Titan Mare Explorer

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Titan Mare Explorer
Artist's impression of TiME lake lander
Mission typeTitan lander
Operator NASA
Mission duration7.5 years
Cruise: 7 years;
3–6 months at Titan
Spacecraft properties
Dry mass700 kg ("representative value" landed mass) [2]
Power140 W
Start of mission
Launch date2016 (proposed) [3] [4] [5]
Not taken beyond proposal
Rocket Atlas V 411
Launch site Cape Canaveral SLC-41
Contractor United Launch Alliance

Titan Mare Explorer (TiME) is a proposed design for a lander for Saturn's moon Titan. [3] TiME is a relatively low-cost, outer-planet mission designed to measure the organic constituents on Titan and would have performed the first nautical exploration of an extraterrestrial sea, analyze its nature and, possibly, observe its shoreline. As a Discovery-class mission it was designed to be cost-capped at US$425 million, not counting launch vehicle funding. [4] It was proposed to NASA in 2009 by Proxemy Research as a scout-like pioneering mission, originally as part of NASA's Discovery Program. [6] The TiME mission design reached the finalist stage during that Discovery mission selection, but was not selected, and despite attempts in the U.S. Senate failed to get earmark funding in 2013. [7] A related Titan Submarine has also been proposed. [8] [9]


Discovery-class finalist

TiME was one of three Discovery Mission finalists that received US$3 million in May 2011 to develop a detailed concept study. The other two missions were InSight and Comet Hopper. After a review in mid-2012, NASA announced in August 2012 the selection of the InSight mission to Mars. [10]

Specifically, with launch specified prior to the end of 2025, TiME's arrival would have been in the mid-2030s, during northern winter. This means the seas, near Titan's north pole, are in darkness and direct-to-Earth communication is impossible. [11]

Missions to land in Titan's lakes or seas were also considered by the Solar System Decadal Survey. Additionally, the flagship Titan Saturn System Mission, which was proposed in 2009 for launch in the 2020s, included a short-lived battery-powered lake lander. [6] [12] Opportunities for launch are transient; the next opportunity is in 2023–2024, the last chance in this generation. [13]


The discovery on July 22, 2006, of lakes and seas in Titan's northern hemisphere confirmed the hypothesis that liquid hydrocarbons exist on it. [14] In addition, previous observations of southern polar storms and new observations of storms in the equatorial region provide evidence of active methane-generating processes, possibly cryovolcanic features from the interior of Titan. [12]

Most of Titan goes centuries without seeing any rain, but precipitation is expected to be much more frequent at the poles. [1]

It is thought that Titan's methane cycle is analogous to Earth's hydrologic cycle, with meteorological working fluid existing as rain, clouds, rivers and lakes. [14] TiME would directly discern the methane cycle of Titan and help understand its similarities and differences to the hydrologic cycle on Earth. [1] [12] If NASA had selected TiME, Ellen Stofan—a member of the Cassini radar team and the current Chief Scientist of NASA—would lead the mission as principal investigator, whereas the Applied Physics Laboratory (APL) would manage the mission. [15] Lockheed Martin would build the TiME capsule, with scientific instruments provided by APL, Goddard Space Flight Center and Malin Space Science Systems.


Comparison of Ligeia's size (left) with Lake Superior on Earth (right) PIA09184 -Titan Sea and Lake Superior.jpg
Comparison of Ligeia's size (left) with Lake Superior on Earth (right)

TiME's launch would have been with an Atlas V 411 rocket during 2016 and arriving to Titan in 2023. The target lake is Ligeia Mare (78°N, 250°W). [1] It is one of the largest lakes of Titan identified to date, with a surface area of about ~100,000 km2. The backup target is Kraken Mare. [3] [12]

Science objectives

The Titan Mare Explorer would undergo a 7-year simple interplanetary cruise with no flyby science. Some science measurements would be made during entry and descent, but data transmissions would begin only after splashdown. The science objectives of the mission are: [3] [12]

  1. Determine the chemistry of a Titan sea. Instruments: Mass Spectrometer (MS), Meteorology and Physical Properties Package (MP3).
  2. Determine the depth of a Titan sea. Instrument: Meteorology and Physical Properties Package (Sonar) (MP3).
  3. Constrain marine processes on Titan. Instrument: Meteorology and Physical Properties Package (MP3), Descent and surface cameras.
  4. Determine how the local meteorology over the sea varies on diurnal timescales. Instrument: Meteorology and Physical Properties Package (MP3), cameras.
  5. Characterize the atmosphere above the sea. Instrument: Meteorology and Physical Properties Package (MP3), cameras.

Malin Space Science Systems, which builds and operates camera systems for spacecraft, signed an early development contract with NASA to conduct preliminary design studies. [16] There would be two cameras. One would take pictures during the descent to the surface of Ligeia Mare, and the other would take pictures after landing. [16]

A Meteorology and Physical Properties Package (MP3) [17] would be built by the Applied Physics Laboratory. This instrument package would measure wind speed and direction, methane humidity, pressure and temperature above the 'waterline', and turbidity, sea temperature, speed of sound and dielectric properties below the surface. A sonar would measure the sea depth. Acoustic propagation simulations were performed and sonar transducers were tested at liquid-nitrogen temperatures to characterize their performance at Titan conditions. [18]

Power source

Titan in front of Dione and Saturn Ringside with Titan and Dione.jpg
Titan in front of Dione and Saturn

Titan's thick atmosphere and the weak sunlight at Titan's distance from the Sun rules out the use of solar panels. [19] [20] Had it been selected by NASA, the TiME lander would have been the test flight of the Advanced Stirling Radioisotope Generator (ASRG), [6] which is a prototype meant to provide availability of long-lived power supplies for landed networks and other planetary missions. For this mission, it would be used in two environments: deep space and non-terrestrial atmosphere. The ASRG is a radioisotope power system using Stirling power conversion technology and is expected to generate 140–160 W of electrical power; that is four times more efficient than RTGs currently in use. Its mass is 28 kg and will have a nominal lifetime of 14 years. [3] Though it continues ASRG research, [21] NASA has since cancelled the Lockheed contract that would have readied an ASRG for a 2016 launch, and has decided to rely on existing MMRTG radioisotope power systems for long-range probes. [22] [23]


The capsule would not need propulsion: the wind and possible tidal currents are expected to push this buoyant craft around the sea for months. [5]


The vehicle would have communicated directly with Earth and, in principle, it could be possible to maintain intermittent contact for several years after arrival: Earth finally goes below the horizon as seen from Ligeia in 2026. [24] It will not have a line of sight to Earth to beam back more data until 2035. [25]

Surface conditions

Huygens surface color.jpg
Huygens view of Titan's surface
Huygens surface color sr.jpg
Same with different data processing

Models suggested that waves on Ligeia Mare do not normally exceed 0.2 meters (0.66 ft) during the intended season of the TiME mission and occasionally might reach just over 0.5 meters (1.6 ft) in the course of a few months. [26] Simulations were performed to evaluate the capsule's response to the waves and possible beaching on the shore. [27] The capsule is expected to drift on the surface of the sea at 0.1 m/s, pushed by currents and wind with typical speeds of 0.5 m/s, and not exceeding 1.3 m/s (4.2 feet/second). [24] The probe would not be equipped with propulsion, and while its motion cannot be controlled, knowledge of its successive locations could be used to optimize scientific return, such as lake depth, temperature variations and shore imaging. Some proposed location techniques are measurement of Doppler shift, Sun height measurement, and Very Long Baseline Interferometry. [24]

Potential habitability

The chance to discover a form of life with a different biochemistry than Earth has led some researchers to consider Titan the most important world on which to search for extraterrestrial life. [28] A few scientists hypothesize that if the hydrocarbon chemistry on Titan crossed the threshold from inanimate matter to some form of life, it would be difficult to detect. [28] Moreover, because Titan is so cold, the amount of energy available for building complex biochemical structures is limited, and any water-based life would freeze without a heat source. [28] However, some scientists have suggested that hypothetical life forms may be able to exist in a methane-based solvent. [29] [30] Ellen Stofan, TiME's Principal Investigator, thinks that life as we know it is not viable in Titan's seas, but stated that "there will be chemistry in the seas that may give us insight into how organic systems progress toward life." [31]

Similar mission concepts

Further reading

See also

Related Research Articles

<span class="mw-page-title-main">Titan (moon)</span> Titan is the largest moon of Saturn and second largest moon in our solar system

Titan is the largest Moon of Saturn and the second-largest moon in our Solar System, larger than any of the dwarf planets of the Solar System. It is the only moon known to have a dense atmosphere, and is the only known object in space other than Earth on which clear evidence of stable bodies of surface liquid has been found.

<span class="mw-page-title-main">Colonization of Titan</span> Proposed concepts for the human colonization of Titan

Saturn's largest moon Titan is one of several candidates for possible future colonization of the outer Solar System, though protection against extreme cold is a major consideration.

<span class="mw-page-title-main">Exploration of Saturn</span> Overview of the exploration of Saturn

The exploration of Saturn has been solely performed by crewless probes. Three missions were flybys, which formed an extended foundation of knowledge about the system. The Cassini–Huygens spacecraft, launched in 1997, was in orbit from 2004 to 2017.

<span class="mw-page-title-main">Life on Titan</span> Scientific assessments on the microbial habitability of Titan

Whether there is life on Titan, the largest moon of Saturn, is currently an open question and a topic of scientific assessment and research. Titan is far colder than Earth, but of all the places in the Solar System, Titan is the only place besides Earth known to have liquids in the form of rivers, lakes, and seas on its surface. Its thick atmosphere is chemically active and rich in carbon compounds. On the surface there are small and large bodies of both liquid methane and ethane, and it is likely that there is a layer of liquid water under its ice shell. Some scientists speculate that these liquid mixes may provide prebiotic chemistry for living cells different from those on Earth.

<span class="mw-page-title-main">Atmosphere of Titan</span> Only thick atmosphere of any moon in the Solar System

The atmosphere of Titan is the dense layer of gases surrounding Titan, the largest moon of Saturn. It is the only thick atmosphere of a natural satellite in the Solar System. Titan's lower atmosphere is primarily composed of nitrogen (94.2%), methane (5.65%), and hydrogen (0.099%). There are trace amounts of other hydrocarbons, such as ethane, diacetylene, methylacetylene, acetylene, propane, PAHs and of other gases, such as cyanoacetylene, hydrogen cyanide, carbon dioxide, carbon monoxide, cyanogen, acetonitrile, argon and helium. The isotopic study of nitrogen isotopes ratio also suggests acetonitrile may be present in quantities exceeding hydrogen cyanide and cyanoacetylene. The surface pressure is about 50% higher than on Earth at 1.5 bars which is near the triple point of methane and allows there to be gaseous methane in the atmosphere and liquid methane on the surface. The orange color as seen from space is produced by other more complex chemicals in small quantities, possibly tholins, tar-like organic precipitates.

<span class="mw-page-title-main">Advanced Stirling radioisotope generator</span>

The advanced Stirling radioisotope generator (ASRG) is a radioisotope power system first developed at NASA's Glenn Research Center. It uses a Stirling power conversion technology to convert radioactive-decay heat into electricity for use on spacecraft. The energy conversion process used by an ASRG is significantly more efficient than previous radioisotope systems, using one quarter of the plutonium-238 to produce the same amount of power.

<span class="mw-page-title-main">Lakes of Titan</span> Hydrocarbon lakes on Titan, a moon of Saturn

Lakes of ethane and methane on Titan, Saturn's largest moon, have been detected by the Cassini–Huygens space probe, and had been suspected long before. The large ones are known as maria (seas) and the small ones as lacūs (lakes).

<span class="mw-page-title-main">Climate of Titan</span> Climate of Titan, the largest moon of Saturn

The climate of Titan, the largest moon of Saturn, is similar in many respects to that of Earth, despite having a far lower surface temperature. Its thick atmosphere, methane rain, and possible cryovolcanism create an analogue, though with different materials, to the climatic changes undergone by Earth during its far shorter year.

<span class="mw-page-title-main">Kraken Mare</span> Largest hydrocarbon lake on Titan

Kraken Mare is the largest known body of liquid on the surface of Saturn's moon Titan. It was discovered by the space probe Cassini in 2006, and was named in 2008 after the Kraken, a legendary sea monster. It covers an area slightly bigger than the Caspian Sea on Earth, making it the largest known lake in the Solar System.

<span class="mw-page-title-main">Ligeia Mare</span> Sea on Titan

Ligeia Mare is a lake in the north polar region of Titan, the planet Saturn's largest moon. It is the second largest body of liquid on the surface of Titan, after Kraken Mare. Larger than Lake Superior on Earth, it is mostly composed of liquid methane, with unknown but lesser components of dissolved nitrogen and ethane, as well as other organic compounds. It is located at 78° N, 249° W, and has been fully imaged by the Cassini spacecraft. Measuring roughly 420 km (260 mi) by 350 km (217 mi) across, it has a surface area of about 126,000 km2, and a shoreline over 2,000 km (1,240 mi) in length. The lake may be hydrologically connected to the larger Kraken Mare. Its namesake is Ligeia, one of the sirens in Greek mythology.

<span class="mw-page-title-main">Titan Saturn System Mission</span> Joint NASA–ESA proposal

Titan Saturn System Mission (TSSM) was a joint NASA–ESA proposal for an exploration of Saturn and its moons Titan and Enceladus, where many complex phenomena were revealed by Cassini. TSSM was proposed to launch in 2020, get gravity assists from Earth and Venus, and arrive at the Saturn system in 2029. The 4-year prime mission would include a two-year Saturn tour, a 2-month Titan aero-sampling phase, and a 20-month Titan orbit phase.

<span class="mw-page-title-main">Punga Mare</span> Sea on Titan

Punga Mare is a lake in the north polar region of Titan, the planet Saturn's largest moon. After Kraken Mare and Ligeia Mare, it is the third largest known body of liquid on Titan. It is composed of liquid hydrocarbons. Located almost adjacent to the north pole at 85.1° N, 339.7° W, it measures roughly 380 km (236 mi) across, greater than the length of Lake Victoria on Earth. Its surface area is ~61,000 km2. Its namesake is Punga, in Māori mythology ancestor of sharks, rays and lizards and a son of Tangaroa, the god of the sea.

<span class="mw-page-title-main">Jingpo Lacus</span> Lake on Titan

Jingpo Lacus is a lake in the north polar region of Titan, the planet Saturn's largest moon. It and similarly sized Ontario Lacus are the largest known bodies of liquid on Titan after the three maria. It is composed of liquid hydrocarbons. It is west of Kraken Mare at 73° N, 336° W, roughly 240 km long, similar to the length of Lake Onega on Earth. Its namesake is Jingpo Lake, a lake in China.

Titan Lake In-situ Sampling Propelled Explorer (TALISE) is a Spanish space probe proposed in 2012 that would splash-down in Ligeia Mare, the second largest lake on Saturn's moon Titan. TALISE would navigate across the lake for six months to one year.

Vid Flumina is a river of liquid methane and ethane on Saturn's moon Titan. The river has been compared to the Nile. It is more than 400 km (249 mi) long and flows into Titan's second largest hydrocarbon sea, Ligeia Mare. The surface of Titan is mostly water ice, so Vid Flumina is a river of methane and ethane flowing across and cutting canyons into ice as though it were bedrock. NASA scientists think that it likely has rapids, whirlpools and waterfalls, just like rivers on Earth.

<i>Dragonfly</i> (spacecraft) Robotic space exploration mission to Titan

Dragonfly is a planned spacecraft and NASA mission to send a robotic rotorcraft to the surface of Titan, the largest moon of Saturn. It is planned to be launched in June 2027. It would be the first aircraft on Titan and is intended to make the first powered and fully controlled atmospheric flight on any moon, with the intention of studying prebiotic chemistry and extraterrestrial habitability. It would then use its vertical takeoffs and landings (VTOL) capability to move between exploration sites.

<span class="mw-page-title-main">Mayda Insula</span> Island on Kraken Mare on Titan

Mayda Insula is an island in the Kraken Mare, a body of liquid composed primarily of methane, on Saturn's largest moon Titan. Mayda Insula is the first island (insula) to be named on a planet or moon other than Earth.

<span class="mw-page-title-main">Oceanus (Titan orbiter)</span>

Oceanus is a NASA/JPL orbiter mission concept proposed in 2017 for the New Frontiers mission #4, but it was not selected for development. If selected at some future opportunity, Oceanus would travel to Saturn's moon Titan to assess its habitability. Studying Titan would help understand the early Earth and exoplanets which orbit other stars. The mission is named after Oceanus, the Greek god of oceans.

Ralph D. Lorenz is a planetary scientist and engineer at the Johns Hopkins Applied Physics Lab. whose research focuses on understanding surfaces, atmospheres, and their interactions on planetary bodies, especially Titan, Venus, Mars, and Earth. He currently serves as Mission Architect of Dragonfly, NASA's fourth selected New Frontiers mission, and as participating scientist on Akatsuki and InSight. He is a Co-Investigator on the SuperCam instrument on the Perseverance rover, responsible for interpreting data from its microphone. He leads the Venus Atmospheric Structure Investigation on the DAVINCI Discovery mission to Venus. He is the recipient of the 2020 International Planetary Probe Workshop (IPPW) Al Seiff memorial award, and the 2022 American Geophysical Union's Fred Whipple Award for contributions to planetary science.

<span class="mw-page-title-main">Titan Submarine</span> Proposed NASA submarine to land on Titan

The Titan Submarine is a proposed mission that was proposed by Steven Oleson, a technical expert at NASA’s Glenn Research Center in Ohio. It will send a submarine to Saturn’s moon Titan. It is a mission that will specialize in understanding and explore in learning either Kraken Mare or Ligeia Mare, some of Titan’s largest lakes.


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