NASA James Webb Space Telescope Crosses Midway in Final Test

by Barbara R. Abercrombie
0 comment

What is going on

The JWST team has completed 10 of the 17 “modes” or checkpoints on the way to start up the telescope.

Why it matters

Successful testing means we’re still on track to receive the first JWST images this summer.

It’s almost time.

NASA is releasing its first-ever interstellar discoveries, courtesy of the groundbreaking James Webb Space Telescope. From July 12, we can see the universe through a much brighter lens.

And in preparation for the much-anticipated day, JWST researchers painstakingly perfected each of the scope’s groundbreaking equipment — on that front, we’ve got an update.

NASA scientists announced this week that they have successfully calibrated the eye of a JWST-mounted device called NIRSpec. This is a pretty big milestone because of the streamlined way NASA has organized the path to regular Webb use. The agency has to go through 17 instrument modes, which you can think of as test checkpoints, through analysis and observation before JWST boots up completely.

So, counting in NIRSpec performance, the agency has officially passed half the mode book — bringing the total to 10 out of 17.

“The recent confirmation of the acquisition of NIRSpec targets…prepares the NIRSpec team for our final commissioning activities,” the team said. “We can’t wait to see the first scientific observations of NIRSpec this summer!”

In fact, “the team has started collecting some of the first scientific data,” according to the agency’s publication.

A Brief Summary of the James Webb Specifications

There are four major components to JWST, each contributing to the 17 modes described by the agency. Note that almost all of these facets rely on infrared light detection, meaning they can study a portion of the electromagnetic spectrum invisible to human eyes.

“Studying the intensity or brightness of light across the wavelengths can provide important diagnostic information about the nature of various objects in the universe,” the JWST team said. “From extrasolar planets around distant stars to faint galaxies at the edge of the universe and objects in our solar system.”


A comparison of Hubble’s visible and infrared views of the Monkey Head Nebula. While Hubble has some infrared capabilities, it’s nothing compared to Webb.


You can read about the science of infrared in more detail here — but back to JWST’s technology army, here’s the breakdown.

The alpha instrument is probably the Near-Infrared Camera or NIRCam. NIRCam will essentially take the lead in detecting and imaging the cosmos as it was when time began. “If NIRCam doesn’t work, the telescope won’t work,” Alison Nordt, director of space science and instrumentation at aerospace giant Lockheed Martin, which has been part of the JWST since its inception, says.

Lockheed Martin engineer Alison Nordt works on Webb’s NIRCam.

Lockheed Martin

Then there’s the Mid-Infrared Instrument, or MIRI, which has a camera and spectrograph aimed at dissecting items illuminated by light in the mid-infrared electromagnetic region, and the Near-Infrared Imager and Slitless Spectrograph, or NIRISS, which is an exoplanet-hunting machine.

Also, on board the JWST, you will find a navigation system, also known as the fine guidance sensor, ensuring the scope is not lost. And finally, the star of NASA’s latest update is the Near-Infrared Spectrograph or NIRSpec.

This collage shows a picture of all of Webb’s major instruments.


What is NIRSpec?

“The Near-Infrared Spectrograph is the Webb telescope’s instrument that observes spectra of astrophysical and planetary objects at near-infrared wavelengths,” the JWST team said.

A NIRSpec MSA-based target acquisition process simulation demonstrated on the NIRSpec sharpness control image. NIRSpec uses “reference stars,” which you can see here, observed through solid slits in the device.

NASA, ESA, and the NIRSpec team

In other words, it examines phenomena in space that emit light in the near-infrared region, but instead of just imaging those objects, it can study their chemical makeup. That is the intrigue of spectrography. You get more than a picture of a planet; you contact details of what it would be like to be on it.

An optimized high-resolution simulation of a star seen through a NIRSpec micro shutter. To properly estimate the intensity of NIRSpec scientific spectra, we need to know the positioning of the targets within a tenth of the shutter width.

NASA, ESA, and the NIRSpec team

And as for target acquisition, the JWST team says NIRSpec has an important mirror, which can place cosmic targets in their proper locations as the telescope examines. This is crucial because such information helps NIRSpec’s spectrograph know where to look.

The mirror does this in two ways: the Wide Aperture Target Acquisition (WATA) and the Micro-Shutter Assembly-based Target Acquisition (MSATA). During testing, the team said WATA performed “excellent” and MSATA made solid progress, and luckily for us, both successes give us great cosmic images, like the one at the top.

Furthermore, regarding MSATA, the JWST team says this method is quite difficult to establish. It requires an accurate estimate of the spectral intensity from the iNIRSpec science within a tenth of the shutter width of the device. That’s incredibly precise. For context, it’s “the approximate size of a bumblebee, 1.5 centimeters, as seen from 150 kilometers away,” the team said.

With NASA behind these successes, there are only seven modes to go before we reach July 12 — the day we’ve all been waiting for.

To the stars, JWST.

Related Posts