April 3, 2019

Trace Gas Orbiter

Artist’s impression of TGO entering Mars orbit. Credits: ESA/ATG medialab

The Trace Gas Orbiter (TGO) was captured into Mars orbit after an aerobraking manoeuvre that lasted two hours. It remained in this highly eccentric orbit—250 km – 100,000 km—for four days. In January 2017, a new sequence of manoeuvres put TGO into an elliptical orbit—150 km – 33,000 km—inclined 74° to the equator, completed in one day. And from 6 April 2017 to early 2018, the satellite performed aerobraking manoeuvres to bring it into a circular 400-km orbit, circling the planet in 120 minutes.

TGO scientific instruments

NOMAD (Nadir and Occultation for MArs Discovery)A spectrometer suite covering a wide range of wavelengths (including infrared to ultraviolet) to identify the components of the Martian atmosphere.

Principal Investigator: Ann Carine Vandaele, Belgium

Co-PIs: José Lopez Moreno, Spain; Giancarlo Bellucci, Italy; Manish Patel, United Kingdom.
Participating countries: BE, SP, IT, UK, USA, CA.
ACS (Atmospheric Chemistry Suite)This suite of three infrared spectrometers is helping scientists to investigate the chemistry and structure of the Martian atmosphere. ACS complements NOMAD by extending the coverage at infrared wavelengths, and by taking images of the Sun to better analyse the solar occultation data.

Principal Investigator: Oleg Korablev, Space Research Institute (IKI), Russia.

Co-PIs: Franck Montmessin, France; François Forget, France.

Participating countries: RU, FR
CaSSIS (Colour and Stereo Surface Imaging System)A high-resolution camera (5 metres per pixel) capable of obtaining colour and stereo images over a wide swath. CaSSIS will provide the geological and dynamical context for sources or sinks of trace gases detected by NOMAD and ACS.

Principal Investigator: Nicolas Thomas, University of Bern, Switzerland.

Participating countries: CH, IT.
FREND (Fine Resolution Epithermal Neutron Detector)This neutron detector is mapping the presence of hydrogen on the Martian surface, targeting deposits of near-surface water ice.
Principal Investigator: Igor Mitrofanov, Space Research Institute (IKI), Russia.


In addition to its scientific instruments, TGO is carrying two Electra radiotransceivers supplied by NASA to relay commands and data between Earth and the surface of Mars. When ExoMars 2020 arrives, TGO will be configured to serve as the main telecommunications relay for the European Rosalind Franklin rover and the Russian Kazachok platform.

The first Electra radiotransceiver for TGO being installed and tested at Thales Alenia Space in Cannes, June 2014. Credits: NASA/JPL-Caltech/ESA/TAS

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