WEST LAFAYETTE, Ind. – A new look at the stars, a deeper look in time and some of the most beautiful, dizzying and breathtaking views ever seen by human eyes: that’s what the James Webb Space Telescope (JWST) promises to deliver when it publishes its first handful of images on Tuesday (July 12). As he has been from the beginning, astronomer Danny Milisavljevic will be there to see, explain and anticipate dazzling new scientific discoveries.
An assistant professor of physics and astronomy at Purdue University College of Sciences, Milisavljevic (pronounced milli-sahv-la-vich) helps details of the world’s newest and most powerful telescope: the JWST, the successor to the Hubble Space Telescope, which allowed people to see further into space and deeper into time. After the launch at the end of December and gets his job in Januarythe JWST has been calibrating his instruments and prepare for his role as the longest eyes of mankind.
“It will be an emotional moment to see these images for the first time,” Milisavljevic said. “The images represent the culmination of decades of work for thousands of people around the world. We expect to see unprecedented images of the universe, which will explore the cosmos more deeply than ever before and reveal some of the oldest stars and galaxies. Finally, we are really going to see what this telescope can do!”
Since its launch in 1990, Hubble’s discoveries have changed humanity’s understanding of the stars, their place in them, and physics itself.
The JWST is larger, more complex and orbits farther from Earth than Hubble, opening up unprecedented opportunities for interstellar quests. JWST looks even further into space and time, and with an unprecedented range of wavelengths and power of definition. The knowledge it reveals could help scientists take the next small steps in the universe — and discern where people want to go and why.
Milisavljevic leads a team of nearly 40 scientists and researchers from more than 30 institutions — including the Universities of Harvard, Princeton and Johns Hopkins, as well as the Los Alamos National Laboratory and the SETI Institute — in studying Cassiopeia A, one of the more enigmatic objects in the universe. Cassiopeia A is made up of the remnants of a supernova explosion and has a neutron star at its heart that doesn’t behave the way scientists think neutron stars should behave.
“JWST allows us to look at stellar objects at wavelengths and resolutions we’ve never been able to use before,” Milisavljevic said. “Supernova remnants are leftover explosions — that’s what we’ll study. We’ll be able to study what type of star was there before the explosion, the physics of the explosion, the type of dust that spawned it and what made it all happen. all the materials for life – the oxygen we breathe, the iron in our blood.”
Bigger, further, better
JWST is bigger than Hubble. The primary mirror is about 20 feet wide, while Hubble’s is only 8 feet wide. Hubble’s telescopes looked primarily at objects in the ultraviolet, visual and near-infrared wavelengths. But many objects astronomers want to see and study — such as the universe’s oldest galaxies, exoplanets and stars — are hidden behind dust clouds. Infrared wavelengths allow scientists to get a clearer picture than visual wavelengths of light could give them.
Hubble rode into space aboard the shuttle Discovery. Hubble’s orbit is about 350 miles up. JWST orbits Earth from nearly a million miles away — four times farther than the moon and 2,500 times farther than Hubble.
JWST’s house is a special place in space called L2, or the second Lagrange Point. It is a place where, thanks to the orbital dynamics of the Earth, the Moon and the Sun, it will remain in a fixed position relative to the Earth – always keeping the Earth between itself and the Sun. This is an ideal location from which to observe the universe, as the satellite will not need to use too much fuel to alter its orbit, an essential consideration as it will be so far away from its home planet.
Eyes on the sky
Milisavljevic is collaborating on several JWST projects and serves as the principal investigator on watching Cassiopeia A, a supernova remnant about 11,000 light-years away.
The project will take place during the first year of JWST’s research, starting after it reaches L2. JWST will use infrared imaging and spectroscopy to investigate Cassiopeia A. Scientists want to study how it formed and look at the neutron star, an X-ray source at the heart of the cloud of stardust.
“This proposal, like the telescope itself, has been years in the making,” Milisavljevic said. “Proposals usually take a few weeks; this one lasted for years. Many people are involved, with many overlapping and potentially competing research interests. I was able to convince them that, united as an ultimate dream team of researchers, we are stronger than our separate parts.”
Supernovae resulting from collapsing stars are among the most influential phenomena in any galaxy when it comes to building stars and planetary systems. But they are also not well understood at all. Insights into how Cassiopeia A formed will help scientists understand more about how stars live and die, how metals are distributed throughout galaxies, and possibly even investigate the origin of life itself.
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