The European Space Agency (ESA) has narrowed a field of 27 proposals down to three in a search for its next medium-sized mission. The finalists include projects to study the atmospheres of planets around nearby stars, the characteristics of distant high-energy objects, and how the sun heats the solar wind and planetary atmospheres. The three teams will receive funding to develop their concepts for several years before a final decision is made. The winning mission will get a budget up to €450 million and will launch in 2025.
ESA’s current science program, known as Cosmic Vision 2015-2025, periodically chooses large- and medium-sized missions in open competitions. (Small missions are usually funded by individual nations on their own or in small collaborations.) Two large missions are now in development and the selection of a third will begin next year; three medium-sized missions are also in the works.
The finalists announced yesterday for the fourth medium-sized mission include the Atmospheric Remote-Sensing Infrared Exoplanet Large-survey (Ariel), which will help planetary scientists understand how our solar system differs from others by studying the chemistry and physical conditions of exoplanet atmospheres. The Turbulence Heating ObserveR (Thor) will examine how the sun warms its plasma and so dissipates heat through the solar system via the solar wind. And the X-ray Imaging Polarimetry Explorer (Xipe) will look at x-rays from the more violent denizens of the universe—supernovas, galaxy jets, black holes, and neutron stars—and for the first time measure their polarization in high resolution to understand how matter behaves under extreme conditions.