The fully assembled James Webb Space Telescope has completed tests in Southern California to verify that the $ 10 billion mission can withstand the sound and vibration it will see during its planned launch late next year on a European rocket. Ariane 5.
“With the completion of its environmental tests, #NASAWebb it reached a monumental milestone and proved it could withstand the deafening noise, screeching tremors and vibrations experienced during launch, ”tweeted Thomas Zurbuchen, associate administrator of NASA’s science mission directorate.
Environmental testing at a Northrop Grumman facility in Redondo Beach, California put the Webb Observatory through the rigors of launch. Northrop Grumman and NASA teams first subjected the observatory to an acoustic test to simulate the sonic energy it will see during launch.
The engineers detonated the observatory with high frequency sound pressure levels in excess of 140 decibels, “with a spectrum tuned to the specific signature of the Ariane 5 rocket that will travel through space.” Sensors within the acoustic test chamber measured nearly 600 individual channels of motion data, about six times more than in a typical spacecraft vibration and acoustic test campaign.
“The observatory’s complex size and shape required significantly larger measurements to ensure success,” NASA said in a statement.
Then the engineers moved the JWST – clad inside a movable cleanroom to protect its sensitive mirrors, instruments and other spacecraft systems – to a different facility at the Northrop Grumman factory and placed it on a vibrating table. The table shook the observatory on the vertical and horizontal axes to test its ability to withstand the low-frequency energy imparted during rocket launch.
“Environmental tests demonstrate Webb’s ability to survive the rocket’s journey into space, which is the most violent part of its journey into orbit about one million miles from Earth,” said Bill Ochs, Webb Project Manager at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “The multinational group of people responsible for performing the acoustic and vibration test is made up of an exceptional and dedicated group of people typical of the entire Webb team.”
The individual elements of the spacecraft and telescope had already passed similar environmental tests, but recent milestones marked the first time that the entire observatory has undergone full-scale acoustic and vibration testing.
Segments of the observatory, such as its spacecraft platform and telescope, have also completed thermal vacuum tests to verify their performance under the extreme temperature changes they will see in the airless environment of deep space.
In the months leading up to the start of environmental testing, engineers completed a comprehensive systems test on Webb and a test of the mission’s ground infrastructure.
NASA and Northrop Grumman performed environmental tests with Webb in its launch configuration, with its mirrors, sunshield, and solar panels folded down as they will be positioned to fit inside the Ariane 5 rocket shell.
In the coming months, engineers will implement the observatory in its operational configuration to verify that the actuators and mechanisms are still in good condition after passing the acoustic and vibration tests. Implementations will include opening Webb’s 21.3-foot (6.5-meter) segmented diameter and unfolding the mission’s five-layer thermal sunshade down to the size of a tennis court.
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NASA officials said preliminary analysis of recent environmental tests suggests the observatory passed the tests successfully. “But full verification of the flight’s validity will happen after Webb successfully completes the final implementation tests,” NASA said.
The ground crews will then fold up the observatory and place it in a special container for transport by sea to the Guiana Space Center in South America operated by Europe. The teams there will prepare Webb for launch on an Ariane 5 rocket and the observatory will be in space the next time it unfolds the telescope wings, sunscreen and other appendages.
NASA announced in July that JWST’s launch would be postponed to October 31, 2021, a seven-month postponement from its previous March 2021 launch date. Officials blamed the coronavirus pandemic, which slowed testing to Northrop Grumman, and other technical problems for the delay.
Webb is the largest and most powerful space telescope ever built. The observatory’s infrared instruments will scan the earliest and most distant borders of the universe to study some of the first stars and galaxies that formed after the Big Bang more than 13.5 billion years ago.
Astronomers will also use Webb to observe how galaxies form and evolve, to study the birth of stars, and to learn more about the atmospheres of planets that may be hospitable to life outside our solar system.
The launch of Ariane 5 is part of the European Space Agency’s contribution to the JWST mission, along with part of the observatory’s scientific payload. The Canadian Space Agency is also a mission partner with NASA and ESA.
ESA has signed a launch contract with Arianespace to provide Ariane 5 launch services for the JWST mission. The Ariane 5 will send the space telescope to an observation point nearly one million miles (1.5 million kilometers) from Earth.
During the most recent Ariane 5 launch in August, engineers tested small modifications to the rocket’s payload fairing, designed to meet the stringent requirements for the one-of-a-kind astronomical observatory.
Engineers changed the design of the air intakes on the Ariane 5 payload cover – built by RUAG Space in Switzerland – to address the fear that a depressurization event could damage the Webb Observatory when the fairing discharges after the take off. Officials were concerned that residual air trapped in the folded membranes of Webb’s sunshield could cause an “undue stress condition” at the time of the fairing separation.
In a recent interview, the director of ESA’s space transportation division said the space agency has made a commitment to ensuring that an Ariane 5 is ready for the launch of the Webb observatory. There are only eight Ariane 5 missions yet to be completed before ESA and Arianespace fully switch to the next-generation European Ariane 6 rocket, which is slated for an inaugural test launch in the second half of 2021.
“We are ready with Ariane 5 waiting for James Webb,” said Daniel Neuenschwander, ESA’s director of space transport.
While European teams are ready for the debut of the Ariane 6 rocket and continue to introduce small updates for the Ariane 5, Neuenschwander said ESA is committed to using an Ariane 5 launcher with “fully qualified” components for the costly mission. JWST.
“We will use what we have ready for James Webb,” he said. “I will only give the green light to any point that is fully qualified. If they (the JWST team) are ready, I am confident that we will be ready, especially with the new date of October 2021 “.
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