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. [1] [2] [3] [4]
The LIFE orbiter concept was proposed by a team led by Peter Tsou to NASA's 13th Discovery Mission solicitation, [3] but the mission was not selected by NASA for Phase-A design study. [5]
Enceladus is a small icy moon with jets or geysers of water erupting from its surface that might be connected to active hydrothermal vents at its subsurface water ocean floor, [6] [7] [8] [9] [10] where the moon's ocean meets the underlying rock, a prime habitat for life. [11] [12] The geysers could provide easy access for sampling the moon's subsurface ocean, and if there is microbial life in it, ice particles from the sea could contain the evidence astrobiologists need to identify them. [13] [14]
The 15-year LIFE mission would use a 'Tanpopo' aerogel collector [14] similar to the one NASA used in the Stardust sample return mission to return cometary dust in 2006. The proposed spacecraft would enter into Saturn orbit and enable multiple flybys through Enceladus's icy plumes. After spending about two years in orbit as slow as 2 km/s around Saturn, [2] LIFE would use its propulsion system to escape Saturn and begin the ~4.5 year long voyage back to Earth with the collected particles in a return capsule. [15] [16] The spacecraft may sample Enceladus's plume, the E ring of Saturn, and the Titan upper atmosphere. [2]
In December 2014, NASA announced that it would be selecting finalists in June 2015 to submit proposals for a future Discovery Program mission, and selecting a winning proposal in September 2016. The selected mission must launch by the end of 2021. [17] The mission would have a $425 million development cost cap, and it would reach Saturn after a series of gravity assists past Venus and the Earth. Samples from Enceladus's plume would make it to Earth about 14 years later. [1] In September 2016, NASA announced that five proposals had been selected for further study. [18] [ needs update ]
As currently envisioned, the probe's science payload would consist of: [1]
The samples collected would be returned to Earth for extensive analyses.
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.
Europa, or Jupiter II, is the smallest of the four Galilean moons orbiting Jupiter, and the sixth-closest to the planet of all the 95 known moons of Jupiter. It is also the sixth-largest moon in the Solar System. Europa was discovered independently by Simon Marius and Galileo Galilei and was named after Europa, the Phoenician mother of King Minos of Crete and lover of Zeus.
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 tiger stripes of Enceladus consist of four sub-parallel, linear depressions in the south polar region of the Saturnian moon. First observed on May 20, 2005, by the Cassini spacecraft's Imaging Science Sub-system (ISS) camera, the features are most notable in lower resolution images by their brightness contrast from the surrounding terrain. Higher resolution observations were obtained by Cassini's various instruments during a close flyby of Enceladus on July 14, 2005. These observations revealed the tiger stripes to be low ridges with a central fracture. Observations from the Composite Infrared Spectrometer (CIRS) instrument showed the tiger stripes to have elevated surface temperatures, indicative of present-day cryovolcanism on Enceladus centered on the tiger stripes.
"Astrobiology of Icy Worlds". astrobiology.nasa.gov. December 2014. Archived from the original on 2024-05-16. Retrieved 2024-05-16.
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.
The habitability of natural satellites is the potential of moons to provide habitats for life, though it is not an indicator that they harbor it. Natural satellites are expected to outnumber planets by a large margin and the study of their habitability is therefore important to astrobiology and the search for extraterrestrial life. There are, nevertheless, significant environmental variables specific to moons.
Interplanetary contamination refers to biological contamination of a planetary body by a space probe or spacecraft, either deliberate or unintentional.
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.
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.
The selection process for Mission 13 and 14 of the Discovery program began in February 2014, as NASA drafted an Announcement of Opportunity (AO) for the next Discovery mission. The winning mission proposals received $450 million in funding towards mission development and construction, along with bonus funding if missions were able to incorporate certain technologies. For Discovery Mission 13 and 14, NASA received 28 proposals, 16 of which notably centered around small Solar System bodies. Lucy, a multiple-flyby mission to the Jupiter trojans, and Psyche, a mission to the metallic asteroid 16 Psyche, were announced as the winners of the competition in January 2017, with launches in October 2021 and October 2023, respectively.
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.
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.
Enceladus Life Signatures and Habitability (ELSAH) is an astrobiology concept mission proposed in 2017 to NASA's New Frontiers program to send a spacecraft to Enceladus to search for biosignatures and assess its habitability. The Principal Investigator is Christopher P. McKay, an astrobiologist at NASA Ames Research Center, and the managing NASA center is Goddard Space Flight Center. No details of the mission have been made public, but observers speculate that it would be a plume-sampling orbiter mission.
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.
The Enceladus Icy Jet Analyzer (ENIJA) is a time-of-flight mass spectrometer developed to search for prebiotic molecules like amino acids and biosignatures in the plumes of Saturn's moon Enceladus.
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.