Friday, March 11, 2016

Europe Goes to Mars: ESA and Roscosmos Embark on a Joint Martian Endeavor

Some of the team at Baikonur who are preparing the ExoMars 2016 spacecraft for launch, pictured in front of the Proton rocket. The Trace Gas Orbiter and the entry, descent and landing demonstrator module, called Schiaparelli, are inside the fairing (with the ExoMars logo). Photo Credit: KhSC

All eyes on Europe next week as the European Space Agency (ESA) and the Russian Roscosmos State Corporation are sending their joint endeavor to Mars. The mission, known as ExoMars (Exobiology on Mars), dedicated to search for biosignatures of life on the Red Planet, is awaiting its launch scheduled for Monday, Mar. 14 from the Site 200/39 at the Baikonur Cosmodrome in Kazakhstan.

Monday liftoff will start the first of two missions under the ExoMars program, by sending an atmosphere research orbiter named Trace Gas Orbiter (TGO) and the Entry, Descent and Landing Demonstrator Module (EDM) called 'Schiaparelli'. These two spacecraft will be send to space by a Russian Proton-M rocket in configuration with the Briz-M upper stage. The second mission is slated to be launched in May 2018 and will carry a robotic rover.

The launch of ExoMars 2016 was initially scheduled for Jan. 7 but was postponed due to the need of additional inspections of the mission equipment. Now, the liftoff is set for Monday, Mar. 14 at 4:31 a.m. EST (9:31 GMT).

ExoMars project started to get its shape in July-August 2009, when ESA signed contracts with NASA and Roscosmos to develop the mission. However, due to budgetary cuts in 2012, NASA terminated its participation in the project. One year later, Roscosmos became the main partner for ESA, when the agencies singed a deal obligating the Russian side to deliver launch services, scientific instruments for TGO and landing systems together with rover instruments for the mission in 2018.

ExoMars cooperation shows that despite current political tensions between Europe and Russia, the two space agencies can still work side by side in space exploration.

"ExoMars is a unique example of the Russian–European cooperation in deep-space exploration. The mission of 2016 is just the first stage of our cooperation and, in the future, Roscosmos and ESA plan many joint projects to explore near and deep space," said Sergey Saveliev, Deputy General Director of Roscosmos.

The launch campaign started in December 2015, when TGO and Schiaparelli lander arrived at Baikonur. The engineering teams, from Thales Alenia Space, the ExoMars project team, instrument teams, and specialists from the Baikonur Cosmodrome have been extensively working to conduct a series of tests to fully prepare these two spacecraft before they are mated with each other.

Removal of a protective cover from the high-gain antenna of the ExoMars 2016 Trace Gas Orbiter. Photo Credit: TsENKI
Removal of a protective cover from the high-gain antenna of the ExoMars 2016 Trace Gas Orbiter. Photo Credit: TsENKI

TGO was joined with the lander in mid-February and all the electrical connections between the two spacecraft were established. On Feb. 21, TGO was fueled with about 1.5 ton of MON (mixed oxides of nitrogen) and one ton of MMH (monomethylhydrazine). It’s worth noticing that the stack is the heaviest spacecraft composite ever to be sent to Mars.

The final phase of preparations for the launch started with mating the ExoMars 2016 spacecraft composite with the Proton-M rocket’s Briz-M upper stage. The composite was installed on top of Briz-M on Feb. 29, after being mated with the launch vehicle adapter (LVA) inside the cleanroom at the Baikonur Space Center. Next, the stack consisting of the upper stage and the spacecraft composite was encapsulated within the launcher fairing, ready for transportation by train to the area where it was joined with the Proton-M launch vehicle. The rocket was rolled out to the launch pad on Mar. 11 and is currently awaiting liftoff in a vertical position.

After the launch, the rocket will orbit the Earth for nearly 11 hours until it reaches an altitude of about 3,045 miles (4,900 kilometers). Briz-M will then eject the ExoMars spacecraft with a velocity of some 20,500 mph (33,000 km/h), sending it on an interplanetary journey to Mars. The first signals from the spacecraft are expected to be received at 4:28 p.m. EST (21:28 GMT) by Italian Space Agency’s (ASI) Malindi ground station in Kenya, and relayed to the European Space Operations Centre (ESOC), ESA’s mission control, in Darmstadt, Germany.

“While we’ll be monitoring TGO’s liftoff and the boost phase very closely, in fact, for us, the most critical moment occurs after the spacecraft separates from the launcher upper stage, when it sends its first signals,” said ExoMars Spacecraft Operations Manager Peter Schmitz.

The commissioning phase will last first six weeks after launch, during which the spacecraft instruments and systems will be intensively checked by the instrument teams and the mission control teams at ESOC. In July, ExoMars will enter the cruise phase. At this stage, ground station passes are only scheduled three times weekly for routine checks to verify the health and functionality of the spacecraft.

In the end of July, the mid-course trajectory correction maneuver will be performed to line the spacecraft up to intersect with Mars in October. The lander is expected to separate from TGO on Oct. 16, and three days later, when the orbiter will be inserted into Martian orbit, Schiaparelli will try to land on the Red Planet.

TGO, built by Thales Alenia Space, 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, with improved spatial resolution compared with previous measurements. TGO is able detect a wide range of atmospheric trace gases such as methane, water vapor, nitrogen oxides and acetylene.

The orbiter’s dimensions are: 11.5 x 6.5 x 6.5 feet (3.5 x 2 x 2 meters) with solar wings spanning 57.4 feet (17.5 meters) and providing up to 2,000 W of power. It has a mass of approximately 4.3 tons.

TGO is equipped in four scientific instruments for the detection of trace gases: Nadir and Occultation for MArs Discovery (NOMAD), Atmospheric Chemistry Suite (ACS), Colour and Stereo Surface Imaging System (CaSSIS) and Fine Resolution Epithermal Neutron Detector (FREND).

NOMAD combines three spectrometers, two infrared and one ultraviolet, to perform high-sensitivity orbital identification of atmospheric components, including methane and many other species, via both solar occultation and direct reflected-light nadir observations. ACS will help scientists to investigate the chemistry and structure of the Martian atmosphere. It will complement NOMAD by extending the coverage at infrared wavelengths, and by taking images of the sun to better analyze the solar occultation data. CaSSIS is a high resolution camera capable of obtaining color and stereo images over a wide swathe. It will provide the geological and dynamical context for sources or sinks of trace gases detected by NOMAD and ACS. FREND is a neutron detector that will map hydrogen on the surface, revealing deposits of water-ice near the surface.

TGO will enter a highly elliptical orbit that takes four Martian days to complete one revolution. Aerobraking manoeuvres between January and November 2017 will bring the orbiter into a circular orbit at 250 miles (400 kilometers) above the surface. Science operations will begin in December 2017 and will continue for two years.

TGO is also tasked with releasing the Schiaparelli lander to allow it perform a landing on the Martian surface. The orbit will support part of the data transmission during lander’s descent and surface operations.

Moving the ExoMars Entry, Descent and Landing Demonstrator Module (EDM) Structural Model (SM) from its ground handling trolley to the Multishaker (in the background) at ESA's European Space Research and Technology Centre (ESTEC) in Noordwijk, the Netherlands, for vibration testing. Photo Credit: ESA - Anneke Le Floc'h
Moving the ExoMars Entry, Descent and Landing Demonstrator Module (EDM) Structural Model (SM) from its ground handling trolley to the Multishaker (in the background) at ESA's European Space Research and Technology Centre (ESTEC) in Noordwijk, the Netherlands, for vibration testing. Photo Credit: ESA - Anneke Le Floc'h

Schiaparelli is expected to demonstrate the capability of ESA to perform a controlled landing on Mars. It will also deliver a science package that will operate on the surface of the Red Planet for a short duration after landing, planned to last approximately from two to four Martian days.

After separation from TGO, the lander will coast to Mars remaining in hibernation mode in order to reduce its power consumption. It will be activated a few hours before entering Martian atmosphere, at an altitude of about 76 miles (122.5 kilometers). Schiaparelli will make use of its aerodynamic heatshield during the atmospheric entry and will deploy its parachute when approximately 7 miles (11 kilometers) above the surface. The lander’s liquid propulsion system will be activated to reduce the speed to less than 4.35 mph (7 km/h) when it is about 6.5 feet (2 meters) above the ground. The engines will the switched off and the module will drop to the ground. Schiaparelli will land on Meridiani Planum – a plain containing an ancient layer of hematite, an iron oxide, that almost always forms in an environment containing liquid water.

The landing of Schiaparelli will be the second European attempt to land on Mars after the Beagle 2 spacecraft failed to do it on Dec. 25, 2003. No contact was received at the expected time of landing on Mars, and ESA declared the mission lost in February 2004.

The lander, built by Thales Alenia Space, is about 5.4 feet (1.65 meters) in diameter and 5.9 feet (1.8 meters) high and has a mass of 1,322 lbs. (600 kg). It is designed to be capable of landing on a terrain with rocks as high as 1.3 feet (0.4 meters) and slopes as steep as 12.5 degrees. It is expected to be operational for up to eight Martian days after landing.

Schiaparelli is fitted with a series of sensors that will monitor the behavior 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.

Schiaparelli’s surface payload, the DREAMS (Dust Characterisation, Risk Assessment, and Environment Analyser on the Martian Surface) package, consists of a suite of sensors to measure the 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 electrification (Atmospheric Radiation and Electricity Sensor; MicroARES).

In addition to the surface payload, a camera called DECA (Entry and Descent Module Descent Camera) on the EDM will operate during the descent. It will deliver additional scientific data and exact location data in the form of images. It will be used to image the Martian surface as it approaches the landing site, to determine the transparency of the Martian atmosphere, and to support the generation of a 3-D topography model of the surface of the landing region.

The lander will carry out a program known as AMELIA (Atmospheric Mars Entry and Landing Investigation and Analysis), to study Schiaparelli’s engineering data to reconstruct its trajectory and determine atmospheric conditions, such as density and wind, from a high altitude to the surface.

Schiaparelli carries the Combined Aerothermal and Radiometer Sensors Instrument Package, called COMARS+, which is installed on the back cover of Schiaparelli will gather the data to study this. COMARS+ consists of three small (22-mm-diameter) combined sensors (COMARS) spaced equally across the rear cover of Schiaparelli, one broadband radiometer, and an electronic box.

The lander is also equipped in INRRI - a Cube Corner laser Retroreflector (CCR) located on the zenith-facing surface of Schiaparelli, the ExoMars entry, descent, and landing demonstrator. It will enable Schiaparelli to be located from Mars orbiters by laser ranging, both during Schiaparelli’s mission lifetime and, as it is passive and maintenance free, afterwards.

Schiaparelli descent sequence. Image Credit: ESA/ATG medialab
Schiaparelli descent sequence. Image Credit: ESA/ATG medialab

The 190-foot tall (58-meter) Proton-M booster that will be used to launch ExoMars, measures 13.5 feet (4.1 meters) in diameter along its second and third stages, with a first stage that has a diameter of 24.3 feet (7.4 meters). The total overall height of the Proton booster’s three stages is 138.8 feet (42.3 meters).

The rocket’s first stage consists of a central tank containing the oxidizer surrounded by six outboard fuel tanks. Each fuel tank also carries one of the six RD‑276 engines that provide power for the first stage. The cylindrical second stage is powered by three RD-0210 engines along with one RD‑0211 engine. Meanwhile, the third stage is powered by a single RD-0213 engine and a four-nozzle vernier engine. Guidance, navigation, and control of the Proton-M during operation of the first three stages is carried out by a triple redundant closed-loop digital avionics system mounted in the Proton’s third stage.

The Briz-M is powered by a pump-fed gimbaled main engine. This stage is composed of a central core and an auxiliary propellant tank that is jettisoned in flight following the depletion of the stage’s propellant. The Briz-M control system includes an onboard computer, a three-axis gyro stabilized platform, and a navigation system. The quantity of propellant carried is dependent on specific mission requirements and is varied to maximize mission performance.

Monday’s launch will be the second Proton mission this year and the second orbital flight from Baikonur as well.

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