Planetary Contamination II: Soviet and U.S. Practices and Policies

The accompanying article of Horowitz et al. concluded with the view that the COSPAR recommendations regarding Mars should be adjusted to reflect new environmental information. Specifically, it was concluded that viable terrestrial microorganisms which are transported to Mars inside solid components in sealed spaces have a low probability of being released to the surface or atmosphere, and that, if any are released, they are not likely to infect the planet. We suggest, in addition, that both the COSPAR recommendations and U.S. planetary quarantine policy should be altered to take into account past and continuing Soviet practice regarding the exploration of Mars and Venus. No amount of analysis by COSPAR, or of costly, self-imposed restrictions by the U.S. on its own planetary exploration program, can reduce the probability of contamination of either Venus or Mars below what the Soviets have already made it, or will make it as they continue their large planetary effort. All that U.S. policy can accomplish is to insure that U.S. efforts do not significantly increase the probability above that level. Any recommended policy which would require the U.S. to apply significantly more stringent restrictions is illogical in that, in effect, the U.S. would be asked to increase greatly the cost and complexity of its planetary program without achieving any significant reduction in the probability of actual contamination. There exists some parallelism between the problem of planetary quarantine and that of radioactive fallout from atmospheric nuclear testing, although the desirable solution to the quarantine problem is not merely to stop all activity. Both are multilateral problems, and individual national policy necessarily must reflect the policy of other nations. Thus, the real questions that must be faced by COSPAR, and by the U.S., are, (i) What is the prob able number of viable terrestrial microorganisms already transported to Venus and to Mars? and (ii) What is the total number to be expected in the next decade or so from foreseeable Soviet efforts alone? Then COSPAR can recommend, and the U.S. can decide, that the total U.S. contribution should be equal to some specified fraction of the total present and future Soviet contribution. This approach in turn suggests that every effort should be made to induce the Soviets to supply additional de tails on the Zond 2 and Venus 3 mission and trajectory and, particularly, on the procedure used for sterilizing the components and assembly of both space craft. With such information, the probable number of viable terrestrial microorganisms deposited on Venus and Mars could be estimated well enough to permit a realistic quantitative analysis of what U.S. policy and practice should be. However, if more complete information on Soviet practice cannot be obtained, then, it seems to us, the U.S. has no logical alternative but to permit greater engineering freedom in lander delivery technique and to accept gaseous and other nonthermal sterilization procedures, where necessary, in its own program. By relying on the demonstrated U.S. spacecraft reliability to insure that the U.S. contribution to planetary contamination will remain significantly less than the Soviet contribution, we could reduce significantly the cost and time required to carry out serious scientific investigations of the surfaces of Venus and Mars.