Vega flight VV15

Vega flight VV15 was the 15th flight of the Vega launcher, and its first failure.[1][2]

Vega flight VV15

Artwork featured on visitors' brochures
Vega launch
Launch	11 July 2019, 01:53:03 UTC
Operator	Arianespace
Pad	Centre Spatial Guyanais, ELV
Payload	FalconEye1
Outcome	Failure
Vega launches

Payload

The flight, with a total payload mass of about 1279 kg, was a single-payload mission that should have deployed the FalconEye1 satellite into orbit.[3][4]

FalconEye1

FalconEye1, a high resolution Earth observation satellite built by Airbus Defence and Space and Thales Alenia Space, for the United Arab Emirates Armed Forces (UAEAF), had a lift-off mass of approximately 1197 kg, and was the only satellite on board the flight.[4][3]

Mission description

Launch date

The launch, initially planned for 5 June 2019, was postponed several times due to unfavourable weather conditions. The 15th Vega flight finally lifted off from the ELV launch pad in Kourou, French Guiana on 11 July 2019 at 01:53:03 UTC (10 July 2019 at 22:53:03 local time).

Planned orbit

The mission was planned to last 57 minutes and 09 seconds from lift-off until separation, placing its payload into a quasi-circular sun-synchronous target orbit with a mean altitude of about 611 km.[4][3]

Launch log

It was the 311th Arianespace mission (the 6th in 2019), and the 15th Vega launch (the 2nd in 2019).

FalconEye1 was Airbus Defence and Space's 131st and Thales Alenia Space 159th spacecraft to be launched by Arianespace.

Failure

Initial statements

Only 9 minutes after liftoff, a first statement was read by Luce Fabreguettes, Arianespace's executive vice-president for missions, operations and purchasing, indicating that "[...] about 2 minutes after liftoff, around the Zefiro 23 (Z23) ignition, a major anomaly occurred, resulting in the loss of the mission. [...] From the first flight data analysis we will get in the coming hours more precise information, and we will communicate to everybody at the soonest. [...]".[5]

Arianespace later repeated in a press release that "approximately two minutes after the Vega launcher’s liftoff, shortly after ignition of the second stage (Z23), a launcher anomaly occurred – leading to the premature end of the mission".[2]

Avio also published the same press release and also a video by their CEO confirming the event: "Approximately two minutes after the Vega launcher’s liftoff, shortly after ignition of the second stage, a launcher anomaly occurred – leading to the premature end of the mission", and "At present, the cause of the anomaly is still unknown and is under investigation".[6][7]

Inquiry commission

On the day of the incident, Arianespace and ESA announced that an inquiry commission would be appointed to investigate the causes of the failure and to produce recommendations allowing the Vega launcher to resume safe operations. It has been co-chaired by ESA's inspector general, Toni Tolker-Nielsen, and Arianespace's chief technical officer, Roland Lagier, and also included representatives from CNES and Avio.[2][8][6][7]

On 4 September 2019, the inquiry commission submitted its findings, that were released the next day on 5 September 2019. In particular, a structural failure on the second stage's forward dome area resulting from higher temperatures was identified as the most probable cause of the failure:

"The Commission identified as the most likely cause of the anomaly a thermo-structural failure in the forward dome area of the Z23 motor. Other possible causes such as inadvertent activation of the Z23 neutralization system have been found unlikely".

Furthermore, after specific investigations, the Independent Inquiry Commission did not find any evidence of a malicious act".[9][10][11]

On 6 December 2019, Avio released its further findings, revealing that a thermal protection design flaw on the second stage's forward dome area was the root cause of this launch failure that allowed a hot gas leaking into the critical structural part of the forward dome area. Avio engineers were able to replicate the same failure mode with this launch failure.[12] The issue was addressed though adding more thermal protection and taking other measures.[13]

Chronology

The recorded parameters streamed to ground controllers revealed that at T+00:02:10.850, shortly after ignition of the second stage's Zefiro 23 motor, a sudden and violent event occurred on the second stage that led to breaking up the launch vehicle into two main parts: the second stage and the rest of the vehicle. Beginning at T+00:02:15, the trajectory recorded veered off course. Knowing that the vehicle was in an unrecoverable condition, the range safety officer sent a destruct signal at T+00:03:33.660, which was confirmed as executed. At T+00:05:14.025, the telemetry was lost. Soon after the loss of telemetry, the vehicle crashed into the Atlantic Ocean.[9][10]

Aftermath

A set of corrective actions will be implemented by the rocket manufacturer to fix and reinforce the suspected part to prevent the repeat of the failure.[10][9][11][12] Arianespace expected to resume Vega flight by late March 2020, almost nine months of hiatus.[12] The maiden flight of upgraded Vega C would be in the second quarter of 2020.[14] UAE Armed Forces announced the cancellation of subsequent FalconEye 2 satellite to be launched on a Vega rocket and ordered Arianespace to switch to a more expensive Soyuz rocket.[15]

References

1. "Vega Flight VV15 - Arianespace". arianespace.com. Arianespace. Retrieved 10 July 2019.
2. "Vega Flight VV15 failure: Arianespace and ESA appoint an independent inquiry commission". Arianespace. 11 July 2019. Retrieved 11 July 2019.
3. "Vol VV15 : Arianespace au service d'un programme d'observation de la Terre au profit des Émirats Arabes Unis" [Flight VV15: Arianespace at the service of an Earth observation programme for the profit of the UAE] (PDF) (Launch kit). Arianespace. June 2019. Retrieved 11 July 2019.
4. "Flight VV15: Arianespace at the service of an Earth observation programme for the profit of the UAE" (PDF) (Launch kit). Arianespace. June 2019. Retrieved 11 July 2019.
5. "🔴 LIVE LAUNCH of Arianespace Vega Flight VV15 – FalconEye1 + FAILURE". Youtube. 10 July 2019. Retrieved 11 July 2019.
6. "Vega VV15". Avio.com. 11 July 2019. Retrieved 14 July 2019.
7. Ranzo, Giulio (11 July 2019). "Vega Flight VV15: Giulio Ranzo CEO of Avio". Avio.com.
8. "Vega Flight VV15 failure: Arianespace and ESA appoint an independent inquiry commission". European Space Agency. 11 July 2019. Retrieved 12 July 2019.
9. "Vega flight VV15: findings of the Independent Inquiry Commission's investigations". European Space Agency. 5 September 2019. Retrieved 14 September 2019.
10. "Vega Flight VV15: Findings of the Independent Inquiry Commission's investigations". Arianespace. 5 September 2019. Retrieved 6 September 2019.
11. Henry, Caleb; Berger, Brian (5 September 2019). "Second stage blamed as Vega targets early 2020 return to flight". SpaceNews.com. SpaceNews. SpaceNews. Retrieved 6 September 2019.
12. "New updates about Vega Flight in 2020".
13. Berger, Eric (17 June 2020). "An Italian-made rocket faces a big test on Thursday night". Ars Technica. Retrieved 18 June 2020.
14. Henry, Caleb (20 November 2019). "ESA setting aside funds for Vega launcher return to flight". SpaceNews.com. Retrieved 7 December 2019.
15. Safronov, Ivan. "Объединенные Арабские Эмираты выбрали российскую ракету вместо европейской". Ведомости (in Russian). Vedomosti. Vedomosti. Retrieved 29 November 2019.

External links

• Vega Flight VV15 at Arianespace (Archived 29 June 2019)