ESA Vega launching

Pléiades Neo 4 | Vega

Lift Off Time/Launch Window
(Subject to change)
August 16, 2021 01:47 UTC
August 15, 2021 22:47 FGT
Mission Name
Pléiades Neo 4, Flight VV19
Launch Provider
(What rocket company is launching it?)
(Who’s paying for this?)
Airbus Defence and Space, Unseen Labs, La Sapienza University of Rome, MTA Centre for Energy Research, and SITAEL S.p.A
Launch Location
ELV-1, Guiana Space Centre, French Guiana, France
Payload mass
~980 kg (2,200 lb)
Where are the satellites going?
700 x 700 km 98.2° Sun-Synchronous Orbit (SSO)
Will they be attempting to recover the first stage?
No, this is not a capability of Vega
Where will the first stage land?
The booster will crash into the Atlantic Ocean
Will they be attempting to recover the fairings?
No, this is not a capability of Vega
Are these fairings new?
How’s the weather looking?
This will be the:
– 2nd flight of the Vega rocket in 2021
– 19th launch of a Vega rocket
– 44th launch from pad ELV-1 (formerly ELA-1)
– 307th orbital launch from Centre Spatial Guyanais (any rocket type)
– 78th orbital rocket launch of 2021
Where to watch
Arianespace’s official stream (once available)

What does all this mean?

Arianespace will be launching the Pléiades Neo 4 satellite atop a Vega rocket from their equatorial launch site ELV-1, at the Guiana Space Centre, in the French Guiana. The Pléiades Neo 4 mission is a follow up to the Pléiades Neo 3 mission, which launched atop a Vega rocket on April 29, 2021. Additionally, Arianespace will launch four smallsats: LEDSAT, RadCube, BRO-4, and µHETsat.

What is Pléiades Neo 4?

Pléiades Neo 4 is the second very high resolution Earth observation satellite in the Pléiades Neo constellation. Once complete, the Pléiades will consist of four active satellites in two different orbital planes (spaced 180° apart), allowing the constellation to image the entire globe several times each day. The constellation will provide 30 cm per-pixel resolution images of the ground several times per day; the satellites use the European Data Relay Satellite constellation to provide humans with near real-time access to the satellites’ imagery. The next pair of satellites, Pléiades Neo 5 and 6, are expected to launch on Vega in 2022.

The satellites are owned and operated by Airbus Defense and Space, who describe the satellites as having defense applications, such as monitoring enemy asset movement, and urban applications, such as monitoring the effects of climate change, pollution, and emergency service response.

Additionally, due to the high resolution of the constellation, the Pléiades Neo 4 satellite will be used to help update map services.

Pléiades Neo 4 satellite
Pléiades Neo satellite rendering (Credit: Airbus)

Rideshare Payloads


LEDSAT, or LED-based small Satellite, is a 1U CubeSat that was developed by Sapienza Space Systems and Space Surveillance Laboratory (S5Lab), from the University of Rome, and will be operated by La Sapienza University of Rome. It is an educational CubeSat developed by students, with the leadership of professors, which aims to demonstrate the ability to optically track a smallsat while it is not illuminated by the sun. Traditional optically tracked satellites can only be tracked when the satellite is in the sun and the ground-based telescope is in the dark. However, if the satellite illuminated itself with LEDs (hence the name LEDSAT), the satellite could be tracked whenever the ground-based telescope is in the dark regardless of if the satellite is in the sun. This will, in theory, lead to increased accuracy and increased precision when tracking the satellite’s position and velocity.

The satellite has a mass of 1 kilogram (2 lb) and was selected to be launched during the European Space Agency’s (ESA) “Fly Your Satellite!” program in 2017. The satellite does not have any propulsion and is powered by solar cells positioned around the CubeSat and batteries to power the satellite during darkness.

A render of the LEDSAT. (Credit: LEDSAT team)


RADCUBE is a 3U CubeSat, which is part of the Cosmic Radiation Observatory Satellite System (CROSS) constellation, built and operated by the MTA Centre for Energy Research. The satellite will monitor cosmic radiation and space weather in near real-time.

The satellite has no on-board propulsion and it is powered by solar cells on top of the spacecraft and batteries.

Artist’s render of the RADCUBE. (Credit: MTA Centre for Energy Research)


The Breizh Reconnaissance Orbiter (BRO) constellation is a constellation of spectrum monitoring and electromagnetic intelligence service signal intelligence satellites. The BRO-4 satellite is the fourth satellite in the planned seven satellite constellation; the previous three satellites have launched on Rocket Lab’s Electron rocket.

The BRO-4 satellite will survey maritime activities, and will be used to help stop illegal fishing and other environmentally unfriendly behavior. The BRO constellation is operated by UnseenLabs.


The µHETsat satellite is a collaboration between ESA, the Italian Space Agency (ASI), and SITAOL S.p.A. The satellite is built on the SITAEL S-75 satellite bus; however, the bus is equipped with the HT100 Hall Effect Thruster. The goal of the µHETsat satellite is to validate that both the satellite bus and the Hall Effect Thruster work as designed.

A Hall Effect Thruster is a type of ion thruster where ions are accelerated by an electric field. A Hall Effect Thruster uses a magnetic field to limit the electrons’ axial motion. This method of accelerating electrons is highly efficient, resulting in a specific impulse of roughly 1,600 seconds.

Vega Rocket

Arianespace’s Vega is a small-lift rocket, sitting alongside its siblings, the heavy lift Ariane V and medium lift Soyuz. The rocket’s name comes from the brightest star in Lyra constellation. Vega consists of three solid motor stages with a liquid propellant upper stage on top, making four stages in total.

Built by the Italian aerospace company Avio, the rocket is 30 m (98 ft) tall overall, and has a diameter of 3 m (~10 ft) at its widest section. Its mass at time of launch is 137,000 kg (302,000 lb). It can deploy a payload mass of 1,430 kg (3,150 lbs) to a polar orbit of 700 km altitude with 90° inclination.

Vega had one launch failure (VV15) in 2019 and another (VV17) in 2020. The anomaly on VV15 was found to most likely be due to a thermo-structural failure in the forward dome area of the Z23 motor. The failure on VV17 was confirmed in December 2020 to be due incorrectly connected cables in the rocket’s AVUM upper stage.

Artist's view of Vega
Vega rocket (left) alongside Vega-C, Ariane 5, and two Ariane 6 configurations. (Credit: ESA–David Ducros, Jacky Huart, 2016)

Vega First Stage – P80

The first stage, known as P80, is 10.6 m long, with a diameter of 3 m. Its total mass at time of launch is 98,590 kg (217,350 lb). It uses Hydroxyl-terminated polybutadiene (HTPB) for propellant, a substance that combines the fuel and the oxidizer together. Once all its propellant has been consumed, the remaining dry mass is only 7,330 kg.

The rocket motor burns for a duration of 110 seconds, and has a specific impulse of 280 seconds. While burning, it generates an average thrust of 3,015 kN.

Vega Second Stage – New Zefiro 23

The second stage, called Zefiro 23, has a length of 7.5 m, and a diameter of 1.9 m. Its total mass at time of launch is 25,935 kg (57,180 lb).

The rocket motor burns for a duration of 77 seconds, and has a specific impulse of 287.5 seconds. While burning it delivers an average thrust of 1,122 kN.

When depleted of fuel, the left-over shell has a mass of 1,935 kg.

ESA Vega rocket
Exploded view of Vega’s stages. (Credit: ESA)

Vega Third Stage – Zefiro 9

The third stage, known as Zefiro 9, has a length of 3.9 m and a diameter of 1.9 m. Its total mass at time of launch is 11,406 kg (25,146 lb).

This stage’s motor burns for a duration of 117.1 seconds, with a specific impulse of 295.2 seconds. During its firing, it generates an average thrust of 314 kN.

After its burn, the remaining chassis and nozzle have a mass of 906 kg.

Vega Fourth Stage – AVUM

The final stage of the Vega rocket, called AVUM (for Attitude & Vernier Upper Module), has a length of 1.7 m and a diameter of 2 m. This stage uses hypergolic propellants, specifically unsymmetrical di-methyl hyrdazine (UDMH) for fuel and nitrogen tetroxide (N2O4) as oxidizer.

The propellant mass on this stage is 572 kg. After burning, the remaining dry mass of the stage is 538.6 kg.

This stage’s engine burns for a duration of 723 seconds, with a specific impulse of 314.6 seconds. After this burn, it enters a coast phase for ~37 minutes. Following the coast period, the engine will restart for a second burn. The second burn lasts for just over one minute.

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