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SOIR - Solar Occultation InfraRed Spectrometer

SOIR is a compact high resolution spectrometer developed for the ESA VENUS EXPRESS mission and integrated in the SPICAV instrument.


Name: SOIR Spectrometer
Mission: Venus Express
Application: Atmosphere Monitoring
Life: Launched in 2009; mission ended in 2014


Instrument Description

SOIR operates in the IR wavelength range of 2200 to 4300 nm and measures absorption spectra of minor constituents in the Venusian atmosphere. It uses an echelle grating, combined with an IR Acousto-Optic Tunable Filter (AOTF).

SOIR was developed by Belgian partners on behalf of ESA. OIP, as a subcontractor for IASB-BIRA [B], was responsible for the design and development of the optical system of the SOIR spectrometer.

The project was performed for ESA-PRODEX and funded by BELSPO. IASB-BIRA was the principle investigator.

Mission

Venus Express, ESA’s first mission to Venus began in March 2001, with a call for ideas from the scientific community on how best to reuse the spacecraft platform developed for Mars Express. On 5 November 2002, ESA gave the go-ahead to proceed with Venus Express, and only three years later the aptly named spacecraft began its journey towards the second planet from the Sun.

Venus Express is a satellite optimised for studying the atmosphere of Venus, from the surface right up to the ionosphere.

 

OIP’s Participation

OIP, as a subcontractor to BIRA-IASB [B], was responsible for the design and development of the optical system of the SOIR spectrometer, as part of the SPICAV payload. OIP was also in charge of the opto-mechanical assembly and electrical assembly of the electronic cards and harnesses.

OIP  participated in the phase A, B, C and D. The Kick-off of Phase C/D took place in August 2003. Less than 2 years later, 2 fully flight worthy instruments were ready. OIP delivered a Flight Model (FM) on June 16th, 2005 and a Flight Spare (FS) on December 22nd, 2005 to BIRA-IASB.

Status

Venus Express was launched from the Baikonur Cosmodrome in Kazakhstan on 9 November 2005. A Soyuz-Fregat rocket carried it into space and placed the spacecraft in its transfer orbit to Venus. After an interplanetary cruise that lasted 5 months, Venus Express arrived at Venus on 11 April 2006.

At its closest, Venus Express reached an altitude of 250km and at its furthest, it was 66000km away from the planet.
After the conclusion of its main scientific mission in May 2014, the spacecraft’s altitude at closest approach to Venus was lowered to 130km and eventually reaching a minimum of 129.2km on 11 July.

On 28 November 2014, mission control lost contact with Venus Express. After a re-established contact, it was determined that the spacecraft likely ran out of propellant. On 16 December 2014 ESA declared the Venus Express mission over. The last signal of the Spacecraft’s X-band was detected on 18 January 2015.

For over years, Venus Express has gathered useful data on the Venusian Atmosphere that lead to major discoveries, to which SOIR supported a lot.

The SOIR spectrometer had the highest spectral resolution (λ/Δλ>20,000) ever flown in a planetary mission. Vertical profiles of CO, HDO, H2O, HCl, SO2, CO2 isotopes and temperature are regularly retrieved, as well as aerosols. The SOIR spectrometer has proven its high potential for the detection of minor key species for the understanding of the chemical and dynamical processes occurring in the Venus mesosphere. This is why the concept was taken over for other instruments & missions, such as the NOMAD spectrometer onboard ExoMars2016, investigating the Martian atmosphere.

Partners

SOIR was developed by Belgian partners on behalf of ESA. OIP, as a subcontractor to BIRA-IASB [B], was responsible for the design and development of the optical system of the SOIR spectrometer, as well as the electronic assembly and harnessing.
The project was funded by ESA/PRODEX.

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