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Home / Science / Russian Rokot Thrower to orbit the Sentinel 3B Earth Observation Satellite

Russian Rokot Thrower to orbit the Sentinel 3B Earth Observation Satellite



  Engineers connect the Sentinel 3B spacecraft to the Rokot payload adapter. Photo Credit: S. Corvaja / ESA

Engineers connect the Sentinel 3B spacecraft to the Rokot payload adapter. Photo Credit: S. Corvaja / ESA

A Russian Rokot launcher is expected to put the European Sentinel-3B Earth Observation satellite into orbit at 1:57. EDT (17:57 GMT) April 25, 2018, from location 133/3 at the Plesetsk Cosmodrome.

The campaign for this mission began on March 17, 2018, when an Antonov aircraft transporting the Sentinel 3B spacecraft from France landed in Archangelsk, Russia. There he was transported one day later by train to Plesetsk.

  Final assembly of the Rokot launcher on the launch pad

Final assembly of the Rokot launcher on the launch pad. Photo Credit: Eurockot Launch Services

"The French satellite's voyage was slightly hampered by the icy winter weather here in Russia, but now it's safe in the milder clean room environment," said Kristin Gantois, technical director of Sentinel-3 in a European Space Agency on March 23 news release

At the end of March, engineers were busy with initial tests of the spacecraft, along with electrical tests of the Rokot launcher and controls of the Briz missile -KM upper school. The numerous tests included checking the GPS units, the onboard time synchronization mechanisms, and the payload data handler mass storage.

Refueling operations of the spacecraft were conducted between 11th and 13th April. Meanwhile, the teams also filled the upper tier of Briz-KM with propellant gases, paving the way for the final phase of pre-launch activities.

After refueling, the satellite was connected to the Briz KM upper stage in April 16. This was the first step toward full launcher integration.

Next was the final dress rehearsal, which took place two days before the start. If everything goes as planned, the state commission is expected to give the go ahead.

Wednesday's flight should take about 1 hour and 20 minutes to bring the Sentinel 3B satellite into the sun. Synchronous orbit (SSO) at a height of about 503 miles (810 kilometers), tilted 98.65 degrees. If everything works smoothly, the satellite is injected into its proper orbital point. This last phase of the flight – is mainly based on the Briz-KM upper stage and the two burns whose job it is.

Built by Thales Alenia Space Sentinel-3B is an earth observation satellite dedicated to monitoring the world's oceans and the vegetation of the Earth. It measures approximately 12.1 by 7.2 by 7.2 feet (3.7 by 2.2 by 2.2 meters). The 1,200 kg satellite is designed for a service life of approximately seven years.

The Sentinel-3B probe combines a multispectral optical element with an altimetry component. The instruments on the satellite have been developed to allow measurements of the ocean and ice surface as well as the water topography on the mainland.

To achieve its goals, Sentinel-3B has four instruments to work together as a single entity. The Medium-Resolution Ocean and Land Color Instrument (OLCI) is designed to deliver multi-spectral data with a ground resolution of up to 300 meters per pixel with a 1,270-kilometer strip.

Meanwhile, the Sea and Land Surface Temperature Radiometer (SLSTR) has been developed to provide highly accurate temperature measurements of the earth's surface with a ground resolution of 1,640 to 3,280 feet (500 to 1,000 meters).

The third instrument developed on Sentinel-3B is a dual-frequency (Ku and C-band) Advanced Synthetic Aperture Radar Altimeter (SRAL) developed by Envisat and CryoSat satellites. If it works as intended, it should provide altimeter data with a spatial resolution of about 300 meters along the satellite track.

The fourth device is a Dual Frequency Microwave Radiometer (MWR) based on satellite technology that was derived from Envisat. The main purpose of this component is to correct the delay of radar altimeter signals traveling through the atmosphere. The MWR should also serve to measure total atmospheric water vapor columns.

If everything goes as planned, Sentinel-3B is expected to come to its twin Sentinel-3A, which was launched on February 16, 2016. A 140 degree orbit separation should help both satellites measure ocean features such as vortices as accurately as possible.

The Sentinel spacecraft is part of the Copernicus program, which is the result of close collaboration between ESA, the European Commission, Eumetsat, France CNES Space Agency, Industry, Service Providers and Data Users

Formerly Global Monitoring for Environment and Security (GMES), the project aims at an autonomous, multi-level earth observation function. It uses accurate and timely data to provide important information services to improve the management of the environment. It is hoped that this will help mitigate the effects of climate change and ensure civil security.

"Sentinel-3 is a very complex mission, and I am very proud to say that it keeps its promise," said Sentinel -3 Head of Mission Susanne Mecklenburg said in July 2017 .

ESA is responsible for the development of the space segment component of the Copernicus program and operates the Sentinel 1 and Sentinel 2 satellites. EUMETSAT is responsible for operating the Sentinel 3 spacecraft and delivering the marine elements of the mission, as well as serving and delivering data from the Sentinel 4, 5 and 6 satellite instruments.

The Rokot launcher first rose in November 1990, is a 95 foot (29 meter) high liquid-propelled three-stage rocket, manufactured by Eurockot Launch Services . With a total mass of approximately 107 tons, the rocket is capable of transporting up to two tonnes to near-Earth orbit and 1.2 tonnes to SSO. The launcher uses the SSB-19 / (RS-18) "Stiletto" intercontinental rocket for its first two stages.

Briz-KM upper school measures 2.6 meters (2.6 feet) long, 8.2 feet (2.5 meters) in diameter. With a mass of about 6.5 tons, this stage uses a S5.98M rocket engine that burns for up to 50 minutes to get its payload into orbit. The control system of the stage includes an on-board computer, a three-axis gyro-stabilized platform and a navigation system. The amount of fuel carried depends on the specific mission requirements and varies to maximize mission performance.

Tagged: ESA Plessezk Rokot Cosmodrome Roscosmos Sentinel-3B Range

Tomasz Nowakowski

Tomasz Nowakowski owns Astro Watch, one of the leading astronomy and science blogs on the Internet. Nowakowski has contacted SpaceFlight Insider to collaborate on the two space related websites. Nowakowski's generous offer was greeted with thanks. The two organizations are now working to better communicate important developments in space exploration.


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