NASA MEPAG Special Regions Science Analysis Group Findings April 13, 2006
1. INTRODUCTION
1a. “Special Regions”–History and the Current Problem
In 2002, COSPAR introduced the term “special region” as a part of Mars planetary protection policy. Prior to 2002, planetary protection related requirements for spacecraft going to the martian surface consisted of two categories that were distinguished by the purpose of the mission:
- IVa. Landers without extant life detection investigations
- IVb. Landers with extant life detection investigations.
However, by 2002 exploration results (primarily from the MGS orbiter, and soon after confirmed by Mars Odyssey) strongly suggested that some parts of Mars might be more likely than others to attract interest for extant life investigations and potentially be more vulnerable to the effects of Earth-sourced biological contamination. This led to the introduction of the concept of “special regions,” which are environments on Mars that need a high degree of protection independent of the mission purpose.
In April 2002, a COSPAR planetary protection workshop formulated a draft definition of “special region” and proposed that a new mission categorization, Category IVc, be established for missions that come (or might come) into contact with them. This proposal was presented to COSPAR at its 2002 meeting, and was formally adopted shortly afterwards (http://www.cosparhq.org/scistr/PPPolicy.htm). NASA followed up by incorporating the special regions concept into its policy by means of modification of NASA Procedural Requirements 8020.12C Planetary Protection Provisions for Robotic Extraterrestrial Missions, which was issued in 2005.
In 2005, an NRC committee (referred to as NRC PREVCOM) completed a NASA-requested detailed 2-year study entitled Preventing the Forward Contamination of Mars (NRC, 2006). In their analysis of “special regions,” NRC PREVCOM found that in using the current special region definition, “there is at this time insufficient data to distinguish with confidence “special regions” from regions that are not special.” They also raised an important issue of scale—”Mars exhibits significant horizontal and spatial diversity on km to cm spatial scales,” but some of the relevant observational data have a spatial resolution no better than ~3×105 km2. NRC PREVCOM recommended an interim policy in which all of Mars is considered a “special region.”
For further information on planetary protection policy and history related to Mars, the interested reader is referred to excellent recent reviews by DeVincenzi et al. (1998) and NRC (2006).
1b. This study
Purpose. At the November 2005 MEPAG meeting, NASA requested that MEPAG prepare a community-based analysis of the definition of “special region,” and if possible, propose clarifications that make the definition more useful for mission planning and PP implementation. MEPAG in turn chartered the Special Regions Science Analysis Group (SR-SAG) and gave it the following assignment:
- Propose, if it is possible to reach consensus, a quantitative clarification of the definition of “special region” that can be used in a practical way to distinguish between regions on Mars that are “special,” “non-special,” and “uncertain.”
- Prepare a preliminary analysis, in text form, of the kinds of martian environments that should be considered “special” and “non-special.” If possible, also represent this in map form.
Methodology. The SR-SAG consisted of 27 members with scientific backgrounds in various aspects of microbial survival, physics, geology, and planetary protection. The group included three members who also served as part of NRC PREVCOM. The SAG met by means of weekly teleconferences (with several sub-groups working in parallel) in December 2005 and January 2006, along with extensive e-mail exchange. From February 6-8, a three-day Special Regions Workshop was held in Long Beach, CA to integrate results.
