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Letter Report
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From page 1... ... In response to your request, the Task Group on Planetary Protection Requirements for Venus Missions was formed (the membership of the task group is listed in Attachment 1) and met at the Southwest Research Institute in Boulder, Colorado, on October 3-5, 2005. Read the entire page →
From page 2... ... The known aspects of the present-day environment of Venus offer compelling arguments against there being significant dangers of forward or reverse biological contamination, regardless of the unknowns. Full details are contained in the attached "Assessment of Planetary Protection Requirements for Venus Missions." Because of the extreme temperature at the Venus surface, the fact that concentrated H2SO4 is sterilizing for all known Earth organisms, the consideration that the Venus cloud environment is extremely dehydrating and oxidizing, and the realization that any life forms adapted to the Venus clouds would not survive in Earth conditions, with respect to planetary protection issues, the task group concluded as follows: � No significant risk of forward contamination exists in landing on the surface of Venus; � No significant forward-contamination risk exists regarding the exposure of spacecraft to the clouds in the atmosphere of Venus; � No significant back-contamination risk exists concerning the return of atmospheric samples from the clouds in the atmosphere of Venus; and � No significant risk exists concerning back contamination from Venus surface sample returns. Read the entire page →
From page 3... ... Sincerely, Jack W Szostak, Chair Task Group on Planetary Protection Requirements for Venus Missions Attachment: Assessment of Planetary Protection Requirements for Venus Missions Read the entire page →
From page 4... ... to address three issues in terms of their implications for planetary protection: 1. Assess the surface and atmospheric environments of Venus with respect to their ability to support Earth-origin microbial contamination, and recommend measures, if any, that should be taken to prevent the forward contamination of Venus by future spacecraft missions; 2. Read the entire page →
From page 5... ... Water vapor ranges from a few parts per million at the top of the cloud deck to a few tens of parts per million at the base. However, the cloud droplets are formed of extremely concentrated sulfuric acid. Read the entire page →
From page 6... ... has a long track record of assessing the biological potential of Venus and making recommendations concerning appropriate planetary protection guidelines for Venus missions. In 1970, for example, the SSB's predecessor, the Space Science Board, commented as follows:8 A slight possibility exists that terrestrial organisms could grow on airborne particles near to the cloud tops of Venus. Read the entire page →
From page 7... ... . The planetary protection characterization resulting from the two NRC studies conducted in the 1970s was that although Venus was of some interest with respect to issues of chemical and biological evolution -- for example, to studies relating to the divergent evolutions of Earth, Mars, and Venus -- the chances of contaminating Venus with terrestrial organisms are so slight that no special requirements need be levied on spacecraft missions to that planet. Read the entire page →
From page 8... ... Even if life did independently arise on the surface of Venus, it is very clear that it must have eventually become extinct or migrated to the cloud environment as the runaway greenhouse effect heated up the surface of the planet and evaporated most of the volatiles, except for those that recondensed in the global cloud deck. Any life remaining in the cloud deck would have had to adapt to conditions that do not overlap the range of conditions inhabited by life on Earth. Read the entire page →
From page 9... ... The dominant factor in this assessment is the concentration of sulfuric acid (and corresponding lack of free water) in cloud droplets in Venus's atmosphere. Read the entire page →
From page 10... ... However, the cloud droplets are formed of extremely concentrated sulfuric acid, with weight percents ranging from 85 percent at the top of the cloud deck (with a slight dip to 82 percent within the upper cloud layer) to 98 percent at the bottom of the lower cloud layer. Read the entire page →
From page 11... ... NASA has a clear need to obtain external guidance on the planetary protection requirements for Venus missions that is based on a careful assessment of the most recent planetological and biological information. Without such guidance, NASA cannot provide the appropriate guidelines to mission designers, nor can it establish operational procedures for future Venus missions. Read the entire page →
From page 12... ... � Atmospheric probes, including balloons -- Venus's cloud layers are an environment of moderate temperature and pressure. However, because the cloud droplets consist of concentrated sulfuric acid, any terrestrial organisms would be rapidly destroyed by chemical degradation. Read the entire page →
From page 13... ... GRINSPOON, Southwest Research Institute ANTHONY D KEEFE, Archemix Corporation GARY J Read the entire page →
From page 14... ... Category III includes certain types of missions (typically a flyby or orbiter) to a target body of chemical evolution or origin-of-life interest, or for which scientific opinion holds that the mission would present a significant chance of contamination which could jeopardize future biological exploration. Read the entire page →
From page 15... ... If any sign of the existence of a non-terrestrial replicating organism is found, the returned sample must remain contained unless treated by an effective sterilization procedure. Category V concerns are reflected in requirements that encompass those of Category IV plus a continuous monitoring of mission activities, studies, and research in sterilization procedures and containment techniques. Read the entire page →
From page 16... ... , Neville Woolf (University of Arizona) , and Linda Amaral Zettler (Marine Biological Laboratory) Read the entire page →

From page 1...

... In response to your request, the Task Group on Planetary Protection Requirements for Venus Missions was formed (the membership of the task group is listed in Attachment 1) and met at the Southwest Research Institute in Boulder, Colorado, on October 3-5, 2005.

Letter Report Pages 1-16

Letter Report
Pages 1-16