February 16, 2005

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Planetary Protection All of the Planets, All of
the Time
February 16, 2005
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Planetary Protection

• Objective
• Protect the scientific integrity of other solar
  system bodies for future discovery of life,
  remnants of past life, and the precursors of life
  (forward contamination)
• Protect the Earth from possible hazards of
  returned extraterrestrial material (back
  contamination)
• Project responsibility
• Failure to comply with PP requirements can result
  in launch prohibition

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Microbial Life Abounds on Earth

• Microbial world accounts for all known life forms
  for nearly 90 of the Earths history
• They are everywhere
• 109 cells/g typical soil sample
• 106 cells/ml in open ocean
• Have helped shape our search for extraterrestrial
  life
• Earth microbes have been observed to thrive in
  extreme environments (extremophiles)
• Sulfur oxidizing bacteria found in mid-ocean
  vents (500 C)
• Psychrophiles in Antartic dry valleys (0 C)
• Halophiles in salt ponds
• Acidophiles in Rio Tinto, Spain (pH 2)
• Demococcus radiodurans thrive in extreme radiation

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Planetary Protection vs. Contamination Control

• Contamination control
• Particulate and molecular contamination on flight
  systems to ensure payload instruments proper
  function
• CC requirements derived from science requirements
• Planetary Protection (forward contamination)
• Requirements levied by NASA for benefit of
  present and/or future science
• Biological and organic contamination control on
  all flight hardware that reaches another planet
• Some overlap, but not all methodologies in common

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Historical Perspective

• 1958 National Academy of Sciences forms Space
  Science Board
• SSB calls for the conduct of planetary
  exploration in a fashion which ... prevents
  contamination of celestial objects...
• 1963 On basis of SSB input, NASA adopts
  following policy
• Lunar spacecraft will reduce microbial load to a
  minimum through the use of assembly and check out
  in clean rooms and the application of surface
  sterilants after final assembly and check out
  Mars flights will have less than a 10-4
  probability of hitting the planet, while landers
  will be sterilized after complete assembly and
  checkout Venus flights will have less than 10-2
  probability of hitting the planet.
• 1964 COSPAR adopts following policy
• 10-4 or less for viable organism on lander or
  probe (anywhere!) and accidental impact by
  unsterilized flyby or orbiter lt 3x10-5
• 1967 International Treaty signed by U.S.
• MOON TREATY - States parties to the treaty shall
  pursue studies of outer space... so as to avoid
  their harmful contamination and also adverse
  changes in the environment of the Earth...
• 1967 NASA PP Policy adopts COSPAR resolution
• NASA first version of 8020.7 and 8020.12

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COSPAR PP Mission Constraints

• Depend on the nature of the mission and the
  target planet
• Assignment of categories for each specific
  mission/body
• Specific measures regarding
• Spacecraft operating procedures
• Spacecraft organic inventory
• Handling of returned samples
• Spacecraft trajectories and materials
• Intentional and unintentional deposition of Earth
  organisms on other solar system bodies
• End of mission disposition of spacecraft and its
  components

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NASA PP Policy

• The conduct of scientific investigations of
  possible extraterrestrial life forms, precursors,
  and remnants may not be jeopardized. In addition,
  the Earth must be protected from the potential
  hazards posed by extraterrestrial sources.
  Therefore, for certain space-mission/target-planet
  combinations, controls on organic and biological
  contaminations carried by spacecraft shall be
  imposed.
• Planetary Protection Officer
• Prescribe standards, guidelines and procedures
• Conduct reviews
• Certify compliance
• PP policy does not apply to
• Earth orbiting missions
• Lunar missions
• Human missions

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Governing Documents

• NASA Policy Directive 8020.12B Planetary
  Protection Provisions for Robotic
  Extraterrestrial Missions
• Defines PP mission categories
• Details PP requirements
• Establishes schedules and documentation for
  reviews
• Include PP parameter specifications
• NASA Policy Directive 5340.1C NASA Standard
  Procedures for the Microbial Examination of Space
  Hardware
• Defines specific procedures for the microbial
  examination of space hardware and associated
  environments

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Mission Categories
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Example Mission Categorizations

• Category I Any mission type to Sun or Mercury
• Category II Any mission type to Venus, Jupiter,
  Saturn, Uranus, Neptune, Pluto, outer planet
  satellites (except Europa), comets, asteroids
• Category III Fly-bys or Orbiters to Mars,
  Europa
• Category IV Landers or Probes to Mars or Europa
• Cat. IVa Without life-detection experiments
• Cat. IVb With life-detection experiments
• Category V Earth return from any
  extraterrestrial solar system body (except the
  Moon)
• Restricted Earth return
• Unrestricted Earth return

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Planetary Protection Categorizations
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Scope of Work

• Categories I and II
• Little cost or risk, technically simple, but
  expert assistance needed
• Categories III and IVa
• Significant costs and risks, technically
  difficult
• Implementation methods and required tasks cross
  several areas of typical Project WBS
• Categories IVb and V restricted Earth return
• Great costs and risks, technically challenging

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Project Implementation

• Planning
• PP Plan, Subsidiary Plans
• Cuts across mission and flight systems
• Managed like any other project resource
• Planned, tracked, margined
• Analysis
• Bacterial burden accounting
• Biological contamination control
• Reports and reviews, documentation

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Category III Requirements for Mars

• Orbiter missions can either choose to achieve
  bioburden levels equivalent to Viking pre-flight
  sterilization total bioburden (5 x 105 spores)
• OR
• Meet the following orbital lifetime requirements
• 20 years after launch at gt 99 probability and
• 50 years after launch at gt 95 probability

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Category IV A/B Requirements for Mars

• Categories IVA
• Lander systems not carrying instruments for the
  investigation of extant life are restricted to a
  biological burden no greater than Viking lander
  (3 x 105 spores) pre-sterilization levels
• Category IVB
• Lander systems designed to investigate extant
  life are required to meet the requirements of
  Category IVA, plus
• The entire landed system must be sterilized at
  least to Viking post-sterilization biological
  burden levels or to levels of biological burden
  reduction driven by the nature and sensitivity of
  the particular life-detection experiment,
  whichever are more stringent
• Or
• The subsystems which are involved in the
  acquisition, delivery and analysis of samples
  used for life detection must be sterilized to
  these levels and a method of preventing
  recontamination of the sterilized subsystems and
  the contamination of the material to be analyzed
  is in place

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Mars Category IVA PP Burden Requirements

• Maximum value for exposed external and internal
  surfaces is 3 x 105 spores and a max average
  density of 300 spores/m2
• Values at launch (no allowance for inflight
  environments or surface conditions) per lander
  system or landing event
• Assay per Viking standards or demonstrated
  equivalence

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Category IV Implementation

• Implementing Procedures
• Trajectory biasing
• Clean room assembly
• Selected microbial reduction
• Organics inventory and archive
• Documentation
• PP Plan
• Pre-launch PP report
• Post-launch PP report
• End of mission report
• Subsidiary plans

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Approaches for Hardware Design

• Design for tolerance to assays
• Design for cleaning
• Smooth surfaces
• Accessibility before closeout
• Minimize accountable surfaces with HEPA filters
  or sealing
• Average encapsulated microbial density is 130 per
  cm-3 for all non-metallic volumes
• HEPA filters capable of removing 99.97 of all
  particles greater than 3x10-7 m in size
• Design for microbial reductions
• Heat tolerance (125 C for 50 hours)
• Especially important for impacting hardware with
  encapsulated spore burden rules
• Design for recontamination prevention

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Common PP Procedures

• Alcohol wipes (exterior surfaces) Isopropyl or
  ethyl alcohol swabbing. Not applicable to
  interior and encased surfaces which are
  inaccessible
• Dry heat 105-180 C for 1 to 300 hours. Viking
  performed DHMR at 111.7 C for 30 hours and was
  credited with a bioload reduction factor of 104.
  Problems caused by thermomechanical
  incompatibility with this environment (typically
  for electrical components).
• Radiation Typically 2.5 Mrad of gamma radiation.
  Problems encountered include optical changes in
  instrumentation and damage to solar cells,
  electronics
• Hydrogen peroxide Only applicable to exposed
  surfaces

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Time/Temperature for Sterilization

• Short time/temperature conditions at which all
  terrestrial organisms associated with spacecraft
  hardware will be eradicated
• 500 C for 0.5 sec
• Applies to exposed, mated and encapsulated burden
• Typically used for heatshield surfaces

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Cost

• PP implementation must be well planned and
  managed
• Costs increase with mission categorization
• Mars Category IV-A missions typically spend 1 of
  total project budget on planetary protection
• Category IV-B missions will spend much more,
  perhaps 5

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References

• Planetary Protection Policies and Practices
  Course Notes, Nov-03.
• NPD 8020.7E Biological Contamination Control for
  Outbound and Inbound Planetary Spacecraft, Feb-99
• NPG 8020.12B Planetary Protection Provisions for
  Robotic Extraterrestrial Missions, Apr-199
• NPG 5340.1D NASA Standard Procedures for the
  Microbial Examination of Space Hardware, Jan-00
• Preventing Forward Contamination of Europa,
  National Academy of Sciences SSB, 2000,
  http//www7.nationalacademies.org/ssb/europamenu.h
  tml
• Europa Orbiter Preliminary PP Requirements,
  Apr-99
• JPL Project Managers Training, 2002.
• JPL reference site http//planpro.jpl.nasa.gov/in
  dex.htm
• PP Bibliography http//dcypser.tripod.com/pp/plan
  etpr.html
• Astrobiology Web http//www.astrobiology.com/prot
  ection.html
• Summary article by John Rummel and Michael Meyer
  http//calspace.ucsd.edu/marsnow/library/mars_expl
  oration/robotic_missions/landers/sample_return/pla
  netary_protection1.html