Mad About Science: The James Webb space telescope

By Brenden Bobby
Reader Columnist

You might have noticed the name of this telescope in the news recently and thought to yourself, “I wonder why the science guy hasn’t written anything about this in the paper? I bet I know something he doesn’t.”

I guarantee this: You certainly know many things that I don’t.

My hesitancy to write about the James Webb Space Telescope can be chalked up to immense hubris, unfounded self-importance and wild superstition. Those who remember the Hubble Space Telescope launch (exactly one month after I was born) will know that the telescope had a defect in its primary mirror. Fortunately, the Hubble was close enough to Earth that NASA was able to undertake a mission to fix the telescope — if something were to go wrong with the James Webb telescope, a fix would be impossible.

While Hubble sits about 560 miles above the Earth’s surface, the JWST will be parked 932,056 miles away. The craft’s destination is called a Lagrange point, and is designated as L2. The significance of this point is that it’s a space where the gravitational pull of Earth and the orbital motion of the body cancel each other out.

This means the spacecraft can effectively “park”; it doesn’t need to expend fuel to maintain a stable orbit, which can prolong the duration of its mission dramatically.

The telescope is huge, with its primary mirror stretching 21 feet across. This mirror is actually broken up into three large pieces that are further divided into 18 hexagonal mirror panels, which form its unique honeycomb shape. In comparison, the mirror of the Hubble — which has taken some of the most detailed images of the universe humankind has ever seen — is only about eight feet across.

The James Webb Space Telescope boasts another incredible feature that Hubble lacks. In addition to its huge area for collecting light, it can also peer into the infrared spectrum, a feat made possible thanks to the sun shields mounted opposite this mirror. These shields keep the mirror in near-perfect darkness. In space, there’s no atmosphere to trap heat, which means any heat trapped or reflected by the shielding won’t interfere with infrared readings on the other side. This means that half of the craft will be kept at nearly 0 degrees Kelvin or absolute zero, the point in which matter stops moving entirely.

This might sound like a dismal prospect, but these are perfect conditions for getting a crystal-clear view into the universe. Have you ever sat outside and star gazed? At first, everything seems pitch black, except for the odd star or satellite flickering overhead. Over time you’ll begin to see more stars, and eventually a huge swath of the Milky Way cutting across the sky. This gradual growth of light is from your pupils expanding to allow in more light, which captures the faint light of the distant stars. If you were to turn on your phone and check a text message, you’d be blinded. This is the same principle behind the space telescope: The fewer sources of nearby light it has to contend with, the more effectively it will be able to look outward toward places we haven’t seen in detail.

The first leg of the telescope’s journey was the most harrowing. In order to fit on the rocket, the telescope needed to be folded up like an origami crane. When it comes to rockets, the less surface area you have, the less air you need to displace and the less energy you need to expend in order to deliver your payload from the ground to its destination. This means that NASA engineers have to be a little crafty when it comes to their payload designs. thirty minutes after launch, the telescope’s solar array was the first to deploy. This would supply the telescope with the power it needs to operate. Two hours after launch the antenna deployed, so that it could communicate with scientists on Earth.

Three days after launch, the first stages of the sunshield deployed. Four days after launch, the tower, which houses the mirror array and the vital instruments for its operation, deployed up and away from the sun shield. At this point, much of the “unfolding” began as the extending mid-boom arms of the sun shield moved laterally outward, pulling the large foil-like membrane with them and then tensioning them to create an accordion-like structure that would keep heat away from the mirror.

NASA’s engineers held their collective breath during the mirror deployment, as two sections of three mirrors each unfolded and locked into place on the main array over the course of two days. If a single part failed at any point during this entire, complicated unfolding process, the $10-billion mission could be a catastrophic failure.

Luckily, everything seemed to work, and I can breathe easy knowing that my superstition about writing an article too early would doom the mission was complete fallacy.

The telescope will spend the next five months pointed at a single star as a reference point as it precisely calibrates its mirrors and tests its numerous instruments. If you were expecting some flashy images of the cosmos, you’re going to have to wait until summer, at least.

So what should we expect from the telescope? The telescope boasts the ability to view objects at least nine times fainter than anything Hubble can capture. Additionally, the ability to peer into the infrared spectrum may be able to let us gaze at stars we never even knew about, as well as spy on planets in other solar systems to a degree. It’s believed that we may be able to peer far enough out to see what the universe looked like just a few hundred million years after the big bang.

What might that look like? I guess we’re just going to have to wait around and find out.

Stay curious, 7B.