The James Webb Space Telescope (JWST) is a space telescope designed to conduct infrared astronomy. It is the largest telescope in space, and is equipped with high-resolution and high-sensitivity instruments, allowing it to view objects too old, distant, or faint for the Hubble Space Telescope. This enables investigations across many fields of astronomy and cosmology, such as observation of the fir The spacecraft bus is the primary support component of the JWST, hosting a multitude of subsystems for computing, communications, electrical power, propulsion, and structure. Along with the sunshield, it forms the spacecraft element of the space telescope. The spacecraft bus is on the Sun-facing "warm" side of the sunshield and operates at a temperature of about 300 K (27 °C; 80 °F). The spacecraft bus has a mass of 350 kg (770 lb) and must support the 6,200 kg (13,700 lb) space telescope. It is primarily made of a graphite composite material. The assembly was completed in California in 2015. It was integrated with the rest of the space telescope, leading to its 2021 launch. The spacecraft bus can rotate the telescope with pointing precision of one arcsecond and isolates vibration to 2 milliarcseconds. Webb has two pairs of rocket engines (one pair for redundancy) to make course corrections on the way to L2 and for station keeping – maintaining the correct position in the halo orbit. Eight smaller thrusters are used for attitude control – the correct pointing of the spacecraft. The engines use hydrazine fuel (159 liters or 42 U.S. gallons at launch) and dinitrogen tetroxide as oxidizer (79.5 liters or 21.0 U.S. gallons at launch). An L2 orbit is unstable, so JWST needs to use propellant to maintain its halo orbit around L2 (known as station-keeping) to prevent the telescope from drifting away from its orbital position. It was designed to carry enough propellant for 10 years, but the precision of the Ariane 5 launch and the first midcourse correction were credited with sa To make observations in the infrared spectrum, Webb must be kept under 50 K (−223.2 °C; −369.7 °F); otherwise, infrared radiation from the telescope itself would overwhelm its instruments. Its large sunshield blocks light and heat from the Sun, Earth, and Moon, and its position near the Sun–Earth L2 keeps all three bodies on the same side of the spacecraft at all times. Its halo orbit around the L2 point avoids the shadow of the Earth and Moon, maintaining a constant environment for the sunshield and solar arrays. The resulting stable temperature for the structures on the dark side is critical to maintaining precise alignment of the primary mirror segments. The sunshield consists of five layers, each approximately 0.1mm thick. Each layer is made of Kapton E film, coated The spacecraft bus is the primary support component of the JWST, hosting a multitude of subsystems for computing, communications, electrical power, propulsion, and structure. Along with the sunshield, it forms the spacecraft element of the space telescope. The spacecraft bus is on the Sun-facing "warm" side of the sunshield and operates at a temperature of about 300 K (27 °C; 80 °F). The spacecraft bus has a mass of 350 kg (770 lb) and must support the 6,200 kg (13,700 lb) space telescope. It is primarily made of a graphite composite material. The assembly was completed in California in 2015. It was integrated with the rest of the space telescope, leading to its 2021 launch. The spacecraft bus can rotate the telescope with pointing precision of one arcsecond and isolates vibration to 2 milliarcseconds. Webb has two pairs of rocket engines (one pair for redundancy) to make course corrections on the way to L2 and for station keeping – maintaining the correct position in the halo orbit. Eight smaller thrusters are used for attitude control – the correct pointing of the spacecraft. The engines use hydrazine fuel (159 liters or 42 U.S. gallons at launch) and dinitrogen tetroxide as oxidizer (79.5 liters or 21.0 U.S. gallons at launch). An L2 orbit is unstable, so JWST needs to use propellant to maintain its halo orbit around L2 (known as station-keeping) to prevent the telescope from drifting away from its orbital position. It was designed to carry enough propellant for 10 years, but the precision of the Ariane 5 launch and the first midcourse correction were credited with saving enough onboard fuel that JWST may be able to maintain its orbit for around 20 years instead. Space.com called the launch "flawless". Official NASA / STScI / ESA / French website JWST NASA – Tracking Page − Launch to Final Calibrations (and more) JWST NASA – About page − Timeline details / Webb orbit / L2 / Communicating JWST Text – Most Critical Events – Launching and Deployment (2021) JWST Video (031:22): Highlights − Technical Engineering Details (2021) JWST Video (012:02): 1st Month – Launching and Deployment (animation; 2017) JWST Video (008:06): 1st Month − Launching and Deployment (update; 2021) JWST Video (003:00): 2nd Month − Mirror Alignment details (2/11/2022) JWST Videos (Mission Control Live) – Deployment Events − Now Successfully Completed (2022): LAUNCH (005:07; 25 Dec 2021) ⇒ SEPARATION (003:14; 25 Dec 2021) (mirror) ⇒ James Webb Space Telescope: Sunshield Deployment – Mission Control Live SUNSHIELD (152:45; 4 Jan 2022) ⇒ James Webb Space Telescope: Secondary Mirror Deployment – Mission Control Live SECONDARY MIRROR (087:15; 5 Jan 2022) ⇒ James Webb Space Telescope: Primary Mirror Deployment – Mission Control Live PRIMARY MIRROR (242:29; 8 Jan 2022) ⇒ News Update on James Webb Space Telescope's Full Deployment FINAL DEPLOYMENT (085:15; 8 Jan 2022) ⇒ Media Briefing: What's Next for the James Webb Space Telescope ARRIVAL AT L2 (077:14; 24 Jan 2022) ⇒ JAMES WEBB TELESCOPE First Photos, Data & Calibrations Explained TESTINGS & CALIBRATIONS ⇒ The First Thing That James Webb Will See FIRST LIGHT Video of talk by Prof. Jonathan Fortney on studying exoplanets with JWST (2025)