Orateur
Description
The 2020 decadal survey in Astronomy and Astrophysics in the US (released in 2021) proposed a program of ground and space-based activities and recommended critical actions to carry-out its identified most compelling science goals. It stated that to address the major science questions identified by the Panel on Cosmology, the cosmic microwave background remains the single most important phenomenon that can be observed. It endorsed a ground-based CMB project, CMB-S4, and mentioned a CMB Probe as a possible candidate for the second Probe solicitation in the 2030s.
Since Astro2020, the CMB landscape has changed significantly. In 2025, CMB-S4 was cancelled, leaving a critical gap after the completion of Stage-3 ground-based experiments. Progress has been made in understanding the impact of Galactic foregrounds on inflationary science constraints. Technologies and launch capabilities relevant for a CMB Probe have progressed. The international landscape vis-a-vis a CMB space mission has evolved. All of these developments compel a critical re-evaluation of the role of a CMB Probe, both for a possible mid-decade review and in advance of upcoming Decadal Survey planning activities.
In this context, a CMB Science Analysis Group has been set-up to review the scientific, technological, and programmatic landscape. In this talk, I will review ongoing activities and future steps in preparation for a potential Probe-Class CMB space mission in the US, to be selected in the 2030s for a launch in the 2040s.