The James Webb Space Telescope promises to push our knowledge of the final frontier even further. Today’s telescopes spot exoplanets orbiting distant stars. The JWST could give us our first look at the atmospheres shrouding them. But first, it needs to get off the ground and into its orbit. Let’s take a look at what the first 30 days for the James Webb Space Telescope will look like.
James Webb Space Telescope Launch at Kourou, French Guiana
On a clear day in October 2018, engineers will take one final look at the Ariane 5 rocket and its precious payload as it sits on a launch pad at the Guiana Space Center.
The Guiana Space Center is a French and European spaceport that has been launching rockets for 40 years. While not as busy as Florida’s space coast, the folks here know their stuff. And they will need to be at the top of their game next October. The James Webb Space Telescope is one of the most anticipated space launches ever. Plus, a joint ESA and JAXA mission to Mercury (BepiColombo) is also slated to launch the same month.
With the pre-flight checks done, the countdown begins. Moments before liftoff, the Ariane 5 rocket liquid engine ignites – followed immediately by the thundering roar of two solid rockets flanking it. The moment scientists and space fans have been waiting for is finally here. Liftoff!
Here’s an Ariane 5 rocket launch from November 17, 2016 showing us what we can expect next October.
A couple of minutes after launch, the Ariane 5 rocket reaches maximum acceleration. The solid boosters on each side flame out and are jettisoned (check the 3:00-minute mark in the video above for a stunning look at this as it happens).
With the thick upper atmosphere behind it, the payload fairing protecting the James Webb Space Telescope is jettisoned. Shortly after, the first stage engine uses up the last bit of fuel, shuts down and separates from the second stage.
Before the second stage motor fires up, the James Webb Space Telescope is on a slightly downward trajectory as it cruises above the Atlantic Ocean. That doesn’t last long as the second stage motor ignites and pushes the JWST towards its final resting place, L2 orbit.
But the telescope’s first 20 minutes are still fraught with peril. Because the telescope will use infrared light for most of its observations, it needs to be extremely cold. We’re talking nearly -400 degrees Fahrenheit. That means even the tiniest exposure to the sun is bad. During the second stage burn, a series of oscillations (steady back and forth movements) are performed. This protects parts of the telescope from temperatures approaching 185 degrees Fahrenheit on the hot side.
A few more minutes go by, and the James Webb Space Telescope separates from the second stage. Just 25 minutes have passed since the Ariane 5 rocket engines fired up at the Guiana Space Centre. It only feels like hours have passed by, but the hard work is still ahead.
The James Webb Space Telescope deploys
As it passes the geosynchronous orbit where most communication and weather satellites are located, the telescope begins deploying its solar array at around 30 minutes post-launch. Successful deployment of the solar array means the telescope won’t have to worry about power for its 5+ year mission (the goal is for 10+ years).
For the rest of the first day, the onboard control system will keep tabs on the spacecraft and adjust its position as it sees fit for power generation or course corrections.
With course corrections completed and the first full day in the books, the James Webb Space Telescope cruises past the orbit of the moon. The team back on Earth will be keeping a constant eye on the telescope as they prepare for the rest of the deployment to make the JWST an operational telescope.
On day 3, the slow (very slow) deployment of the sunshield pallets begin. Every step of the mission is important, but this stage is one of the most crucial. Without the protection from the heat of the Sun, the James Webb Space Telescope turns into a very expensive piece of space junk.
This infographic shows where the equipment is located on the James Webb Space Telescope and how the five-layer sunshield protects the telescope’s most sensitive equipment.
While the sunshield helps big time, the JWST team on the ground have to constantly monitor temperatures within the most sensitive instruments. That’s because the infrared detectors generate heat when they are being used. It’s also why the telescope uses an open-design versus a closed-design.
For the camera and spectrograph in the Mid-Infrared Instrument (MIRI), even more cooling is needed. A two-stage cryocooler (it’ll put your fridge to shame) will bring the MIRI’s temperature to a frigid 7 Kelvin (-447 degrees Fahrenheit). Just 12 degrees Fahrenheit shy of absolute zero.
Next up is the tower separating the telescope and instruments from the sunshield and spacecraft. Then, the aft flap deploys. This helps balance the pressure from the sun’s light on the telescope. It might not seem like much, but the sun can have a dramatic effect on a spacecraft. NASA’s Kepler uses pressure created from the sun to balance itself after two of its reaction wheels failed. The aft flap on the JWST helps keep the spacecraft always pointing in the correct direction.
On the fifth day after launch, the sunshield begins to deploy fully. By the start of the sixth day, the sunshield is completely protecting the telescope from the sun.
About a week later (11 days after launch), once the sunshield deployment is completely done – the secondary mirror and aft radiator deploys into position. Heat from the instruments is released into space here.
Two wings fold into place completing what will become the largest telescope in space. Each wing holds three of Webb’s 18 primary mirror segment and is necessary for the telescope to fit into the launch vehicle.
The James Webb Space Telescope is deployed.
Nearly one month after liftoff, a trajectory correction is initiated, placing the Webb telescope in a halo orbit at the L2 point. It won’t be exactly at the L2 point but instead, circle around it. Slight course corrections will be needed each year to keep the telescope in this position. The L2 point also places the JWST in the same position relative to Earth in the sky. That’ll make communication with it (via the Deep Space Network) easy.
Once the second month gets under way, the first image from the NIRCam will be captured. It’ll be blurry, and that’s to be expected. The 18 mirrors making up the primary mirror won’t be aligned yet. 44 days after launch, the JWST team will begin aligning each mirror.
After 90 days, each mirror should be aligned to work together as a single optical surface. The first science-quality images should be on their way to Earth. Six months in and the team should have every instrument calibrated and ready to go.
The science mission will begin. From the first bright spots after the Big Bang to in-depth study of discovered exoplanets to how our solar system evolved. The James Webb Space Telescope is expected to change astronomy.
Here’s a YouTube video showing what the first days of the JWST will look like.
Thirty days of intense pressure for decades worth of science.
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