NASA gives the green light to power the James Webb Space Telescope – Spaceflight Now – .

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NASA gives the green light to power the James Webb Space Telescope – Spaceflight Now – .


NASA engineers have cleared teams from the Guyana Space Center in South America to begin loading 63 gallons of fuel and oxidant into the James Webb Space Telescope, after further testing showed the observatory had failed. suffered no damage during a processing incident in the cleanroom earlier this month.

During a review of “fuel consent” held on Wednesday, November 24, the heads of mission agreed to begin the process of loading propellants at the Guyanese spaceport the next day.

“Additional tests were carried out this week to ensure the health of the observatory following an incident when the release of a hose clamp caused a vibration throughout the observatory,” said NASA in a statement Wednesday.

The start of propellant loading keeps the $ 9.7 billion James Webb Space Telescope on track for takeoff on December 22 aboard a European Ariane 5 rocket. The half-hour launch window s ‘opens at 7:20 a.m. EST (12:20 p.m. GMT; 9:20 a.m. PST).

The propellant loading operations inside the Guiana Space Center’s S5B refueling cell will take around 10 days, according to NASA. The 10-day period includes steps to prepare, purge and pressurize elements in the spacecraft bus, the lower section of the 35-foot-high (10.66-meter) observatory.

Charging the thruster itself will take place over several hours over two separate days, mission team members told Spaceflight Now.

The Webb Telescope spacecraft bus, built by Northrop Grumman, will be filled with 42 gallons (159 liters) of hydrazine and 21 gallons (79.5 liters) of dinitrogen tetroxide, a mixture of storable fuel and oxidant to power the mission’s 20 rocket boosters.

Four of the small engines – a main thruster and redundant in two nacelles – will consume fuel and oxidant for the main course correction maneuvers. Webb has eight other thruster modules, each with two small motors to push the observatory with a single pound of thrust, providing pointing control in concert with rotating reaction wheels inside the spacecraft.

Ground crews wearing self-contained protective suits will be inside the cleanroom while the toxic thrusters are loaded. The technicians will also load pressurized helium into the spacecraft.

Webb’s space bus provides propulsion, electrical power, and communications for the observatory.

NASA announced last week that Webb’s launch was delayed from December 18 to 22 after officials ordered additional tests on the spacecraft.

The space agency said a “sudden and unexpected release” of a clamp band sent a vibration through the observatory on November 9, when technicians mated Webb to his launcher adapter, a device that connects the observatory on the upper floor of Ariane 5. rocket.

The adapter’s high-voltage clamping system secures the spacecraft to the rocket until the command to separate Webb about half an hour after take-off.

RUAG Space, a Swiss company specializing in the construction of rocket structures and other components, provided the payload adapter system for the Ariane 5 and Webb rockets, according to articles posted on the social media pages of the ‘business.

Processing work within the S5 payload installation of the Guyanese Space Center is carried out under the “overall responsibility” of Arianespace, the French provider of Ariane 5 program launch services. The European Space Agency, junior partner of Webb, pays the launch as part of his contribution to the mission.

Once refueled, Webb will be transferred to the final assembly building at the French Guiana spaceport, where a crane will hoist the observatory to the top of its Ariane 5 launcher.

The James Webb Space Telescope is folded into the launch configuration to fit inside the 17.7-foot-wide (5.4-meter) payload shroud of the Ariane 5 rocket. Once in space, the observatory will deploy an electricity-generating solar panel and high-gain communications antenna, then launch a series of decisive deployments of its five-layer sunshade, which will open to the size of a tennis court . .

Webb, designed to peer deeper into the cosmos than ever before, has 18 gold-coated beryllium mirror segments that will combine to create the largest telescope mirror ever sent to space, with a diameter of 21.3 feet (6.5 meters). Some of the mirrors are mounted on deployable wings that must fold up to set up the telescope for scientific observations.

Next, the telescope’s infrared detectors must cool to cryogenic temperatures, with parts of the instruments cooled near absolute zero to a temperature of 7 Kelvin (minus 447.1 degrees Fahrenheit).

The telescope’s mirror segments each have tiny mechanical actuators to adjust focus and alignment. The design makes Webb the most expensive and complex science mission to ever launch into space.

“When you’re working on a $ 10 billion telescope, conservatism is the order of the day,” said Thomas Zurbuchen, chief science officer of NASA.

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Follow Stephen Clark on Twitter: @StephenClark1.

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