VenSpec Suite

VenSpec science goals

VenSpec will provide unprecedented insights into the current state of Venus and its past evolution. VenSpec will perform a comprehensive search for coupling between atmosphere, surface and interior processes (e.g. volcanic activity) by targeting atmospheric signatures, thermal signatures and compositional signatures, as well as a global map of surface composition.

VenSpec consortium

The VenSpec consortium structure is a balance between a fully integrated instrument and three completely independent instruments. It builds on a long history of collaboration between the consortium partners. The Table below shows the shared responsibilities of each European partner with respect to the VenSpec channels. The VenSpec consortium consists of three sub-instruments with a joint science team. The shared management of the consortium structure allows to leverage the synergies between the three instruments and minimize the resources, while at the same time ensuring that each partner can develop their contributions largely independently.

VenSpec instrument suite

The VenSpec instrument suite consists of three channels: VenSpec-M, VenSpec-H, VenSpec-U, and the Central Control Unit (CCU). All three channels have their independent optics due to the very different imaging concepts and wavelengths ranges covered. The instruments are all nadir pointing.

VenSpec-M is a pushbroom multispectral imaging system which will provide near-global compositional data on rock types, weathering, and crustal evolution by mapping the night-side emission of Venus surface and lower atmosphere in 14 near-IR spectral transparency “windows” covering the spectral range 0.79-1.51 μm. A total of six bands sound the surface in the five atmospheric windows between 0.86 and 1.18 μm. The broadest “window” at 1.02 μm is covered with two filters to obtain information on the spectral slope of the surface reflectance within the “window”. Eight additional channels provide measurements of atmospheric water vapour abundance as well as cloud microphysics and dynamics and stray light permitting an accurate correction of atmospheric interference on the surface data. Continuous observation of Venus’ thermal emission in the surface windows will place tight constraints on current day volcanic activity.

VenSpec-H (Venus Spectrometer with High resolution) will measure minor atmospheric species to investigate volcanic activity and surface–atmosphere interactions on Venus. Operating in nadir geometry, it will observe the lower atmosphere on the night side and above the clouds on the day side. The instrument targets key volcanic and cloud-forming gases in the first scale height and at 30–40 km altitude. Monitoring of H₂O, HDO, CO, SO₂ and OCS will help identify composition anomalies linked to eruptions and contribute to understanding cloud maintenance and volatile cycling.

VenSpec-U will monitor sulphured minor species (mainly sulphur monoxide SO and sulphur dioxide SO₂) and the as yet unknown UV absorber at Venus cloud top. It will therefore complement the two other channels by investigating how the atmosphere above the clouds interacts with the atmosphere below the clouds, and especially characterise to which extent atmospheric processes such as thermal tides and volcanic plumes are able to disturb the atmosphere through the thick Venusian clouds. A twin channel (0.3 nm in high- resolution between 205 and 235 nm, 2 to 5 nm in low-resolution between 190 and 380 nm) spectral imager able to operate in nadir would be especially suited to such a task.