Bias disclaimer: I think that returning samples from Mars to Earth at a point in time where we also suspect there is a chance that there is microbial life on Mars is ill-advised and arrogant. We are already scared of ancient viruses we don't know about trapped frozen in permafrost here on Earth being released as the climate warms. Even if a microbe doesn't infect humans, all it has to be able to do is to infect something e.g. algae in the ocean, wheat, rice or corn, honey bees, gut bacteria, and the planet or at least humanity is at severe risk. Random examples of news items are shown below.
Sometimes sample return missions go bad and need to be recovered in the desert after they break open.
The capsule broke open on impact, and part of the inner sample capsule was also breached. The damage was less severe than might have been expected given its velocity; it was to some extent cushioned by falling into fairly soft ground.
From New York Times Science tweet
It survived tens of thousands of years in suspended animation and managed to reproduce once it was thawed out
update 7: CNN's August 18, 2023 New study warns against risks of ‘time-traveling pathogens’ outlines the results of recent simulations of the dangers of the release of ancient viruses of Earth origin back into the ecosphere.
update 6: CNN's July 29, 2023 A worm has been revived after 46,000 years in the Siberian permafrost
Scientists have revived a worm that was frozen 46,000 years ago — at a time when woolly mammoths, sabre-toothed tigers and giant elks still roamed the Earth.
The roundworm, of a previously unknown species, survived 40 meters (131.2 feet) below the surface in the Siberian permafrost in a dormant state known as cryptobiosis, according to Teymuras Kurzchalia, professor emeritus at the Max Planck Institute of Molecular Cell Biology and Genetics in Dresden and one of the scientists
[...] Organisms in a cryptobiotic state can endure the complete absence of water or oxygen and withstand high temperatures, as well as freezing or extremely salty conditions. They remain in a state “between death and life,” in which their metabolic rates decrease to an undetectable level, Kurzchalia explained.
“One can halt life and then start it from the beginning. This a major finding,” he said, adding that other organisms previously revived from this state had survived for decades rather than millennia.
One of the researchers, Anastasia Shatilovich, revived two of the worms at the institute by simply rehydrating them with water, before taking around 100 worms to labs in Germany for further analysis, transporting them in her pocket.
update 5: CNN's March 8, 2023 Scientists have revived a ‘zombie’ virus that spent 48,500 years frozen in permafrost begins:
Warmer temperatures in the Arctic are thawing the region’s permafrost — a frozen layer of soil beneath the ground — and potentially stirring viruses that, after lying dormant for tens of thousands of years, could endanger animal and human health.
update 4: From the spaceflight-focused Journal Icarus Recovery and Identification of Viable Bacteria Immured in Glacial Ice
By identifying the features that facilitate microbial survival within terrestrial ice, extrapolations to the likelihood of microorganisms surviving frozen in water ice on Mars, Europa, or within comets will be improved.
as well as Glacier ice archives nearly 15,000-year-old microbes and phages Zhong, ZP., Tian, F., Roux, S. et al. Microbiome 9, 160 (2021):
Bacteria of above phyla have been successfully cultured from very old frozen glacier ice [18,19,20,21], including some that were believed to have been preserved for >750,000 years  because of the subzero temperatures and low water activities within the ice matrix. Some bacteria were preserved as spores in glacier ice [22, 23]. Although there is currently no direct evidence for in situ activity, some studies have hinted at the possibility of microbial activity in frozen glacier ice based on the detection of some excess gases (e.g., CO2, CH4, and N2O), which may be produced by post-depositional microbial metabolism [24,25,26].
These all discuss survivability of whole bacteria and larger organisms as well. From the BBC's :
But the new study, published in Current Biology on Monday, suggested they could last for thousands of years, if not indefinitely.
"The takeaway is that a multicellular organism can be frozen and stored as such for thousands of years and then return back to life - a dream of many fiction writers," Stas Malavin, of Russia's Institute of Physicochemical and Biological Problems in Soil Science, told the Press Association.
- This animal survived 24,000 years frozen in the Siberian permafrost
- Frozen in Siberian Permafrost for 24,000 Years, Microscopic Animal Comes Back to Life
“The takeaway is that a multicellular organism can be frozen and stored as such for thousands of years and then return back to life—a dream of many fiction writers,” said (Stas) Malavin. (a co-author of the study)
From Wikipedia's Bdelloidea:
The main characteristics that distinguish bdelloids from related groups of rotifers are exclusively parthenogenetic reproduction and the ability to survive in dry, harsh environments by entering a state of desiccation-induced dormancy (anhydrobiosis) at any life stage. They are often referred to as "ancient asexuals" due to their unique asexual history that spans back to over 25 million years ago through fossil evidence. Bdelloid rotifers are microscopic organisms, typically between 150 and 700 µm in length. Most are slightly too small to be seen with the naked eye, but appear as tiny white dots through even a weak hand lens, especially in bright light.
update 2: See Life on Mars? Scientists Find Mars Has Right Ingredients for Present-Day Microbial Life Beneath Its Surface which links to (paywalled) Earth-like Habitable Environments in the Subsurface of Mars
"NASA stands up these independent boards to help the agency learn from past experiences and uncover subtle issues in space systems that may not have yet received sufficient attention," said David Thompson, retired president of Orbital ATK, who will chair the new board. "This review will give us the chance to focus on overall mission success and to consider potential improvements that can be made early in the program to help ensure that outcome."
Now that's what I'm talkin' about!! Image of the Genesis crash site below illustrates one such "subtle issue." ;-)
- Science: Scientists pull living microbes, possibly 100 million years old, from beneath the sea
- NYTimes: These Microbes May Have Survived 100 Million Years Beneath the Seafloor
- National Geographic: Ancient "Giant Virus" Revived From Siberian Permafrost
- BBC: There Are Diseases Hidden in the Ice and They are Waking Up
- PNAS: In-depth study of Mollivirus sibericum, a new 30,000-y-old giant virus infecting Acanthamoeba
- Live Science: Frozen Giant Virus Still Infectious After 30,000 Years
Typing "back contamination" in the search box on the main page https://sma.nasa.gov/ returns results that include:
Safeguarding Earth from back contamination is the highest planetary protection priority
from Planetary Protection Knowledge Gaps for Human Extraterrestrial Missions Workshop Report NASA Ames, March 24-26 2015
Safeguarding the Earth from potential back contamination is the highest planetary protection priority in Mars exploration.
From 2nd COSPAR WORKSHOP on: Refining Planetary Protection Requirements for Human Missions May 15-16, 2018 and COSPAR WORK MEETING on Developing Payload Requirements for Addressing PP Gaps on Natural Transport of Contaminants on Mars May 17-18, 20 18 BOX 1: COSPAR Planetary Protection Principles and Implementation Guidelines for Human Missions to Mars
Considering the (small) potential for there to be microbes in Martian samples robotically returned to Earth, what precautions are planned to prevent an accident or anomaly or something else unlikely but not impossible from releasing them into Earth's environment? Will there be hazmat crews ready to go if another Genesis-like land crash happens for example? What if it crashes into water?
Please don't post answers that this is not likely to happen; this is a question about the extent of precautions.