Artist rendering depicting the separation between the Trace Gas Orbiter (TGO) and the Schiaparelli lander in the vicinity of Mars. Image credit: ESA

Sep 9, 2015 Counting down to ExoMars 2016

Sen—The exciting new mission to explore the mystery of life on Mars is about to begin. Engineers at the European Space Agency (ESA) and its contractors are putting the finishing touches on the ExoMars-2016 mission, which aims to deploy a state-of-the-art spacecraft into orbit around the Red Planet and drop an experimental lander onto its surface.

After years of development, the European team and their colleagues in Russia have just six weeks left before the scheduled delivery of the dual spacecraft to Baikonur on October 21, for integration with the Russian Proton rocket slated to launch on Jan. 7, 2016.

"We are almost confident that the 2016 mission will be launched in 2016, (despite some problems) but this is normal," says Francis Rocard, head of Solar System programs at the French Space Agency, CNES.

Like all missions to the Red Planet, the ExoMars-2016 has to depart within a narrow astronomical window, which will not re-open again for around two years. For ExoMars-2016, the primary launch window will close on January 27, however a backup opportunity will be available in March 2016.

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The Schiaparelli lander, also known as the Entry, Descent and landing Demonstrator (EDM), being integrated with its mothership, the Trace Gas Orbiter (TGO) at the Cannes, France, facility of Thales Alenia Space on April 11, 2015. Image credit: ESA

A scouting group of ExoMars engineers is expected to travel to Baikonur before the end of this month to make sure that all the launch facilities are in order for the special delivery. Like many other payloads, ExoMars will be airlifted to Baikonur aboard a Russian-built Antonov-124 Ruslan transport plane landing at the historic Yubileiny runway originally built for the Russian Shuttle Buran.

Sources at ESA say that the overall preparations for the ExoMars-2016 launch are going smoothly, but there are a few concerns, mainly due to late delivery of the mission's all but one scientific instrument. A couple of technical glitches are also being resolved on the spacecraft itself.

According to Walter Cugno, ExoMars Program Director at Thales Alenia Space in Italy, a pair of potentially leaky pressure transducers (sensors) was discovered in the propulsion system of the Schiaparelli lander, named after an Italian astronomer credited with the discovery of Martian "canals." The supplier of the device found welding problems in all of its sensors produced since 2012. The engines are absolutely critical for the successful landing on Mars and any potential problem with their components has to be treated very seriously.

"It is quite a critical issue but we are working on it," Cugno said.

Although the rollout of the ExoMars-2016 spacecraft to Baikonur was recently advanced by five days, the schedule is very tight with only a few days available to the team to resolve any new unexpected problems.

To save time, the orbiter's main high-resolution camera known as CaSSIS (for Color and Stereo Surface Imaging System), which can see details as small as five meters on the Martian surface, will be shipped to Baikonur separately and integrated with the rest of the spacecraft there. However, the critical operation conducted outside of the spacecraft's main assembly site might carry a risk for the hyper-sensitive instrument.

The CaSSIS camera will provide a visual context for the sources of gases, such as life-hinting methane, to be "sniffed" by the two primary instruments, which gave the orbiting spacecraft its name—the Trace Gas Orbiter, or TGO. Belgium leads the development of the NOMAD (Nadir and Occultation for MArs Discovery) instrument that will provide detailed analysis of the Martian atmosphere at various wavelengths.

Scientists from the Moscow-based Space Research Institute, IKI, provided an infrared sensor also designed to analyze the atmospheric chemistry, as well as a neutron detector, capable of sensing hydrogen (hence water ice) under the surface of Mars.

In addition to final work on the spacecraft and its instruments, mission control specialists are currently busy with final tests and rehearsals for the mission. Along with European ground stations, a large antenna dish in Shelkovo near Moscow also joined the upcoming effort to listen for the ExoMars-2016 signals. It will expand the "pipeline" for the transmission of invaluable scientific data from the mission back to Earth. The Russian ground station has already practiced getting telemetry from Mars Express, Europe's current spacecraft orbiting the Red Planet.

Besides the scientific bonanza promised by ExoMars-2016, it is also designed to serve as a testbed for critical phases of the much more risky ExoMars-2018 rover mission, hopefully, coming to the launch pad two years later.

The 600-kilogram Schiaparelli lander from the 2016 mission is the first attempt in Europe to land a probe on the Red Planet since the Beagle 2 space probe released by Mars Express. Though Beagle 2 appears to have landed, it failed to work and was regarded as lost. The agency hopes to learn from the 2016 landing experience to help with preparations for the two-ton lander carrying the ExoMars-2018 rover.

Despite a much larger size, both landers share the same shape and will use the same type of ballistic entry to land, says Jorge Vargo, the ExoMars Project Scientist at ESA's ESTEC center in Netherlands.

The radar and the inertial measurement unit used in Schiaparelli will be also recycled for the 2018 mission.

In addition, the computers that were originally developed for the 2016 mission will be also reused in 2018.

Finally, the 16-meter parachute, which will slow down Schiaparelli for the touchdown, will be scaled up to 35 meters to serve as the main parachute in the 2018 mission.

In July, NASA's Ames research center in Mountain View, California, put Schiaparelli's parachute to a series of wind tunnel tests, which were convincing enough for ESA to abandon the idea of dropping the parachute with a mockup cargo from a high-altitude balloon.

If launched on time, ExoMars-2016 will reach the vicinity of Mars at the beginning of October 2016. The lander should separate from the orbiter on October 10 and the Trace Gas Orbiter spacecraft will enter orbit around the planet two days later. The orbiter will use the so-called aerobraking, or the friction of the upper Martian atmosphere, to enter its final orbit, while saving propellant in the process.

The Schiaparelli lander is expected to operate on the surface of Mars for only few days depending on the life of its internal batteries, however, the orbiter should continue on until at least 2020, so it could serve as a communications relay station between the ExoMars-2018 rover and ground control.

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