Home / Science / The successful launch of the Ariane 5 fills the European navigation fleet – Spaceflight Now

The successful launch of the Ariane 5 fills the European navigation fleet – Spaceflight Now

An Ariane 5 rocket dropped off at 1125 GMT (07:25 EDT, 8:25 am French Guiana time) from the Guiana Space Center in South America. Photo: ESA / CNES / Arianespace – Photo Optique Video of the CSG – Service Optique

The last flight of a discontinued version of the European Ariane 5 launch vehicle added four more satellites to the European Galileo navigation constellation on Wednesday for the launch of the full global service in 2020 to stay on course.

Launched with an older, unproductive upper-level powered by toxic, storable hydrazine ignited by the 47-meter-high Ariane 5 ES rocket Vulcain 2 main engine at 1125: 01 GMT (7:25:01 pm EDT; 8:25 : 01 am French Guiana time) from the Guayana Space Center on the northeastern coast of South America.

Seven seconds later, two solid rockets fired simultaneously to send the Ariane 5 launcher into a clear morning sky above the French Guiana spaceport. The steerable booster nozzles steered the missile northeast, and the strapping engines burned their solid propellant and were dropped for about 2 minutes, 19 seconds, after takeoff.

Sniffing supercooled liquid hydrogen and liquid oxygen at a speed of 705 pounds (320 kilograms) per second, firing the Vulcain 2 engine for nine minutes before dropping the core stage and falling back into the earth's atmosphere.

The Ariane 5's Aestus engine fired seconds later and burned an elliptical transfer orbit for almost 11 minutes, covering more than 14,000 miles (nearly 23,000 kilometers) above the Earth. After a three-hour coast, the Aestus engine ignited for more than six minutes and changed its orbit to create a circular path around the planet.

Telemetry radioed from the rocket to the launch controllers in French Guiana showed the four 1,576-pound (715 kilograms) Galileo satellites, which are intentionally separated from their carrier module in two pairs at 20-minute intervals.

An artist's illustration of four Galileo satellites orbiting from an upper stage of the Ariane 5 rocket. Credit: ESA-P. Carril

A separate inspection team in Toulouse, France, took over responsibility for the satellites shortly after separation from the Ariane 5 rocket. The engineers confirmed that all four spacecraft were healthy after unfolding their power generation solar cells after a scheduled post-launch activation sequence.

Officials declared the launch a success and gave the European Galileo navigation fleet 26 satellites, including 22 in the last four years. So far, the 26 Galileo satellites launched so far set up seven Soyuz boosters and three Ariane 5 rockets, completing the program's first deployment in space.

"Today, all parameters were green and the sky was completely blue." Said Stephane Israel, CEO of Arianespace, in a post-launch speech at the Kourou spaceport, French Guiana. "It has been an outstanding success for Europe, with 12 Galileo satellites launched by Ariane 5 in less than three years."

Wednesday's mission was the last flight of the Ariane 5 ES version of Europe's hustler rocket. All future Ariane 5 launches will use the Ariane 5 ECA configuration, the most common variant of the European rocket.

The difference between the two variants is the Ariane 5 ECA, which flies with a hydrogen-powered HM7B upper-stage engine, can only be detonated once in space. Missions such as Galileo satellite deployment require multiple upper-level firing, while most commercial satellite launches require only one

The Ariane Group, prime contractor for the Ariane rocket family and parent company of Arianespace, is developing a new machine called Vinci for Europe's next-generation Ariane 6 rocket. The VINCI is to be re-ignited in space.

Paul Verhoef, Director of Navigation for the European Space Agency, said the Galileo network is fully operational by 2020, a milestone that has been further consolidated with the successful launch on Wednesday [19659003] ESA is a specialized and procured entity for the Galileo program, managed by the European Commission, the executive body of the European Union.

The program is expected to cost EU Member States 10 billion euros (11.7 billion US dollars) by 2020, according to the European Commission

Elżbieta Bieńkowska, European Commissioner for the Internal Market, Industry and Entrepreneurship, named the launch on Wednesday an "important milestone in the history of Galileo." 19659003] "This launch brings the constellation to 26 satellites and really brings Galileo one step closer to full operational capability."

Illustration of the artist of Galileo navigation satellites in orbit. Credit: OHB

Upon completion, the Galileo constellation will consist of approximately 30 satellites, including 24 operational spacecraft and approximately six replacement parts spread over three 23,222-kilometer orbital aircraft.

The satellites launched Wednesday are the latest in a second series of navigation platforms ordered from OHB in Germany, which builds the spacecraft, and British SSTL, a provider of navigation payloads.

Galileo will pause until the end of 2020 The first pair of another 12 Galileo satellites ordered by the OHB / SSTL team from ESA and the European Commission are ready for take-off. The next series of Galileo satellites will be launched with the European Ariane 6 rocket, with two each on board the lighter configuration of the next generation launch vehicle with two solid-fuel solid boosters.

"We are happy with what we have the moment, and with the delivery of the next batch in 2020," said Verhoef.

Officials said the addition of the four satellites launched on Wednesday – along with the eventual integration of two Galileo spacecraft launched in a false orbit in 2014 and the activation of the Galileo ground systems – should allow the European Commission to use the grid for 2020 to declare the full operation ready.

In December 2016, the European Commission commissioned Galileo's first services, integrating Galileo-based navigation signals alongside the US military's GPS satellites and the Glonass fleet of the Russian military.

But without a full At least 24 satellites still have gaps in the Galileo coverage. In addition to the two Galileo satellites flying in the wrong orbit, another spacecraft suffered an antenna failure and can not provide services.

Nonetheless, officials said these gaps will be closed in the next few years and the satellites in orbit provide better position estimates than required

"Galileo's performance promises to be not only very good, but also very good," said Rodrigo da Costa, program manager for Galileo services at the European Agency for Global Navigation Satellite Systems. or GSA.

"Seven years later we have 26 satellites in orbit," said Jean-Yves Le Gall, president of the French space agency CNES. "We've got a system that's going to be the best in the world, we're talking about 400 million users, the numbers are going up all the time."

"The accuracy is enormous," Le Gall said after launching on Wednesday, "with our system we know whichever street we are on. "

Most new smartphones integrate Galileo data with GPS signals in their navigation apps, and each year more cars are equipped with Galileo-compatible navigation systems, officials said GPS and Galileo are signaling more accurate position and time fixes to users of the provider than would be possible with a single network.

Galileo's full-operational milestone planned for 2020 will come when "the constellation is complete ground segment" Verhoef said

"This is often forgotten," Verhoef told reporters Tuesday, "the focus is always on launching satellites but I can tell you that the mission is happening in reality on the ground. All of this has to be ready, trapped and working together as a system before any sort of operational capability can be explained.

The four satellites launched on Wednesday are nicknamed Anna, Ellen, Samuel and Tara, the names of the children who have won

Verhoef said engineers have solved a problem common to some of the older Galileo navigation satellites None of the clock errors have affected a satellite's navigation capability, but some spacecraft have lost redundancy in their navigational payloads.

"The clocks on the ground have been fixed, and the orders have been corrected, and we had one Number of take operational measures on the clocks in orbit, "Verhoef said and declined to provide details about the corrective actions during a pre-launch teleconference with reporters.

" It was, as so often with these things, a very small mistake, but it has led to a pretty big result, and you just have to dig very deep and to the spec ialists go to find out what happened, "said Verhoef. "What resulted was an internal short in the clocks, and of course, after you have a short circuit, it's over and they're dead."

Arianespace's next mission is scheduled for August 21st when a light goes out The Vega launcher will launch ESA's Aeolus Earth satellite to orbit global wind profiles. This is followed by another Ariane 5 mission – the 100th Ariane 5 mission – on September 15 with two commercial communications satellites

E-mail the Author [19659003] Follow Stephen Clark on Twitter: @ StephenClark1 .

Source link