SP-4902 The Planetary Quarantine Program


Implementation and Policy Directives


[25] DR. ABE SILVERSTEIN'S LETTERS written in October 1959 were partially quoted earlier, together with the comment that they constituted the first formal NASA policy directive on spacecraft sterilization. They all contained the statement that "payloads which might impact a celestial body must be sterilized before launching." This was an unequivocable statement, with no qualification, and sterilization is an absolute term.

While this directive could not have been completely unexpected, since those involved with imminent launchings were aware of the recommendations the biologists had been making, its immediate application posed innumerable difficulties. To begin with, these activities were in the hands of physical scientists and engineers who had little previous experience with biology, much less with sterilization techniques, and no knowledge of what the application of these treatments would do to the spacecraft they were designing. Sterilization at that time was usually thought of in hospital terms, involving small items such as those used in surgery. The technique predominantly used was autoclaving-wet steam at pressures of about 25 psi over atmospheric-and was usually conducted in small pressure chambers. This was hardly applicable to spacecraft.

The Lederberg ad hoc committee on spacecraft sterilization had stated that one research group, the U.S. Army BioLabs, had experience dating back to World War II in sterilizing objects as large as army trucks and as delicate as laboratory balances. They recommended that this experience be utilized. Dr. Silverstein's letters repeated this recommendation, and, shortly afterward, NASA and the U.S. Army signed an interagency agreement formalizing this cooperation. BioLabs [26] had developed gaseous sterilization techniques, particularly around the use of volatile and noncorrosive ethylene oxide, which could be used in simple plastic containers at ambient temperatures and pressures. The SSB and Dr. Silverstein's directives recommended that this technique be explored.

A complicating factor which eliminated sole reliance on a simple terminal gaseous sterilization of an assembled spacecraft soon evolved. This gaseous treatment would take care of microorganisms only on exposed surfaces. Lederberg had expressed concern that microorganisms might be protected between the threads of screws, for example, or in plastics or potting materials used to protect electronic components. The lunar launches then in the planning stage involved hard landings, which could cause such buried contamination to become exposed. Until this time, only surface sterilization had been a concern. No surgeon after an operation would crumble the instruments he had used and drop them into the open wound before he sewed up the incision he had made. This, however, was essentially what could happen on a hard lunar landing. In the absence of any restraining atmosphere, the exposed contaminated parts could be transported, depending upon their initial velocity and trajectory, to distances far beyond the landing site.

The Army BioLabs group looked into this matter of buried contamination. After exploratory experiments, they found that hardy microorganisms could indeed survive certain polymerization processes of plastics, and, moreover, that many electronic components-capacitors, resistors, transformers-as received from the manufacturer contained viable microorganisms inside them which grew when the components were cracked or crushed open, even after being surface sterilized with ethylene oxide.

This information was reported at the annual convention of the Society of American Bacteriologists in Philadelphia in May 1960 and subsequently published in Science (Phillips and Hoffman, 1960).

There were only two known sterilization techniques at that time which could be used for such buried contamination-heat and penetrating radiation. Radiation had considerably less effect on microorganisms than on higher forms of life. Very high dosages were required, in the order of three to five megarads, rather than dosages in the hundreds or low thousands which were lethal to higher life forms. Many spacecraft components simply could not withstand this treatment. Heat too had its drawbacks. Sterilization dosages were well worked out for autoclaving, requiring only 15 to 20 minutes at temperatures around 125°C. But steam could no more penetrate to the buried microorganisms than could the sterilizing gases. Heat in that [27] case had to be dry heat, even if applied in an autoclave. Microorganisms in the dry state, as opposed to those freely exposed to wet steam, were much more resistant. At temperatures in the range of 160°C to 170°C, four or more hours were required for sterilization. Moreover, because of these long exposure times and high temperatures the process had been little used and, hence, there were few data available. No data were available on dry heat sterilization rates at lower, and presumably less damaging, temperatures. The Army BioLabs in a few exploratory experiments determined that at 125°C exposure times extending to 24 hours would probably be required.

Meanwhile JPL was finding in planning for the Ranger program that it was not possible to live up to the absolute terms of the Silverstein directive.

The whole Ranger program was beset with difficulties, of which attempts at sterilization were only a part, but a particularly annoying part. This whole experience has been carefully documented in Project Ranger. A Chronology (Hall, 1971). This publication lists chronologically all the pertinent documents dealing with the Ranger history, together with a short summary of their contents. The following paragraphs summarize rather briefly the part that sterilization played in this attempt at lunar exploration.

On March 8, 1960, JPL established spacecraft sterilization guidelines for the Ranger project, and in April a Spacecraft Sterilization Panel decided that they would only generate techniques with Rangers I and 11, which were to be Earth orbiters. Then they would utilize these techniques with Rangers 111, IV, and V, which were planned to take TV pictures prior to hard lunar impacts. Later in April 1960, JPL released detailed in-house procedures which included first a dry heat treatment and then a terminal gaseous sterilization at the launch site.

Further studies with spacecraft components were taking place during the delays that occurred in the Ranger program, and JPL was finding it impossible to sterilize all Ranger components internally. Such terms as "sterilization to the extent feasible" began to creep into correspondence. Then on December 23, 1960, after considerable staffing, NASA issued a memorandum to Program Directors at NASA headquarters and Directors of field stations on the subject: "Decontamination and sterilization procedures for lunar and planetary space vehicles." The memo was signed by Hugh L. Dryden, NASA Deputy Administrator, for T. Keith Glennan, Administrator. The directive restated that "effective decontamination and sterilization procedures for lunar and planetary space vehicles are essential." It called for extensive studies to be initiated to achieve this goal. Sterilization plans for each mission would be prepared for the [28] NASA Associate Administrator and no mission would be flown until he had approved the planned procedures. Waivers could be granted if certain essential components could not be sterilized internally as well as externally.

The requested studies, particularly on dry heat sterilization, were initiated at JPL. In addition, NASA headquarters supported an extensive basic research program on dry heat with other contractors, beginning with the Wilmot Castle Company contract in March 1961. This effort has continued under various investigators to the present.

At this point it is advisable to list the various U.S. Lunar and planetary flight missions, together with their launch dates, or projected launch dates in the cast of certain planned planetary missions (see Table III). To keep the chronology straight, it should be noted that the first object to impact the Moon was the U.S.S.R. Luna 2 launched in September 1959. Soviet officials stated that Luna 2 had been given a sterilization treatment prior to launch, but details of the methods used were never made available.

Ranger 1, not launched until August 1961, went into a lower Earth orbit than planned. As a result of the failure of its Agena booster, Ranger 11 failed in its November 1961 launch attempt and did not go into orbit. Ranger 111, the first attempted lunar lander, missed the Moon by about 23,000 miles, and the TV pictures are unusable. Not until April 1962, with Ranger IV, was the U.S. able to repeat the Soviet accomplishment of landing an object on the Moon. This flight was by no means a complete success. No TV pictures were returned. The space vehicle went out of control and crashed on the far side of the Moon.


Table III. U.S. space launches of planetary quarantine interest.

Lunar missions

Aug 58

Thor-Able Pioneer


Oct 58

Pioneer I


Nov 58

Pioneer 2


Dec 58

Pioneer 3


Mar 59

Pioneer 4

Flyby, missed Moon

Nov 59

Atlas-Able 4


Sep 60

Atlas-Able 5A


Dec 60

Atlas-Able 5B


Aug 61

Ranger I

Failed, nonlunar

Nov 61

Ranger 2

Failed, nonlunar

Jan 62

Ranger 3

Flyby, missed Moon

Apr 62

Ranger 4

Impact, no TV

Oct 62

Ranger 5

Flyby, missed Moon

Jan 64

Ranger 6

Impact, no TV

Jul 64

Ranger 7

Impact, TV

Feb 65

Ranger 8

Impact, TV

[29] Mar 65

Ranger 9

Impact, TV

May 66

Surveyor I

Soft landing, TV

Sep 66

Surveyor 2

Impact, no TV

Apr 67

Surveyor 3

Soft landing, TV

Jul 67

Surveyor 4

Impact, no TV

Sep 67

Surveyor 5

Soft landing, TV

Nov 67

Surveyor 6

Soft landing, TV

Jan 68

Surveyor 7

Soft landing, TV

Aug 66

Lunar Orbiter 1

Orbit, then impact

Nov 66

Lunar Orbiter 2

Orbit, then impact

Feb 67

Lunar Orbiter 3

Orbit, then impact

May 67

Lunar Orbiter 4

Orbit, then impact

Aug 67

Lunar Orbiter 5

Orbit, then impact

Dec 68

Apollo 8

Manned circumlunar

Mar 69

Apollo 9

Manned orbit

May 69

Apollo 10

Manned orbit

Jul 69

Apollo 11

Manned landing

Nov 69

Apollo 12

Manned landing

Apr 70

Apollo 13

Aborted landing; manned circumlunar

Jan 71

Apollo 14

Manned landing

Jul 71

Apollo 15

Manned landing

Apr 72

Apollo 16

Manned landing

Dec 72

Apollo 17

Manned landing

Aug 71

P&F Satellite

Orbit, launched from Apollo 15

Apr 72

P&F Satellite

Orbit, launched from Apollo 16; impact

Jul 66

Explorer 33

Flyby, missed lunar orbit

Jul 67

Explorer 35

Selenocentric (lunar) orbit

Jun 73

Explorer 49

Selenocentric (lunar) orbit

Mars missions

Nov 64

Mariner 3


Nov 64

Mariner 4

Flyby, TV

Feb 69

Mariner 6

Flyby, TV

Mar 69

Mariner 7

Flyby, TV

May 71

Mariner 8


May 71

Mariner 9

Mars probe in orbit, TV



Lander and orbiter (proposed)

Venus missions

Jul 62

Mariner 1


Aug 62

Mariner 2


Jun 67

Mariner 5


Mariner Venus/Mercury 1973 mission

Nov 73

Mariner 10


Outer planets missions

Mar 72

Pioneer 10

Jupiter flyby

Apr 73

Pioneer 11

Jupiter, Saturn flyby

Aug 77


Jupiter, Saturn flyby (proposed)

[30] Ranger V, launched in October 1962, had a power loss, missed the Moon, and again sent back no pictures. Rangers III, IV, and V had all received dry heat treatments and a terminal sterilization treatment with gas.

The series of Ranger failures aroused a storm of protest, both within the government and in the press. In spite of the fact that some failures were definitely due to other causes, there were claims that the sterilization treatments, particularly dry heat, were at least partially responsible. This could not actually be proven, but the suspicion caused a heavy flow of memoranda and letters both within NASA and JPL and between them. Waivers grew instead of decreased in numbers. What was more, the climate was changing. The scientific community had never presented a unified front demanding sterilization for lunar, as opposed to planetary, missions. Those claiming it was unnecessary were becoming more vocal. In July 1962 at the NAS Iowa Summer Study, the Working Group on Biology, with Dr. Allan H. Brown as Chairman and Dr. C.S. Pittendrigh as Vice Chairman, concluded that "contamination of the Moon does not constitute as serious a problem as is the case of the planets. Nevertheless, lunar contamination should be kept at a feasible minimum." They added, "Planning for Manned Landings on the Moon and planets must be based on the assumption that sterility precautions will still be required during the phase of manned exploration."

Moreover, priorities were changing. The manned space program was well along. President Kennedy had stated to Congress in May 1961 that the U.S. would land a man on the Moon "within this decade." And wherever man went, his flora of microorganisms would accompany him. The hope now was that contamination could be kept to such a minimum that it would not interfere with tests for the presence of biological matter on returned lunar samples.

As early as November 1962, JPL was told to stop dry heat treatments on components for the future Ranger vehicles. There was a last ditch effort to keep the requirement for a terminal gaseous surface sterilization treatment of the assembled vehicle, but that too was dropped in later correspondence.

This change of policy was not made official until September 9, 1963, when NASA issued its Management Manual NMI-4-4-1, "NASA Unmanned Spacecraft Decontamination Policy." The management instruction stated under policy for the Moon that


1. The NASA policy is based on acceptance of the scientific opinion that lunar surface conditions would mitigate against reproduction of known terrestrial microorganisms and that, if subsurface penetration of viable organisms were to be caused [31] by spacecraft impact, proliferation would remain highly localized.
2. It is the NASA policy to protect the Moon from widespread or excessive contamination until sufficient information has been obtained concerning the Moon, to ensure that scientific studies will not be jeopardized.


The management instruction further stated under "Required Procedures" that clean-room assembly policies be adopted, sporicidal agents be used when "appropriate" to reduce surface contamination, and final assembly be wrapped and handled in such a way as to prevent accumulation of contamination during its shipment to the launch site. This was the policy followed on the subsequent Ranger spacecraft, as well as on the Surveyor and Lunar Orbiter spacecraft.

Ranger Vl again failed to return TV pictures, but the last three Rangers, Vll, Vlll, and IX, were complete successes, and the live TV pictures returned, up until the vehicles crashed on the Moon's surface, were viewed by millions throughout the world. The despair over the U.S. space program turned overnight into complete pride of accomplishment.

Ranger was followed by the seven Surveyor launches, five of which-including the first-successfully showed closeup details of the lunar surface. Also, the Lunar Orbiter program's five missions effectively mapped the Moon and furnished the basis for choosing landing sites for the Apollo astronauts. The late President Kennedy's goal was accomplished on schedule when Apollo 11 astronauts Armstrong and Aldrin set foot on the moon on July 20, 1969.

The abandoned lunar sterilization policies were replaced by quarantine policies. On August 24, 1967, NASA entered into an Interagency Agreement, "Protection of the Earth's Biosphere from Lunar Sources of Contamination," with the Departments of Agriculture; Interior; and Health, Education, and Welfare. All of these agencies had regulatory responsibilities concerning prevention of introduction of alien plant, animal, or human parasites or disease into the United States. The National Academy of Sciences was also a party to this interagency agreement. Under this agreement, the Manned Spacecraft Center in Houston issued Management Instruction 8030.1, dated January 9, 1967, and entitled "Assignment of Responsibility for the Prevention of Contamination of the Biosphere by Extraterrestrial Life." This was followed by the implementary "Quarantine Schemes for Manned Lunar Missions," prepared by the Interagency Committee on Back-Contamination which had representatives of all parties to the interagency agreement.

NPD 8020.13, April 4, 1969; NPD 8020.14, July 16, 1969; NMD/A [32] 8020.15, July 16, 1969; and NMD/M 8020.16, July 23, 1969, all implemented the interagency agreement dealing with back-contamination, extraterrestrial exposure, and authority to deal with any cases that might occur. These quarantine provisions were two-fold in purpose. One was the prevention of back-contamination. However unlikely one considered the existence of live microorganisms on the Moon to be, they could not be completely ruled out beforehand, and the covert introduction of alien life forms to the Earth's biosphere could be catastrophic. A second reason was protection of the precious lunar samples from any possible terrestrial contamination until they could be carefully examined for the presence of any trace biological component, viable or nonviable. The Lunar Receiving Laboratory was therefore built at the Manned Spacecraft Center in Houston, and the Mobile Quarantine Facility was constructed to transport both astronauts and samples there from the naval recovery carrier. During the short helicopter trip from the splashdown site to the carrier, the samples were in sealed containers and the astronauts wore a specially designed Biological Isolation Garment. The public, as well as the scientists, detected several possible gaps in the quarantine procedure, and protests, particularly from the medical profession, were numerous, but these were blunted by the fact that all the gaps had been foreseen and were authorized by regulatory authorities outside of NASA.

On September 6, 1967, NASA issued NPD 8020.8, "Outbound Lunar Biological Contamination Control: Policy and Responsibility." It noted that, while the object of the early phases of lunar exploration had been "complete sterility," each probe that impacted the Moon had carried a number of microorganisms. It quoted the recommendations of the SSB to minimize contamination and to develop a sterile drilling system so that subsurface lunar samples could be collected and returned aseptically during the Apollo missions. This directive was updated by NPD 8020.8A on May 2, 1969, just before the Apollo 11 manned landing.

NASA NMI-4-4-1, which lifted lunar sterilization requirements, kept them for planetary missions, however. It stated, "It is the policy of the NASA to prevent the biological contamination of the planets until sufficient information has been obtained concerning the planets to ensure that biological studies will not be jeopardized and that no hazard to earth exists."

Not listed in Table IV were two planned 1966 Mars flights which were canceled, primarily for budgetary reasons, and never became attempted launchings. Both, however, were of considerable planetary quarantine interest during the planning stages. A planned Voyager [33] launch was to land an Automated Biological Laboratory on the surface of Mars. A sterilization plan was written for this launch before the project was canceled. The second canceled launch, Mariner-Mars 1966, was to have been a flyby, although at one time in the planning stages a small landing capsule was considered.

NASA NMI-4-4-1 was replaced on September 6, 1967, by NASA Policy Directive 8020.7, "0utbound Spacecraft: Basic Policy Relating to Lunar and Planetary Contamination Control." This document restated that no planetary mission would transport terrestrial life to the planets "within probabilities established by issuances implementing this policy." For the first time, the unworkable absolute ban was dropped. It also specified that "microbial life landed on the Moon ....shall be identified, quantified and, insofar as possible, located" so that it could be identified as terrestrial if found in returned samples. The implementation of this latter directive appeared in NHB 5340.1A, "NASA Standard Procedures for the Microbiological Examination of Space Hardware," October 1968.

Basic quarantine policy for planetary missions appeared in NPD 8020.10 also dated September 6, 1967, and updated by NPD 8020.10A, "Outbound Planetary Biological and Organic Contamination Control Policy and Responsibility," August 1, 1972. Both documents contained the following provision:


Biological Contamination. The basic probability of one in one thousand (1 x 10-3) that a planet of biological interest will be contaminated shall be used as the guiding criterion during the period of biological exploration of Mars, Venus, Mercury, Jupiter, other planets and their satellites that are deemed important for the exploration of life, life precursors or remnants thereof.


NASA directive NHB 8020.12, "Planetary Quarantine Provisions for Unmanned Planetary Missions," April 1969, directed that quarantine plans for planetary missions be submitted to the Planetary Quarantine Officer for approval, and again spoke not in absolute terms, but in probabilities of contamination, in line with the international agreements.