Two Pléiades Neo Earth-imaging satellites lost in failure of European Vega C rocket – Spaceflight Now

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

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

The launch operator of the Vega C rocket, Arianespace, confirmed that the mission failed to bring the two Pléiades Neo optical imaging satellites into orbit. The preliminary focus of the failure investigation was on the second stage of the Vega C rocket.

The 114-foot (34.8-meter) tall rocket lifted off from the Guiana Space Center at 8:47:31 p.m. Space. The goal was a sun-synchronous polar orbit.

The Vega C’s powerful solid-fuel P120C first-stage propellant burned for almost two and a half minutes, producing a million pounds of thrust to accelerate the rocket into the upper atmosphere. Heading north from the South American coast, the rocket detached from the spent first-stage engine casing and ignited a Zefiro 40 second-stage engine to continue the ascent into space.

But Arianespace said in a news release that the rocket had problems about 2 minutes and 27 seconds after liftoff, near the start of the Zefiro 40 engine firing.

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

Telemetry from the rocket showed that the vehicle lost speed approximately three and a half minutes into the flight, when the Zefiro 40 engine should have been propelling the Vega C to faster speeds. The rocket appeared to reach a maximum altitude of about 360,000 feet, or 110 kilometers. Tracking data indicated that the rocket re-entered the atmosphere over the Atlantic Ocean, and the final measurement showed Vega C about 570 miles (917 kilometers) north of the spaceport before it likely disintegrated from heating and the aerodynamic forces.

“I want to deeply apologize to our client, Pléiades Neo and Airbus Defense and Space, for this failure tonight,” said Israël. “And now we will need to work with all of our partners to better understand why the Zefiro 40 malfunctioned tonight, leading to mission failure.”

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

The Zefiro 40 second stage, like the other solid fuel booster stages of the Vega C, is produced by the rocket’s main contractor, the Italian aerospace company Avio. The second stage engine is designed to burn its 40 ton (36 metric ton) supply of prepackaged solid propellant in approximately 90 seconds.

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

The Vega C rocket replaces the solid fuel first and second stages of the old Vega rocket with wider and heavier engine cases. The third stage engine is unchanged, and the resettable liquid fuel fourth stage has the same type of engine but carries more propellant. The updated Vega C is taller than the original Vega rocket configuration and has a larger payload fairing provided by Swiss company Beyond Gravity, formerly known as RUAG Space.

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

Europe’s Vega family of rockets has now suffered three failures in 22 flights. All three failures have occurred in the last eight launches of the Vega rocket, following 14 consecutive successful flights since the Vega launcher entered service in 2012.

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

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

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

File photo of a Zefiro 40 second stage engine stacking before the first launch of Vega C. Credit:
ESA-Manuel Pedoussaut

The Pléiades Neo satellites feature improvements over Airbus’ two first-generation Pléiades Earth observation satellites launched in 2011 and 2012. Airbus says it fully funded the development of the Pléiades Neo satellites, with the intention of selling the images 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 facilities in Toulouse, France.

The four-satellite program was expected to cost Airbus about 600 million euros, or roughly $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. That’s 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 of the first two Pléiades Neo satellites showing their capabilities, showing lava flows from volcanic eruptions, large-scale music and sporting events, and views of planes and rockets at airports and spaceports.

The image resolution of Airbus’ four Pléiades Neo satellites is comparable to the resolution provided by Maxar’s six-satellite WorldView Legion surveillance satellites due to begin launch next year. The companies are competitors and provide the highest resolution Earth observation images on the global commercial market.

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

A single Pléiades Neo satellite, using a new agile pointing capability enabled by check-moment gyroscopes, can rotate from side to side to observe the same location every other day. Once all four satellites are in orbit, the constellation will be able to take images of anywhere on Earth twice a day.

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

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

Applications of Pléiades Neo imagery include urban planning and city management, climate change assessments, and determination of pollution impacts. Satellites may also be tasked with assessing damage from natural disasters, and the images have military applications as well.

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 family of rockets is designed to launch 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 carrying up to 5,070 pounds (2.3 metric tons) of payload mass into a 435-mile-high (700-kilometer) polar orbit, a increase over the 3,300 pound (1.5 metric ton) capacity of the base model Vega rocket.

ESA and the European Commission reached an agreement with Arianespace last month to launch five satellites for the European Copernicus Earth Observing System on Vega C rockets. The new agreement increased Arianespace’s order book 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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