Cosmic Vision: organize missions around fundamental questions

Cosmic Vision was created in 2005 after community consultation. Its questions concern how planets and conditions for life arise, how the Solar System works, the laws governing nature, and the origin and contents of the Universe. These themes connect planetary exploration with astronomy and fundamental physics rather than treating them as unrelated destination lists.

A mission contributes by making particular measurements relevant to those questions. Observing many galaxies, investigating the Sun or visiting an icy-moon system requires different instruments and operating environments. Sharing a planning framework does not make the resulting data interchangeable. The scientific objective must still lead to a specific measurement and a way to evaluate competing explanations.

Cosmic Vision includes large, medium, small and fast mission classes, alongside collaborative missions. Examples include Juice as a large mission, Solar Orbiter and Euclid as medium missions, and Cheops as a small mission. The classes concern program scale and implementation opportunities. They are not a ranking that makes every large mission scientifically more valuable than every smaller one.

The Euclid preparation photograph connects the portfolio with a physical observatory under development. Its cosmological investigation requires calibrated imaging, spectra and analysis, rather than merely a successful assembly photograph. Mission selection, hardware readiness, launch and delivery of scientific products are separate parts of realizing the program’s questions.

The familiar label Cosmic Vision 2015–2025 describes a planning horizon — open definition, not a statement that every associated spacecraft launched and finished work within those years. Mission preparation and operations extend across later dates. Changes in technology, partners and resources can affect implementation while a scientific objective remains relevant.

Consider a fictional comparison between a focused small observatory and a large planetary mission. Compare the questions each can answer, the uncertainty of its measurements, its feasibility and the resources required. Do not compare only spacecraft size or the excitement of an image. A balanced portfolio can support different scales of investigation while judging every claim against the evidence its mission can actually obtain.