impact could be launched into an escape trajectory, free to travel through the Solar System.

We know that bacteria can survive almost indefinitely, freeze dried, and protected from radiation within chunks of space rock. So it’s possible they could make the journey from Mars to Earth, crossing the orbit of our planet.

Even more amazingly, the meteorites that enter the Earth’s atmosphere would protect some of the bacterial inhabitants inside. As the Earth’s atmosphere is thick enough to slow down the descent of the space rocks, the tiny bacterialnauts could survive the entire journey from Mars, through space, to Earth.

In February 2013, asteroid DA 2014 safely passed by the Earth. There are several proposals abounding about bringing asteroids closer to our planet to better examine their structure. Credit: NASA/JPL-Caltech — Credit: NASA/JPL-Caltech

If we do find life on Mars, how will we know it’s actually related to us? If Martian life has the similar DNA structure to Earth life, it’s probably related. In fact, we could probably trace the life back to determine the common ancestor, and even figure out when the tiny lifeforms make the journey.

If we do find life on Mars, which is related to us, that just means that life got around the Solar System. It doesn’t help us answer the bigger question about whether there’s life in the larger Universe. In fact, until we actually get a probe out to nearby stars, or receive signals from them, we might never know.

An even more amazing possibility is that it’s not related. That life on Mars arose completely independently. One clue that scientists will be looking for is the way the Martian life’s instructions are encoded. Here on Earth, all life follows “left-handed chirality” for the amino acid building blocks that make up DNA and RNA. But if right-handed amino acids are being used by Martian life, that would mean a completely independent origin of life.

Of course, if the life doesn’t use amino acids or DNA at all, then all bets are off. It’ll be truly alien, using a chemistry that we don’t understand at all.

There are many who believe that Mars isn’t the best place in the Solar System to search for life, that there are other places, like Europa or Enceladus, where there’s a vast amount of liquid water to be explored.

But Mars is close, it’s got a surface you can land on. We know there’s liquid water beneath the surface, and there was water there for a long time in the past. We’ve got the rovers, orbiters and landers on the planet and in the works to get to the bottom of this question. It’s an exciting time to be part of this search.