The first stars in these early galaxies produced the chemical elements of life as we know it - the very star stuff that we’re made of. The telescope can see mid-infrared wavelengths that will allow it to spot galaxies born just 200 million years after the Big Bang. Scientists want to see those fleeing galaxies, which is where JWST comes in. These galaxies are very far away, and due to the expansion of the universe, they are moving away from us so fast that the wavelengths of their light have shifted into the infrared, far beyond Hubble’s detection capabilities. The oldest galaxies in the deep field images formed just 400 million years after the Big Bang.īut there are even older galaxies that escaped Hubble’s detection. These images are filled with countless glittering galaxies and distant objects captured by Hubble after it stared at the same patch of sky over multiple days. To understand how the two telescopes relate to one another, we need to look back through Hubble’s famous deep field images. JWST was designed to pick up where Hubble left off in studying the early universe. Is JWST a successor or replacement for Hubble? What does that mean? As we celebrate the release of JWST's stunning first images, let’s compare the two telescopes and explore what to expect from JWST’s images of the cosmos. While JWST is sometimes called Hubble’s replacement, NASA thinks of it as a successor. JWST built on three decades of discoveries by the iconic Hubble Space Telescope. The initial release showcased the observatory’s abilities. NASA finally released the James Webb Space Telescope’s first full-color science images on July 12. The European Space Agency is picking up the launch costs, with a French-built Ariane rocket providing Webb’s lift from French Guiana.The wait is over. Webb’s price tag is an estimated $10 billion that includes the first five years of operation. That doesn’t include all the shuttle flights for launch and repairs. NASA’s tab for Hubble from its 1970s development until now: $16 billion, adjusted for inflation. Webb also is years late with huge cost overruns. Hubble was years late and millions over budget by the time it rocketed into orbit in 1990. Webb will constantly face the nightside of Earth as the spacecraft and planet swoop around the sun in unison. This is where the gravitational forces of the Earth and sun balance, requiring minimal fuel for a spacecraft to stay put. Webb is bound for more a more distant spot - 1 million miles (1.6 million kilometers) away at what’s called the second Lagrange point. The altitude was dictated by the capabilities of NASA’s space shuttles, which delivered Hubble to orbit and then made five service calls. Hubble circles 330 miles (530 kilometers) overhead. Each of the 18 hexagonal segments are the size of a coffee table and coated with ultra-thin gold, an ideal reflector of infrared light. It’s also segmented, allowing it to fold like a drop-leaf table for launch. That’s because Webb’s mirror is made of beryllium, a strong but lightweight metal. The mirror spans more than 21 feet (6.5 meters), yet is lighter than Hubble’s, which is 8 feet (2.4 meters) across. To discern the universe’s first, faint stars, Webb requires the largest mirror ever launched for astronomy. Multiple layers also better protect against micrometeorite hits. Between each of the sunshield’s five layers is a gap so heat can escape out the sides. To stay chilled, Webb carries a parasol the size of a tennis court. That’s why Webb’s detectors need to run at minus 400 degrees Fahrenheit (minus 240 degrees Celsius). The shorter visible and ultraviolet wavelengths emitted by the first stars and galaxies have been stretched as the universe expands, so Webb will see them in their elongated, heat-emitting infrared form. Webb has infrared vision, allowing it to pierce cosmic clouds of dust. Hubble sees what we see - visible light - with a little ultraviolet and infrared thrown in. “It’s like looking at the picture book of my kids and missing the first two years, right? Trying to figure out where they come from,” said NASA science chief Thomas Zurbuchen. Astronomers are eager to close the 300 million year gap with Webb and draw ever closer in time to the Big Bang, the moment the universe formed 13.8 billion years ago. Hubble has stared as far back as 13.4 billion years, disclosing a clumpy runt of a galaxy that is currently the oldest and farthest object ever observed. This light will reveal how the original stars looked 13.7 billion years ago. Webb is expected to behold light from the universe’s first stars and galaxies, beyond Hubble’s range.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |