Now that NASA’s James Webb Space Telescope has safely arrived at its launch site in French Guiana, on the northeastern coast of South America, technical teams have begun making progress on the final checklist of preparations before liftoff later this year.

These preparations are expected to last 55 days from the observatory’s arrival by ship to the day of launch.

After Webb arrived at the Arianespace clean room facilities in French Guiana, contamination control technicians ensured the observatory is clean and contaminant free following its 5,800 mile journey. Then engineers ran a final set of electrical and functional tests and checked the stowed mechanical configuration to ensure delivery went smoothly. A trained crew in special hazmat suits will soon begin the two-week process of loading the spacecraft with the hydrazine fuel and nitrogen tetroxide oxidizer it will need to power its rocket thrusters to maintain its orbit. Next, Webb will move to the nearby vehicle integration building to be lifted and mounted on top of the Ariane 5 rocket “stack.” The final few remove-before-flight “red-tag” items are taken off, and a few remaining add-before-flight “green tag” items are installed. Then the rocket fairing is lifted and lowered over top and locked into place, signifying the conclusion of a long journey. At this point, Webb will be very nearly ready to launch from Europe’s Spaceport, also known as the Guiana Space Center (CSG).

NASA’s James Webb Space Telescope rolls to its final stop before launch from Arianespace’s ELA-3 launch complex at Europe’s Spaceport in French Guiana, on the northeastern coast of South America. Credit: NASA/Chris Gunn

As a fully integrated launch vehicle with Webb as the payload, the Ariane rocket will roll out to the launch pad a few days before launch. Engineers monitor the rocket via electrical connections running from the payload control room to the pad through an umbilical attachment to the vehicle that separates at liftoff. A few hours before liftoff, the rocket is loaded with liquid hydrogen fuel and liquid oxygen oxidizer. About a half hour before launch, engineers in the payload control room switch the spacecraft from external electrical power to the spacecraft’s on-board battery.

Webb’s launch will be a pivotal moment for NASA and its partners, ESA (European Space Agency) and the Canadian Space Agency (CSA), but it is only the beginning. The following 29 days will be an exciting but harrowing time. Thousands of parts must work correctly, in sequence, to unfold Webb and put it in its final configuration, all while it flies through the expanse of space alone, to a destination nearly one million miles away.
The greatest origin story of all unfolds with the James Webb Space Telescope. The 29 days following liftoff will be an exciting but harrowing time. Thousands of parts must work correctly, in sequence, to unfold Webb and put it in its final configuration, all while it flies through the expanse of space alone, to a destination nearly one million miles away. Credit: NASA Goddard Space Flight Center/Michael McClare

A more detailed breakdown of what lies ahead for Webb:

Webb’s 29 days on the edge begin upon liftoff. After 206 seconds of flight, at an altitude of about 75 miles above the atmosphere, the two halves of the rocket fairing that shields the observatory during ascent are separated by a pyrotechnic system with springs that expose the observatory to space. Ground teams expect to receive communication from Webb shortly after separation. Webb will then separate from the launch vehicle nearly 28 minutes after launch, and from this point on the ground team at the Space Telescope Science Institute in Baltimore will be in full control, to begin the most complex sequence of deployments ever attempted in a single space mission.

To unfold the history of the universe, we must first unfold this telescope. Following launch, over 300 single point failure items and 50 major deployments must work to ensure optimal science.

Upon its arrival at the launch site in Kourou, French Guiana, engineers quickly set about unpacking, cleaning, and preparing the James Webb Space Telescope in its remaining days on Earth. Credit: NASA/Chris Gunn

Webb’s first deploymentthe extension of its solar array, will occur between 31 to 33 minutes after liftoff, stopping the drain on the observatory’s internal battery by supplying nearly 2 kilowatts of power to drive the spacecraft’s electrical systems and avionics. To enable the highest data rate communication to the ground through NASA’s Deep Space Network (DSN), the onboard medium and high-gain antenna platform is deployed at two hours.

At 12 and a half hours after launch, Webb will fire its thrusters, performing the first of several critical course corrections that send the observatory towards its final destination in orbit. The observatory will pass the Moon nearly two and a half days after launch, faster than the time it took Apollo astronauts to reach lunar orbit.

Webb’s first large deployment, the extension of its sunshield frame known as a unitized pallet structure, folds down nearly three days after launch, opening the observatory up to continue expanding. This represents the start of all major deployments and is scheduled to take approximately five hours for both front and back pallets to fold down completely.

Four days after launch, a deployable tower will extend to separate the telescope mirrors and instruments from the spacecraft bus. This separation effectively isolates the telescope from vibrations and conducted heat coming from the spacecraft bus. Additionally, this extension allows for the rest of Webb’s larger deployable components, like its sunshield and primary mirror, to have enough room to make their own sequence of complex movements afterwards.

Sunshield membrane deployments formally begin approximately five days after launch, as special covers that protect the sunshield during ascent will roll out of the way. Next, a critical juncture in the mission will occur when all of the 107 sunshield release mechanisms, or special pins that keep the five sunshield layers locked into place, need to fire on cue and pull themselves out to free the membranes. After all sunshield pins have been successfully removed, two wings, known as mid-booms, extend to pull each of the sunshield layers out into their characteristic diamond formation nearly a day later. Following full deployment, each of the five layers are tensioned and separated using special pulleys and motor systems. Sunshield deployments and tensioning are expected to conclude between eight to nine days after liftoff but can be slowed down to circumvent any unforeseen issues if they arise.,50735575.html

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