Astrobiology is a scientific field within the life and environmental sciences that studies the origins, early evolution, distribution, and future of life in the universe by investigating its deterministic conditions and contingent events. As a discipline, astrobiology is founded on the premise that life may exist beyond Earth.
Cassini–Huygens, commonly called Cassini, was a space-research mission by NASA, the European Space Agency (ESA), and the Italian Space Agency (ASI) to send a space probe to study the planet Saturn and its system, including its rings and natural satellites. The Flagship-class robotic spacecraft comprised both NASA's Cassini space probe and ESA's Huygens lander, which landed on Saturn's largest moon, Titan. Cassini was the fourth space probe to visit Saturn and the first to enter its orbit, where it stayed from 2004 to 2017. The two craft took their names from the astronomers Giovanni Cassini and Christiaan Huygens.
Enceladus is the sixth-largest moon of Saturn and the 19th-largest in the Solar System. It is about 500 kilometers in diameter, about a tenth of that of Saturn's largest moon, Titan. It is mostly covered by fresh, clean ice, making it one of the most reflective bodies of the Solar System. Consequently, its surface temperature at noon reaches only −198 °C, far colder than a light-absorbing body would be. Despite its small size, Enceladus has a wide variety of surface features, ranging from old, heavily cratered regions to young, tectonically deformed terrain.
The New Frontiers program is a series of space exploration missions being conducted by NASA with the purpose of furthering the understanding of the Solar System. The program selects medium-class missions which can provide high science returns.
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.
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.
The Planetary Science Decadal Survey is a serial publication of the United States National Research Council produced for NASA and other United States Government Agencies such as the National Science Foundation. The documents identify key questions facing planetary science and outlines recommendations for space and ground-based exploration ten years into the future. Missions to gather data to answer these big questions are described and prioritized, where appropriate. Similar decadal surveys cover astronomy and astrophysics, earth science, and heliophysics.
The Cassini space probe was deliberately disposed of via a controlled fall into Saturn's atmosphere on September 15, 2017, ending its nearly two-decade-long mission. This method was chosen to prevent biological contamination of any of the moons of Saturn now thought to offer potentially habitable environments. Factors that influenced the mission end method included the amount of rocket fuel left, the health of the spacecraft, and funding for operations on Earth.
Enceladus Life Finder (ELF) is a proposed astrobiology mission concept for a NASA spacecraft intended to assess the habitability of the internal aquatic ocean of Enceladus, which is Saturn's sixth-largest moon of at least 146 total moons, and seemingly similar in chemical makeup to comets. The spaceprobe would orbit Saturn and fly through Enceladus's geyser-like plumes multiple times. It would be powered by energy supplied from solar panels on the spacecraft.
Journey to Enceladus and Titan (JET) is an astrobiology mission concept to assess the habitability potential of Enceladus and Titan, moons of Saturn.
Life Investigation For Enceladus (LIFE) was a proposed astrobiology mission concept that would capture icy particles from Saturn's moon Enceladus and return them to Earth, where they could be studied in detail for signs of life such as biomolecules.
Enceladus Explorer (EnEx) is a planned interplanetary orbiter and lander mission equipped with a subsurface maneuverable ice melting probe suitable to assess the existence of life on Saturn's moon Enceladus.
THEO is a feasibility study for a New Frontiers class orbiter mission to Enceladus that would directly sample its south pole water plumes in order to study its internal habitability and to search for biosignatures. Specifically, it would take advantage of the direct sampling opportunities of a subsurface ocean.
Dragonfly is a planned NASA spacecraft mission to send a robotic rotorcraft to the surface of Titan, the largest moon of Saturn. It is planned to be launched in July 2028 and arrive in 2034. 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.
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.
Explorer of Enceladus and Titan (E2T) is a space mission concept that would investigate the evolution and habitability of the Saturnian satellites Enceladus and Titan and is proposed by the European Space Agency in collaboration with NASA.
The Ocean Worlds Exploration Program (OWEP) is a NASA program to explore ocean worlds in the outer Solar System that could possess subsurface oceans to assess their habitability and to seek biosignatures of simple extraterrestrial life.
CAESAR is a sample-return mission concept to comet 67P/Churyumov–Gerasimenko. The mission was proposed in 2017 to NASA's New Frontiers program mission 4, and on 20 December 2017 it was one of two finalists selected for further concept development. On 27 June 2019, the other finalist, the Dragonfly mission, was chosen instead.
Christopher R. Glein is an American geochemist at the Southwest Research Institute in San Antonio, TX. He studies planetary science, astrobiology, and organic geochemistry. Glein was the first to describe how Saturn's moon Enceladus is the only known body, besides Earth, that has all of the requirements necessary for life. Glein has been involved in multiple spacecraft missions, leading to significant findings about Pluto, Enceladus, and Titan. In 2017, he was recognized for Outstanding Contributions to the ESA Rosetta Mission by the European Space Agency.
The Enceladus Orbilander is a proposed NASA Flagship mission to Saturn's moon Enceladus. The Enceladus Orbilander would spend a year and a half orbiting Enceladus and sampling its water plumes, which stretch into space, before landing on the surface for a two-year mission to study materials for evidence of life. The mission, with an estimated cost of $4.9 billion, could launch in the late 2030s on a Space Launch System or Falcon Heavy with a landing in the early 2050s. It was proposed in the 2023–2032 Planetary Science Decadal Survey as the third highest priority Flagship mission, after the Uranus Orbiter and Probe and the Mars Sample Return program.
