2013 Mars Science Orbiter
Encyclopedia
The ExoMars Trace Gas Orbiter (TGO), sometimes referred to as Trace Gas Mission (TGM) by NASA
, is a flexible collaborative proposal within NASA and the European Space Agency
(ESA) to send a new orbiter
-carrier to Mars
in 2016 as part of the European-led ExoMars
mission.
This orbiter would deliver the ExoMars Entry, Descent and Landing Demonstrator Module (EDM) static lander
and then proceed to map the sources of methane on Mars and other gases, and in doing so, help select the landing site for the ExoMars rover
to be launched on 2018.
However, following the Mars Joint Exploration Initiative, it was agreed that the European-lead Trace Gas Orbiter (TGO) would carry several instruments originally meant for the MSO, so NASA scaled down the objectives and focused on atmosphere trace gases detection instruments for their incorporation in ESA's Exomars Trace Gas Orbiter, to be launched in 2016.
If launched, the Trace Gas Orbiter (TGO) would be the successor to the Mars Reconnaissance Orbiter
, which may still be operational at that time. The TGO would be launched as part of the ExoMars
program in 2016 together with a static lander built by the European Space Agency
.
Under the collaboration proposal, the European ExoMars
mission would be split into two parts: an orbiter/lander mission in 2016 that would include the TGO and a static lander build by ESA; this would be followed by the ExoMars rover
mission in 2018 —also to be launched with an Atlas V
rocket. This joint ESA-NASA mission could help settle whether the methane source in that planet is of biological or geological origin, and would apparently reconcile technological and science goals with available budgets.
for seven months into a more circular orbit for science observations and would provide communications relay
for the ExoMars rover to be launched in 2018, and would continue serving as a relay satellite for future landed missions until 2022.
The mission would require detection, characterization of spatial and temporal variation, and localization of sources for a broad suite of atmospheric trace gases
:
Detection:
Nature of the methane source requires measurements of a suite of trace gases in order to characterize potential biochemical and geochemical processes at work. The orbiter would require 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 would be of 1-10 parts per trillion.
Characterization:
Localization:
downlinks on Spirit and Opportunity have only 1/600th the capability of the Mars Reconnaisance 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 aide. The orbital science mission, the TGO would provide the EDM lander and ExoMars rover with telecommunication relay and would continue serving as a relay satellite for future landed missions until 2022.
NASA
The National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...
, is a flexible collaborative proposal within NASA and the European Space Agency
European Space Agency
The European Space Agency , established in 1975, is an intergovernmental organisation dedicated to the exploration of space, currently with 18 member states...
(ESA) to send a new orbiter
Orbiter
An orbiter is a space probe that orbits a planet.-Asteroids:*NEAR Shoemaker...
-carrier to Mars
Mars
Mars is the fourth planet from the Sun in the Solar System. The planet is named after the Roman god of war, Mars. It is often described as the "Red Planet", as the iron oxide prevalent on its surface gives it a reddish appearance...
in 2016 as part of the European-led ExoMars
ExoMars
ExoMars is a European-led robotic mission to Mars currently under development by the European Space Agency with collaboration by NASA...
mission.
This orbiter would deliver the ExoMars Entry, Descent and Landing Demonstrator Module (EDM) static lander
Lander (spacecraft)
A lander is a spacecraft which descends toward and comes to rest on the surface of an astronomical body. For bodies with atmospheres, the landing is called atmospheric reentry and the lander descends as a re-entry vehicle...
and then proceed to map the sources of methane on Mars and other gases, and in doing so, help select the landing site for the ExoMars rover
Rover (space exploration)
A rover is a space exploration vehicle designed to move across the surface of a planet or other astronomical body. Some rovers have been designed to transport members of a human spaceflight crew; others have been partially or fully autonomous robots...
to be launched on 2018.
History
A 2016 Mars Science Orbiter (MSO) or Trace Gas Mission (TGM) was originally envisioned in 2008 as an all NASA endeavor aiming for a late 2013 launch window.However, following the Mars Joint Exploration Initiative, it was agreed that the European-lead Trace Gas Orbiter (TGO) would carry several instruments originally meant for the MSO, so NASA scaled down the objectives and focused on atmosphere trace gases detection instruments for their incorporation in ESA's Exomars Trace Gas Orbiter, to be launched in 2016.
If launched, the Trace Gas Orbiter (TGO) would be the successor to the Mars Reconnaissance Orbiter
Mars Reconnaissance Orbiter
Mars Reconnaissance Orbiter is a NASA multipurpose spacecraft designed to conduct reconnaissance and Exploration of Mars from orbit...
, which may still be operational at that time. The TGO would be launched as part of the ExoMars
ExoMars
ExoMars is a European-led robotic mission to Mars currently under development by the European Space Agency with collaboration by NASA...
program in 2016 together with a static lander built by the European Space Agency
European Space Agency
The European Space Agency , established in 1975, is an intergovernmental organisation dedicated to the exploration of space, currently with 18 member states...
.
Under the collaboration proposal, the European ExoMars
ExoMars
ExoMars is a European-led robotic mission to Mars currently under development by the European Space Agency with collaboration by NASA...
mission would be split into two parts: an orbiter/lander mission in 2016 that would include the TGO and a static lander build by ESA; this would be followed by the ExoMars rover
Rover (space exploration)
A rover is a space exploration vehicle designed to move across the surface of a planet or other astronomical body. Some rovers have been designed to transport members of a human spaceflight crew; others have been partially or fully autonomous robots...
mission in 2018 —also to be launched with an Atlas V
Atlas V
Atlas V is an active expendable launch system in the Atlas rocket family. Atlas V was formerly operated by Lockheed Martin, and is now operated by the Lockheed Martin-Boeing joint venture United Launch Alliance...
rocket. This joint ESA-NASA mission could help settle whether the methane source in that planet is of biological or geological origin, and would apparently reconcile technological and science goals with available budgets.
Science
The TGO would separate from the ExoMars stationary lander and provide it with telecommunication relay for 8 sols after landing. Then the TGO would aerobrakeAerobraking
Aerobraking is a spaceflight maneuver that reduces the high point of an elliptical orbit by flying the vehicle through the atmosphere at the low point of the orbit . The resulting drag slows the spacecraft...
for seven months into a more circular orbit for science observations and would provide communications relay
Communications satellite
A communications satellite is an artificial satellite stationed in space for the purpose of telecommunications...
for the ExoMars rover to be launched in 2018, and would continue serving as a relay satellite for future landed missions until 2022.
The mission would require detection, characterization of spatial and temporal variation, and localization of sources for a broad suite of atmospheric trace gases
Atmosphere of Mars
The atmosphere of Mars is relatively thin and is composed mostly of carbon dioxide . There has been interest in studying its composition since the detection of trace amounts of methane, which may indicate the presence of life on Mars, but may also be produced by a geochemical process, volcanic or...
:
Detection:
Nature of the methane source requires measurements of a suite of trace gases in order to characterize potential biochemical and geochemical processes at work. The orbiter would require very high sensitivity to (at least) the following molecules and their isotopomers:
water
Water
Water is a chemical substance with the chemical formula H2O. A water molecule contains one oxygen and two hydrogen atoms connected by covalent bonds. Water is a liquid at ambient conditions, but it often co-exists on Earth with its solid state, ice, and gaseous state . Water also exists in a...
(H2O), hydroperoxyl
Hydroperoxyl
The hydroperoxyl radical, also known as the perhydroxyl radical, is the protonated form of superoxide with the chemical formula HO2.-Reactivity:The superoxide anion, O2−, and the hydroperoxyl radical are in equilibrium in aqueous solution:...
(HO2), nitrogen dioxide
Nitrogen dioxide
Nitrogen dioxide is the chemical compound with the formula it is one of several nitrogen oxides. is an intermediate in the industrial synthesis of nitric acid, millions of tons of which are produced each year. This reddish-brown toxic gas has a characteristic sharp, biting odor and is a prominent...
(NO2), nitrous oxide
Nitrous oxide
Nitrous oxide, commonly known as laughing gas or sweet air, is a chemical compound with the formula . It is an oxide of nitrogen. At room temperature, it is a colorless non-flammable gas, with a slightly sweet odor and taste. It is used in surgery and dentistry for its anesthetic and analgesic...
(N2O), methane
Methane
Methane is a chemical compound with the chemical formula . It is the simplest alkane, the principal component of natural gas, and probably the most abundant organic compound on earth. The relative abundance of methane makes it an attractive fuel...
(CH4), acetylene
Acetylene
Acetylene is the chemical compound with the formula C2H2. It is a hydrocarbon and the simplest alkyne. This colorless gas is widely used as a fuel and a chemical building block. It is unstable in pure form and thus is usually handled as a solution.As an alkyne, acetylene is unsaturated because...
(C2H2), ethylene
Ethylene
Ethylene is a gaseous organic compound with the formula . It is the simplest alkene . Because it contains a carbon-carbon double bond, ethylene is classified as an unsaturated hydrocarbon. Ethylene is widely used in industry and is also a plant hormone...
(C2H4), ethane
Ethane
Ethane is a chemical compound with chemical formula C2H6. It is the only two-carbon alkane that is an aliphatic hydrocarbon. At standard temperature and pressure, ethane is a colorless, odorless gas....
(C2H6), formaldehyde
Formaldehyde
Formaldehyde is an organic compound with the formula CH2O. It is the simplest aldehyde, hence its systematic name methanal.Formaldehyde is a colorless gas with a characteristic pungent odor. It is an important precursor to many other chemical compounds, especially for polymers...
(H2CO), hydrogen cyanide (HCN), hydrogen sulfide
Hydrogen sulfide
Hydrogen sulfide is the chemical compound with the formula . It is a colorless, very poisonous, flammable gas with the characteristic foul odor of expired eggs perceptible at concentrations as low as 0.00047 parts per million...
(H2S), carbonyl sulfide
Carbonyl sulfide
Carbonyl sulfide is the chemical compound with the formula OCS. Commonly written as COS, it is a colourless flammable gas with an unpleasant odor. It is a linear molecule consisting of a carbonyl group double bonded to a sulfur atom...
(OCS), sulfur dioxide
Sulfur dioxide
Sulfur dioxide is the chemical compound with the formula . It is released by volcanoes and in various industrial processes. Since coal and petroleum often contain sulfur compounds, their combustion generates sulfur dioxide unless the sulfur compounds are removed before burning the fuel...
(SO2), hydrogen chloride
Hydrogen chloride
The compound hydrogen chloride has the formula HCl. At room temperature, it is a colorless gas, which forms white fumes of hydrochloric acid upon contact with atmospheric humidity. Hydrogen chloride gas and hydrochloric acid are important in technology and industry...
(HCl), carbon monoxide
Carbon monoxide
Carbon monoxide , also called carbonous oxide, is a colorless, odorless, and tasteless gas that is slightly lighter than air. It is highly toxic to humans and animals in higher quantities, although it is also produced in normal animal metabolism in low quantities, and is thought to have some normal...
(CO) and ozone
Ozone
Ozone , or trioxygen, is a triatomic molecule, consisting of three oxygen atoms. It is an allotrope of oxygen that is much less stable than the diatomic allotrope...
(O3). Detection sensitivities would be of 1-10 parts per trillion.
Characterization:
- 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.)
Localization:
- Mapping of multiple tracers (e.g., aerosols, water vapor, 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 localize sources might require tracing molecules at the ~1 part per billion concentration.
Instrumentation
The two space agencies issued on January 18, 2010 an Announcement of Opportunity inviting scientists to propose instruments to be carried on the mission. Once the proposals have been evaluated, the winning teams will build the actual hardware. Like Mars Reconnaisance Orbiter, the Trace Gas Orbiter would be a hybrid science-telecom orbiter. Development of the spacecraft’s five science instruments is well under way. NASA is responsible for four sensors and ESA is contributing the fifth. Its maximum science payload mass is projected to be about 115 kg. The proposed payload instruments are:- MATMOS (Mars Atmosphere Trace Molecule Occultation Spectrometer) - Solar occultation Fourier transform IR spectrometerFourier transform spectroscopyFourier transform spectroscopy is a measurement technique whereby spectra are collected based on measurements of the coherence of a radiative source, using time-domain or space-domain measurements of the electromagnetic radiation or other type of radiation....
- NOMAD (High Resolution Solar Occultation and NadirNadirThe nadir is the direction pointing directly below a particular location; that is, it is one of two vertical directions at a specified location, orthogonal to a horizontal flat surface there. Since the concept of being below is itself somewhat vague, scientists define the nadir in more rigorous...
Spectrometer) - Occultation + mapping IR, Vis/UV spectrometer - EMCS (ExoMars Climate Sounder) - Thermal IR spectrometerInfrared spectroscopyInfrared spectroscopy is the spectroscopy that deals with the infrared region of the electromagnetic spectrum, that is light with a longer wavelength and lower frequency than visible light. It covers a range of techniques, mostly based on absorption spectroscopy. As with all spectroscopic...
- MAGIE (Mars Atmospheric Global Imaging Experiment) - Wide-angle Vis/UV camera
- HiSCI (High Resolution Color Imager) - High resolution, colour, stereo camera
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 capabilitydownlinks on Spirit and Opportunity have only 1/600th the capability of the Mars Reconnaisance 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 aide. The orbital science mission, the TGO would provide the EDM lander and ExoMars rover with telecommunication relay and would continue serving as a relay satellite for future landed missions until 2022.