Sentinel-2 in the Vega launch tower. Image: ESA-CNES-ARIANESPACE/Optique vidéo du CSG–T. Leduc
Update 6:41 p.m. EDT: Arianespace announced that the mission is scrubbed for a Tuesday night launch attempt and is working towards an opportunity on Wednesday, Sept. 4.
The European Space Agency (ESA) is preparing to complete its transition to its Vega-C rocket with the final launch of its first-generation Vega rocket. The mission, dubbed VV24, will carry an Earth-imaging satellite to a sun-synchronous orbit.
Liftoff of the 22nd and final Vega rocket is set for Wednesday, Sept. 4, at 10:50 p.m. GFT (9:50 p.m. EDT, 0150 UTC) from Europe’s Spaceport in Kourou, French Guiana. During the final hours before the mission was set to launch, Arianespace posted to social media that the mission was scrubbed for its first launch attempt on Tuesday.
“Due to electrical issues on the ground links #VV24 launch chronology was interrupted,” Arianespace wrote on X, formerly Twitter. “Checks are being conducted to confirm a new launch attempt tomorrow, Sept. 4, at 10:50 p.m. local time in Kourou. The launcher and its passenger, Sentinel-2C, are in stable and safe conditions.”
The mission was initially cleared to proceed through a launch readiness review that wrapped up on Sept. 2.
The Copernicus Sentinel-2C satellite will be deployed from the launcher about 57 minutes and 20 seconds after liftoff. Officials expect to acquire signal from the spacecraft within 12 minutes of separation.
“We are really delighted to start the Vega year with the European Union’s flagship program, Copernicus, enhancing life on Earth,” said Stéphane Israël, the CEO of Arianespace, the company which manages the Vega rocket. “This mission really highlights Arianespace’s commitment to space for better life on Earth.”
Israël said the launch campaign, which formally began on July 12, has been “running perfectly well”. He said that the spacecraft began fueling on Aug. 16 and it was integrated with the upper stage on Aug. 27.
Beginning of the end
The Vega rocket began its service back in 2012 and launched 21 times since then. The goal was to have a smooth, overlapping transition from Vega to the Vega-C rocket, but an upper-stage issue during the second flight of Vega-C put a wrench in that plan.
On Dec. 20, 2022, about 151 seconds into flight, that rocket encountered “a progressive decrease in the chamber pressure” on the second stage of the rocket (Zeifro40).” An Independent Enquiry Commission (IEC) investigation and subsequent testing followed.
Back in October 2023, a spokesperson for Arianespace told Spaceflight Now that the final Vega launch was aiming for the first quarter of 2024, following a return to flight mission of Vega-C by the end of 2023. However, those plans also shifted as work continued to better understand the anomaly.
“I can reassure you there’s no commonality between that failure and Vega. Even the Zeifro40 engine is not used on that vehicle,” said Toni Tolker-Neilsen, ESA’s Director of Space Transportation, during a prelaunch news conference. “We have completely redesigned the Zeifro40 nozzle to make it much more robust and we have made a very successful test of this motor with the new nozzle design.”
That test happened in July and a second test is on tap for October. Tolker-Neilsen said there is “very good confidence” in the results of the July test and he said they believe the testing next month will also go smoothly, setting up a return to flight in November.
“This planning has been stable [for] many, many months. More than a year, we have had a very stable situation and we have been following a plan that was set out in the middle of last year, actually, and I’m very confident that we’ll be able to make it,” Tolker-Neilsen said.
“It would be a launch of Sentinel-1C, which is waiting for its launch.”
Vega joined the @ESA_transport family of launch vehicles at Europe’s Spaceport in French Guiana in 2012. Tonight’s launch will be the last for #Vega, it is being replaced by Vega-C. Let’s have a look at this rocket’s history!
https://t.co/Dl5EU2RdQz pic.twitter.com/HIhXScdw54
— ESA space history (@ESA_History) September 3, 2024
Once the transition happens, Arianespace will be responsible for all the launches up to VV29, which represents a total of six missions, including the VV24 flight of Vega. After that point, Avio becomes the “sole launch provider and operator of Vega,” according to Israël.
He said they have missions booked through VV39 with a range of customers, starting with the European Commission. Starting this month, the ESA member states decided that Avio would start commercializing Vega-C and looking for non-governmental customers in addition to those from the various governmental bodies.
Tolker-Neilsen said there are four Vega-C launches planned in 2025 and five in 2026. Israël affirmed that the customers are there to fill this manifest, adding that “it will be the responsibility of Avio, for sure, five Vega-C per year from 2026 onwards.” He said they would like to see an annual cadence of nine to 11 Ariane 6 launches alongside five Vega-C missions.
Quarter century of Copernicus
The spacecraft onboard the Vega rocket set to launch Tuesday night is part of a program that is marking 26 years this year. There are seven, first-generation satellites that are in operation and there are 13 more satellites planned.
Currently, Sentinel-2A and Sentinel-2B operate in the same orbit, but 180 degrees apart. At an altitude of 786 km (488.4 mi.), they will image all of the Earth’s coastal and land waterways ever five days using 13 spectral bands.
The first two Sentinel-2 satellites are orbiting at an inclination of 98.62 degrees.
Once it’s commissioned, Sentinel-2C, the third in the Sentinel-2 series, will replace Sentinel-2A, which launched on June 23, 2015. Similarly, once Sentinel-2D launches, it will replace Sentinel-2B, which launched on March 7, 2017.
“There are already two satellites flying, but actually they are aging. It’s very important to launch a new satellite before the others are aging too much,” said Mauro Facchini, the European Commission’s Head of Unit for Earth Observation.
The Sentinel-2C spacecraft is fueled with 133 kg of hydrazine and then pressurized the tank with helium up to 21 bars. The process was carried out over shifts by the propulsion team from AGG Lampoldshausen on Aug. 16, 2024. Image: ESA-CNES-ARIANESPACE/Optique vidéo du CSG–S. Martin
ESA said the two-satellite constellation is similar in mission goals to NASA’s Landsat program and the French Satellite pour l’Observation de la Terre (SPOT) satellite series, which have been in operation since 1972 and 1986 respectively.
The Sentinel-2 satellites have a lifespan of about 7.25 years, which includes a three-month, in-orbit commissioning phase. The batteries have a 12-year operational lifespan, to account for end of life, deorbiting maneuvers.
They feature a MultiSpectral Instrument (MSI), which ESA said uses a so-called “push-broom concept.”
“A push-broom sensor works by collecting rows of image data across the orbital swath and utilises the forward motion of the spacecraft along the path of the orbit to provide new rows for acquisition,” ESA wrote. “The average period of observation over land and coastal areas is approximately 17 minutes and the maximum period of observation is 32 minutes.”
These satellites have been used to help bolster agriculture as wells as monitoring the health of forests and monitoring methane.