Low Earth orbit, then the Moon by accident

Water bears in space — the documented flights.

Tardigrades are the first animals shown to survive open-space exposure. That sentence has a paper, a spacecraft, and a lot of later folklore. This page keeps the folklore in its cage.

Earth from Apollo 17, the Blue Marble — Earth from Apollo 17 (NASA, public domain). The tardigrades’ actual flights were unmanned capsules and a shuttle, not this mission — the marble is the neighborhood.

Milnesium tun SEM — A *Milnesium tardigradum* tun. This is the posture that flew on FOTON-M3.

Earth from space — Earth from orbit. Public-domain / Commons.

Recovered Foton reentry capsule, same family as FOTON-M3 — A recovered Foton capsule (Foton-12). FOTON-M3 used the same spherical reentry architecture.

ESA BIOPAN facility exhibited after flight — ESA BIOPAN after flight (this display is BIOPAN-5 / Foton-M2, 2005). TARDIS rode BIOPAN-6 on FOTON-M3 two years later.

Space Shuttle Endeavour on pad 39A for STS-134 — Endeavour on pad 39A for STS-134 (2011) — TARDIKISS flew on this mission. NASA / public domain.

Endeavour docked to the ISS during STS-134 — Endeavour docked to the ISS, STS-134. NASA / public domain.

Model of the SpaceIL Beresheet lander — Beresheet model, SpaceIL. The real lander crashed 11 April 2019 with Arch Mission tardigrades aboard.

LRO image of the Beresheet crash site on the Moon — LRO: Beresheet impact site, 22 April 2019. NASA / public domain.

Timeline

1964 idea

Radiation first

May, Maria, and Guimard (and later reviews) already pointed at tardigrades as radiation-tolerant metazoans. Space exposure was a thought experiment for decades before a Biopan door opened.

Sep 2007

FOTON-M3 — TARDIS, TARSE, RoTaRad

The Russian FOTON-M3 capsule flew ~12 days in low Earth orbit (on the order of 250–290 km). ESA’s Biopan-6 platform opened samples to space. Three tardigrade efforts rode along:

TARDIS (Tardigrades in Space) — K. Ingemar Jönsson and colleagues. Desiccated Milnesium tardigradum and Richtersius coronifer exposed to vacuum, and to vacuum plus UV. Result: vacuum was tolerated; full solar UV was brutal; a few M. tardigradum still revived after UV-all. Paper: Jönsson, Rabbow, Schill, Harms-Ringdahl & Rettberg, 2008, Current Biology 18:R729–R731, “Tardigrades survive exposure to space in low Earth orbit.”
TARSE (Tardigrade Resistance to Space Effects), part of LIFE — Rebecchi, Altiero, Guidetti, Bertolani and colleagues. Paramacrobiotus richtersi (then often Macrobiotus richtersi) flown dehydrated and hydrated inside the BIOKON, not as naked vacuum samples. Desiccated animals fared best. Follow-up papers in 2009–2011.
RoTaRad (Rotifers, Tardigrades and Radiation) — radiation-focused samples on the same flight.

This is the mission behind almost every “tardigrades survived space” headline. Ten days, two well-studied eutardigrades in TARDIS, UV as the real villain.

May 2011

STS-134 / TARDIKISS

Space Shuttle Endeavour’s last flight (STS-134) carried BIOKIS / DAMA experiments to the ISS. TARDIKISS (Tardigrades in Space) flew desiccated Paramacrobiotus richtersi and Ramazzottius oberhaeuseri for about 16 days in a closed Biokon — microgravity and cosmic radiation, not an open Biopan. Survival was high (reported above 91% in the Rizzo et al. follow-up), and animals reproduced afterward. Paper: Rizzo, Altiero, Corsetto, Montorfano, Guidetti & Rebecchi, “Space Flight Effects on Antioxidant Molecules in Dry Tardigrades: The TARDIKISS Experiment.”

TARDIKISS was also a prototype mood for the Planetary Society’s LIFE experiment, which was supposed to ride Fobos-Grunt to Phobos. Fobos-Grunt never left Earth orbit and was destroyed on reentry. No tardigrades on Phobos.

11 Apr 2019

Beresheet crash

SpaceIL’s Beresheet lander failed its braking burn and hit Mare Serenitatis. Bolted to it was the Arch Mission Foundation Lunar Library — nickel discs of archives, DNA samples, and thousands of dehydrated tardigrades, some described as embedded in epoxy / “artificial amber.” Their presence was widely reported after the crash (CNN, BBC, August 2019), not as a biology experiment with a recovery plan.

Whether any tun survived the impact is unknown. Later shock-physics commentary put tardigrade survival limits around ~1 GPa / roughly the crash-speed ballpark, which is a reason for skepticism, not a graveside certainty. They cannot complete a life cycle on the dry Moon. This is not a second TARDIS.

Wikipedia “Tardigrades in space” is a decent map. Primary: Jönsson et al. 2008 Curr Biol; Rebecchi et al. TARSE papers; Rizzo et al. TARDIKISS; contemporaneous ESA FOTON-M3 mission notes. We do not add unpublished ISS rumors. More outbound links on Sources.

Crash test: the 0.9 km/s limit

When rocks hit planetary surfaces, speeds are kilometres per second and shock pressures are in the gigapascal range. Could tardigrades survive impacts like that?

Traspas & Burchell 2021, Astrobiology, measured a limit in the lab. Tardigrades survived impacts up to 0.9 km/s, equivalent to 1.14 GPa shock pressure, and did not survive above it.

Shock is harsher than a squeeze. That impact limit is significantly lower than their static-pressure limit.

For the Moon, survival in terrestrial impact ejecta is impossible at the average lunar impact speed of such ejecta. Around 40% of such ejecta hit at vertical speeds low enough to permit survival.

From Mars to Phobos, at a typical impact speed, martian ejecta striking Phobos would not permit viable transfer of tardigrade-like organisms. A lower-speed fraction might.

The same limit is relevant to spacecraft collecting samples while flying through plumes from Europa and Enceladus. A shock limit around 1 GPa helps set mission scenarios and collection methods when the goal is viable material.

Beresheet crashed on 11 April 2019 with Arch Mission tardigrades aboard. This paper gives a lab-measured limit for how hard an impact a tardigrade can take. It does not report what happened to those animals.

Paired Lunar Reconnaissance Orbiter views of the Beresheet crash site: a cratered plain, then the same ground with a bright impact scar — LRO before and after the Beresheet crash site. The bright patch is the impact scar. NASA / GSFC / Arizona State University, public domain.

Read: Traspas & Burchell 2021, Astrobiology 21(7):845–852 (doi:10.1089/ast.2020.2405, PMID 33978458). Listed on Sources.