Trace Gas Orbiter

The European Space Agency's Trace Gas Orbiter (TGO) is a spacecraft designed to study the atmosphere of Mars and the trace gases within it. It was launched on March 14, 2016, as part of the ExoMars mission, which is a joint endeavor between the European Space Agency (ESA) and the Russian space agency, Roscosmos.

Why was the TGO mission necessary?

One of the main goals of the ExoMars mission is to search for signs of past or present life on Mars. To achieve this goal, the mission includes two parts: the TGO orbiter and the Rosalind Franklin rover. The TGO orbiter's primary objective is to study the Martian atmosphere in detail, including its composition and how it varies over time. By doing so, scientists hope to better understand the planet's geological and biological evolution and its potential habitability.

The TGO mission was necessary because previous Mars missions, including the Mars Express mission (also carried out by the ESA), have found evidence of trace gases in the Martian atmosphere that are potential indicators of biological activity. For example, in 2003, the Mars Express mission detected methane in the Martian atmosphere. Methane is a gas that is usually produced by biological activity on Earth, but it can also be produced by geological processes. This discovery was significant because it suggested that there might be some form of life on Mars, but it was not conclusive. Therefore, further research was necessary to determine the source of the methane and whether it was biogenic or not.

In addition to methane, the Martian atmosphere also contains other trace gases, such as nitrogen dioxide and water vapor, that can provide clues about the planet's geological and atmospheric processes. The TGO mission was designed to study these gases in detail, as well as their interactions with the Martian environment.

How was the TGO mission carried out?

The TGO mission was carried out using a spacecraft that was specifically designed for the task. The spacecraft was built by Thales Alenia Space in Italy and was launched on a Proton rocket from the Baikonur Cosmodrome in Kazakhstan. The launch took place on March 14, 2016, and the spacecraft arrived at Mars on October 19, 2016.

Once at Mars, the TGO orbiter began its mission by entering an elliptical orbit around the planet. The orbiter's instruments then began to scan the Martian atmosphere, measuring the concentration of various gases and particles and mapping their distribution over time. The orbiter's instruments were designed to detect trace gases at very low concentrations, with sensitivities that were several orders of magnitude higher than those of previous Mars missions.

The TGO orbiter is equipped with four scientific instruments:

The Atmospheric Chemistry Suite (ACS) – This instrument is designed to measure the concentration of several gases in the Martian atmosphere, including methane, nitrogen dioxide, and water vapor. The ACS consists of three spectrometers, each of which uses different wavelengths of light to detect specific gases.

The Nadir and Occultation for Mars Discovery (NOMAD) – This instrument is designed to study the atmosphere of Mars by looking at how the light from the sun or a star is absorbed by the gases in the atmosphere. NOMAD consists of three spectrometers that cover different wavelengths of light, allowing them to detect a wide range of gases.

The CaSSIS (Colour and Stereo Surface Imaging System) – This instrument is a high-resolution camera that can take color images of the Martian surface. It is designed to help scientists understand the geological processes that have shaped the planet's surface.

The FREND (Fine Resolution Epithermal Neutron Detector) – This instrument is designed to detect the presence of hydrogen in the Martian soil. Hydrogen 

is an indicator of the presence of water, which is essential for life as we know it. The FREND instrument is also used to study the structure and composition of the Martian soil.

The TGO orbiter also has a communications relay function, which allows it to act as a communications link between the Rosalind Franklin rover and Earth. This is important because the rover cannot communicate directly with Earth due to the distance and the fact that the signal strength would be too weak.

In addition to its scientific objectives, the TGO mission also has practical applications. For example, the data collected by the orbiter can be used to improve our understanding of the Martian atmosphere and its potential impact on human missions to the planet. The orbiter's data can also be used to help plan future missions to Mars.

What was the cost of the TGO mission?

The total cost of the ExoMars mission, which includes the TGO orbiter and the Rosalind Franklin rover, is estimated to be around €1.5 billion ($1.8 billion USD). This includes the cost of developing, building, and launching the spacecraft, as well as the cost of operating the mission.

What were the achievements of the TGO mission?

The TGO mission has already achieved several significant milestones since its launch in 2016. For example, the orbiter's instruments have detected and measured the concentration of several trace gases in the Martian atmosphere, including methane, nitrogen dioxide, and water vapor. These measurements have provided important insights into the geology and biology of the planet and have helped to further our understanding of the potential for life on Mars.

One of the most significant achievements of the TGO mission is the detection of methane in the Martian atmosphere. The orbiter's measurements have shown that the concentration of methane varies over time and space, suggesting that there may be localized sources of the gas on the planet. While the source of the methane is still uncertain, these findings have renewed interest in the possibility of microbial life on Mars.

The TGO mission has also provided important data on the Martian atmosphere and its potential impact on future human missions to the planet. For example, the orbiter's measurements of the Martian radiation environment have helped to inform the design of radiation shielding for future manned missions.

Overall, the TGO mission has been a significant achievement for the European Space Agency and its partners. The data collected by the orbiter has provided important insights into the geology and biology of Mars, and has helped to pave the way for future exploration of the planet.