Monday, March 14, 2016

Proton-M Rocket Successfully Sends European ExoMars Mission on a Journey to the Red Planet

ExoMars 2016 liftoff. Credit: ESA–Stephane Corvaja

European mission to Mars has officially began today its seven-month 300-million-mile trip to reach the Red Planet. A Proton-M rocket, carrying the ExoMars (Exobiology on Mars) spacecraft, has blasted off to space on time, at 4:31 a.m. EST (9:31 GMT), from the Site 200/39 at the Baikonur Cosmodrome in Kazakhstan. The mission, developed jointly by the European Space Agency (ESA) and the Russian Roscosmos State Corporation, is heading to Mars to search for biosignatures of life on the planet.

Proton-M took to the skies with two passengers encapsulated in its payload fairing: the Trace Gas Orbiter (TGO) and the Entry, Descent and Landing Demonstrator Module (EDM) called “Schiaparelli”. These two spacecraft are a part of the first out of two ExoMars missions planned. The second, scheduled for the launch in May 2018, will send a robotic rover to Mars.

The rocket, boosted by the power of its six engines, commenced a short vertical climb, before pitching and rolling towards northeast direction. The first stage of the launch vehicle accelerated the mission for nearly two minutes until it was jettisoned. Then, the second stage took the control over the flight, operating for about three and a half minutes.

The separation of the second stage occurred approximately five minutes and 27 seconds into the flight. 18 seconds later, the rocket’s payload fairing detached from the launch vehicle unveiling the two ExoMars 2016 spacecraft. Third stage continued the trip for about four minutes. Nine minutes and 42 seconds, this stage also separated, sending the stack consisting of the Briz-M upper stage and the payload, on an 11-hour flight to reach an altitude of about 3,045 miles (4,900 kilometers).



Briz-M will eject the ExoMars spacecraft at 3:12 p.m. EST (20:12 GMT) with a velocity of some 20,500 mph (33,000 km/h), sending it on an interplanetary journey to Mars. Solar array deployment will be completed as soon as the spacecraft reaches a stable orientation.

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.

The spacecraft will finish its initial set of checkouts and reconfigurations within three days after the launch. Then, it will enter its commissioning phase. One week after liftoff, the mission will have the opportunity of carrying out a trajectory correction maneuver to remove launch vehicle insertion errors and set up the proper trajectory for deep space cruise. The commissioning phase will last until Apr. 24 and will includes detailed checks of the orbiter and the lander. The spacecraft will stay in a quiet cruise mode with only three communications sessions per week until the end of June.

At the end of July, the mid-course trajectory correction maneuver will be performed to line the spacecraft up to intersect with Mars in October. During the journey to Mars and while in orbit at the planet, TGO will communicate with Earth via ESA’s Malarg├╝e ground station in Argentina and New Norcia ground station in Australia. The lander is expected to separate from the 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 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.

After separation from TGO, the lander will coast to Mars remaining in hibernation mode in order to reduce its power consumption. About one hour before hitting the atmosphere, it will emerge for the last time from hibernation and begin to prepare the on-board systems for the critical events to follow.

The separation of the payload fairing during the ExoMars 2016 launch sequence. The Trace Gas Orbiter and the Schiaparelli entry, descent and landing demonstrator module can be seen as the fairing falls away. Credit: ESA–David Ducros
The separation of the payload fairing during the ExoMars 2016 launch sequence. The Trace Gas Orbiter and the Schiaparelli entry, descent and landing demonstrator module can be seen as the fairing falls away. Credit: ESA–David Ducros

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 touch-down speed will be a few meters per second, and the impact force will be absorbed by a crushable structure on the underside of the lander, similar to the crumple zone in a car. The entire entry, descent, and landing sequence will take less than six minutes,” ESA said.

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.

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 launch campaign for the ExoMars 2016 mission started in December 2015 when the TGO and the Schiaparelli EDM lander arrived at Baikonur. The TGO was joined with the lander in mid-February and all the electrical connections between the two spacecraft were established. On Feb. 21, the TGO was fueled with about 1.5 metric tons of MON (mixed oxides of nitrogen) and one metric ton of MMH (monomethylhydrazine).

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 March 11. ESA’s mission control conducted the dress rehearsal for the mission one day later. The realistic, eight-hour practice began using the actual mission control systems and ground tracking stations that will be employed on launch day and during flight, stepping through the preflight procedures while following the minute-to-minute network countdown to the moment of liftoff. Specialists from areas such as flight dynamics, ground stations, ground software and systems also took part in the rehearsal, sitting in their own control rooms and working together via voice and data loops between each other and to the launch control center at Baikonur and the ground stations.

Countdown operations for the mission began 11.5 hours ahead of the planned launch time with the activation of the Briz-M upper stage for a series of checkouts. During the first several hours of the countdown, engineers were busy making final hands-on preparations on the Proton-M launch vehicle. The rocket was powered up approximately six hours ahead of liftoff, to begin checkouts of the guidance system and spacecraft abort unit. Then, the Russian State Commission met to provide the formal approval for propellant loading operations. The propellant loading procedures finished about three hours prior to launch.

The 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. The TGO is able to detect a wide range of atmospheric trace gases such as methane, water vapor, nitrogen oxides, and acetylene.

The orbiter’s dimensions are 11.5 × 6.5 × 6.5 feet (3.5 × 2 × 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 metric tons.

The TGO is equipped with 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 to infrared wavelengths, and by taking images of the Sun to analyze better 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.

ExoMars 2016 Schiaparelli descent sequence. Credit: ESA/ATG medialab
ExoMars 2016 Schiaparelli descent sequence. Credit: ESA/ATG medialab

The Schiaparelli 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 for reconstructing its trajectory and attitude to 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, afterward.

ExoMars project began to materialize 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 signed 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.

The 190-foot tall (58-meter) Proton-M booster, which was used to launch ExoMars 2016, 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 was the second Proton mission this year and the third orbital flight from Baikonur. ExoMars 2016 is Proton’s first interplanetary flight in nearly two decades and Briz-M’s first ever journey beyond Earth’s orbit.

1 comment:

  1. I doubt Mars kept its atmosphere long enough for life to have evolved. But I would be glad to be wrong. Of course, if none is ever found, doesn't mean that life is at all rare throughout the universe. It is out there. But the distances are so great that the odds of contacting another civilization are very close to zero.

    ReplyDelete