committee review. It could range between the notional budget used here up to a significant (perhaps on the order $200 million) mission-specific technology program starting mid-decade.

The committee’s proposed program is designed to allow a habitable-exoplanet imaging mission to be well formulated in time for consideration by the 2020 decadal survey.

Priority 2 (Medium, Space). Technology Development for a 2020 Decade Mission to Probe the Epoch of Inflation

Detecting the B-mode polarization pattern on the cosmic microwave background impressed by gravitational waves produced during the first few moments of the universe both would provide strong evidence for the theory of inflation that is so crucial to our understanding of how structures form, and would open a new window on exotic physics in the early universe in regimes not accessible even to the most powerful particle accelerators on Earth. Progress in measuring both the polarization and the fine-scale anisotropy of the cosmic microwave background radiation is proceeding rapidly with ground-based telescopes in Antarctica and Chile and space-based instruments.

The recommended enhanced Suborbital program, as described below, as well as Missions of Opportunity made possible by an augmented Explorer program, will provide opportunities for substantive balloon experiments to probe the polarization signal to faint levels. NASA through the APRA program, as described below, should augment support for CMB technology development at a modest level. If the combined space and ground-based program is successful in making a positive detection of B-modes from the epoch of inflation, it is further recommended that NASA should then embark on an enhanced program of technology development, with a view to preparing a mature proposal for a dedicated space mission to study inflation through CMB observations for consideration by the 2020 decadal survey. If this observational goal is not met, then the suborbital programs and the broad technology development programs should continue to be supported at the same early-decade level with the goal of further improving detection limits.

In summary, significant progress on CMB studies, including the understanding of foregrounds, is certain given the successful operation of Planck and the suborbital and ground-based facilities that are currently operating or will come on line soon. A successful detection of B-modes from inflation could trigger a mid-decade shift in focus toward preparing to map them over the entire sky. In this case a notional decadal budget of $60 million is proposed. However, the level of late-decade investment required is uncertain, and the appropriate level should be studied by a decadal survey implementation advisory committee review. It could range between

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