astronomy

Trace Gas Orbiter

Trace Gas Orbiter is a astronomy topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Trace Gas Orbiter rather than just read about it. In short: The ExoMars Trace Gas Orbiter (TGO or ExoMars Orbiter) is a collaborative project between the European Space Agency (ESA) and the Russian Roscosmos agency that sent an atmospheric research orbiter and the Schiaparelli demonstration lander to Mars in 2016 as part of the European-led ExoMars programme. A key goal is to gain a better understanding of methane (CH4) and other trace gases present in the Martian atmosphere…

Key takeaways

Trace Gas Orbiter belongs to astronomy; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Trace Gas Orbiter to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Trace Gas Orbiter from memory before moving on to harder problems.

Reference excerpt

The ExoMars Trace Gas Orbiter (TGO or ExoMars Orbiter) is a collaborative project between the European Space Agency (ESA) and the Russian Roscosmos agency that sent an atmospheric research orbiter and the Schiaparelli demonstration lander to Mars in 2016 as part of the European-led ExoMars programme. A key goal is to gain a better understanding of methane (CH4) and other trace gases present in the Martian atmosphere that could be evidence for possible biological activity. Manufactured by Thales Alenia Space, TGO's major scientific payloads were developed by Belgium, France, Russia, and Switzerland. TGO launched on a Proton-M rocket from Baikonur Cosmodrome Site 200 on 14 March 2016. The Trace Gas Orbiter delivered the Schiaparelli lander on 16 October, which crashed on the surface due to a premature release of the parachute. TGO has been orbiting Mars since 19 October 2016 and performing science observations of the planet since April 2018. The ExoMars programme will continue with the Rosalind Franklin rover in 2028, which will search for biomolecules and biosignatures; the TGO will operate as the communication link for the lander and rover and provide communication for other Mars surface probes with Earth.

Spacecraft

Instruments

Like the Mars Reconnaissance Orbiter, the Trace Gas Orbiter is a hybrid science and telecom orbiter. Its scientific payload mass is about 113.8 kg (251 lb) and consists of:

The Nadir and Occultation for Mars Discovery (NOMAD) has two infrared and one ultraviolet spectrometer channels. Developed by Belgium. The Atmospheric Chemistry Suite (ACS) has three infrared spectrometer channels. Developed by France and Russia. The Colour and Stereo Surface Imaging System (CaSSIS) is a high-resolution, 4.5 m per pixel (15 ft/pixel), colour stereo camera for building accurate digital elevation models of the Martian surface. It will also be an important tool for characterising candidate landing site locations for future missions. Developed by Switzerland. The Fine-Resolution Epithermal Neutron Detector (FREND) is a neutron detector that can provide information on the presence of hydrogen, in the form of water or hydrated minerals, in the top 1 m (3 ft 3 in) of the Martian surface. Developed by Russia. NOMAD and ACS are providing the most extensive spectral coverage of Martian atmospheric processes so far. Twice per orbit, at local sunrise and sunset, they are able to observe the Sun as it shines through the atmosphere. Detection of atmospheric trace species at the parts-per-billion (ppb) level are possible.

Science goals The FREND instrument is mapping hydrogen levels to a maximum depth of 1 m (3 ft 3 in) beneath the Martian surface. Locations where hydrogen is found may indicate water-ice deposits, which could be useful for future crewed missions. Particularly, the mission is characterising spatial, temporal variation, and localisation of sources for a broad list of atmospheric trace gases. If methane (CH4) is found in the presence of propane (C3H8) or ethane (C2H6), that would be a strong indication that biological processes are involved. However, if methane is found in the presence of gases such as sulfur dioxide (SO2), that would be an indication that the methane is a byproduct of geological processes.

Detection

The nature of the methane source requires measurements of a suite of trace gases in order to characterise potential biochemical and geochemical processes at work. The orbiter has very high sensitivity to (at least) the following molecules and their isotopomers: water (H2O), hydroperoxyl (HO2), nitrogen dioxide (NO2), nitrous oxide (N2O), methane (CH4), acetylene (C2H2), ethylene (C2H4), ethane (C2H6), formaldehyde (H2CO), hydrogen cyanide (HCN), hydrogen sulfide (H2S), carbonyl sulfide (OCS), sulfur dioxide (SO2), hydrogen chloride (HCl), carbon monoxide (CO) and ozone (O3). Detection sensitivities are at levels of 100 parts per trillion, improved to 10 parts per trillion or better by averaging spectra which could be taken at several spectra per second.

Characterisation Spatial and temporal variability: latitude–longitude coverage multiple times in a Mars year to determine regional sources and seasonal variations (reported to be large, but still controversial with present understanding of Mars gas-phase photochemistry) Correlation of concentration observations with environmental parameters of temperature, dust and ice aerosols (potential sites for heterogeneous chemistry)

Localisation Mapping of multiple tracers (e.g., aerosols, water vapour, CO, CH4) with different photochemical lifetimes and correlations helps constrain model simulations and points to source/sink regions To achieve the spatial resolution required to localise sources might require tracing molecules at parts-per-billion concentrations

Relay telecommunications

Due to the challenges of entry, descent and landing, Mars landers are highly constrained in mass, volume and power. For landed missions, this places severe constraints on antenna size and transmission power, which in turn greatly reduce direct-to-Earth communication capability in comparison to orbital spacecraft. As an example, the capability downlinks on Spirit and Opportunity rovers had only 1⁄600 the capability of the Mars Reconnaissance Orbiter downlink. Relay communication addresses this problem by allowing Mars surface spacecraft to communicate using higher data rates over short-range links to nearby Mars orbiters, while the orbiter takes on the task of communicating over the long-distance link back to Earth. This relay strategy offers a variety of key benefits to Mars landers: increased data return volume, reduced energy requirements, reduced communications system mass, increased communications opportunities, robust critical event communications and in situ navigation aid. NASA provided an Electra telecommunications relay and navigation instrument to assure communications between probes and rovers on the surface of Mars and controllers on Earth. The TGO will provide the Rosalind Franklin rover with telecommunications relay; it will also serve as a relay satellite for future lander missions.

History

… excerpt ends here. Continue reading the full article.

Illustrations

Worked examples

Example 1 — a first encounter with Trace Gas Orbiter

Start with the simplest possible case. Write down what Trace Gas Orbiter claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In astronomy, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Trace Gas Orbiter before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Trace Gas Orbiter ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Trace Gas Orbiter

In research: Trace Gas Orbiter appears in astronomy research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Trace Gas Orbiter in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Trace Gas Orbiter is common in secondary-school and first-year university syllabi. It links to neighbouring topics 2016 in Kazakhstan, Attached spacecraft, European Space Agency missions to Mars, so understanding it makes those chapters shorter.
In everyday life: Look for Trace Gas Orbiter outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

Affiliate

Preply — study more efficiently by working with a personal tutor. 50% off.

How to study Trace Gas Orbiter in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Trace Gas Orbiter means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Trace Gas Orbiter out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Trace Gas Orbiter in simple terms?

Why does Trace Gas Orbiter matter?

Because it connects several astronomy ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Trace Gas Orbiter?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Trace Gas Orbiter.