ESA Vega launching

THEOS-2, TRITON & Others | Vega

Lift Off Time
October 09, 2023  – 01:36:25UTC
October 08, 2023 – 22:36:25 GFT
Mission Name
THEOS-2, TRITON & others | Vega, Flight VV23
Launch Provider
(What rocket company launched it?)
(Who paid for this?)
– Geo-Informatics and Space Technology
Development Agency (GISTDA) (for THEOS-2)
– Taiwan Space Agency (TASA) (for FORMOSAT-7R)
Launch Location
ELV, Centre Spatial Guyanais, Kourou, French Guiana
Payload mass
1240 kg
Where did the satellites go?
Sun-synchronous orbit, 617 km x 600 km, 97.9° inclination
Did they attempt to recover the first stage?
No, this is not a capability of Vega
Where did the first stage land?
The booster crashed into the Atlantic Ocean
Did they attempt to recover the fairings?
No, this is not a capability of Vega
Were these fairings new?
How was the weather?
This was the:
– 1st flight of a Vega rocket (any variant) in 2023
– 21st launch of a Vega rocket
– 49th launch from pad ELV (formerly ELA-1)
– 309th orbital launch from Centre Spatial Guyanais (any rocket type)
– 164th orbital rocket launch of 2023
Where to watch
Official livestream

What Does All This Mean?

Arianespace launched its small-lift rocket, Vega, from its equatorial launch site in French Guiana. It sent several satellites to a Sun-synchronous orbit (SSO). The main payloads were THEOS-2, which is a high resolution Earth observation satellite, and FORMOSAT-7R, which is a weather satellite looking at ocean winds. There were several smaller satellites that were to be deployed alongside the main payload. Descriptions of these appear later in this article.

How Did It Go?

The launch took off exactly at the expected time, and all staging events proceeded nominally during the trip to initial parking orbit. Once in orbit, after a cruising phase of nearly one hour, the first payload deployments were ready. During the cruise phase, the Avum 4th stage ignited on two occasions to adjust the spacecraft’s position and velocity for deployments.

The first two payloads to deploy were THEOS-2 and FORMOSAT-7R/Triton, the two primary payloads for the mission. These were deployed simultaneously.

After a second cruise phase of another 50 minutes, involving two more upper stage engine firings, the remaining 10 payloads were then deployed. After all payloads had been deployed, the upper stage made its fifth and final burn, ensuring that the stage would burn up in the atmosphere on its next closest approach to Earth, or perigee.

The two primary payloads were deployed at an altitude of 601 km. Of the secondary CubeSats that were to have been deployed later in flight, two of these payloads apparently did not deploy correctly.

The ESTCube-2 and ANSER-Leader CubeSats are thought to have remained attached to the respective deployers, according to an email from Arianespace to the affected teams. There are several reasons for suspecting this outcome:

  • There was no telemetry information from the deployment systems to indicate that deployment had taken place. This could have been instrumentation failure rather than deployment failure, on its own. However:
  • NORAD released data indicating that 10 satellites (the two primary vehicles plus 8 of the CubeSats) were in orbit, instead of 12 as expected.
  • The relevant teams have not been able to make contact with the two payloads in question.

For the ANSER-Leader spacecraft, its loss may not have a large effect on the mission. Any of the ANSER satellites can assume the role of leader if necessary. A spokesperson for INTA stated that “at this point, we are nominally operating the remaining two [spacecraft]”.


THEOS-2 stands for Thailand Earth Observation System-2.

This satellite is a very high-resolution Earth-observation optical satellite, with up to 0.5 m ground resolution. It is the 7th Thai satellite to be launched by Arianespace. 143rd Airbus Defence and Space satellite to be launched by Arianespace. The Thailand satellite will provide a lifespan of 10 years. It uses S-band radio for telemetry and X-band for payload downlink, at ~140 Mbit/s.

THEOS-2 will operate over Thailand every day, and will return to pass over previous locations every 26 days. It can tilt up to 45 degrees for imaging and has a swath of 10.3 km width. It is capable of recording at least 74,000 km2 of images every day.

THEOS-2 satellite
THEOS-2 (Credit: Surrey Satellite Technology Limited)


FORMOSAT-7R is known in English as Triton and in Chinese as “liefengzhe” (wind hunter).

It is designed to measure air-sea interactions. It uses GNSS reflectometry (GNSS-R) technology to record wave height and sea-surface wind speed. This will help predict the path of future typhoons. Wind speeds between 3 m/s and 70 m/s are theoretically measurable. The R&D for the GNSS-R instrument was developed by Taiwanese scientists and engineers.

FORMOSAT-7R has a mass of 50 k. Its size is 1.0 m x 1.2 m x 1.25 m. Its expected mission duration is five years. It will return data to a ground station in Alaska 14 times per day and Taiwan twice per day.

FORMOSAT-7R (Credit: Taiwan Panorama)

Rideshare Payloads


ANSER is an acronym for Advanced Nanosatellite Systems for Earth observation Research. This is a set of three Cubesats working together for Earth Observation objectives:

  • Study and monitor quality of inland water (reservoirs) over the Iberian peninsula
  • Develop key technologies for efficiently addressing complex space missions using satellite clusters.

ANSER Leader features a miniature panchromatic camera. The two Follower satellites are each carrying a Fragmented Cinclus hyperspectral camera, in the 400 – 850 nm range.

The ANSER mission is led by Spain’s Instituto Nacional de Técnica Aeroespacial (INTA).

ANSER satellite
ANSER (Credit: INTA)


N3SS is an acronym for Nanosat 3U pour la Surveillance du Spectre. It is a demonstration system for detecting and localizing radio-frequency jamming on civil spectrum.

CNES is responsible for the satellite development and in-flight operations. U-Space is the prime contractor for the spacecraft platform.

N3SS satellite
N3SS (Credit: CNES)

CSC-1 & 2

These are a pair of 6UXL Cubesats.

CSC-1 has a miniature star tracker for attitude determination from Solar MEMS Technologies, and arc-second accurate star tracker provided by KU Leuven University. It will also monitor radiation effects resulting from an in-orbit flight experiment provided by KU Leuven University.

CSC-2 has a radiation monitor built by Czech company esc Aerospace s.r.o. It will perform in-orbit low frequency noise characteristics using a magnetic measurement system.

CSC satellite
CSC (Credit: ISL)


This is a technology demonstrator for Plasma brake / E-sail module developed by the Finnish Meteorological Institute, and Dual Earth Observation cameras for testing Normalized Difference Vegetation Index (NDVI) data using Cubesat payloads.

The satellite platform includes cold gas thrusters, a star tracker, and multiple sets of reaction wheels for demonstration of deep space capabilities, outside of Earth’s magnetosphere.

ESTCUBE-2 satellite
ESTCUBE-2 (Credit: University of Tartu, Finland)


This is an in-orbit demonstration mission that will test Internet of Things (IoT) communications over 5G cellular technology. NanoAvionics are providing the spacecraft platform, OQTech are the prime body for operating the mission. This is the second satellite manufactured by NanoAvionics to be launched by Arianespace.

MACSAT satellite


PRETTY is an acronym for Passive REflecTomeTry and dosimetrY is a 3U Cubesat, featuring two payloads.

  • Primary – passive reflectometer in the L5 band for use with GPS and Galileo navigation systems.
  • Secondary – radiation monitor for Total Ionizing Dose and Single Event Effect measurements.

This is the first satellite where the Graz University of Technology is the customer and the manufacturer.

PRETTY satellite


PVCC is an acronym for Proba-V Companion Cubesat, which is a 12U Earth Observation in-orbit demonstration system.

The payload consists of a spare spectral imager that was developed for the VEGETATION instrument, previously launched on a Proba-V satallite in 2013.

PVCC is an ESA mission supported by Aerospacelab (ASL) as the prime contractor, with VITO and Swedish Space Corporation as subcontractors.

PVCC satellite
PVCC (Credit: Aerospacelab & ESA)

Vega Rocket

Arianespace considers Vega to be its small-lift rocket. Vega sits alongside its siblings, the heavy lift Ariane V and medium lift Soyuz. The rocket’s name comes from the brightest star in the constellation of Lyra. It 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 3.0 m (~10 ft) at its widest section. Its mass at time of launch is 137,000 kg (302,000 lbs). 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 has 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 to 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 11.7 m long, with a diameter of 3.0 m. Its total mass at time of launch is 96,243 kg (212,180 lbs). It uses Hydroxyl-terminated polybutadiene (HTPB) for propellant. This is a substance that combines the fuel and the oxidizer together. The PSLV rocket flown by ISRO, and the M-5 rocket flown by JAXA, also use HTPB.

When all its propellant has been consumed, the remaining dry mass is only 8,533 kg.

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

Vega Second Stage – Zefiro 23

The second stage, called Zefiro 23, has a length of 8.39 m, and a diameter of 1.9 m. Its total mass at time of launch is 26,300 kg (57,980 lbs).

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 2,486 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 4.12 m and a diameter of 1.9 m. Its total mass at time of launch is 12,000 kg (26,450 lb).

This stage’s motor burns for a duration of 119.6 seconds, with a specific impulse of 295.9 seconds. During its firing, it generates an average thrust of 317 kN.

After its burn, the remaining chassis and nozzle have a mass of 1,433 kg.

Vega Fourth Stage – AVUM

The final stage of the Vega rocket, called AVUM (for Attitude & Vernier Upper Module), has a length of 2.04 m and a diameter of 2.18 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 577 kg. After burning, the remaining dry mass of the stage is 111 kg.

AVUM upper stage can be restarted up to 5 times. A typical ascent consists of two burns, the first to reach an intermediate orbit, with a second burn to reach the final orbit.

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