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JWST

After years of delays and price overruns, NASA's James Webb Infinite Telescope assembly is running smoothly and budgeted some critical milestones. We concluding checked in on the telescopes overall progress last March, and the EU was confident enough of its progress to fix a launch date last December. If things continue to become well, the JWST volition fly in October, 2018.

JWST vs. Hubble

JWST vs. Hubble Space Telescope

NASA is expected to finish assembling the main mirror surface on the JWST in the near-futurity, as well as the deep-freeze calibration tests on the telescope'southward diverse instruments. The new telescope's mirror is far larger than Hubble's (21 feet in bore versus 8 feet) and is assembled from eighteen separate "panes" of beryllium.

The image below shows the wavelengths that the two telescopes can "see" in:

Spectrum capabilities

There'south some overlap betwixt the JWST and the Hubble, but Hubble is primarily designed as a visible-calorie-free telescope, with some infrared capabilities. The JWST, in dissimilarity, specializes in infrared, with some ability to observe in the visible spectrum.

cosmic_timeline

The James Webb Infinite Telescope volition attempt to peer back equally far every bit the and then-called "dark age" of the universe

The above shows how the JWST's capabilities compare to mutual ground-based observatories, likewise every bit diverse instruments aboard the Hubble. Hubble'due south capabilities take evolved considerably over time, and it'south expected that the JWST will follow a similar trajectory. The ultimate goal for the James Webb telescope is to push button the purlieus of what we can observe dorsum to the so-called "Dark Ages" of the universe. While light existed during this epoch, the universe wasn't transparent yet. The dark ages mark the practical limit for what we can hope to discover with any telescope.

Why use space telescopes at all?

Ane question that'due south popped upwards from time to time when we cover astronomy is why nosotros bother building space-based telescopes at all. The Hubble Space Telescope fires the imagination and offers some incredible vistas, but its 8-human foot mirror is dwarfed by ground-based hardware. When the European Extremely Large Telescope (East-ELT) achieves beginning light in 2024, its collecting area will be 978m2 compared with Hubble's 4.5m2. Ground-based telescopes also take superior athwart resolution to space-based counterparts. So why pay the enormous toll of edifice a space-based telescope in the first place?

First, considering the pesky atmosphere gets in the way. The low-cal that reaches us from other stars is adulterate and distorted as it passes through the atmosphere, changing the nature of what we find. This is why we build telescopes at high altitudes — information technology's literally easier to see the universe when nosotros've got less atmosphere in the way.

2d, the temper absorbs a keen deal of useful spectrum, astronomically speaking. While you lot can do visible-light and radio astronomy from the ground, infrared, ultraviolet, and X-ray astronomy are varying degrees of incommunicable when on World.

There's a tertiary factor to consider, equally well. Ground-based telescopes tin can resolve bright objects more accurately than Hubble or the JWST, only space-based telescopes can see dim objects that a ground-based facility could never find. We apply both types of facilities because they serve dissimilar missions and needs, and can comport dissimilar types of research.