This Wednesday, Oct. 19th, a European Space Agency (ESA) probe named ” Schiaparelli” will parachute to the surface of Mars following a fiery plunge through the atmosphere. Launched from Earth last March, Schiaparelli hitched a ride to Mars onboard the Trace Gas Orbiter, a satellite that will spend the next few years scanning the Red Planet for chemical signs of life–especially biogenic methane. Follow the action on the ESA’s live webcast.

Source: Spaceweather

The 2016 ExoMars Trace Gas Orbiter is the first in a series of Mars missions to be undertaken jointly by the two space agencies, ESA and Roscosmos. A key goal of this mission is to gain a better understanding of methane and other atmospheric gases that are present in small concentrations (less than 1% of the atmosphere) but nevertheless could be evidence for possible biological or geological activity.

Schiaparelli separating from the Trace Gas Orbiter. Credit: ESA/ATG medialab

Investigations with observatories in space and on Earth have demonstrated the presence of small amounts of methane in the Martian atmosphere that has been shown to vary with location and time. Since methane is short-lived on geological time scales, its presence implies the existence of an active, current source of methane. It is not clear, yet, whether the nature of that source is biological or chemical. Organisms on Earth release methane as they digest nutrients. However, other purely geological processes, such as the oxidation of certain minerals, also release methane.

The Trace Gas Orbiter carries a scientific payload capable of addressing this scientific question, namely the detection and characterisation of trace gases in the Martian atmosphere. From its approximately 400-km-altitude science orbit, the instruments onboard the Trace Gas Orbiter will be deployed to detect a wide range of atmospheric trace gases (such as methane, water vapour, nitrogen oxides, acetylene), with an improved accuracy of three orders of magnitude compared to previous measurements.

The Trace Gas Orbiter will monitor seasonal changes in the atmosphere’s composition and temperature in order to create and refine detailed atmospheric models. Its instruments will also map the subsurface hydrogen to a depth of a metre, with improved spatial resolution compared with previous measurements. This could reveal deposits of water-ice hidden just below the surface, which, along with locations identified as sources of the trace gases, could influence the choice of landing sites of future missions.

Communicating on Mars

Deployment test of the high-gain antenna. Credit: ESA – B. Bethge

The Trace Gas Orbiter carries the Entry, Descent and landing demonstrator Module (EDM), known as Schiaparelli, on the journey from Earth towards Mars and, as it approaches the planet, deploys it for entering the Martian atmosphere on its way to land on the surface of the planet. After deployment, the Orbiter will monitor the UHF transmission from Schiaparelli from its coasting to Mars until its landing on the Red Planet. It will also facilitate the real-time transmission to Earth of the most important data measured by Schiaparelli.

Scientific investigations will take top priority until the second mission in the ExoMars programme begins, with the arrival of the ExoMars rover in 2021. At that stage the Orbiter will become a valuable Mars telecommunications asset, providing communication services to the Rover operating on the surface of Mars. The Orbiter will act as a data relay centre for sending commands to the rover and downloading data to Earth through the ESA space communications network.

 

 

The ExoMars Trace Gas Orbiter Design

The Trace Gas Orbiter spacecraft, designed by ESA, builds on the heritage accumulated from earlier ExoMars mission scenarios. The main characteristics of the Orbiter are determined by the functions that it will perform and the launch vehicle, a Proton launcher, provided by Roscosmos.

 

Source: ESA

One of the core scientific goals of any mission to Mars is the search for evidence of life. The best approach is to investigate the surface where the evidence may lie.

The key element for accessing the surface of Mars and one of the greatest challenges in space exploration is the successful execution of the entry, descent and landing sequence.

This is one of the reasons why since the late 1960s there have been so many missions attempting to land on the surface of Mars, some being successful, many others ill-fated.

Schiaparelli – an entry, descent and landing demonstrator module – is a technology demonstration vehicle carried by the ExoMars Trace Gas Orbiter (TGO). Schiaparelli and TGO were launched on 14 March 2016 on a Proton rocket from the Baikonur cosmodrome in Kazakhstan.  Schiaparelli will demonstrate the capability of ESA and European industry to perform a controlled landing on the surface of Mars. The preparation for this mission enhances Europe’s expertise and enables the testing of key technologies which could be used in subsequent missions to Mars.

Although designed to demonstrate entry, descent and landing technologies, Schiaparelli also offers limited, but useful, science capabilities. It will deliver a science package that will operate on the surface of Mars for a short duration after landing, planned to last approximately 2-4 sols (Martian days).

 

Arriving at Mars

Schiaparelli has started its journey to Mars attached to the Trace Gas Orbiter. They were launched on a Proton rocket on 14 March 2016 and will arrive approximately 7 months later at Mars.

Coast

• Three days before reaching the atmosphere of Mars, on 16 October, Schiaparelli separated from the Orbiter.

• The module is now coasting to Mars during which phase it will remain in hibernation mode in order to reduce its power consumption.

• Schiaparelli will be activated a few hours before entering the atmosphere of Mars, at an altitude of 122.5 km and a speed of approximately 21 000 km/h.

Entry

• An aerodynamic heatshield will protect Schiaparelli from the severe heat flux and deceleration, so that at an altitude of about 11 km, when the parachure is deployed, it will be travelling at around 1650 km/h.

Descent

• The module will first release the front heatshield and then the rear heatshield will also be jettisoned.

• Schiaparelli will turn on its Doppler radar altimeter and velocimeter to locate its position with respect to the Martian surface.

Landing

• The liquid propulsion system will be activated to reduce the speed to less than 7 km/h when it is 2m above the ground. At that moment the engines will the switched off and the lander will drop to the ground.

• As Schiaparelli lands, the final shock will be cushioned by a crushable structure built into module.

• The primary landing site has been identified: it is a plain known as Meridiani Planum. This area interests scientists because it contains an ancient layer of hematite, an iron oxide that, on Earth, almost always forms in an environment containing liquid water.

A communication link between Schiaparelli and the Trace Gas Orbiter will facilitate the real-time transmission of the most important data measured by the module. The complete set of data acquired will be transmitted to the Orbiter within 8 sols after the landing (a solar day on Mars, or sol, is 24 hours and 37 minutes).

 

 

The ExoMars Schiaparelli Design

Schiaparelli builds on a heritage of designs that have been evaluated and tested by ESA during earlier ExoMars studies. The module accommodates a series of sensors that will monitor the behaviour of all key technologies during the mission. These technologies include a special material for thermal protection, a parachute system, a radar Doppler altimeter system, and a braking system controlled by liquid propulsion. The data will be sent back to Earth for post-flight reconstruction in support of future European missions to Mars.

The main characteristics of Schiaparelli are provided in the table below:

 

The design activities are performed by European industry, led by Thales Alenia Space – Italy under the close supervision of ESA.

Schiaparelli science and engineering sensors

Because Schiaparelli is primarily demonstrating technologies needed for landing, it does not have a long scientific mission lifetime: it is intended to survive on the surface for just a few days by using the excess energy capacity of its batteries. However, a set of engineering and scientific sensors will analyse the local environment during descent and after landing.

Schiaparelli carries a small science payload, called DREAMS (Dust Characterisation, Risk Assessment, and Environment Analyser on the Martian Surface), to study the environment. DREAMS consists of a suite of sensors to measure the local wind speed and direction (MetWind), humidity (DREAMS-H), pressure (DREAMS-P), atmospheric temperature close to the surface (MarsTem), the transparency of the atmosphere (Solar Irradiance Sensor, SIS), and atmospheric electric fields (Atmospheric Radiation and Electricity Sensor; MicroARES) at Mars. The payload will operate on the surface of Mars for 2–8 sols.

In addition, there is an investigation known as AMELIA, for entry and descent science data collection using the spacecraft engineering sensors.

A separate instrumentation package, COMARS+, will monitor the heat flux on the back cover of Schiaparelli as it passes through the atmosphere.

A compact array of laser retroreflectors, called INRRI, is attached to the zenith-facing surface of Schiaparelli. This can be used as a target for Mars orbiters to laser-locate the module.

Source: ESA