James Webb telescope to begin sun shield deployment



An illustration depicts the James Webb Space Telescope’s massive sun shield (in pink), which is the size of a tennis court, as it begins to unfold. Image courtesy of NASA

Dec. 28 (UPI) — The large, powerful James Webb Space Telescope flew past the moon’s orbit Monday, and is to begin unfolding its tennis court-sized sun shield Tuesday, astronomers in charge of the project said.

The $10 billion observatory, designed to see farther than the Hubble Space Telescope, is on a 29-day journey to its eventual destination over 1 million miles from Earth after a flawless launch from South America on Christmas Day.

The launch was a critical and risk-fraught event, but the real work for astronomers in charge of Webb only began Saturday, Massimo Stiavelli, an astronomer and mission head for the Webb project, said in an interview.

“We are just starting the deployments for the shield, and they go very slowly, so it will take about three days,” Stiavelli said. “There are very few things that are time-critical in the deployment. We are not built for speed.”

Massimo works in the control room at the Maryland-based non-profit Space Telescope Science Institute, which operates Hubble and Webb. NASA, along with telescope builder Northrop Grumman, also have dozens of personnel at the institute.

A European Ariane 5 rocket sent the telescope on its precise path Saturday, so accurately that NASA said the spacecraft was able to conserve some fuel, which may allow the telescope to operate longer than its expected 10-year lifespan, Stiavelli said.

Scientist hope to view some of the universe’s oldest galaxies using Webb, along with pulsars, exoplanets and supermassive black holes.

The telescope carries its own fuel to fire thrusters for maneuvering. It already completed a thruster burn to make a small course correction.

“Each activity, like the burn that happened yesterday, involves a whole team of people, like a rocket launch, who have to approve the action by saying ‘go’ or ‘no go’,” Stiavelli said on Monday.

As the sun shield expands, it also will block the thrusters’ heat from the telescope itself because Webb’s infrared instruments must be super-chilled to minus-370 degrees F to see properly, he said.

“The need for such cold temperatures also is why we have to send the telescope so far from Earth, so that the light and energy from Earth and the moon don’t interfere,” Stiavelli said.

Despite the need for distance, NASA also wants to maintain communication with the telescope. So astronomers chose a point in space at which the gravity of Earth and the sun balance out — known as a Lagrange point.

The Webb telescope will slowly circle a location known to scientists as Lagrange point 2. The gravity balance at that point will help keep the spacecraft in orbit around the sun at a relatively constant speed and position with the Earth, but more than 1 million miles farther out from the sun.

“In orbit around the point, we can shield the telescope from the Earth, moon and sun, but we will still get sunlight on the solar panels for electric power,” Stiavelli said.

After the sun shield is fully extended, controllers will send commands to unfold the main reflective dish, which is greater than 21 feet across and coated with gold, Heidi Hammel, an astronomer and vice president of the Washington, D.C.-based non-profit Association of Universities for Research in Astronomy, said in an interview.

“We’ll spend the next two to three months on the reflective mirrors. They move them really, really slowly, at the rate that grass grows, basically,” Hammel said.

After that, the four major instruments on Webb will be activated, cooled and positioned.

“We can’t cool the instruments quickly because we want to avoid any ice condensation,” she said.

After the telescope reaches the Lagrange point, it will orbit that location with small course corrections, roughly every 21 days, she said.

NASA and the institute haven’t revealed what images they will release first once the telescope starts to operate mid-year, Hammel said. She expects to see amazing images of galaxies or nebulae.

“Until we are on the other side of all of the deployment and commissioning, we will continue biting our nails,” Hammel said. “We’re not out of the woods yet. We had a picture-perfect launch, but there is still a tremendous amount of work to be done before this telescope is ready for science.”

The International Space Station is pictured from the SpaceX Crew Dragon Endeavour during a flyaround of the orbiting lab that took place following its undocking from the Harmony module’s space-facing port on November 8. Photo courtesy of NASA



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