NASA’s James Webb Space Telescope has reached L2: What Happens Next

The James Webb Space Telescope hanging in space after separating from the Ariane rocket over the Gulf of Aden between Yemen and Somalia. Credit: NASA / ESA

Since its launch on Christmas Day, astronomers have been enthusiastic about the complex deployment and deployment of NASA’s James Webb Space Telescope.

Just around the time this article was published, Webb is expected to reach a location called Earth-Sun’s second Lagrange point (L2). This is a point in space about 1.5 million kilometers away from the Earth (opposite the Sun), and gravity from both the Sun and the Earth helps balance the movement of satellites in orbit. ..

Now the astronomy community—Including my team Astronomers at Swinburne University — Preparing for a new era of major discoveries.

30 years and US $ 10 billion

In 2012, I was looking forward to the launch of Webb and wrote an article on The Conversation, which recalls the surprisingly early days of its predecessor, the Hubble Space Telescope.

At that time, the planned launch date for Webb was 2018. When the project was first conceived in the 1990s, the goal was to launch it before 2010. Why did it take nearly 30 years and cost more than US $ 10 billion (about A $ 14 billion)? , How to get Webb off the ground?

First, it is the largest telescope in space, equipped with a 6.5m diameter gold-coated mirror (compared to Hubble’s 2.4m mirror). The size is complicated because the entire structure needs to be folded to fit inside the nose cone of the Ariane rocket.

This is an approximation of the path that Webb follows at point L2 as it orbits the Sun and Earth.

Second, there were two major engineering wonders to be achieved with Webb.for Large telescope To produce the clearest image possible, the surface of the mirror should be aligned very accurately along the curve. For Webb, this means deploying and deploying the 18 hexagonal segments of the primary mirror and the secondary mirror with an accuracy of 1 in 25 billion meters.

Also, Webb monitors Infrared lightTherefore, in order to maximize the sensitivity, it is necessary to keep it at a very low temperature (about -233 ° C). This means that you must be far from the Earth, the source of heat and light. It also needs to be completely protected from the sun. This is achieved with a 20m multi-layer reflective sunshield.

All of Webb’s major spacecraft deployments, including the deployment of the Primary Mirror and Sunshield, were completed on January 8. The entire process contained over 300 single points of failure (mechanisms that only work once). The remaining small moves will take place over the next few months.

Main mission

Webb’s main mission is to witness the birth of the first person. Performer And early cosmic galaxies. As light from these very faint galaxies travels across the vast cosmic bay, 13.8 billion years Over time, it is stretched by the overall expansion of the universe in what we call “”.Cosmological redshift“.

Deployment sequence of the James Webb Space Telescope. Credit: NASA

This stretch is young and hot Giant star Webb receives as infrared. Therefore, the mirror is coated with gold. Compared to silver and aluminum, gold is better at reflecting infrared and red light.

The web can see much more infrared light than the Hubble. It is also up to 1 million times more sensitive than ground-based telescopes, where the infrared radiation of the Earth’s own high-temperature atmosphere drowns out light from distant galaxies.

Due to these previous technical limitations, the first billion years of space history have been barely explored. I don’t know when and how the first star was formed. This is a complicated question, as stars produce heavy elements when they die. These elements pollute the interstellar gas in the galaxy and alter the behavior and decay of this gas to form later generations of stars.

Like the Milky Way, all current star formation we can observe is from concentrated interstellar gas. We have not yet seen how stars are formed with pristine gas. Heavy element— No such state has existed for over 13 billion years.

However, we believe that the formation from the original gas is likely to have had a significant impact on the characteristics of the first star population.


Compared to these Hubble images, Webb provides a much clearer view of the first billion years after the Big Bang (line below). Hubble could hardly detect the brightest objects from this point on. credit: NASA / ESA

Deep Space Observatory

In addition to studying the early universe, Webb will be NASA. “Great Observatories“And we support a variety of other projects.

This allows scientists to look into dust-covered areas, such as the center of the galaxy. Supermassive black hole Areas of lurking or strong star formation in our galaxies and elsewhere. Webb is also sensitive to the coldest objects, such as very low-mass stars and planets orbiting other stars in the Milky Way.

One of Hubble’s major improvements is that it is fully equipped with Webb. Spectroscopy, Breaks down light into its component wavelengths. This allows you to accurately measure the galaxy’s cosmic redshift and understand which elements the galaxy is made of.

The web near the house helps to find molecules such as the solar system, the Milky Way, water in nearby galaxies, ammonia, carbon dioxide (and many other molecules). You will be able to see these in the atmosphere of the planets around the nearby stars, which is especially exciting for the exploration of extraterrestrial life.

Launch of James Webb Space Telescope. Credit: NASA

Astronomers are waiting for the first data to be collected in the next few months. The telescope continues to move and the mirror segment makes small nanometer-sized movements to focus while the most dramatic and dangerous mechanical movements are complete. This will take weeks as the telescope cools to operating temperature.

Perhaps the most exciting aspect to me is completely unknown. With Webb, you can observe the previously dark era of the universe, where physical conditions were very different from those of modern universes.

The history of astronomy suggests that the discovery of a paradigm shift can be expected.

Video: James Webb Space Telescope: A New View of the Universe

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NASA’s James Webb Space Telescope has reached L2: What Happens Next

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