Tuesday January 31, 2023

NASA’s James Webb Space Telescope, a revolutionary instrument from NASA, reaches final orbit in space

NASA’s new James Webb Space Telescope made its final course correction maneuver today, placing itself in its final resting spot in space after traveling hundreds of thousands of kilometres through space over the past month. The observatory will now live in perpetuity at approximately 1 million miles from Earth. This gives it a front row view of the oldest stars and galaxies in the Universe. The telescope was too large to be launched in its final form. It had to be folded inside its rocket. JWST started a complex routine of shape-shifting, unfurling and other choreography once it was in space. This was a feat that no spacecraft had ever accomplished before. JWST managed to complete every step flawlessly. It completed its major deployments on January 8, and then blossomed into its full configuration.
There was a lot of anxiety surrounding those deployments. They had to go according to plan; one failure could have ended JWST’s entire mission. The mission team’s anxiety didn’t stop when unfurling was completed. JWST had to be in the correct position in space to complete its mission. The vehicle could end up in the wrong orbit or miss its target trajectory if the observatory doesn’t slow down today. This failure could have made it difficult for scientists to communicate with the space observatory, which is worth nearly $10 billion.
JWST successfully completed this last maneuver. “JWST has had remarkable success over the past month and is a tribute all the people who spent many years, even decades, to ensure mission success,” Bill Ochs (the JWST project manager at NASA’s Goddard Space Flight Center) stated in a statement.
[embedded content]
Although it had taken JWST a month to get to this point, JWST was able to take it to its final destination today. JWST’s onboard thrusters were fired for approximately 5 minutes at 2PM ET. It was the third course correction burn that JWST had done. This slowed the spacecraft enough to place it in a precise orbit in space.
JWST is currently orbiting around an invisble point in space called an Earth-Sun Lagrange. It’s a mysterious area of space in which the gravity and centripetal force of the Sun and Earth are just right, allowing objects remain in a relatively stable position. Jean-Paul Pinaud (Northrop Grumman’s ground operations delta-V leader), told The Verge that there is a tug of war where gravity balances out perfectly. Pinaud is the primary contractor for JWST. “So no one wins that tug-of-war.”
Five of these Lagrange points are shared by the Earth and the Sun. They are scattered all over our planet. One is located directly between the Earth’s Sun and the Sun, and one is on the opposite side from us. JWST orbits around L2, a Lagrangian point on the Earth’s far side. JWST is in this position and will orbit around L2 Lagrangian point, which is on the far side of the Earth from the Sun. JWST will always be approximately 1 million miles from us, no matter where Earth is in its orbit around the Sun.
JWST’s track around L2 is actually quite wide. It covers roughly the same distance as the Earth and Moon. The observatory cannot stay on this trajectory forever without help. L2 is also known as “pseudo stable”, meaning that objects orbiting this location will have a tendency towards drifting in one direction. Pinaud describes it as “like sitting on a horse’s saddle.” Pinaud says, “You’re kinda stable when you’re on a saddle of horse.” Imagine yourself as a marble… From head to tail you’ll likely roll to the center of the saddle but once you move to either side of it, you’ll just fall to the ground.”
JWST will need to make minor adjustments to its trajectory over its lifetime. The telescope will fire its thrusters every 20 days to keep it on track in its orbit. These adjustments will ultimately determine how long JWST can remain active in space. The observatory’s mission will be ended when the propellant runs dry in 10 to 20 years. (JWST’s flight to space, the Ariane 5 rocket launched it on such an amazing trajectory that the telescope’s life expectancy will be much longer than originally anticipated.
It might seem complicated, and it requires extra effort to keep JWST stable. For a variety reasons, L2 is an attractive location for this observatory. The best thing about L2 is its distance from the Earth and Sun. JWST was designed to collect infrared radiation, which is associated with heat. This design means that the telescope must be kept extremely cold at all times. It is equipped with a sunshield, which will always face the Sun. This shield will reflect the Sun’s heat and keep it extra cold. NASA must be careful not to let any nearby objects emit heat or infrared light, which could cause JWST to lose its observations. NASA has placed the telescope at a distance of nearly 1,000,000 miles from Earth to ensure that infrared light from the Moon and Earth will not heat or interfere with the telescope.
L2 is also very powerful from a power perspective, as one side of JWST always faces the Sun. The telescope’s heated side has a solar panel that constantly receives sunlight to generate power. This luxury is not available to other spacecraft, like the Hubble Space Telescope orbiting around Earth. Hubble loses the Sun’s view when it orbits at night and must store energy in its batteries. JWST will never experience this. “We have basically unlimited power for mission operations, so we don’t need to worry about any eclipses,” Kyle Hott (Northrop Grumman’s mission systems engineering lead for JWST) tells The Verge.
There are downsides to constantly switching between day/night when orbiting the Earth. Extreme temperature fluctuations can jostle and vibrate spacecrafts, causing their instruments to degrade over the years. JWST will continue to operate at approximately the same temperature throughout its life.
Then there’s the benefit of constant communication. JWST will always be at the same distance from Earth as L2, because L2 is always in the same location relative to Earth. This means that we can stay in constant contact with the observatory. Hott says, “We can kind of be pulled along at L2 Earth-Sun system, so that we have that nice convenient constant communication with the vehicle.” “And so that simplifies just about all of the mission operations aswell.”
This important finale ends the observatory’s risky journey through space and paves the way for science to finally start. JWST’s observations will still be delayed. Engineers and scientists will soon begin aligning the telescope’s mirrors precisely before commissioning it. They will also test all its instruments to ensure they are ready to collect the first extraordinary images ever taken of the oldest stars and galaxies in our Universe.
This process could take several months, but if everything goes well, the first historic images captured by JWST could return to Earth as soon this summer.

Back to Top
%d bloggers like this: