James Webb Space Telescope - Blog Posts

Are We Alone? How NASA Is Trying to Answer This Question.

One of the greatest mysteries that life on Earth holds is, “Are we alone?”

At NASA, we are working hard to answer this question. We’re scouring the universe, hunting down planets that could potentially support life. Thanks to ground-based and space-based telescopes, including Kepler and TESS, we’ve found more than 4,000 planets outside our solar system, which are called exoplanets. Our search for new planets is ongoing — but we’re also trying to identify which of the 4,000 already discovered could be habitable.

Unfortunately, we can’t see any of these planets up close. The closest exoplanet to our solar system orbits the closest star to Earth, Proxima Centauri, which is just over 4 light years away. With today’s technology, it would take a spacecraft 75,000 years to reach this planet, known as Proxima Centauri b.

How do we investigate a planet that we can’t see in detail and can’t get to? How do we figure out if it could support life?

This is where computer models come into play. First we take the information that we DO know about a far-off planet: its size, mass and distance from its star. Scientists can infer these things by watching the light from a star dip as a planet crosses in front of it, or by measuring the gravitational tugging on a star as a planet circles it.

We put these scant physical details into equations that comprise up to a million lines of computer code. The code instructs our Discover supercomputer to use our rules of nature to simulate global climate systems. Discover is made of thousands of computers packed in racks the size of vending machines that hum in a deafening chorus of data crunching. Day and night, they spit out 7 quadrillion calculations per second — and from those calculations, we paint a picture of an alien world.

While modeling work can’t tell us if any exoplanet is habitable or not, it can tell us whether a planet is in the range of candidates to follow up with more intensive observations. 

One major goal of simulating climates is to identify the most promising planets to turn to with future technology, like the James Webb Space Telescope, so that scientists can use limited and expensive telescope time most efficiently.

Additionally, these simulations are helping scientists create a catalog of potential chemical signatures that they might detect in the atmospheres of distant worlds. Having such a database to draw from will help them quickly determine the type of planet they’re looking at and decide whether to keep observing or turn their telescopes elsewhere.

Learn more about exoplanet exploration, here. 

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The Science Goals of the James Webb Space Telescope

Our James Webb Space Telescope is an epic mission that will give us a window into the early universe, allowing us to see the time period during which the first stars and galaxies formed. Webb will not only change what we know, but also how we think about the night sky and our place in the cosmos. Want to learn more? Join two of our scientists as they talk about what the James Webb Telescope is, why it is being built and what it will help us learn about the universe…

First, meet Dr. Amber Straughn. She grew up in a small farming town in Arkansas, where her fascination with astronomy began under beautifully dark, rural skies. After finishing a PhD in Physics, she came to NASA Goddard to study galaxies using data from our Hubble Space Telescope. In addition to research, Amber's role with the Webb project’s science team involves working with Communications and Outreach activities. She is looking forward to using data from Webb in her research on galaxy formation and evolution.

We also talked with Dr. John Mather, the Senior Project Scientist for Webb, who leads our science team. He won a Nobel Prize in 2006 for confirming the Big Bang theory with extreme precision via a mission called the Cosmic Background Explorer (COBE) mission. John was the Principal Investigator (PI) of the Far IR Absolute Spectrophotometer (FIRAS) instrument on COBE.  He’s an expert on cosmology, and infrared astronomy and instrumentation. 

Now, let’s get to the science of Webb!

Dr. Amber Straughn: The James Webb Space Telescope at its core is designed to answer some of the biggest questions we have in astronomy today. And these are questions that go beyond just being science questions; they are questions that really get to the heart of who we are as human beings; questions like where do we come from? How did we get here? And, of course, the big one – are we alone?

To answer the biggest questions in astronomy today we really need a very big telescope. And the James Webb Space Telescope is the biggest telescope we’ve ever attempted to send into space. It sets us up with some really big engineering challenges.

Dr. John Mather: One of the wonderful challenges about astronomy is that we have to imagine something so we can go look for it. But nature has a way of being even more creative than we are, so we have always been surprised by what we see in the sky. That’s why building a telescope has always been interesting. Every time we build a better one, we see something we never imagined was out there. That’s been going on for centuries. This is the next step in that great series, of bigger and better and more powerful telescopes that surely will surprise us in some way that I can’t tell you.

It has never been done before, building a big telescope that will unfold in space. We knew we needed something that was bigger than the rocket to achieve the scientific discoveries that we wanted to make. We had to invent a new way to make the mirrors, a way to focus it out in outer space, several new kinds of infrared detectors, and we had to invent the big unfolding umbrella we call the sunshield.

Amber: One of Webb’s goals is to detect the very first stars and galaxies that were born in the very early universe. This is a part of the universe that we haven’t seen at all yet. We don’t know what’s there, so the telescope in a sense is going to open up this brand-new part of the universe, the part of the universe that got everything started.

John: The first stars and galaxies are really the big mystery for us. We don’t know how that happened. We don’t know when it happened. We don’t know what those stars were like. We have a pretty good idea that they were very much larger than the sun and that they would burn out in a tremendous burst of glory in just a few million years.

Amber: We also want to watch how galaxies grow and change over time. We have questions like how galaxies merge, how black holes form and how gas inflows and outflows affect galaxy evolution. But we’re really missing a key piece of the puzzle, which is how galaxies got their start.

John: Astronomy is one of the most observationally based sciences we’ve ever had. Everything we know about the sky has been a surprise. The ancients knew about the stars, but they didn’t know they were far away. They didn’t know they were like the Sun. Eventually we found that our own galaxy is one of hundreds of billions of galaxies and that the Universe is actually very old, but not infinitely old. So that was a big surprise too. Einstein thought, of course the Universe must have an infinite age, without a starting point. Well, he was wrong! Our intuition has just been wrong almost all the time. We’re pretty confident that we don’t know what we’re going to find.

Amber: As an astronomer one of the most exciting things about working on a telescope like this is the prospect of what it will tell us that we haven’t even thought of yet. We have all these really detailed science questions that we’ll ask, that we know to ask, and that we’ll answer. And in a sense that is what science is all about… in answering the questions we come up with more questions. There’s this almost infinite supply of questions, of things that we have to learn. So that’s why we build telescopes to get to this fundamental part of who we are as human beings. We’re explorers, and we want to learn about what our Universe is like. 

Webb will be the world's premier space science observatory. It will solve mysteries in our solar system, look beyond to distant worlds around other stars and probe the mysterious structures and origins of our universe – including our place in it. Webb is an international project we’re leading with our partners, ESA (European Space Agency) and the Canadian Space Agency.

To learn more about our James Webb Space Telescope, visit the website, or follow the mission on Facebook, Twitter and Instagram.

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How Do We Learn About a Planet’s Atmosphere?

The first confirmation of a planet orbiting a star outside our solar system happened in 1995. We now know that these worlds – also known as exoplanets – are abundant. So far, we’ve confirmed more than 4000. Even though these planets are far, far away, we can still study them using ground-based and space-based telescopes.

Our upcoming James Webb Space Telescope will study the atmospheres of the worlds in our solar system and those of exoplanets far beyond. Could any of these places support life? What Webb finds out about the chemical elements in these exoplanet atmospheres might help us learn the answer.

How do we know what’s in the atmosphere of an exoplanet?

Most known exoplanets have been discovered because they partially block the light of their suns. This celestial photo-bombing is called a transit.

During a transit, some of the star's light travels through the planet's atmosphere and gets absorbed.

The light that survives carries information about the planet across light-years of space, where it reaches our telescopes.

(However, the planet is VERY small relative to the star, and VERY far away, so it is still very difficult to detect, which is why we need a BIG telescope to be sure to capture this tiny bit of light.)

So how do we use a telescope to read light?

Stars emit light at many wavelengths. Like a prism making a rainbow, we can separate light into its separate wavelengths. This is called a spectrum. Learn more about how telescopes break down light here. 

Visible light appears to our eyes as the colors of the rainbow, but beyond visible light there are many wavelengths we cannot see.

Now back to the transiting planet...

As light is traveling through the planet's atmosphere, some wavelengths get absorbed.

Which wavelengths get absorbed depends on which molecules are in the planet's atmosphere. For example, carbon monoxide molecules will capture different wavelengths than water vapor molecules.

So, when we look at that planet in front of the star, some of the wavelengths of the starlight will be missing, depending on which molecules are in the atmosphere of the planet.

Learning about the atmospheres of other worlds is how we identify those that could potentially support life...

...bringing us another step closer to answering one of humanity's oldest questions: Are we alone?

Watch the full video where this method of hunting for distant planets is explained:

To learn more about NASA’s James Webb Space Telescope, visit the website, or follow the mission on Facebook, Twitter and Instagram. 

Text and graphics credit Space Telescope Science Institute

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