Opening New Frontiers in Space: Choices for the Next New Frontiers Announcement of Opportunity (2008)

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Summary In 2007 NASA began planning to initiate a new competition for a New Frontiers mission. Because NASA has now selected two of the five missions recommended by the National Research Council’s (NRC’s) decadal survey New Frontiers in the Solar System, and because the decadal survey recommended that the agency ask the NRC for further advice on the New Frontiers Program after several selections had been made, in March 2007 NASA asked the NRC to: [P]rovide criteria and guiding principles to NASA for determining the list of candidate missions. These issues include the following: • Should the next New Frontiers solicitation be completely open relative to any planetary mission, or should it state a candidate list of missions as was done in the previous AO? • If a candidate list of missions is preferred, what is the process by which candidate missions should be deter- mined? Specifically, there is a need to review the mission categories identified in the previous AO and see if the list needs to be revised or augmented in light of developments since the release of the last AO. Should consideration be given to a candidate list of appropriate science themes from the NRC decadal survey on solar system exploration rather than to specific missions? The original statement of task for the Committee on New Opportunities in Solar System Exploration: An Evaluation of the New Frontiers Announcement of Opportunity included the words “excluding Mars” in the first question. In September 2007 NASA amended the statement of task so that Mars could be considered in a discus- sion of the future direction of the New Frontiers Program. NASA’s New Frontiers Program is a series of principal-investigator-led solar system exploration missions with a cost cap of $750 million. These missions are larger than the principal-investigator-led Discovery-class missions (with a cost cap of $425 million) but smaller than “flagship” missions, which are led by a NASA center and are defined as larger than $750 million, but in actuality cost several billion dollars. New Frontiers is operated as a program, similar to the Discovery- and Mars Scout-class missions, meaning that Congress and the White House National Research Council, New Frontiers in the Solar System: An Integrated Exploration Strategy, The National Academies Press, Wash- ington, D.C., 2003. Colleen N. Hartman, Acting Associate Administrator for Science Mission Directorate, letter to Lennard A. Fisk, Chair, Space Studies Board, March 21, 2007.  

 OPENING NEW FRONTIERS IN SPACE have agreed to support the existence of a class of missions, and NASA does not have to seek special approval for each individual mission. The New Frontiers Program was created at the recommendation of the NRC’s solar system exploration decadal survey, New Frontiers in the Solar System: An Integrated Exploration Strategy (hereafter the “decadal survey”). The decadal survey recommended that in order to optimize solar system exploration, NASA’s solar system explo- ration program required a series of principal-investigator-led missions larger than the Discovery-class missions, but not as large as flagship missions. When teams led by a principal investigator compete, their proposed missions are often innovative and unique, producing ingenious solutions to difficult challenges and demonstrating many of the best characteristics of U.S. science. However, unlike Discovery, New Frontiers missions must be firmly grounded in scientific priorities established by the decadal survey without relying on new scientific or technology developments. The decadal survey specified five mission candidates and ranked them according to priority: • Kuiper Belt Pluto Explorer, • South Pole-Aitken Basin Sample Return, • Jupiter Polar Orbiter with Probes, • Venus In Situ Explorer, and • Comet Surface Sample Return. The decadal survey stated that although this list was ranked by scientific priority, NASA should not automati- cally select on the basis of that priority and should first consider the overall viability of the proposed mission. NASA followed this advice. For the 2005 New Frontiers announcement of opportunity, NASA clearly stated that the “‘strawman’ missions are in no order of priority,” and in fact the announcement of opportunity did not list them in the same order as the decadal survey. In addition, for the 2005 competition NASA selected the Jupiter polar mission instead of the scientifically higher-ranked (in the decadal survey) lunar mission. To date two New Frontiers missions have been selected: the New Horizons mission to Pluto and the Kuiper Belt and the Juno mission to orbit Jupiter. New Horizons was launched in 2006, flew past Jupiter in early 2007, and is scheduled to fly past Pluto in 2015. Juno is scheduled for launch in 2011 and to reach Jupiter in 2015. Both missions will address fundamental science goals defined in the decadal survey and will significantly enhance scientific understanding of our solar system. The decadal survey listed five additional missions that were not recommended for reasons of “mission sequenc- ing, technological readiness, or budget.” These missions, listed in the following order in the decadal survey, were not ranked according to scientific priority: • Network Science, • Trojan/Centaur Reconnaissance, • Asteroid Rover/Sample Return, • Io Observer, and • Ganymede Observer. Notably, Mars was not included in the New Frontiers Program. In essence, New Frontiers was created to ensure that a medium-size class of missions for the rest of the solar system (excluding Mars) was funded. The decadal survey treated Mars as a separate program with its own integrated list of scientific priorities and missions, some of which were in the same cost range as the New Frontiers missions. In particular, the decadal survey identified the Mars Long-Lived Lander Network as its second-highest-priority medium-size Mars mission, after the Mars Science Laboratory, which is currently scheduled for launch in 2009. National Research Council, New Frontiers in the Solar System: An Integrated Exploration Strategy, The National Academies Press, Wash- ington, D.C., 2003. New Frontiers in the Solar System, p. 197. 

SUMMARY  In drafting this report, the committee used the decadal survey as its guide and the decadal survey’s list of other potential medium-size solar system missions as its starting point. The committee solicited information from a broad range of sources, including NASA’s own solar system advisory groups, and heard about other possible missions and science that were not included in the decadal survey’s review of medium-size missions. The committee recognized that it lacked the scope and time of the decadal survey and did not have the exper- tise or authority to substantially question the decadal survey. As a result, the committee deferred to the insight and authority of the decadal survey whenever possible. However, the committee noted that scientific discoveries have been made since the decadal survey was presented to NASA in summer 2002, and new technologies and technological approaches may be available today. During its deliberations, the committee also recognized that including Mars in the New Frontiers Program was outside the scope considered in the development of the decadal survey. The decadal survey treated Mars as a program, and the committee sees no reason why that should change. Furthermore, the committee believes that allowing any medium-size Mars mission to compete in the New Frontiers Program would run the risk of undercutting the overall Mars Exploration Program, and thus be counter to the decadal survey. The committee believes that this action would be bad for both the New Frontiers Program and the Mars Exploration Program. However, the committee ultimately determined that within the context of comparative terrestrial planetology (i.e., network seismic and meteorological science) the New Frontiers Program is open to Mars missions. The committee strongly believes that the New Frontiers Program is a valuable and vital part of NASA’s solar system exploration program. The committee’s philosophy was to provide NASA with sufficient options and to provide potential proposers with sufficient flexibility in their proposals to enable NASA to select a mission that can be done within the constraints of the New Frontiers Program, particularly the cost cap. The health of the New Frontiers Program was an overriding priority for the committee. New Frontiers has so far been successful in selecting missions that accomplish science that is not possible under the Discovery Program. These missions will make fundamental contributions to scientific understanding of the formation and evolution of the solar system. In reviewing the decadal survey, and listening to presentations by proposers in the previous New Frontiers competition, the committee was concerned that the mission options presented in the decadal survey were overly specific about the methods of accomplishing the science missionsthe so-called “mission architectures.” For example, the Jupiter Mission with Probes described in the decadal survey essentially required atmospheric probes to return data from Jupiter’s atmosphere rather than specifying the information to be gained and leaving the method of obtaining it to those intending to propose a mission. Ultimately, the mission selected, named Juno, utilizes microwave radiometry only to return data on the water abundance in the atmosphere. The committee was concerned that such constraints could make it impossible for anyone to propose a mission that could be accomplished within the cost cap. The committee heard statements that allowing proposers greater latitude in how to return data not only increases ingenuity, but more importantly, also provides the flexibility required to fit missions within the cost and other constraints. The committee determined that rather than specify- ing mission architectures, NASA should emphasize the science to be returned from such a mission and leave the implementation specifics to the teams competing for the opportunity. Recommendation 1: In drafting the rules for the next New Frontiers announcement of opportunity, NASA should emphasize the science objectives and questions to be addressed, and not specify measurements or techniques for the implementation. The committee determined that the three remaining potential missions in the decadal survey’s listSouth Pole-Aitken Basin Sample Return, Venus In Situ Explorer, and the Comet Surface Sample Returnstill have sub- stantial scientific merit and should remain among the options in the next announcement of opportunity. However, the committee also determined that the list of candidate missions should be expanded to include the five other medium-size mission options identified in the decadal survey: Network Science, Trojan/Centaur Reconnaissance, 

 OPENING NEW FRONTIERS IN SPACE Asteroid Rover/Sample Return, Io Observer, and Ganymede Observer. The committee also determined that an additional open option should be made available, which is discussed below. The committee notes that compared to the original five New Frontiers missions identified in the decadal survey, the other five medium-size missions were discussed in less detail. Because of this, the committee has sought to devote significant attention to discussing the background and objectives of these missions in this report. In particular, the Io Observer and Ganymede Observer missions were not discussed in great detail in the decadal survey, and so the committee has devoted more attention to them in Chapter 2 of this report in order to explain their inclusion. Expanding the list accomplishes several important goals: it provides NASA with more options for the next mission selection; it provides potential proposers with more options to produce interesting, innovative, and com- petitive missions; it expands the cadre of participants and the science that will be evaluated by potential proposers, enabling the applicant pool to grow for future competitions; and it provides options to be considered by the next decadal survey. As with prior competitive mission opportunities, NASA should select from this set of missions based both on science priority and on overall mission viability. Recommendation 2: NASA should expand the list of potential missions in the next New Frontiers announce- ment of opportunity to include the three remaining candidate missions—South Pole-Aitken Basin Sample Return, Venus In Situ Explorer, and Comet Surface Sample Return—and also the five additional medium- size missions mentioned in the decadal survey: Network Science, Trojan/Centaur Reconnaissance, Asteroid Rover/Sample Return, Io Observer, and Ganymede Observer. There is no recommended priority for these missions. NASA should select from this set of missions based both on science priority and on overall mis- sion viability. The committee has not prioritized its list of eight missions. Each of these missions is discussed in greater detail in Chapter 2. The committee has also provided mission-specific recommendations for the science goals of each. The lists of goals are as comprehensive as possible but should not be interpreted as all-encompassing. In some cases those mission-specific recommendations introduce significant changes into the possible mission, notably in defining the parameters for the Venus In Situ Explorer and the Network Science missions. The committee noted that these science goals may not all be achievable in a single mission but believes that the choice and prioritization of goals are best left to those proposing and evaluating the missions. The committee was also impressed with arguments it heard about the importance of innovation not only in individual missions, but also in the overall New Frontiers Program, and about the risks of being overly specific on how to accomplish the goals of the decadal survey. Thus, in addition to the eight identified missions, the commit- tee believes that NASA should offer an additional option for other missions in the same size class that can acquire compelling information answering high-priority science questions from the decadal survey. The committee believes that this approach not only will provide an opening for innovation but also might enable the applicant pool for future missions to grow. The committee believes that any such mission will have to meet a very high standard of scientific proof. Possible examples of such missions could include—but are not limited to—shallow atmospheric probes for the outer planets. The committee realized that the New Frontiers mission line is a hybrid, incorporating aspects of both the Discovery- and the flagship-class missions. As such, the committee concluded that the mission options for the next announcement of opportunity cannot be drawn strictly from the decadal survey but rather should be interpreted in light of scientific discoveries made since the decadal survey was conducted in 2002. New discoveries made about several of the targets evaluated in this mission class in some cases enhance the importance of these scientific questions, and in other cases may undercut the original rationale for investigating a target. Planetary exploration is an ongoing endeavor advanced by paradigm-shifting scientific discoveries and mission-enabling technological developments. NASA’s New Frontiers Program will have to adapt to include them. New technologies and technological methods may now exist that were not available even 5 years ago. These technologies could include instrumentation (such as new seismic sensors) or mission-enabling equipment (such as radiation-hardened electronics). The committee concluded that it is important to the health of the program that 

SUMMARY  a method exist for including such innovations, while acknowledging that those proposing missions will have a high standard to meet. Recommendation 3: NASA should consider mission options outside the three remaining and five additional medium-size missions described in the decadal survey that are spurred by major scientific and technologi- cal developments made since the decadal survey. As with any New Frontiers mission, these proposals must offer the potential to dramatically advance fundamental scientific goals of the decadal survey and should accomplish scientific investigations well beyond the scope of the smaller Discovery Program. Both mission- enabling technological advances and novel applications of current technology could be considered. However, NASA should limit its choices to the eight specific candidate missions unless a highly compelling argument can be made for an outside proposal. The basis for these overarching recommendations is discussed further in Chapter 1. However, the mission sections in Chapter 2 provide information that will be vital for drafting the next New Frontiers announcement of opportunity, and this report must be read in its entirety in order to understand the committee’s findings and recommendations. The mission-specific recommendations in Chapter 2 are also included in Chapter 3 for ease of reference. Finally, the committee notes that the New Frontiers Program is intended to be both strategic—based on the science goals established in the decadal survey—and adaptable to new discoveries. The committee believes that it is important for NASA to find a method for incorporating new discoveries into the goals of the program for announcements of opportunity made several years after a decadal survey has been produced. Seeking input from the scientific community via the NRC (in the form of reports such as this one) is one method to achieve this, but not necessarily the only method. The committee hopes that in the future NASA will continue to recognize the importance of such a process.