Space Quarantine

Jose Ribeiro

HET610, SAO

Whenever the Portuguese Navigators from the XV century found a desert island, they used to leave rabbits behind. Their aim was to verify whether the island had conditions for habitability or not. On their way back they would check if the rabbits’ population had grown. They did multiply! And today, farmers from Madeira and some islands in The Azores still fight sporadic rabbits plague.

“Invaders can change ecosystems where they differ substantially from the natives in resource acquisition or utilisation” (1).

Today, the new discoverers enlarged their frontiers beyond Earth, sending exploratory probes and men to space. Although manned spacecraft have so far only landed on the moon, several robotics spacecraft already landed in Mars, Venus, one entered Jupiter’s atmosphere, another landed on the asteroid Eros, and one is now on its way to Titan. In the agenda are also under preparation missions to collect and send to Earth samples from the Martian soil, cometary matter, as well as to send an exploratory probe to Europa.

Very early, since the preparation of the Apollo project, that the biologic risks began to be discussed, as well as the respective prevention protocols against the interplanetary biologic contamination. At first, works were mainly focused on the risks of back contamination, i.e. the risk of lunar soil samples and astronauts bringing extraterrestrial micro organisms, which might somehow contaminate Earth. In 1967 the “Outer Space Treaty” was signed, which “specifically requires that all space exploration must be done in a way that avoids harmful contamination to celestial bodies or adverse changes in the environment of the Earth from the introduction of extraterrestrial materials” (2) (4).

Since then, the development of Planetary Protection (PP) policies has been under the responsibility of the Committee on Space Research (COSPAR) (2) (3), of the International Council of Scientific Unions. In the USA the PP policy is implemented by NASA, who is advised by the Space Studies Board (SSB) (4).

Protocols were created for the prevention of two types of cross-contamination:

- back contamination, that is the introduction on Earth of extraterrestrial contaminating agents brought by men, equipment or samples.

- forward contamination, that is the transport of contaminating agents from Earth to space by spacecraft and men.

Due to an absolute lack of information on extraterrestrial micro-organisms, measures for planetary protection have as parameters the study of the extreme micro-organisms found on Earth (2); yet, this procedure can have certain limitations, as the most extreme environmental conditions found on Earth are soft compared to space environmental conditions. On one hand, our extreme micro-organisms may not survive extraterrestrial environments (what is highly probable), and on the other, extraterrestrial micro-organisms (should they exist) may be highly resistant due to the inhospitable conditions they live in, thus representing an increased risk to the ecosystem on Earth. As adverse as the environmental conditions may be, the micro-organisms on Earth need liquid water in order to survive (1). Therefore, forward contamination risks increase in regions where liquid water exists, as in Mars and in Europa. Yet, there are confirmed exceptions, as the case of the camera of the Surveyor 3 Lander, brought to Earth by the astronauts of Apollo 12, which contained bacteria still viable after two and a half years on the moon (5).

Not long ago, the existence of extreme microbes would be considered scientific fiction, due to peculiar environments they live in:

- in volcanic areas live the extreme Thermophiles, growing at temperatures exceeding 100ºC (6).

- bacterial endospores, the resting stage of certain bacteria, are known to survive for thousands of years, resisting to freezing and vacuum, and resisting moderately to heat and to UV and ionising radiation (6).

- deep subsurface micro-organisms have been found at 700 meters below Earth surface. Some of these species have the capacity of repairing their DNA, denoting great resistance to UV radiation and long-term survival, even in space. Others, the extreme Halophiles are embedded in crystals of salt dated approximately 200 million years old. The Barophilic bacteria was isolated from the deep sea revealing great pressure resistance. The Cryptoendolyth are found in the Antarctic, forming communities within sandstone. They are adapted to extreme low temperatures, low moisture and high winds (6).

- the radiation-resistant bacteria can withstand large doses of radiation. Some have been found within the course of radioactive reactors (6).

Life adapts itself - so, one should not ignore the contamination risks even in zones where survival is highly improbable.

The report of SSB from 1978 “Recommendations on Quarantine Policy of Mars, Jupiter, Saturn, Uranus, Neptune, and Titan” has been updated along the years, as scientific and technologic knowledge develops. Recommendations regarding control of Mars forward-contamination are as follows:

“1. Landers carrying instrumentation for in situ investigation of extant Martian life should be subject to at least Viking-level sterilisation procedures (...)”

“2. Spacecraft (including orbiters) without biological experiments should be subject to at least Viking-level presterilization procedures – such as clean-room assembly and cleaning of all components – for reduction of bioload, but such spacecraft need not be sterilised. (...)” (7).

The main reason for these recommendations is linked to the fact that life detection experiments as well as the equipment used in the experiments are extremely susceptible to biological and chemical contamination by agents on Earth. To detect life on a planet to then conclude that its origin was from Earth, should not be the purpose of such expensive missions.

The Viking-level procedure of sterilisation, first applied to the Viking missions, obeys to the four following steps:

“1. Surfaces were rigorously cleaned to reduce the starting bioburden on the spacecraft (...)”

“2 .Instruments were cleaned and assembled in cleanrooms by workers in surgical attire (...). Both the lander and orbiter were treated in this way.”

“3. The entire lander and its payload were assembled under the same conditions. (...)”

“4. The lander was then placed in an oven and subjected to dry heat in cycles (...)” (8).

Since the Viking mission, NASA has been concerned in practice with the forward-contamination; for example, in the Mars Pathfinder Mission Status from 4th February 1997, it is reported: “The spacecraft will not be placed on a Mars atmospheric entry trajectory until after TCM-3 because of planetary quarantine requirements” (9).

Prevention practice to back-contamination goes back to the Apollo mission, and was under the responsibility of the Lunar Receiving Laboratory (LRL). In this Laboratory the astronauts, a physician, a technician, as also the lunar soil samples, remained under quarantine. The astronauts were submitted to a three week quarantine (10). The astronaut quarantine practice was discontinued after the Apollo 14 mission, as from the outcome of the studies from Apollo 11 and 12 missions, they reached the conclusion that it was not a necessary procedure (11).

Lunar soil samples were all submitted to quarantine. In this case, the protocol aimed to “permit assessment of lunar material so that samples could be released within 30 days from their arrival at the LRL, unless some evidence of extraterrestrial organisms appeared.” (12)

Planetary protection today is so important as any other phase of a space mission. The respect for the ecosystems will be culturally consolidated in developed countries in the next few generations. Earth, as well as other celestial bodies, are not free from an alien contamination. It belongs to NASA History that some engineers and scientists from the Manned Spacecraft Center “felt that the quarantine facility and its elaborate precautions were unnecessary impediments to Apollo operations” (13). Fortunately for mankind, the USA is a country with a financial budget to space exploration. Yet, the risk that poor countries, with access to space technology, neglecting the prevention procedures is dangerously high.

On the other hand, human error is an existing factor: risk evaluation errors and procedure simplification (the urgent deadlines may lead to simplification of certain aspects, which otherwise would be more thoroughly considered).

And, obviously, there may be contamination risks in case panspermia is a reality. The entry in the atmosphere of a contaminated meteor may start an infestation (14); yet this fact is inevitable.

Scientists can also opt to colonise planets with Earth biomass, in order to study the conditions of habitability of those ecosystems. But before, they should take into account the outcome of the “rabbits experiment” of the Portuguese Navigators from the XV century....

References

1- Elliot Levinthal, “Search for the Evidence of Live: Caution and Humility: Where

There’s Water”

http://calspace.uscd.edu/marsnow/library/science/exobiology/

2- Race,M.S. , Rummel, J.D., “Bring Em Back Alive-Or At Least Carefully

http://www.astrobiology.com/adastra/bring.em.back.html

3- “Planetary Protection for Mars Missions”

http://cmex-www.arc.nasa.gov/Exo_Strat/Docs/protection.html

4- “Biological Contamination of Mars-Issues and Recommendations”-Summary

http://www.nas.edu/ssb/bcmarsmenu.htm

5- Daniel Pendick, “The Real Men in Black”, Astronomy mag., July 99, pp.36

6- “Biological Contamination of Mars-Issues and Recommendations”-Chap.4