First spectrum for the optical prototype of the VENSCPEC-U instrument for ESA’s ENVISION mission

News

20 January 2026

December was an eventful month for the development of the VENSPEC-U imaging spectrometer (developed for the ENVISION mission by LATMOS, IRAP, LIRA, and IAA), with the first spectrum from the optical prototype and a Preliminary Design Review (PDR) kick-off meeting on December 18, 2025.

Figure 1: First spectrum of the optical prototype of the VENSPEC-U instrument (HgAr source)

An orbiter around Venus

EnVision is a medium-class ESA mission (M5) scheduled for launch in 2031. Its objectives are to determine the nature of Venus’ geology, its potential current activity, and its interactions with the planet’s atmosphere, in order to understand how Venus and Earth could have evolved so differently.

IRAP is participating in the development of imaging spectrometers covering the UV to infrared wavelength ranges (VENSPEC instrument suite) that will be used to detect temporal variations in surface temperatures and the concentration of volcanic gases in the atmosphere. These measurements will also make it possible to study the interactions between the planet’s surface and atmosphere.

More specifically, IRAP is responsible for developing the mechanical components and mechanism of the ultraviolet channel (VENSPEC-U instrument).

Figure 2: View of the opto-mechanical systems that make up the VENSPEC-U instrument (credit: LATMOS/IRAP)

A first optical prototype…

The IRAP team (two permanent mechanical engineers and one contract mechanical engineer) designed and supervised the production of the various mechanical components of the prototype, which will serve as a prototype for future models of the instrument.

Since April, the team has carried out several missions to participate in the prototype’s AIT activities in the LATMOS clean rooms.

Following the alignment operations carried out by the LATMOS teams, a very promising initial spectrum was obtained.

Figure 3: General view of the OP-B2 prototype (left) and the LR diffraction grid installed in its mount (right) (photo credits: LATMOS)

… which will be followed in 2026 by STM and EM models

In parallel with these activities, the team participated in the preparation of the Preliminary Design Review, whose kick-off meeting took place on December 18, with completion scheduled for early February 2026.

The first two models of the instrument will be completed in 2026. The STM model will be used for structural and thermal validation, and the EM model for functional and electrical validation.

Figure 4: CAD view of the STM model of the VENSPEC-U instrument (credit: IRAP)

All AIT activities for the STM model will take place in IRAP’s clean rooms, with testing scheduled for fall 2026. In anticipation of this busy year, the team will be reinforced by the arrival of a contract mechanical engineer, whom we welcome!

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