The James Webb Space Telescope is finally up, up and away, and Purdue professor Danny Milisavljevic says he couldn’t be happier.
Milisavljevic, an assistant professor of physics and astronomy, brought together a team of 40 scientists across the world to prepare a proposal to investigate Cassiopeia A, a supernova remnant in the constellation Cassiopeia, utilizing the Webb telescope.
“I thought we would be stronger as a team to go in together,” he said. “It’s the broadest base of interdisciplinary scientists you could dream of.
“Our Webb program is targeting the debris field of a supernova explosion. It’s kind of like doing an autopsy on a star that exploded about 340 years ago. This specific supernova remnant is the best example we have of an exploded star to analyze in this way.”
The Webb telescope has been in development for decades, and was designated as the successor to the Hubble Space Telescope. It’s the “largest, most powerful and complex telescope ever built and launched into space,” Milisavljevic said.
The telescope is named for James Webb, who was the administrator of NASA from 1961 to 1968 during the Apollo program, and was launched on Christmas day.
It was first dreamed up in 1989 at the Next Generation Space Telescope Workshop at the Space Telescope Science Institute in Baltimore, Maryland, where scientists began to wonder what would follow the Hubble telescope, according to NASA’s website.
As a result of discussions held at that workshop, the “formal recommendation (made) in 1996 (was) that the telescope should operate in infrared wavelengths and be equipped with a mirror larger than 4 meters,” according to NASA’s website.
Building began in 2004, and individual pieces that were constructed in various locations began to ship to NASA’s Goddard Space Flight Center in Greenbelt, Maryland from 2012 to 2013. Testing began shortly after, and all of Webb’s parts were subject to “numerous tests of extreme temperature and vibration.”
Later in 2017, the parts were shipped to NASA’s Johnson Space Center in Houston, Texas, for “end-to-end optical performance testing in a giant cryogenic temperature vacuum chamber,” according to NASA’s website.
The telescope was finally assembled in 2019, and lift-off took place last Christmas morning at “Arianespace’s ELA-3 launch complex at Europe’s Spaceport located near Kourou, French Guiana,” according to NASA’s website.
Milisavljevic was able to virtually celebrate the launch with his colleagues in the Chaney-Hale Hall of Science, where they were all on different floors due to COVID-19 precautions.
“The launch (was originally supposed to be in) October, then it got pushed to November, and then December 18, and then December 22, and then Christmas Eve, and then Christmas day,” he said. “And yet my team members still came out to be part of the launch party Christmas morning. That really demonstrated their commitment to the project and their awareness of how important it was to share this with as many people as possible.”
The virtual celebration had a panel of speakers, which included Purdue alumnus David Leckrone, who was the senior project scientist of the Hubble telescope from 1992 to 2009, according to the College of Science’s website. He was the lead scientist for “five highly successful Space Shuttle servicing missions to Hubble,” the website reads.
“(Leckrone) helped lead the Hubble Space Telescope for many, many years,” Milisavljevic said. “He had great insight or knowledge of what people would be thinking with a launch like this.”
The Webb telescope is much further from Earth than the Hubble telescope and will be located “approximately one million miles from Earth, orbiting the second Sun-Earth Lagrange point (L2),” according to NASA’s website.
Milisavljevic said multiple teams worked together to make sure that the Webb telescope’s entire mission was nearly foolproof, as the Hubble telescope had a near-fatal error when it was first launched that was able to be serviced due to its proximity to Earth.
“There’s hundreds of ways that Webb could have failed, right? And they’re able to avoid those points of failure,” Milisavljevic said.
One intricate aspect of the Webb telescope is the sunshield, which is the size of a tennis court and is designed to shield one-half of the telescope from the heat of the sun so that it could reach operable temperatures.
The sunshield is currently 125 degrees Fahrenheit on point A and 55 degrees on point B, as opposed to the -348 and -333 degrees on points C and D respectively, according to NASA’s “Where is Webb?” tracker as of Sunday afternoon.
“We have to cool Webb to very cold temperatures to be sensitive to the light from the most distant galaxies and stars,” Milisavljevic said. “For us to understand how the universe evolved to where it is today, we wanted to be able to see light from the first stars and galaxies.
“And the thing is, if you want to look back that far to the observable universe, you need to be sensitive to the infrared wavelengths.“
He said that the Webb telescope would also need time to unfold all of the mirrors and calibrate.
“If you have any experience working with a camera, you know that the first couple of shots aren’t the best,” Milisavljevic said. “All the mirrors need to be focused and the instrument needs to be tested, and they need to run calibration frames.
“All that will take place over the next three, four or five months.”
Milisavljevic said he’s been contacted by people that he hasn’t seen since elementary school, who have asked him about the project or asked him to speak to their kids about the Webb telescope.
“I remember the time when Hubble went up,” he said. “And I hope to be able to nurture that experience for (kids) to recognize just how cool it is that we’re at this exciting moment where we’re watching this new facility get launched and begin to operate.”
Students have also approached Milisavljevic about the Webb telescope and their desire to work with it.
“I didn’t expect that, but I should (have),” he said. “As far as the students, I have regular updates about where Webb is.
“Now that it’s reached L2, we discuss what it’s doing now in terms of calibrations, and I begin to explore the science questions that Webb is attempting to address.”