The VenSpec-H instrument is part of the EnVision payload which was selected by ESA in June 2021. EnVision is a medium class mission to determine the nature and current state of geological activity on Venus, and its relationship with the atmosphere, to understand how Venus and Earth could have evolved so differently.


Volcanic activity on Venus

VenSpec-H is part of the VenSpec suite, including also an IR mapper and a UV spectrometer suite. The science objectives of this suite is to search for temporal variations in surface temperatures and tropospheric concentrations of volcanically emitted gases, indicative of volcanic eruptions; and study surface-atmosphere interactions and weathering by mapping surface emissivity and tropospheric gas abundances. Recent and perhaps ongoing volcanic activity has been inferred in data from both Venus Express and Magellan. Maintenance of the clouds requires a constant input of H2O and SO2. A large eruption would locally alter the composition by increasing H2O ; decreasing D/H ratio and increasing SO2. The latter effect is probably underestimated with respect to the others, since the Venusian interior is thought to be much drier than Earth's, so that the outgassed SO2/H2O ratio may be much higher on Venus. Observations of changes in lower atmospheric SO2 and H2O vapour levels, cloud level H2SO4 droplet concentration, and mesospheric SO2, are therefore required to link specific volcanic events with past and ongoing observations of the variable and dynamic mesosphere, to understand both the importance of volatiles in volcanic activity on Venus and their effect on cloud maintenance and dynamics.

To contribute to this investigation, VenSpec-H is designed to measure H2O and HDO contents in the first scale height of Venus’ atmosphere and probe H2O, HDO, OCS, SO2 in the 30 to 40km altitude range. To assess the performances of our instrument at detecting volcanic eruptions, we defined a couple of scenarios of plume releases and simulated the corresponding spectra.


VenSpec-H is led by Dr. Ir. Ann Carine Vandaele from the Royal Belgian Institute for Space Aeronomy (BIRA-IASB), a federal research institute. BIRA-IASB has a long-standing expertise proposing, designing and building instruments to study the atmospheres of celestial bodies (planets, comets, …).

A dedicated team of engineers and scientists of BIRA-IASB developed the concept and design of the required instrument during the 2.5-years Phase A (2019 - mid-2021), in collaboration with optical engineers from the OIP Sensor Systems company based in Oudenaarde.

They called it VenSpec-H, acronym for Venus Spectrometer with High Resolution. VenSpec-H is a spectrometer with significant heritage from the LNO (Limb, Nadir and Occultation) channel of NOMAD on ExoMars Trace Gas orbiter.

In June 2021, the work quit the conceptual phase, and the technology readiness level needs to be proven in the coming years. The workload has increased in consequence and the consortium has therefore been opened to other ESA State Members. Czech Republic, Germany, the Netherlands, Portugal, Spain and Switzerland* have expressed their interest to join the team, invest funding and overcome all challenges on the way until the launch on November 1st, 2031. The EnVision mission will take 15 months to reach Venus. After several months of aerobraking, the orbiter will be placed in a circular orbit around the planet and will then start its scientific observations. In addition to its key role in the design and the development of the instrument itself in the fields of mechanics and electronics, BIRA-IASB will be the leading science institute holding the PI and the Science Manager and its System Engineering team will coordinate the technical consortium throughout the complete mission foreseen until 2037.


BIRA-IASB wants to acknowledge the support of BELSPO (Belgian Science Policy Office) to the mission and in particular to the VenSpec-H instrument.


*Countries are given in alphabetic order