Two Pleiades Neo Earth-imaging satellites lost due to failure of Europa’s Vega C rocket – Spaceflight Now

Two Pleiades Neo Earth-imaging satellites lost due to failure of Europa’s 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’s €600 million Pleiades Neo commercial Earth observation fleet of four satellites crashed in the Atlantic Ocean shortly after launch from French Guiana on Tuesday night, and fell victim to a failed European Vega C rocket.

The launch operator of the Vega C rocket, Arianespace, confirmed that the mission failed to put 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-tall (34.8-meter) rocket lifted off from the Guyana Space Center at 20:47:31 EST Tuesday (0147:31 GMT Wednesday) with the Pleiades Neo 5 Earth-imaging satellites and 6 for Airbus Defense and Space. The goal was a sun-synchronous polar orbit.

Vega C’s powerful P120C solid-fuel 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 from the South American coast, the rocket detached the first stage engine housing and fired a Zefiro 40 second stage engine 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 engine’s ignition.

“After liftoff and nominal ignition of the P120C, which is the first stage of the Vega, low pressure has been observed in the Zefiro 40, which is the second stage of the Vega,” said Stéphane Israël, director general of ‘Arianespace. And after this low pressure, we have 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 the vehicle losing speed about 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, with the final measurement showing Vega C about 570 miles (917 kilometers) north of the spaceport before it likely disintegrated by heating and aerodynamic forces.

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

Europa’s Vega C rocket on the launch pad in French Guiana, hours before liftoff for the doomed mission with the Pleiades 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 produced by the rocket’s prime contractor, Italian aerospace company Avio. The second stage engine is designed to burn through its 40-ton (36 metric tons) supply 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 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 housings. The third stage engine is unchanged and the liquid fuel restartable fourth stage has the same engine type but carries more propellant. The upgraded Vega C is taller 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 Vega C rocket’s larger Zefiro 40 second stage replaces the Zefiro 23 engine in the base model Vega rocket, adding 50% more solid propellant and generating 293,000 pounds of thrust.

Europe’s Vega rocket family 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.

Researchers blamed a 2019 launch mishap on a “thermostructural failure” in the second stage of the Vega Zefiro 23 rocket. A 2020 launch failure was traced to misplaced cables in the liquid fuel upper stage of the rocket Vega, called the upper module of Attitude and Vernier.

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

The satellites lost 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 Pleiades Neo satellites were launched in 2021 on separate Vega rockets, but Airbus put the constellation’s third and fourth spacecraft on the same mission to take advantage of the heavier payload capacity of the Vega C rocket .

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

The Pleiades Neo satellites are improvements over Airbus’ two first-generation Pleiades Earth observation satellites launched in 2011 and 2012. Airbus says it fully funded the development of the Pleiades Neo satellites, with the intention to sell 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 facility in Toulouse, France.

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

The Pleiades Neo satellites can produce optical images of the Earth’s surface with a resolution of 11.8 inches, or 30 centimeters, according to Airbus. This is good enough to resolve features such as vehicles and road markings. The first two Pleiades 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 Pleiades Neo satellites showing its capabilities, depicting lava flows from volcanic eruptions, large-scale music and sporting events, and views of airplanes and rockets at airports and spaceports.

The image resolution of Airbus’ four Pleiades Neo satellites is comparable to the resolution provided by Maxar’s six-satellite WorldView Legion surveillance satellites that will begin launching next year. The companies compete and offer the highest resolution Earth observation images on the global commercial market.

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

A single Pleiades Neo satellite, using a new agile pointing capability enabled by moment-of-control gyroscopes, can rotate 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 Pleiades Neo spacecraft is designed to operate for at least 10 years. A Pleiades Neo satellite can collect images covering an area of ​​nearly 200,000 square miles (500,000 square kilometers) each day, Airbus says.

The Pleiades Neo 5 and 6 satellites were 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 Pleiades Neo imagery include urban planning and city management, climate change assessments, and determining pollution impacts. Satellites can also be tasked with assessing damage from natural disasters, and the imagery also has military applications.

The Vega C rocket was intended to deploy the Pleiades 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 carry small to medium-sized satellites into orbit. Developed in collaboration 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 to a 435-mile-high polar orbit ( 700 kilometers), an increase over the 3,300-pound (1.5 metric tons) 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 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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