EnVision will be ESA’s next Venus orbit, providing a holistic view of the planet from its inner core to the upper atmosphere to determine how and why Venus and Earth evolved so differently.
The mission was selected by the ESA’s Science Program Committee on 10 June as the fifth mid – range mission in the Agency’s Cosmic Vision plan to launch in the early 2030s.
“A new era in the exploration of our nearest, yet different solar system neighbor awaits us,” says Günther Hasinger, ESA Director of Science. “Together with the recently announced NASA-led Venus missions, we will have an extremely comprehensive science program on this enigmatic planet well into the next decade.”
A key question in planetary science is why our next neighbor in the inner solar system, despite roughly the same size and composition, experienced such a dramatic climate change: instead of being a habitable world like Earth, it has a toxic atmosphere and is shrouded in thick sulfuric clouds. . What history did Venus experience to reach this state, and does this predict the fate of the Earth if it also undergoes a catastrophic greenhouse effect? Is Venus still geologically active? Could it once have hosted an ocean and even sustained life? What lessons can be learned about the evolution of terrestrial planets in general when we discover more Earth-like exoplanets?
EnVision’s innovative instrument package will tackle these major issues. It will be equipped with a range of European instruments, including an echo sounder to detect subterranean stratification and spectrometers to study the atmosphere and surface. The spectrometers monitor trace gases in the atmosphere and analyze surface composition and look for changes that may be associated with signs of active volcanism. A NASA-supplied radar will image and map the surface. In addition, a radio science experiment will examine the planet’s internal structure and gravitational field, as well as the structure and composition of the atmosphere. The instruments will work together to best characterize the interaction between the planet’s different boundaries – from the interior to the surface to the atmosphere – providing a comprehensive global view of the planet and its processes.
EnVision follows ESA’s highly successful Venus Express (2005-2014), which focused primarily on atmospheric research but also made dramatic discoveries that pointed to possible volcanic hotspots on the planet’s surface. JAXA’s Akatsuki spacecraft has also studied the atmosphere since 2015. EnVision will significantly improve the radar images of the surface obtained by NASA’s Magellan in the 1990s. In collaboration with NASA’s upcoming DAVINCI + (Deep Atmosphere Venus Investigation of Noble Gases, Chemistry and Imaging) and VERITAS (Venus Emissivity, Radio Science, InSAR, Topography, and Spectroscopy) missions, the trio with new spacecraft will provide the most comprehensive study of Venus ever .
“EnVision benefits from collaborating with NASA, which combines expertise in European and American expertise in Venus’ science and technology, to create this ambitious mission,” said Günther. “EnVision further strengthens Europe’s role in the scientific exploration of the solar system. Our growing mission fleet will give us and future generations the best insight ever into how our planetary neighborhood works, especially relevant in an era where we are discovering more and more unique exoplanet systems. ”
“We are excited to contribute to ESA’s new exciting mission to study Venus,” said Thomas Zurbuchen, NASA’s Associate Director of Science. “EnVision leverages the strengths of instrument development from both our agencies. Combined with NASA’s Discovery missions to Venus, the scientific community will have a strong and synergistic set of new data to understand how Venus formed and how the surface and atmosphere changed over time. ”
Following an initial call for the fifth middle-class mission concept in 2016, the final competition came down to EnVision and Theseus, Transient High-Energy Sky and Early Universe Surveyor. Theseus would monitor transient events across the sky and in particular focus on gamma-ray bursts from the universe’s first billion years to help shed light on the life cycle of the first stars. While EnVision was recommended by the Senior Science Committee, it was recognized that Theseus also has a very compelling science case that could make extremely important contributions to the field.
The next step for EnVision is to move to the detailed ‘Definition phase’, where the design of the satellite and instruments is completed. After the design phase, a European industrial contractor will be selected to build and test EnVision before launching it on an Ariane 6 rocket. The earliest launch option for EnVision is 2031 with other possible options in 2032 and 2033. The spacecraft would take about 15 months to reach the planet with a further 16 months to achieve orbital circulation through aerobraking. Its 92-minute orbit will be quasi-polar with an altitude of between 220 km and 540 km.
Solar Orbiter, Euclid, Plato and Ariel have already been selected as middle class emissions. Solar Orbiter was launched in February 2020; Euclid, Plato and Ariel will be launched during this decade.
EnVision is an ESA-led mission with important contributions from NASA, which will provide VenSAR (Synthetic Aperture Radar) as well as Deep Space Network support. The other payload instruments are contributed by ESA member countries, with ASI, DLR, BelSPO and CNES leading the procurement of SRS (Subsurface Sounding Radar), VenSpec-M, VenSpec-H and VenSpec-U spectrometers, respectively. Radio science experiment is led by institutes in France and Germany.