Titan Saturn System Mission

{{short description|Cancelled NASA/ESA mission concept to Saturn}}{{More citations needed|date=September 2025}}{{Infobox spaceflight | name = Titan Saturn System Mission | names_list = TandEM

| image = Tssm project.jpg | image_caption = Artist's impression of the three main components of the TSSM exploring [[Titan (moon)|Titan]] | image_size = 300px

| mission_type = [[Saturn]] exploration | operator = [[NASA]]/[[ESA]] | website = [http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=42286 sci.esa.int] | mission_duration = 2 years (proposed)<ref name=2years>{{cite web|url=http://sci.esa.int/science-e/www/area/index.cfm?fareaid=106 |title=TANDEM/TSSM mission summary |access-date=2009-11-08 |date=20 October 2009 |work=European Space Agency }}</ref>

| launch_mass = '''Orbiter''': {{cvt|1613|kg|lb}} | landing_mass = '''[[Hot air balloon#Montgolfier|Montgolfière]]''':{{cvt|600|kg|lb}} '''Lander''': {{cvt|190|kg|lb}}

| launch_date = Proposed: Between 2020 and 2029 | launch_rocket = [[Delta IV Heavy]], [[Space Launch System]]<ref name="nasa.gov"/> Block IB, or [[Atlas V]]

| orbit_reference = [[Titan (moon)|Titan]] | orbit_semimajor = {{cvt|1500|km|mi}} | orbit_inclination = 85° | orbit_period = ~4.8 h

| interplanetary = {{Infobox spaceflight/IP | type = orbiter | object = [[Titan (moon)|Titan]] | arrival_date = c. 2029–2038 (proposed) }}

{{Infobox spaceflight/IP | type = Atmospheric | object = Titan | component = TSSM montgolfière }}

{{Infobox spaceflight/IP | type = lander | object = Titan | component = [[Titan Mare Explorer]] or other TSSM lander proposal | location = [[Ligeia Mare]] }}

| programme = '''[[Large Strategic Science Missions]]''' {{small|''Planetary Science Division''}} | previous_mission = | next_mission = }}

'''Titan Saturn System Mission''' ('''TSSM''') was a joint [[NASA]]–[[ESA]] proposal for an [[exploration of Saturn]] and its [[Moons of Saturn|moons]] [[Titan (moon)|Titan]] and [[Enceladus (moon)|Enceladus]],<ref name=2years /> where many complex phenomena were revealed by ''[[Cassini–Huygens|Cassini]]''. TSSM was proposed to launch in 2020, following which it would have gotten [[gravity assist]]s from [[Earth]] and [[Venus]], and arrived 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 phasing|orbit phase]].

In 2009, a [[EJSM|mission to Jupiter]] and its moons was given priority over ''Titan Saturn System Mission'',<ref name="Rincon2009">{{cite web |url=http://news.bbc.co.uk/1/hi/sci/tech/7897585.stm |title=Jupiter in space agencies' sights |first=Paul |last=Rincon |publisher=[[BBC News]] |access-date=2009-02-20 |date=2009-02-20 }}</ref> although TSSM will continue to be assessed for possible development and launch.

==Origin and status== {{update|section|date=June 2021}}  The Titan Saturn System Mission (TSSM) was officially created in January 2009 by the merging of the ESA's '''Titan and Enceladus Mission''' ('''TandEM''') with NASA's '''Titan Explorer (2007)''' study,<ref>{{cite web|url=http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=44033 |title=TSSM NASA/ESA joint summary report |access-date=2009-11-26 |date=19 Jan 2009 |publisher=ESA }}</ref> although plans to combine both concepts date at least back to early 2008. TSSM was competing against the [[Europa Jupiter System Mission]] (EJSM) proposal for funding, and in February 2009 it was announced that NASA/ESA had given EJSM priority ahead of TSSM.<ref>{{cite web |url=http://www.nasa.gov/topics/solarsystem/features/20090218.html |title=NASA and ESA Prioritize Outer Planet Missions |publisher=NASA |date=February 18, 2009}}</ref><ref>{{cite news |url=http://news.bbc.co.uk/1/hi/sci/tech/7897585.stm |title=Jupiter in space agencies' sights |first=Paul |last=Rincon |date=18 February 2009 |work=BBC News}}</ref> TSSM continued to be studied for a later launch date, near the 2020s. Detailed assessment reports of the mission elements<ref>{{Cite web |url=http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=44201 |title=ESA internal study report on ESA contributions to Tandem/TSSM available |date=12 February 2009 |publisher=[[ESA]]}}</ref> as well as a specific concept for a lake-landing module for [[lakes of Titan|Titan's lakes]] called [[Titan Mare Explorer]] (TiME) with the potential of becoming a part of the TSSM have been proposed in February and October 2009, respectively.

In 2014 it was thought the TSSM might have been revived for a launch on the [[Space Launch System|SLS super-heavy-lift rocket]].<ref name="nasa.gov">{{cite web |url=https://www.nasa.gov/sites/default/files/files/Creech_SLS_Deep_Space.pdf |title=NASA's Space Launch System: A Capability for Deep Space Exploration |first=Stephen |last=Creech |publisher=Strategy & Partnerships Space Launch System (SLS) Program |date=April 2014}}</ref>

The TSSM mission consists of an [[orbiter]] and two Titan exploration probes: a [[Hot air balloon#Montgolfier|hot air balloon]] that will float in Titan's clouds, and a [[Lander (spacecraft)|lander]] that will [[Splashdown (spacecraft landing)|splash down]] on one of its [[methane]] seas.

Both probes’ data are to be relayed to a Titan orbiter. They will be equipped to study Titan's features with instruments for imaging, [[radar]] profiling, and surface as well as atmospheric [[Sample (material)|sampling]], much more complete than done by the [[Cassini–Huygens]] mission.

The spacecraft will use several [[gravity assist]] [[Planetary flyby|flyby]]s of other planets to enable it to reach Saturn. The baseline design envisaged a September 2020 launch, followed by four gravity assists ([[Earth]]–[[Venus]]–Earth–Earth), and arrival at Saturn 9 years later in October 2029. This is one of several available Earth-to-Saturn transfer options from the year 2018 through 2022. Current NASA plans do not give the TSSM a priority, however, and it is unlikely any of the proposed launch dates can be met.

Upon Saturn arrival, in October 2029, the orbiter's [[chemical propulsion system]] would place the spacecraft into orbit around Saturn, followed by a two-year Saturn Tour Phase, characterized by the deployment of the ''in situ'' elements, and including a minimum of seven close Enceladus flybys and 16 Titan flybys. During this period, repeated satellite [[gravity assist]]s and maneuvers will reduce the energy needed to insert into Titan's orbit. As the craft completes its flyby by Enceladus, the orbiter will analyze the unusual [[cryovolcanic]] plumes at the moon's south pole.

The [[Hot air balloon#Montgolfier|Montgolfière]], a hot air balloon, would be released on approach to the first Titan flyby for ballistic entry into Titan's atmosphere for its six Earth months’ mission from April 2030 to October 2030. Based on Cassini–Huygens discoveries, the Montgolfière should be able to circumnavigate Titan at least once during its nominal lifetime at its deployment [[latitude]] of about 20°N, 10 kilometers above Titan's surface.

===Lake lander=== [[File:TSSM-TandEM-Lander.jpg|thumb|The [[Titan Mare Explorer]] (TiME) could become the lake-lander of the TSSM.]] Numerous proposals have been brought forward with respect to the lake-lander concept. One of the most detailed plans so far is the so-called [[Titan Mare Explorer]] (TiME), which had originally been proposed as a separate scout mission, but might eventually be postponed and included in the TSSM.<ref name=TSSM >{{cite news |url=http://www.space.com/businesstechnology/091014-titan-boat-mission.html |title=Nuclear-Powered Robot Ship Could Sail Seas of Titan |date=14 October 2009 |first=Jeremy |last=Hsu |website=Space.com}}</ref><ref name=Stofan >{{Citation | first=Ellen | last=Stofan | author-link=Ellen Stofan | contribution=Titan Mare Explorer (TiME): The First Exploration of an Extra-Terrestrial Sea | title=Presentation to NASA's Decadal Survey | publisher=Space Policy Online | date=25 August 2009 | contribution-url=http://www.spacepolicyonline.com/pages/images/stories/PSDS%20Sat1%20Stofan-TIME.pdf | access-date=2009-11-04 | archive-date=2009-10-24 | archive-url=https://web.archive.org/web/20091024224613/http://www.spacepolicyonline.com/pages/images/stories/PSDS%20Sat1%20Stofan-TIME.pdf | url-status=dead }}</ref> If approved, TiME would be released by the orbiter on its second Titan flyby. Due to Titan's haze layer and its distance to the Sun, the lander cannot be powered by solar panels and it would rely on the new [[Advanced Stirling Radioisotope Generator]] (ASRG),<ref name=Stofan /><ref name=DSMC >{{cite web |url=http://nasascience.nasa.gov/researchers/sara/library-and-useful-links/Green_PSS_June%20508%20final.pdf |archive-url=https://web.archive.org/web/20080921160720/http://nasascience.nasa.gov/researchers/sara/library-and-useful-links/Green_PSS_June%20508%20final.pdf |url-status=dead |archive-date=September 21, 2008 |title=NASA's Planetary Science Division Update |date=June 23, 2008}}</ref> which is a prototype meant to provide availability of long-lived power supplies for landed networks and other planetary missions. The lander will target [[Ligeia Mare]], a northern polar sea of [[liquid hydrocarbon]]s at about 79°N. The probe will descend by parachute, like the [[Huygens probe]] of 2005. During the 6 hours of descent it will analyze the atmosphere and then splashdown on the liquid surface. The plutonium-powered craft's principal function is to sample and analyze organics on the surface for a period of about 3 to 6 months; this would be the first floating exploration of an extraterrestrial sea. In addition to the primary mission, TiME could be equipped with a suite of advanced instruments to study the chemical composition and physical properties of Titan's lakes. This includes a spectrometer to analyze the liquid hydrocarbons, a sonar to map the lakebed, and a weather station to monitor Titan's unique meteorological conditions. Furthermore, mission planners are considering the inclusion of a submersible probe that could be deployed from TiME to explore beneath the surface of Ligeia Mare, providing unprecedented insights into the potential for prebiotic chemistry in Titan's seas. These enhancements would not only expand our understanding of Titan but could also offer clues to the broader question of life's origins in the universe.

==Science goals and objectives== {{unreferenced section|date=October 2017}} The major goals of the TSSM mission can be summarized under four categories: *Explore Titan as a system *Study Titan's organic inventory and astrobiological potential *Constrain Titan's origin and evolution models *Recover information on Enceladus and Saturn's [[magnetosphere]]

[[File:PIA09184 -Titan Sea and Lake Superior.jpg|thumb|Comparison of [[Ligeia Mare]]'s area with [[Lake Superior]] on [[Earth]].]] At Titan, the science goals would be to provide information on such aspects as the composition of the surface and the geographic distribution of the various organic constituents; on the [[methane]] cycle and the [[methane reservoirs]]; on the ages of the surface features, and in particular on whether [[cryovolcanism]] and [[tectonism]] are actively ongoing or are relics of a more active past; on the presence or absence of [[ammonia]], of a [[magnetic field]] and of a sub-surface ocean; on the chemistry that drives complex ion formation in the upper atmosphere; and on a large altitude range in the atmosphere, from 400–900km, which remains poorly explored after Cassini. In addition, much remains to be understood about seasonal changes of the atmosphere at all levels, and the long-term escape of constituents to space.

[[TiME (spacecraft)|TiME]] lander would [[Splashdown (spacecraft landing)|splashdown]] on [[Ligeia Mare]], a [[methane]] sea on Titan's northern hemisphere. It is believed that Titan's methane cycle is analogous to Earth's [[hydrologic cycle]], with meteorological working fluid existing in liquid and gas phase. TiME would directly discern the methane cycle of Titan and help understand its similarities and differences to the hydrologic cycle on Earth.<ref name=Stofan /> However, questions about the sources of re-supply of methane to the atmosphere remain to be answered. This world is built by organic activities which still operate and Cassini–Huygens findings suggest a world with a balance of geologic and atmospheric processes that is the solar system's best analogue to [[Earth]]. Moreover, an interior ocean discovered by Cassini, deep underneath Titan's dense atmosphere and surface is thought to be largely composed of liquid water.<ref>{{Cite web |date=2018-05-02 |title=Titan: Facts |url=https://science.nasa.gov/saturn/moons/titan/facts/ |access-date=2025-07-25 |language=en-US}}</ref> TSSM would be the first mission in the 50 years of space exploration where an extensive and interdisciplinary in situ survey of active organic chemistry and climate on the land, on the sea, and in the air of another world will take place.

==See also== {{commons category}} *[[Kronos (spacecraft)]] *[[Dragonfly (Titan space probe)]]

==References== {{reflist}}

==External links== *[http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=44033 Joint NASA/ESA report on the TandEM/TSSM mission] *[http://www.lesia.obspm.fr/cosmicvision/tssm/tssm-public TSSM official site] *[https://web.archive.org/web/20081207170418/http://www.lesia.obspm.fr/cosmicvision/tandem/index.php TandEM official site] *[https://web.archive.org/web/20070426162116/http://saturn.jpl.nasa.gov/home/index.cfm Cassini/Huygens Mission – NASA] *[http://www.nasa.gov/multimedia/podcasting/jpl-titan20090218.html NASA podcast on the TSSM]

[[Category:European Space Agency space probes]] [[Category:NASA programs]] [[Category:Missions to Saturn]] [[Category:Extraterrestrial orbiters]] [[Category:Proposed NASA space probes]] [[Category:Missions to Titan (moon)]]