Proposal Review: How are PLATO AO‑1 Proposals evaluated?

What the TAC Does

The PLATO Time Allocation Committee (TAC) evaluates all AO‑1 proposals based on their scientific merit, feasibility, and the suitability of PLATO for achieving the proposed objectives. TAC recommendations guide ESA in allocating observing time at the proposal level. The Science Operations Centre (SOC) subsequently uses this input to optimise the observation plan at the target level within PLATO’s telemetry constraints. Final awards are made by ESA’s Director of Science.

Fair and Transparent Review

PLATO’s review process is designed to be transparent, fair, and consistent across scientific domains. It draws on established practices from other ESA missions such as XMM‑Newton, Integral, and CHEOPS. Dual‑anonymous peer review ensures that assessments focus entirely on the scientific content rather than the identity of the proposers. All proposal material and deliberations remain confidential, and conflicts of interest are carefully managed throughout the process.

TAC Structure and Expertise

The TAC is organised into several science panels overseen by a central Chair. Reviewers are appointed by ESA in consultation with its advisory structure and follow formal evaluation guidelines. Proposals are initially assigned to panels based on the scientific category selected by the proposer, although ESA may adjust these assignments to ensure balanced workload and appropriate expertise. When needed, external experts may be invited to provide additional specialised input.

How Proposals Are Evaluated

Before evaluation begins, all reviewers sign confidentiality agreements and declare any conflicts of interest. Each reviewer performs an independent assessment and submits grades and comments. These individual reviews are then discussed during panel meetings, where evaluations are refined and consolidated. A subsequent Chairs Meeting brings together the panel‑level results into a single ranked list covering all proposals. Partial awards may be recommended when only part of a proposal is considered scientifically compelling or feasible.

Evaluation Criteria

Proposals are assessed on their scientific excellence, clarity and relevance of the objectives, robustness of the analysis plan, justification of requested resources, and the suitability of PLATO for achieving the stated goals. The anonymous Scientific Justification forms the core of the assessment. The Technical Justification is reviewed primarily by ESA and subject‑matter experts but is also consulted by the TAC to ensure full understanding of feasibility.

From Ranked List to Award

ESA uses the final ranked list provided by the TAC to schedule observations within PLATO’s operational and telemetry constraints. Awards of observing time are expected to be announced by the end of August.