Ariane flight VA256 was an

Ariane 5 Ariane 5 is a European heavy-lift space launch vehicle developed and operated by Arianespace for the European Space Agency (ESA). It is launched from the Centre Spatial Guyanais (CSG) in French Guiana. It has been used to deliver payloads into ...

rocket flight that launched the

James Webb Space Telescope The James Webb Space Telescope (JWST) is a space telescope which conducts infrared astronomy. As the largest optical telescope in space, its high resolution and sensitivity allow it to view objects too old, distant, or faint for the Hubble Spa ...

into space on 25 December 2021. It was 2021's final Ariane flight, its most valuable payload to date, and the Ariane mission. The launch was described by NASA as "flawless" and "perfect".

Launch configuration

Rocket

Ariane 5 is a heavy lift two-stage rocket with two solid fuel boosters. It was used in its ''ECA'' variant, which offers the highest payload mass capacity. The total launch mass of the vehicle is of the order of .

Payload

The only payload on the flight was the

(JWST), a NASA/ ESA space-based observatory. The launch is one of the European Space Agency's contributions to the project. The telescope had a launch mass of about and a design lifetime of 5 to 10 years.

Preparation campaign

Arrival in Kourou

The payload arrived in

Kourou Kourou () is a commune in French Guiana, an overseas region and department of France in South America. Kourou is famous for being the location of the Guiana Space Centre, the main spaceport of France and the European Space Agency (ESA). It ...

French Guiana French Guiana ( or ; french: link=no, Guyane ; gcr, label= French Guianese Creole, Lagwiyann ) is an overseas department/region and single territorial collectivity of France on the northern Atlantic coast of South America in the Guianas. It ...

, on where it was unloaded from the MN ''Colibri'' cargo ship and transported to the space centre.

Integration incident

On an incident was reported by NASA and Arianespace that a clamp band securing the payload to the adapter was released during integration activities, causing vibrations to the telescope. After some tests were performed, a review board concluded on that no payload component was damaged, and fuelling operations could be started on the next day, with the launch planned for 22 December 2021 at that time.

Fuelling operations

Spacecraft fuelling operations began on , the fuelling system was disconnected on , and verifications were concluded on . The telescope's fuel system was filled with approximately of

hydrazine Hydrazine is an inorganic compound with the chemical formula . It is a simple pnictogen hydride, and is a colourless flammable liquid with an ammonia-like odour. Hydrazine is highly toxic unless handled in solution as, for example, hydrazin ...

and of

dinitrogen tetroxide Dinitrogen tetroxide, commonly referred to as nitrogen tetroxide (NTO), and occasionally (usually among ex-USSR/Russia rocket engineers) as amyl, is the chemical compound N2O4. It is a useful reagent in chemical synthesis. It forms an equilibrium ...

, needed to reach and maintain its orbit after separation from the launch vehicle.

Final assembly

Following the rocket, which had already arrived on , the telescope was moved to the final assembly building ( or ''BAF'') on . The payload was encapsulated inside the fairing on top of the rocket on .

Interface communication issue

On , a joint press release by NASA and Arianespace revealed that "a communication issue between the observatory and the launch vehicle system" was being tackled, further delaying the launch to no earlier than .

Weather issue

Unfavorable weather forecasts for delayed the launch to

Christmas Day Christmas is an annual festival commemorating the birth of Jesus Christ, observed primarily on December 25 as a religious and cultural celebration among billions of people around the world. A feast central to the Christian liturgical year, ...

, .

Launch

The rocket was launched from the

ELA-3 ELA-3 (french: Ensemble de Lancement Ariane 3, lit=Ariane Launch Complex 3), is a launch pad and associated facilities at the Centre Spatial Guyanais in French Guiana. ELA-3 is operated by Arianespace as part of the expendable launch system fo ...

launch pad of the

Guiana Space Centre The Guiana Space Centre (french: links=no, Centre spatial guyanais; CSG), also called Europe's Spaceport, is a European spaceport to the northwest of Kourou in French Guiana, a region of France in South America. Kourou is located approximat ...

on 25 December 2021 at 12:20 UTC (09:20 local time, 7:20 am U.S. EST). The DDO (in French: ''Directeur des Opérations'') of the launch was Jean-Luc Voyer, who concluded his shift by saying, "Go Webb!" The launch was described by NASA as "flawless" and "perfect". A NASA systems engineer said “the efficiency or the accuracy with which Ariane put us on orbit and our accuracy and effectiveness in implementing our mid-course corrections” meant that there is “quite a bit of fuel margin ... roughly speaking, it’s around 20 years of propellant.”

Orbit

The James Webb Space Telescope was injected into a transfer trajectory that took it to the second Earth-Sun

Lagrange point In celestial mechanics, the Lagrange points (; also Lagrangian points or libration points) are points of equilibrium for small-mass objects under the influence of two massive orbiting bodies. Mathematically, this involves the solution of t ...

(L). The separation of the launch vehicle second stage and the spacecraft occurred approximately 27 minutes after liftoff. The second stage downloaded video, the last known time the telescope will be seen, of the separation and initial deployment of the solar panels. After this separation, the telescope became autonomous and began its deployment sequence. About 29 days after liftoff, it executed a maneuver placing it into a

halo orbit A halo orbit is a periodic, three-dimensional orbit near one of the L1, L2 or L3 Lagrange points in the three-body problem of orbital mechanics. Although a Lagrange point is just a point in empty space, its peculiar characteristic is that it can ...

around the L point, where it can perform its science mission. Its next five months were spent on cooling NIRCam and the Mid-Infrared Instrument down further, calibrating its mirrors while focusing on

HD 84406 The James Webb Space Telescope (JWST) is a space telescope which conducts infrared astronomy. As the largest optical telescope in space, its high resolution and sensitivity allow it to view objects too old, distant, or faint for the Hubble Spa ...

, a bright star in the constellation

Ursa Major Ursa Major (; also known as the Great Bear) is a constellation in the northern sky, whose associated mythology likely dates back into prehistory. Its Latin name means "greater (or larger) bear," referring to and contrasting it with nearby Ursa ...

, and testing the instruments.

References

External links

James Webb Space Telescope detaches from Ariane 5 rocket

Ariane flight VA256
at

Arianespace Arianespace SA is a French company founded in 1980 as the world's first commercial launch service provider. It undertakes the operation and marketing of the Ariane programme. The company offers a number of different launch vehicles: the heavy ...

{{James Webb Space Telescope VA256, Ariane flight 2021 in French Guiana 2021 in spaceflight Rocket launchers Rocket launches in 2021 James Webb Space Telescope