The use of tardigrades in space, first proposed in 1964 because of their extreme tolerance to radiation, began in 2007 with the FOTON-M3 mission in low Earth orbit, where they were exposed to space's vacuum for 10 days, and reanimated, just by rehydration, back on Earth. In 2011, tardigrades were on board the International Space Station on STS-134. In 2019, a capsule containing tardigrades was on board the Israeli lunar lander Beresheet which crashed on the Moon.
Tardigrades are small arthropods able to tolerate extreme environments. Many live in tufts of moss, such as on rooftops, where they get repeatedly dried out and rewetted. Others live in the Arctic or atop mountains, where they are exposed to cold. When dried, they go into a cryptobiotic 'tun' state in which metabolism is suspended. [1] [2] They have been described as the toughest animals on Earth. [2] Their DNA is protected from damage, such as by radiation, by Dsup proteins. [3]
In 1964, R.M. May and colleagues proposed that the tardigrade Macrobiotus areolatus would be a suitable model organism for space experiments because of its exceptional radiation tolerance. [2] [4]
In 2001, R. Bertolani and colleagues proposed tardigrades as a model for a study of animal survival in space. [2] [5] As terrestrial experiments on tardigrades proceeded, knowledge of their survival abilities grew, enabling K.I. Jönsson in 2007, [6] and then other researchers such as Daiki Horikawa in 2008 [7] and Roberto Guidetti in 2012, [8] to present evidence that they would resist desiccation, radiation, heat, and cold, suiting them for astrobiological studies. [2]
In 2008, F. Ono and colleagues suggested that tardigrades might be able to survive a journey through space on a meteorite, enabling panspermia, the transfer of life from one planet to another. [9]
Tardigrades have survived exposure to space. In 2007, dehydrated tardigrades were taken into low Earth orbit on the FOTON-M3 mission carrying the BIOPAN astrobiology payload. For 10 days, in the "Tardigrade Resistance to Space Effects" (TARSE) experiment, groups of Paramacrobiotus richtersi tardigrades, some of them previously dehydrated, some of them not, were exposed to the hard vacuum of space, or vacuum and solar ultraviolet radiation. [10] Back on Earth, more than 68% of the subjects protected from solar ultraviolet radiation were reanimated within 30 minutes following rehydration; although subsequent mortality was high, many produced viable embryos. [2] [10]
In contrast, in the "Tardigrades in Space" (TARDIS) experiment, hydrated samples exposed to the combined effect of vacuum and full solar ultraviolet radiation had significantly reduced survival, with only three subjects of Milnesium tardigradum surviving. [10] The space vacuum did not much affect egg-laying in either Richtersius coronifer or M. tardigradum, whereas UV radiation did reduce egg-laying in M. tardigradum. [2] [10]
The third FOTON-M3 experiment, "Rotifers, Tardigrades and Radiation" (RoTaRad) focused mainly on radiation survival. [2]
In 2011, Angela Maria Rizzo and colleagues sent tardigrades on board the International Space Station Endeavour along with extremophiles on STS-134, in the "Tardigrades in Space" (TARDIKISS) experiment. [2] [11] They concluded that microgravity and cosmic radiation "did not significantly affect survival of tardigrades in flight" and that tardigrades were useful in space research, [12] [13] with implications for astrobiology, where they should be suitable model organisms. [14] [8] [15]
The mission was a prototype for the "Living Interplanetary Flight Experiment" (LIFE) [17] which was to have travelled to the Martian moon Phobos on the Russian Fobos-Grunt spacecraft. [18] [19] The spacecraft however failed to leave Earth orbit and was destroyed. [20] [21]
In 2019, a capsule containing tardigrades in a cryptobiotic state was on board the Israeli lunar lander Beresheet which crashed on the Moon. They were described as unlikely to have survived the impact because the shock pressure of the crash would have been well above the 1.14 GPa that they have been measured as surviving. [16] [22] Despite tardigrades' ability to survive in space, they would still need food, lacking on the moon, to be able to grow and reproduce. [23] The possibility that tardigrades survived the crash attracted concern about contamination of the Moon with biological material. [24] However, they are unlikely to become rehydrated because of the lack of liquid water on the Moon. [25]
Spilling tardigrades across the Moon is legal. [26] [27] The Outer Space Treaty only explicitly bans weapons and experiments or tools that could interfere with other missions. [28] Large space agencies typically follow guidelines for sterilizing mission equipment, but there is no single entity to enforce these rules globally. [29]
Animals in space originally served to test the survivability of spaceflight, before human spaceflights were attempted. Later, many species were flown to investigate various biological processes and the effects microgravity and space flight might have on them. Bioastronautics is an area of bioengineering research that spans the study and support of life in space. To date, seven national space programs have flown non-human animals into space: the United States, Soviet Union, France, Argentina, China, Japan and Iran.
Foton is the project name of two series of Russian science satellite and reentry vehicle programs. Although uncrewed, the design was adapted from the crewed Vostok spacecraft capsule. The primary focus of the Foton project is materials science research, but some missions have also carried experiments for other fields of research including biology. The original Foton series included 12 launches from the Plesetsk Cosmodrome from 1985 to 1999.
EXPOSE is a multi-user facility mounted outside the International Space Station (ISS) dedicated to astrobiology. EXPOSE was developed by the European Space Agency (ESA) for long-term spaceflights and was designed to allow exposure of chemical and biological samples to outer space while recording data during exposure.
The Living Interplanetary Flight Experiment was an interplanetary mission developed by the Planetary Society. It consisted of sending selected microorganisms on a three-year interplanetary round-trip in a small capsule aboard the Russian Fobos-Grunt spacecraft in 2011, which was a failed sample-return mission to the Martian moon Phobos. The Fobos-Grunt mission failed to leave Earth orbit and was destroyed.
Tardigrades, known colloquially as water bears or moss piglets, are a phylum of eight-legged segmented micro-animals. They were first described by the German zoologist Johann August Ephraim Goeze in 1773, who called them Kleiner Wasserbär'little water bear'. In 1776, the Italian biologist Lazzaro Spallanzani named them Tardigrada, which means 'slow walker'.
The O/OREOS is a NASA automated CubeSat nanosatellite laboratory approximately the size of a loaf of bread that contains two separate astrobiology experiments on board. Developed by the Small Spacecraft Division at NASA Ames Research Center, the spacecraft was successfully launched as a secondary payload on STP-S26 led by the Space Test Program of the United States Air Force on a Minotaur IV launch vehicle from Kodiak Island, Alaska on 20 November 2010, at 01:25:00 UTC.
Ramazzottius is a genus of water bear or moss piglet, a tardigrade in the class Eutardigrada, named after the Italian zoologist Giuseppe Ramazzotti.
Acutuncus is a genus of tardigrades containing a single species, Acutuncus antarcticus. Tardigrades, which are eight-legged micro-animals, are commonly referred to as water bears or moss piglets and are found all over the world in varying extreme habitats. First discovered in 1904 and originally named Hypsibius antarcticus, Acutuncus antarcticus is the most abundant tardigrade species in Antarctica.
Milnesium tardigradum is a cosmopolitan species of tardigrade that can be found in a diverse range of environments. It has also been found in the sea around Antarctica. M. tardigradum was described by Louis Michel François Doyère in 1840. It contains unidentified osmolytes that could potentially provide important information in the process of cryptobiosis.
Milnesium is a genus of tardigrades. It is rather common, being found in a wide variety of habitats across the world. It has a fossil record extending back to the Cretaceous, the oldest species found so far is known from Turonian stage deposits on the east coast of the United States. Milnesiums are one of the most desiccation and radiation-resistant invertebrates on Earth because of their unique ability to transform into a "tun" state and utilize intrinsically disordered proteins when experiencing extreme environments.
BIOPAN is a multi-user research program by the European Space Agency (ESA) designed to investigate the effect of the space environment on biological material. The experiments in BIOPAN are exposed to solar and cosmic radiation, the space vacuum and weightlessness, or a selection thereof. Optionally, the experiment temperature can be stabilized. BIOPAN hosts astrobiology, radiobiology and materials science experiments.
Exobiology Radiation Assembly (ERA) was an experiment that investigated the biological effects of space radiation. An astrobiology mission developed by the European Space Agency (ESA), it took place aboard the European Retrievable Carrier (EURECA), an unmanned 4.5 tonne satellite with a payload of 15 experiments.
Richtersius is a monospecific genus of tardigrades in the family Richtersiidae; its sole species is Richtersius coronifer. R. coronifer is one of two species of tardigrade that have been shown to survive and continue reproducing after exposure to outer space, specifically in the thermosphere at 258–281 km above sea level with ionizing solar and galactic cosmic radiation for 10 days. However, unlike Milnesium tardigradum, R. coronifer did not survive under these conditions plus UV exposure.
Macrobiotidae is a family of tardigrade. As of 2023, it consists of the following genera:
Beresheet was a demonstrator of a small robotic lunar lander and lunar probe operated by SpaceIL and Israel Aerospace Industries. Its aims included inspiring youth and promoting careers in science, technology, engineering, and mathematics (STEM), and landing its magnetometer, time capsule, and laser retroreflector on the Moon. The lander's gyroscopes failed on 11 April 2019 causing the main engine to shut off, which resulted in the lander crashing on the Moon. Its final resting position is 32.5956°N, 19.3496°E.
Bertolanius is a genus of tardigrades belonging to the family Eohypsibiidae.
Milnesium alpigenum is a species of tardigrade that falls under the Tardigrada phylum. Like its taxonomic relatives it is an omnivorous predator that feeds on other small organisms, such as algae, rotifers, and nematodes. M. alpigenum was discovered by Christian Gottfried Ehrenberg in 1853. It is very closely related to Milnesium tardigradum along with many other species from the Milnesium genus.
From the early 19th century, tardigrades' environmental tolerance has been a noted feature of the group. The animals are able to survive extremes of temperature, desiccation, impact, radiation, and exposure to the vacuum of space.
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