Two Pléiades Neo Earth imaging satellites lost in failure of Europa’s Vega C rocket – Spaceflight Now | Popgen Tech


Illustration of the Vega C rocket with its Zefiro 40 second stage firing. Credit: Arianespace

The last two spacecraft in Airbus’ four-satellite, €600 million commercial Pléiades Neo Earth observation fleet crashed into the Atlantic Ocean shortly after launch from French Guiana on Tuesday night, falling victim to a failure of a European Vega C rocket .

The Vega C rocket’s launch operator, Arianespace, confirmed the mission failed to place the two Pléiades Neo optical imaging satellites into orbit. The initial focus of the failure investigation centered on the Vega C rocket’s second stage.

The 114-foot (34.8-meter) rocket lifted off from the Guiana Space Center on Tuesday at 20:47:31 pm EST (0147:31 GMT Wednesday) carrying the Pléiades Neo 5 and 6 Earth imaging satellites for Airbus Defense and Space. The target was a polar sun-synchronous orbit.

The Vega C’s powerful solid-fuel P120C first stage booster burned for nearly two-and-a-half minutes, producing a million pounds of thrust to accelerate the rocket into the upper atmosphere. Heading north off the South American coastline, the rocket shed its first stage motor casing and fired a second stage Zefiro 40 motor to continue the ascent into space.

But Arianespace said in a press release that the rocket ran into trouble about 2 minutes and 27 seconds after liftoff, near the start of the Zefiro 40 motor fire.

“After liftoff and the nominal ignition of P120C, which is the first stage of the Vega, a depressurization was observed on the Zefiro 40, which is the second stage of the Vega,” said Stéphane Israël, Arianespace’s CEO. . And after this suppression we observed a deviation from the trajectory and a very strong anomaly. Unfortunately, we can say that the mission is lost.”

Telemetry from the rocket showed that the vehicle lost velocity about three and a half minutes into the flight, when the Zefiro 40 motor should have powered the Vega C to faster speeds. The rocket apparently reached an altitude of about 360,000 feet, or 110 kilometers. Tracking data indicated that the rocket re-entered the atmosphere over the Atlantic Ocean, with the final measurement showing the Vega C about 570 miles (917 kilometers) north of the spaceport before disintegrating, likely from heating and aerodynamic forces.

“I want to deeply apologize to our client, Pléiades Neo and Airbus Defense and Space, for this failure tonight,” Israel said. “And we will now have to work with all our partners to better understand why the Zefiro 40 did not work properly tonight, causing the mission failure.”

Europe’s Vega C rocket on the launch pad in French Guiana, hours before liftoff on the doomed mission with the Pléiades Neo 5 and 6 satellites. Credit: ESA/CNES/Arianespace/JM Guillon

The Zefiro 40 second stage, like the Vega C’s other solid-fuel booster stages, is manufactured by the rocket’s prime contractor, Italian aerospace company Avio. The second stage motor is designed to burn its supply of 40 tons (36 metric tons) of prepackaged solid propellant in about 90 seconds.

Tuesday night’s launch was the first commercial flight of Europe’s upgraded Vega C rocket, following the Vega C’s flawless first test flight on July 13.

The Vega C rocket replaces the old Vega rocket’s solid fuel first and second stages with wider, heavier motor casings. The third stage motor is unchanged, and the restartable fluid-operated fourth stage has the same type of engine but carries more propellant. The upgraded Vega C is longer than the original Vega rocket configuration, and has a larger payload fairing provided by the Swiss company Beyond Gravity, formerly known as RUAG Space.

The wider Zefiro 40 second stage on the Vega C rocket replaces the Zefiro 23 motor on the base model of the Vega rocket, adding 50% more solid propellant and generating 293,000 pounds of thrust.

Europe’s Vega rocket family has now had three failures in 22 flights. The three failures occurred on the Vega rocket’s last eight launches, after 14 straight successful flights since the Vega launcher entered service in 2012.

Investigators blamed a 2019 launch mishap on a “thermo-structural failure” on the Vega rocket’s Zefiro 23 second stage. A 2020 launch failure was traced to misplaced cables on the Vega rocket’s liquid-fueled upper stage, called the Attitude and Vernier Upper Module.

The Vega rocket had amassed four straight successful launches, including the debut of the Vega C, before Tuesday night’s doomed mission.

The satellites lost on the Vega C rocket were the third and fourth spacecraft in a quartet of Airbus-built and owned Earth observation satellites. The first two Pléiades Neo satellites were launched on separate Vega rockets in 2021, but Airbus put the third and fourth spacecraft of the constellation on the same mission to take advantage of the Vega C rocket’s heavier payload.

File photo of the stack of a Zefiro 40 second stage motor prior to the first Vega C launch. Credit:
ESA-Manuel Pedoussaut

The Pléiades Neo satellites are improvements over Airbus’ two first-generation Pléiades Earth observation satellites launched in 2011 and 2012. Airbus says it has fully funded the development of the Pléiades Neo satellites, with the intention of selling the imagery commercially to private companies and government users. The company announced the Pléiades Neo program in 2016, and Airbus assembled the Pléiades Neo spacecraft at its facility in Toulouse, France.

The four-satellite program was expected to cost Airbus about 600 million euros, or about $700 million.

The Pléiades Neo satellites can produce optical images of the Earth’s surface with a resolution of 11.8 inches, or 30 centimeters, according to Airbus. It is good enough to resolve features such as vehicles and road markings. The first two Pléiades satellites launched more than a decade ago have a resolution of 19.6 inches or 50 centimeters.

Airbus has released images from the first two Pléiades Neo satellites showing their capabilities, depicting lava flows from volcanic eruptions, large-scale music and sporting events and views of aircraft and rockets at airports and spaceports.

The image resolution of Airbus’s four Pléiades Neo satellites is comparable to the resolution provided by Maxar’s six-satellite WorldView Legion surveillance satellites that begin launching next year. The companies are competitors, providing the highest resolution Earth observation imagery on the global commercial market.

Using laser inter-satellite communication links, the Pléiades Neo satellites will be able to respond quickly to task requests within half an hour, according to Airbus.

A single Pléiades Neo satellite, using a new agile pointing capability enabled by control moment gyroscopes, can turn side to side to observe the same location every two days. Once all four satellites are in orbit, the constellation will be able to image anywhere on Earth twice a day.

Each Pléiades Neo spacecraft is designed to operate for at least 10 years. One Pléiades Neo satellite can collect images every day covering an area of ​​nearly 200,000 square miles (500,000 square kilometers), Airbus says.

The Pléiades Neo 5 and 6 satellites were stacked on top of each other before being encapsulated inside the Vega C rocket’s payload fairing. Credit: ESA/CNES/Arianespace/P. Baudon

The applications for Pléiades Neo images include urban planning and city management, climate change assessments and determining the impact of pollution. The satellites can also be tasked with assessing the damage from natural disasters, and the imagery also has military applications.

The Vega C rocket was intended to deploy the Pléiades Neo 5 and 6 satellites into a polar, or north-south, orbit about 385 miles (620 kilometers) above Earth.

Europe’s Vega rocket family is designed to carry small to medium-sized satellites into orbit. Developed in partnership between Avio and the European Space Agency, the upgraded Vega C rocket is capable of delivering up to 5,070 pounds (2.3 metric tons) of payload mass to a 435-mile-high (700-kilometer) polar orbit transport, an increase over the 3,300 pound (1.5 metric ton) capacity of the base model of the Vega rocket.

ESA and the European Commission reached an agreement with Arianespace last month to launch five satellites for Europe’s Copernicus Earth observation system on Vega C rockets. The new agreement increased Arianespace’s backlog to 15 Vega missions, including 13 Vega C missions and two more launches with the original Vega rocket configuration.

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Follow Stephen Clark on Twitter: @StephenClark1.


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