--- title: "Tardigrades survive space vacuum but not full sunlight; only three lived through a 2007 orbital test" url: https://badiyaa.com/tardigrades-what-they-cannot-survive/ published: 2026-11-03T07:27:00+00:00 modified: 2026-11-03T07:27:00+00:00 section: Science publisher: Badiyaa --- # Tardigrades survive space vacuum but not full sunlight; only three lived through a 2007 orbital test A viral Short calls the water bear unkillable. The research record says the tun state tolerates extremes only briefly, Dsup cuts X-ray DNA damage by about 40 percent, and unfiltered solar UV in orbit killed nearly all of them. Only three tardigrades out of a dehydrated batch flown on the 2007 FOTON-M3 mission came back alive after ten days of full solar ultraviolet in orbit. Vacuum alone did nothing to them. Add unfiltered sunlight, and most of the famous “unkillable” animals died. That detail matters this week because a YouTube Short from @HansrajCreative-1900, posted on October 23 under the title “Tardigrade The Unkillable Animal,” is racing through the viral feeds with the usual list: cold, heat, radiation, the vacuum of space, all shrugged off by an animal half a millimeter long. The clip is a fact-channel explainer, not original footage, and the list is broadly true. What it skips is the fine print. ## The finding: tough, but only while dried out Almost every record in the tardigrade highlight reel was set in the “tun” state, the shriveled, metabolism-off cyst that terrestrial species form when their moss or pond dries up. In that form, according to the [phylum’s reference entry](https://en.wikipedia.org/wiki/Tardigrade), they have endured temperatures from about minus 272 C (minus 458 F) up to 149 C (300 F), the latter only for short periods, plus vacuum, ionizing radiation and crushing pressure. An active, hydrated tardigrade is a different creature. It walks, feeds by piercing plant or animal cells with stylets, lays up to 30 eggs that hatch within 14 days, and can be eaten by mites, spiders and beetle larvae like any other soil animal. Zoologists do not even class the group as extremophiles: the animals endure extremes rather than exploit them, and their odds of dying climb the longer the exposure lasts. ## How the space test actually went A 2017 review of tardigrade space research, [published in Origins of Life and Evolution of Biospheres](https://pmc.ncbi.nlm.nih.gov/articles/PMC5705745/), lists three FOTON-M3 projects; the one that matters for the Short is TARDIS. The 2007 experiment carried 30 dehydrated tardigrades and 30 eggs on FOTON-M3 and split them between vacuum only, vacuum plus UVA and UVB, and vacuum plus the full solar ultraviolet range. Rehydrated back on Earth, the vacuum-only group showed no measurable harm. The partial-UV group lost many tuns; one Richtersius coronifer and 68 percent of the Milnesium tardigradum specimens revived, then died off at a high rate in the following days, and survivors laid fewer eggs. Full sunlight left three M. tardigradum alive. A 2011 flight on the International Space Station, on shuttle mission STS-134, confirmed that tardigrades can ride out microgravity and cosmic radiation. A capsule of tuns also crashed onto the Moon with Israel’s Beresheet lander in 2019; the [record of tardigrade spaceflights](https://en.wikipedia.org/wiki/Tardigrades_in_space) notes the crash shock was likely well above the 1.14 gigapascals they can survive, and even survivors could not rehydrate without liquid water. Nobody has shown that any of them woke up. ## Where the radiation resistance comes from The radiation half of the legend has a named mechanism. In a 2016 paper, Takuma Hashimoto, Takekazu Kunieda and colleagues at the University of Tokyo sequenced the genome of Ramazzottius varieornatus, one of the hardiest species, and found a protein they called Dsup, for damage suppressor, that sits on nuclear DNA. Expressed in human cultured cells, it cut X-ray-induced DNA damage by roughly 40 percent and improved the cells’ survival ([the 2016 paper](https://doi.org/10.1038/ncomms12808)). The same genome showed 1.2 percent or fewer foreign genes, knocking down an earlier claim that tardigrades had borrowed much of their toolkit from bacteria. Forty percent is a real effect. It is not immunity. A 2021 impact study cited in the same reference found the animals survive collisions up to about 900 meters per second and shock pressures near 1.14 gigapascals; faster than that, they are paste. ## Why it matters The “immortal” framing hides the more useful story. Dehydration tolerance in tardigrades runs on intrinsically disordered proteins that form a glass-like matrix inside cells, not on the sugar trehalose that earlier textbooks credited, and in Hypsibius exemplaris 1,422 genes switch on during the drying process. Those proteins, along with Dsup, are the parts biomedical researchers actually want: candidates for protecting human cells and tissues from desiccation and radiation damage. Here is the Badiyaa scorecard for the Short’s claims, checked against the sources above: extreme cold, pass, in the tun state; extreme heat, pass for short exposures only; radiation, pass with a measured 40 percent DNA-protection effect rather than invulnerability; space, pass for vacuum and fail for unfiltered sunlight. ## Limits The temperature records come from short laboratory exposures of dried tuns, not from active animals living at those temperatures, and the tun itself stops working if the drying happens too fast or the animal cannot rehydrate afterward. The Dsup result was measured in human cell cultures, not in people. And the 2007 orbital test used two species out of roughly 1,500 described; most tardigrades have never been near a vacuum chamber. The Short’s creator credits none of this, which is normal for a 60-second format. The next hard number to watch is simpler: the Beresheet tuns have now spent more than seven years on the lunar surface, and nothing in the published record says any of them is still revivable. ## Further reading - [Wikipedia: Tardigrade](https://en.wikipedia.org/wiki/Tardigrade) - [Wikipedia: Tardigrades in space](https://en.wikipedia.org/wiki/Tardigrades_in_space) - [Hashimoto et al. 2016, Extremotolerant tardigrade genome (doi:10.1038/ncomms12808)](https://doi.org/10.1038/ncomms12808) - [Erdmann & Kaczmarek 2017, Tardigrades in Space Research – Past and Future (PMC5705745)](https://pmc.ncbi.nlm.nih.gov/articles/PMC5705745/) *Image: Hoddyfool, CC BY-SA 4.0 via Wikimedia Commons* *This article was produced with AI assistance and reviewed by our Editorial Desk. [How we work](https://badiyaa.com/editorial-policy/).*