NASA’s New Flagship Astronomy Mission: The James Webb Space Telescope

The most complex and prominent telescope namely James Webb Space Telescope (JWST), or Webb, has captivated a huge interest from the world-wide publicity.


Webb is an international project led by NASA ad its global companions (the European Space Agency and the Canadian Space Agency) and has recently revealed as a brand-new telescope that is designed to capture the universe’s infancy by tugging deeper into the unknown of the universe to study the formation of hidden galaxies and stars. It’s a promising instrument that has the potential to withhold a full resolution to some of the most inexplicable questions that has never been fully answered by the astrophysics history.

JWST’s construction is hitherto a largest and most significant space mission that NASA has ever attempted, from which the expectations and hopes placed by a whole astrophysics’ community are huge. This future generation of telescope is believed to possess a superseded capability to that of the Hubble Space Telescope and scheduled to launch in the late 2021 as a next NASA’s flagship astronomy mission.  

JWST’s Observable Wavelength Frequency

Angular resolution is considered a most essential component when structuring any kind of observatories or telescopes. This associates with the telescope’s range of wavelength, how far the telescope can see, and the quality of acquiring images and data. In particular, NASA emphasises the construction of future generation telescopes to be able to perform observation at infrared resolution instead of at visible or ultraviolet wavelength like Hubble. In the view of the fact that light from the distant objects is stretched and highly redshift due to the accelerating expansion of the universe, from which their ultraviolet and optical emission are gradually shifted into near-infrared. Likewise, cold objects, like debris disks and planets, strongly emit infrared bands of light and jets, which are impossible for existing short-wavelength telescopes like Hubble to penetrate through. Therefore, the Webb telescope will provide a longer wavelength coverage and greater sensitivity in order to thoroughly conduct its observation far back to the birth of the universe.

The James Webb Space Telescope is oriented to be capable of observing in a long wavelength like orange and red visible light to mid-infrared (0.6 to 28.3 μm), enabling it to gather most data, images and information of hidden stars and galaxies. It might be the hope to decipher some of the most inscrutable astrophysical problems that have been longed for answers.

Webb’s Main Structures

JWST outstands other existing telescopes by its notable mirror components, which will be functioning for the measurement of light from distant galaxies. The Optical Telescope Element of Webb is consisted of some major mechanisms, including the main mirror, the secondary mirror, the frameworks (backplane), and various thermal control to support the mechanism of the telescope.

Its primary mirror composes of eighteen smaller hexagonal mirror segments of 1.3 metres diameter that bind together to form a 6.5 metres diameter mirror coated with gold-plated beryllium. With this improvement in the mirror system, Webb’s clarity of received images and data will surely outdo that of Hubble, whose primary mirror is only 2.4 metres in diameter and is made of aluminium and magnesium fluoride.

The James Webb Space Telescope

However, in order for the JWST to conduct its observation in infrared range and detect extremely faint astronomical signals without interference, it must be kept very cold and stable. Webb is determined to be deploying in space near the Earth-Sun L2 Lagrange point (1.5 million kilometres away), where the gravity of the Earth and the Sun are equal, enabling the telescope to maintain its stability. The telescope is also enclosed inside a large sunshield made of silicon and aluminium-coated Kapton, which will act as a space-blanket to block the sunlight and keeps its mirror and instruments below 50 Kelvins.

In a similar way to other space-based telescopes, one of Webb’s main structure includes a spacecraft bus, which is a telescope’s general assembly of components that connects multiple sub-sections of the telescope together. The spacecraft bus hosts the Optical Telescope Elements, the Deployable Tower Assembly (allows the telescope to lift off the spacecraft when reaching its projected execution region), the Data Handling Subsystem, the MIRO cryocooler, and other minor instruments of the telescope. The Spacecraft Bus itself weights around 350kg and is made primarily of graphite composite materials. It is planned to be on the Sun-facing side and operate at temperature about 300 Kelvins.

Another important aspect of the Spacecraft bus is its proficiency in handling the central computer, the solid-state memory core, and other communication equipment that process and transmit data back and forth to Earth.  

The Journey of the Backplane

Backplane is the spine of the telescope that will be installed to mainly supports the stability of, and add extra mechanical strength to the beryllium hexagonal mirror of the telescope. It is essentially required to be motionless to remain the steadiness of the mirrors and keep them focus on the indications. The black plane will also manage the thermal stability performance at temperature colder than -400o F in order for the mirrors to provide unprecedented look at the deep space well beyond what Hubble has done.

NASA's James Webb Space Telescope Structure Stands Tall

Here is the laborious journey of the backplane

Before deploying into space, the backplane undergoes different constructions and test modules, which include the examination process, which often called the Pathfinder, and the flight process. The Pathfinder is the technology demonstrator, or the non-flight replica of Webb telescope’s actual backplane, but it was only included the centre section and was missing two-sided wings, which folded to each side in launch configuration. At the outset, the testing version of the actual backplane, or the Pathfinder, and was submitted to the rehearsal of the mirror assembly process at NASA Goddard, where all the mirror components were set up in place.

“The delivery of the backplane to Goddard represents another significant step in the evolution of Webb,” said Bill Ochs, James Webb Space Telescope project manager.

Pathfinder was, next, transported to NASA Johnson to be executed in the cryogenic test in Chamber A, in which to ensure mirror will focus crisply in space. The series of technical trials allowed a full checkout of the equipment and faculties in preparation for integration with the flight telescope.

The Journey of the Telescope Structure

Backplane Webb/NASA

The flight telescope comparatively went through the similar testing courses as the Pathfinder. Once successfully passing though the instrumental integration process, including the mirror assembly, and the environmental testing, the telescope was then delivered to NASA Johnson to proceed with the cryogenic testing. After succeeding the cryogenic testing, the telescope finalised the procedure by mating with the sunshield and spacecraft bus at Northrop Grumman.


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Feature Images retrieved from:

Vivian Nguyen

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