A new space telescope to observe the first galaxies in the universe

On December 18, NASA is preparing to launch its next flagship mission in space. The spacecraft, called the James Webb Space Telescope, comes with many risks: its approximately 270-square-foot mirror, which will pick up light from the far reaches of space, launch itself folded up inside a rocket, and then collapse. will deploy far from Earth.

Astronomers are betting that the challenges will be worth it. Many have called James Webb the successor to the Hubble Space Telescope, an instrument launched in 1990 that provided vivid images of the cosmos, including the Pillars of Creation in the Eagle Nebula. Among other goals, James Webb will search the atmospheres of alien planets for what scientists call “biosignatures,” or gases that could, theoretically, indicate the presence of life on the surface.

Meredith MacGregor, assistant professor at CU Boulder’s Center for Astrophysics and Space Astronomy (CASA), will talk about James Webb’s science at a series of events this week at the Fiske Planetarium. The events are sponsored by Colorado-based Ball Aerospace, which designed and built the telescope’s folding mirror.

MacGregor spoke to CU Boulder Today to explain how she, like other astronomers, has been waiting for this launch for a long time.

Why are astronomers so excited to launch this telescope?

In astronomy and astrophysics, every 10 years we have a decennial survey, where the National Academy of Sciences forms a committee that decides what all of American astronomy is going to do over the next decade. When you want to launch something really big, what we call a flagship mission, it has to go through this process. James Webb was selected in the decennial survey published in 2000.

I’ve been hearing about James Webb since I was in high school. Projects like this can span a scientist’s entire career.

It’s also really, really big – James Webb’s mirror stretches over 6 meters in diameter, bigger than any other space telescope to date. How does that make a difference?

With astronomical observations, you care about what we call the collection area. You can think of a telescope as a giant bucket that collects light. The larger the bucket, the more light you collect and the more faint objects you can see with higher resolution.

How does James Webb build on the legacy of the Hubble Space Telescope?

All of NASA’s flagship missions build on each other thanks to the slow progress of astronomy. But James Webb is different from Hubble in many ways. Hubble looks at ultraviolet light. This light has wavelengths shorter than the optical light we can see. James Webb is on the other side of the spectrum, growing in longer wavelengths and infrared light.

What can we see with this kind of light?

Some of James Webb’s main goals relate to understanding the early formation of our universe, which is based on the idea that our universe started with a Big Bang and is expanding. The space between galaxies expands as the universe expands, meaning that the light emitted by galaxies stretches as it travels through space. We call this the cosmological redshift.

So does this allow us to return to the dawn of the universe?

By observing in the infrared, we will see further in time and see the light coming from the first galaxies that formed.

People who study exoplanets, or planets orbiting distant stars, are also very enthusiastic. Why?

Infrared is amazing for observing the gas and dust disks that orbit young stars that could eventually form planets. In other words, we can see the reservoirs of matter that will form new planets. Dust is heated by a star and it glows in the form of heat. Infrared light is basically heat – I emit infrared light while sitting here.

Will James Webb be able to search for possible signs of life on alien planets?

This mission will allow us, we hope, to make the first detections of gas in the atmosphere of exoplanets. We are particularly interested in finding gases like methane that could indicate the presence of life on a planet. We call these biosignatures. If we are successful, astronomy will enter new territory where we can really determine what might be a sign of life and what might not.

What do you think will be the telescope’s greatest contribution to science?

We have a lot of predictions and goals for what James Webb will do. But I’m sure his most exciting discoveries will be about things we can’t even think about right now. Who knows what we’ll find?

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