Titan’s Lakes and the Drive to Explore

by Paul Gilster on June 15, 2012

What is it that makes us want the stars? Surely there are philosophical reasons that push us into the universe, and in his book Quest: The Essence of Humanity (2004), Charles Pasternak delves into ‘questing’ as a drive embedded in the species. But alongside a need to explore I can see two other drivers. One is the urge to know whether life exists elsewhere, and ultimately, whether there are other technological civilizations somewhere in the galaxy. The other is simple survival: We need to move into the universe as a backup plan in case of disaster here on Earth, whether that disaster is caused by an asteroid or a human activity gone awry.

This morning I’m musing on all this in the context of recent news from the outer Solar System, where the data we’re analyzing from the Cassini mission are matched only by our desire to have still further, more targeted explorations. We learn, for example, that Titan has lakes around its equator. Lakes on Titan aren’t a surprise: We’ve already known about lakes of methane and ethane like Ligeia Mare near the moon’s poles. But now we have evidence of a 2400 square kilometer body of liquid with a depth of a meter or more in Titan’s lower latitudes, down in the moon’s ‘tropics,’ where it was thought nothing but sand dunes were likely to be found.

Image: Saturn’s rings lie in the distance as the Cassini spacecraft looks toward Titan and its dark region called Shangri-La, east of the landing site of the Huygens Probe. Credit: NASA/JPL-Caltech/Space Science Institute.

This is a world that gets more interesting all the time. Titan draws our attention not only because of its thick atmosphere — which, coupled with low gravity, makes landing on it a straightforward affair — but also because its methane replaces water in Earth’s hydrological cycle to make it the only other place in the Solar System known to support liquid lakes. The newly found lakes, detected by Cassini’s visual and infrared mapping spectrometer, are found in the area called Shangri-La, not far from where the Huygens probe touched down in 2005. I hadn’t realized a point this NASA news release makes, that when Huygens landed, the heat of its lamp vaporized methane from the ground, an indication that the probe landed in a relatively damp area.

This week’s Nature has the paper, which reports not only on the larger lake but on small, evidently shallow ponds in the same region that can be likened to marshes on Earth, perhaps no more than ankle-deep. Current thinking on Titan’s global circulation had led us to believe that liquid methane in the equatorial regions would quickly evaporate and be carried by the winds to the poles, where it would condense to form the polar lakes, leaving the tropical regions arid. That model would suggest that the tropical lakes are being produced by an underground methane source that floods the surface, forming a kind of oasis.

Caitlin Griffith (University of Arizona) is lead author on the paper:

“An aquifer could explain one of the puzzling questions about the existence of methane, which is continually depleted. Methane is a progenitor of Titan’s organic chemistry, which likely produces interesting molecules like amino acids, the building blocks of life.”

The theory of an underground aquifer is also supported by the fact that rain has been detected falling in the equatorial regions only once, leading the researchers to believe the lakes are not being replenished by rain. Thus we are building the case for an active subsurface hydrology on the frigid moon as liquid hydrocarbons emerge on the surface to supply methane. The former image of equatorial Titan as a place of nothing more than sand dunes has to be reconsidered. Titan thus builds its reputation as a place of intriguing chemistry on which we’d like to spend some time, perhaps through an airborne probe like AVIATr or the floating Titan Mare Explorer.

Meanwhile, Cassini continues to return interesting information about another world of astrobiological interest, Enceladus. The latest is the observation of so-called ‘dusty plasma’ near the plumes spreading out from the moon’s south polar region. Saturn’s plasma environment is a lively one as Enceladus continues to spew ionized material into the planet’s magnetic field. About 100 kilograms of water vapor per second are known to be blowing out of the so-called ‘tiger stripes’ that mark the cracked surface of the south pole here. The plume is quickly converted into charged particles interacting with the plasma in Saturn’s magnetosphere.

‘Dusty plasma’ is filled with charged dust. Here, the dust behaves as part of the plasma cloud, differentiating it from dust that simply happens to be in the plasma at the time. Lead author Michiko Morooka (Swedish Institute of Space Physics) thinks the observation is a first:

“Such strong coupling indicates the possible presence of so-called ‘dusty plasma’, rather than the ‘dust in a plasma’ conditions which are common in interplanetary space. Except for measurements in Earth’s upper atmosphere, there have previously been no in-situ observations of dusty plasma in space.”

The work follows up on studies by Sven Simon (University of Cologne) and Hendrik Kriegel (University of Braunschweig) — reported in this JPL news release — that showed negatively charged dust grains had to be in the plume to account for the observed perturbation of Saturn’s magnetic field. The plume itself, known to contain water vapor, ice particles and organic molecules, presumably flags the presence of a subsurface ocean in which the basic ingredients for life to get a start may well be present. Mission concepts like the Enceladus Explorer, from the German Aerospace Center, would use a drilling probe to reach the liquid water reservoir.

The question of life in the universe is deeply stirring and compels us to search nearby worlds to learn whether life could have evolved under dramatically different conditions than here on Earth. Ultimately, our SETI efforts are directed toward slaking the same thirst for knowledge as we try to find out whether intelligence — or at least technological savvy — is common or a rare feature of the universe. Missions are always at the mercy of available resources and budgetary constraints, but the long-term forces of curiosity and survival compel us out into the system. Timetables are useless, but it’s hard to see these drivers being ignored by future generations.

The Titan paper is Griffith et al., “Possible tropical lakes on Titan from observations of dark terrain,” Nature 486 (14 June 2012), pp. 237–239 (abstract). On the Enceladus plasma work, see Morooka et al., “Dusty plasma in the vicinity of Enceladus,” Journal of Geophysical Research (Space Physics), Vol. 116 (2011), A12221 (abstract).

tzf_img_post

Tony D June 15, 2012 at 13:42

Any chance Titan becomes habitable, more Earthlike, when the Sun becomes a Red Giant? Thanks.

Joy June 15, 2012 at 19:07

@Tony D
Sorry, when Sol becomes a red giant and Titan warms, possibly towards temperatures humans would find comfortable, the atmosphere would be lost. Titan does not have enough gravity to retain a dense atmosphere at liquid water temperatures.

Tom June 15, 2012 at 19:52

It would be interesting if there was a way to build a space elevator on Titan?
With all the ice in Saturn’s rings and hydrocarbons abundantly available on Titan, you can set up a sophisticated refinery. Though I would go with a thorium reactor for powering these kind of facilities. everything from liquefied oxygen to synthetic fertilizers. I think you can get plastics out of that raw material? Even genetically modified microbe or algies to process more exotic mixes? Maybe ship this stuff to Earth, But it might be more practical to ‘capture’ a comet and tow it to L2?

Adam Crowl June 15, 2012 at 21:59

TonyD
Contrary to the negative answer you received, as the Sun climbs to Red-Giant there will be a time when it is warm enough to sustain an ocean of ammonia-water, without the atmosphere leaking away en masse into space. However the time period lasts mere millions of years, then all the former ice moons will face the full luminosity of the Sun’s Red Giant Tip and heavy solar wind before the 100 million year respite of the Helium Main Sequence. Titan will be as hot as Mercury for a million years while the Sun belches forth about a third of its mass, so whether anything will remain of its surface ices is an open question. A Moon-sized ball of hydrated silicates might remain. Likewise the Galilean moons. But nothing will remain of what they were before that billennial heat-bath.

jkittle June 16, 2012 at 13:26

dusty plasmas! what a concept. these might be fashioned from nanoparticles and might contain, for example, dehydrated microbes! ( if the enceladus has life in its under ice oceans)

Rob Henry June 16, 2012 at 18:32

Tom,
The faster a world spins, the easier it is to build a space elevator from. calculating the needed elevator tensile strength and exact necessary cable length takes slightly too much time for offhand, and proof of concept calculations – but calculating the stationary point that is (in some respects) the centre of the elevator, is easy. Here this coincides with L2, which is 52,000 km, compared to 36,000 km for Earth. Considering that the gravity is much lower here also, perhaps your concept might work – but it doesn‘t sound way easier than Earth, as if the case for Mars (and even more so for Ceres).

Michael Simmons June 17, 2012 at 23:20

I think that one of the requirements for the development of higher life forms is a diverse and complex weather system.
This discovery reenforces the need to investigate Titan in much greater detail.
Sending something like the Mars Science Laboratory to Titan would a return a vastly amount of new knowledge. Much more than anything any further probes to Mars would return.
Even if this didn’t find some form of life, it would give us greater insight into a totally alien weather system.

James Jason Wentworth June 18, 2012 at 0:35

Since frozen methane sinks in liquid methane (and I believe this is also the case for ethane), the floors of the Titanian lakes and ponds might be very thick layers of frozen methane and ethane. If so, might that mean that the liquid hydrocarbons are upwelling from below at considerable pressure in a manner somewhat analogous to magma or geyser steam on Earth, or (perhaps in the case of the shallow ponds) that the liquids flow gently upward through cracks in the ice (maybe via capillary action?). In any event, finding out how these substances–which are gases under normal circumstances on Earth–behave as part of Titan’s “hydrosphere” and “lithosphere” will be as fascinating as discovering how frozen carbon dioxide (along with water) snow and ice shape the landscapes of Mars.

ljk June 18, 2012 at 13:54

Titan, along with the rest of the Sol system, will have been used for building material for the Dyson Swarm long before our star starts going red giant.

Of course our distant descendants could build an exact duplicate of the Sol system for nostalgia purposes, some really rich guy, etc., thus we may still have a Titan and can see if it will indeed become nicer to life in that far epoch.

Ken_Space June 20, 2012 at 11:00

ljk, wdn’t there be no point in building a duplicate Sol system, when we cd have a hologram of it instead?

But I’d like to go off on a different tangent: I’m disappointed that lakes on Titan are called “Mare” like lunar ones. There are loads of Mares – sorry, “Maria” – on the Moon, so for other bodies a new name wd help (“Timaria” for Titan? or just a general 1 for anywhere other than the Moon), esp. since the lunar ones aren’t even real lakes!

HughP June 23, 2012 at 22:53

On Earth, temperatures rise as an observer descends. On Titan, how far down would a robotic observer have to go to find liquid water?

ljk July 3, 2012 at 9:07

Titan’s Tides Suggest a Subsurface Sea

by Jason Major on June 28, 2012

Saturn’s hazy Titan is now on the short list of moons that likely harbor a subsurface ocean of water, based on new findings from NASA’s Cassini spacecraft.

As Titan travels around Saturn during its 16-day elliptical orbits, it gets rhythmically squeezed by the gravitational pull of the giant planet — an effect known as tidal flexing (see video below.)

If the moon were mostly composed of rock, the flexing would be in the neighborhood of around 3 feet (1 meter.) But based on measurements taken by the Cassini spacecraft, which has been orbiting Saturn since 2004, Titan exhibits much more intense flexing — ten times more, in fact, as much as 30 feet (10 meters) — indicating that it’s not entirely solid at all.

Instead, Cassini scientists estimate that there’s a moon-wide ocean of liquid water beneath the frozen crust of Titan, possibly sandwiched between layers of ice or rock.

“Short of being able to drill on Titan’s surface, the gravity measurements provide the best data we have of Titan’s internal structure.”

– Sami Asmar, Cassini team member at JPL

“Cassini’s detection of large tides on Titan leads to the almost inescapable conclusion that there is a hidden ocean at depth,” said Luciano Iess, the paper’s lead author and a Cassini team member at the Sapienza University of Rome, Italy. “The search for water is an important goal in solar system exploration, and now we’ve spotted another place where it is abundant.”

Full article here:

http://www.universetoday.com/96027/titans-tides-suggest-a-subsurface-sea/

ljk September 27, 2012 at 14:23

27 September 2012

** Contacts are listed below. **

Text & Images:

http://www.europlanet-eu.org/outreach/index.php?option=com_content&task=view&id=391&Itemid=41

NAVIGATING THE SEAS OF TITAN

Humanity has landed a rover on Mars. Now, say scientists, it’s time to land a boat on Titan. This outlandish scenario could become reality, according to engineers presenting their proposals at the European Planetary Science Congress on 27 September.

Titan, Saturn’s largest moon, is one of the most Earth-like bodies in the solar system. With a thick atmosphere, a diameter between that of Earth and the planet Mercury, and a network of seas, lakes and rivers, it is in many respects more like a planet than a moon like the Earth’s.

The Cassini-Huygens mission, which studied Titan extensively in the 2000s, confirmed that lakes, seas and rivers of liquid hydrocarbons (similar to household gas) exist, covering much of the satellite’s northern hemisphere. Although it eventually landed on solid ground, the Huygens lander was designed to be able to float for a short period.

The new plans, called the Titan Lake In-situ Sampling Propelled Explorer, proposes a boat-probe, propelled by wheels, paddles or screws. The probe would land in the middle of Ligeia Mare (the biggest lake, near Titan’s north pole), then set sail for the coast, taking scientific measurements along the way. The mission would last around six months to a year.

“The main innovation in TALISE is the propulsion system,” says Igone Urdampilleta (SENER), a member of the TALISE team. “This allows the probe to move, under control, from the landing site in the lake, to the closest shore. The displacement capability would achieve the obtaining of liquid and solid samples from several scientific interesting locations on Titan’s surface such as the landing place, along the route towards the shore and finally at the shoreline.”

Titan’s environment is too cold for life as we know it, but its environment, rich in the building blocks of life, is of great interest to astrobiologists. The satellite’s atmosphere is made up largely of nitrogen (like Earth’s), is rich in organic compounds and hydrogen cyanide, which may have played a role in the emergence of life on Earth.

The TALISE concept is being developed as a partnership between SENER and the Centro de Astrobiologï¿œa in Madrid, Spain. This mission concept is the result of a ‘Phase 0′ study. In the following phases the feasibility study and a preliminary mission architecture would be realized to consolidate a possible technical proposal for future space science mission call.

Press Contacts:

Anita Heward
EPSC 2012 Press Officer
+44 7756 034243
anita.heward@europlanet-eu.org

Oliver Usher
EPSC 2012 Press Officer
+44 7754 130109
o.j.usher@gmail.com

EPSC Press office (24-28 September only)
+34 91 722 3020, +34 91 722 3021
Fax: +34 91 722 3022

Science Contact:

Igone Urdampilleta
igone.urdampilleta@sener.es
+34 918078782, cell: +34 663549738
(Dr. Urdampilleta will be at the conference only on 27 Sept.)

Images

http://www.europlanet-eu.org/outreach/images/stories/epsc2012/talise_3.jpg

Wheeled concept for TALISE probe

This rendering of the proposed TALISE probe shows one possible means of propulsion: wheels on either side of the probe.
Credit: SENER

http://www.europlanet-eu.org/outreach/images/stories/epsc2012/talise_2.jpg

Screw concept for TALISE probe
This rendering of the proposed TALISE probe shows one possible means of propulsion: screws on either side of the probe.
Credit: SENER

http://www.europlanet-eu.org/outreach/images/stories/epsc2012/talise_1.jpg

Paddle concept for TALISE probe
This rendering of the proposed TALISE probe shows one possible means of propulsion: paddle wheels on either side of the probe.
Credit: SENER

SENER

SENER is a private engineering and technology group founded in 1956, which seeks to offer its clients the most advanced technological solutions and which enjoys international recognition, thanks to its independence and its commitment to innovation and quality. SENER has a workforce of more than 5,200 professionals and a turnover of ᅵ1.16 billion (2011 figures). SENER engages in the specific activities of Engineering and Construction, and also has industrial holdings in companies involved in Energy and Environment, as well as in Aeronautics.

European Planetary Science Congress 2012

The European Planetary Science Congress (EPSC) is the major European meeting on planetary science and attracts scientists from Europe and around the World. The 2012 program includes more than 50 sessions and workshops. The EPSC has a distinctively interactive style, with a mix of talks, workshops and posters, intended to provide a stimulating environment for discussion. This year’s meeting will take place at the IFEMA-Feria de Madrid, Spain, from Sunday 23 September to Friday 28 September 2012. EPSC 2012 is organized by Europlanet, a Research Infrastructure funded under the European Commission’s Framework 7 Program, in association with the European Geosciences Union, with the support of the Centro de Astrobiologï¿œa of Spain’s Instituto Nacional de Tï¿œcnica Aeroespacial (CAB-INTA). Details of the Congress and a full schedule of EPSC 2012 scientific sessions and events can be found at the official website:

http://www.epsc2012.eu/

Europlanet

The Europlanet Research Infrastructure is a major (ᅵ6 million) program co-funded by the European Union under the Seventh Framework Program of the European Commission.

The Europlanet Research Infrastructure brings together the European planetary science community through a range of Networking Activities, aimed at fostering a culture of cooperation in the field of planetary sciences, Transnational Access Activities, providing European researchers with access to a range of laboratory and field site facilities tailored to the needs of planetary research, as well as on-line access to the available planetary science data, information and software tools, through the Integrated and Distributed Information Service. These programs are underpinned by Joint Research Activities, which are developing and improving the facilities, models, software tools and services offered by Europlanet RI.

Europlanet Project website:
http://www.europlanet-ri.eu/

Europlanet Outreach website:
http://www.europlanet-eu.org/outreach

Follow #epsc2012 @europlanetmedia on Twitter

Comments on this entry are closed.

{ 1 trackback }