Take a Gander up there

UA Astronomers Help NASA Space Telescope Explore Universe’s Past

Illustration courtesy of NASA / University of Arizona An artist’s impression of what the James Webb Space Telescope will look like in space. The telescope’s massive mirror is seen on top made out of 18 hexagonal sections.
Illustration courtesy of NASA / University of Arizona An artist’s impression of what the James Webb Space Telescope will look like in space. The telescope’s massive mirror is seen on top made out of 18 hexagonal sections.

By Jeff Gardner

A husband and wife team of University of Arizona professors and their research group are part of an international group of scientists working on NASA’s new James Webb Space Telescope, set to launch on Dec. 22.
The JWST is planned to succeed the Hubble Space Telescope as NASA’s flagship astrophysics mission, and will be able to observe some of the oldest and most remote objects in the universe. George Rieke, UA Regents Professor of Astronomy, describes the mission as “perhaps the most ambitious astronomy project human beings have done.”
George and Marcia Rieke, both UA Regents Professors of Astronomy, have worked with infrared astronomy and NASA missions for decades.
For the JWST, each will work with high-tech infrared imaging devices: Marcia on the telescope’s near-infrared camera, and George on the telescope’s mid-infrared camera. Both instruments observe infrared radiation to collect data on planets in distant solar systems.
“This will provide by far the sharpest and deepest view of the infrared universe,” George said. “In terms of astronomy, this really is a big benchmark.”
The JWST, with initial development dating back to 1996, stretches roughly 70 feet and 45 feet with an estimated cost of $10 billion. It is planned to launch from French Guiana in South America on Dec. 22.
Because of its focus on visible and infrared light, as well as wielding a far larger mirror, the JWST will be able to observe objects too distant for Hubble to detect.
Tucson’s involvement on the project is only natural, as the field of infrared astronomy more-or-less began in the UA’s Lunar and Planetary Laboratory, according to George. Some infrared astronomy observations were conducted in the 1920s, but he explains the field of research didn’t fully kick in until the 1960s with researchers in Tucson.
“The university really led the whole world in infrared astronomy. We’ve had a central role in all kinds of things,” George said. “Infrared astronomy started here with Gerard Kuiper’s 61-inch telescope on Mount Lemmon. The problem with doing it from the ground is the telescope is warm, so it’s pouring out infrared photons and you can’t cool it down because water would condense on it. So going to space is really critical because it’s a vacuum where you can cool the telescope down.”
Over George’s career, infrared telescopes have advanced from containing single sensors to millions of sensors. He also previously worked on NASA’s infrared Spitzer Space Telescope, which launched in 2003 and retired last year.
“Space infrared telescopes have always been small, less than a yard in aperture. And that has to do with what was thought to be constraints on how to get them cold,” George said. “But the big advancement with JWST, as demonstrated by Spitzer, is you can let it cool down by radiating its heat into space. JWST is taking advantage of that by giving us a telescope that is 21 feet, instead of less than three feet. That’s why it’s such a technical marvel.”
This will allow JWST to be far more sensitive than previous space telescopes, with imaging capabilities six to seven times sharper than Spitzer’s.
“The Hubble and Spitzer Space Telescopes revolutionized our understanding of the cosmos,” Marcia said in a UA press release. “But with Webb, we’ll be able to probe galaxies much closer to the Big Bang than ever before. We can currently see galaxies back to 500 to 600 million years post-Big Bang, nearly 13 billion years ago. And even though the universe was so young at that time, the things we see still look pretty familiar—lots of stars have formed, there are supermassive black holes, quasars and so on. However, logic dictates that at some point during the first few hundred million years, these familiar-looking objects must have come from somewhere and evolved… After all, galaxies don’t spring up from nothing, virtually overnight.”
Although both of the Riekes are working on the project, George says there is no sense of competition between the two. After submitting their proposals for the project, he can recall Marcia receiving a phone call of acceptance and shouting joyously down the hall. Then his phone rang with similar news.
“These projects are so big and complicated that competition is generally destructive,” George said.
The telescope’s massive 21-foot diameter presents a unique problem for space launch, as it is too wide to fit into the nose cone of a rocket. To account for this, the JWST will fold up like an umbrella to fit inside the rocket. According to UA, once in space, the telescope will unfold and its instruments will be checked and calibrated, with the telescope’s mirror adjusted to optical perfection. This will happen during a six-month period, after which the telescope will be a million miles from Earth. This point in space will allow the JWST to fly effortlessly with the Earth around the sun, making it possible for the telescope to radio its huge amount of data back to Earth.
“The history of real scientific discoveries is that you can’t predict what they’ll be,” George said. “So I hope the astronomical community uses JWST to discover things we’ve never dreamt of.” ■