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”).3 The decadal survey recommended that in order to optimize solar system exploration, NASA’s solar system exploration 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 automatically 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 sequencing, technological readiness, or budget.”4 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, Washington, D.C., 2003.


New Frontiers in the Solar System, p. 197.

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