James Webb passes critical test as telescope moves toward 2021 launch

by Chris Gebhardt

The James Webb Space Telescope — a collaboration between NASA, the European Space Agency (ESA), and the Canadian Space Agency (CSA) — has successfully completed a critical pre-flight milestone and test that paves the way for continued final testing of the most complex telescope ever built.

At present, James Webb remains on track for a launch from the Guiana Space Centre in Kourou, French Guiana, on an Ariane 5 rocket No Earlier Than 31 October 2021.

The three-way partnership between NASA, ESA, and CSA, follows large-scale, international partnerships for space-based telescopes of the past and results in sharing of the financial output as well as economic and scientific benefits the mission offers.

For the James Webb Space Telescope (JWST), ESA’s primary contribution from a monetary standpoint to the mission was procurement of the launch vehicle, in this case the ESA-built and Arianespace operated Ariane 5 rocket.

This type of monetary service in relation to providing a launch vehicle is a fairly standard interagency operating procedure; the last time such an agreement occurred was between ESA and NASA for the Solar Orbiter mission in February 2020, to which NASA was a partner and bought the launch vehicle: an Atlas V 411 from United Launch Alliance.

In addition to the launch vehicle, ESA is also providing monetary support for the NIRSpec instrument, funding for the Optical Bench Assembly of the MIRI instrument, as well as staff to the Space Telescope Science Institute in Baltimore, Maryland, USA, to help carry out the mission once the telescope is launched.

The other major international partner is the Canadian Space Agency, which has provided the Fine Guidance Sensor, which will be used to point and focus the telescope on observational targets, and the Near-Infrared Imager and Slitless Spectrograph for the study of exoplanets and distant galaxies. 

This partnership ensures ESA and CSA receive guaranteed observation time on the telescope and are one of the first agencies along with NASA to study the data collected by the most advanced observatory ever built. 

Moreover, selection of scientific targets will be a joint effort between NASA, ESA, and CSA, while scientists at large will propose objects of interest as well that may not appear on the list of primary targets identified by the three agencies.

The ability to launch this mission took another major leap forward last week with critical ground segment testing, which marked the first time commands to power up and test JWST’s scientific instruments were sent to the fully assembled observatory.

The commands were issued — as they will be during the mission — from the Mission Operations Center at the Space Telescope Science Institute in Baltimore, Maryland.  Those commands will then be routed to the telescope through the Deep Space Network (DSN) of communication dishes located in Barstow, California, USA; Canberra, Australia; and Madrid, Spain.

Because the actual DSN dishes can only communicate with objects in space, teams used a DSN network emulator — standard procedure for missions that will have to communicate through the network — for the test.

The main purpose of this evaluation was to ensure all four primary instruments functioned as designed and that the telescope was not only able to receive and execute commands from the ground but to downlink data back as well.

“This was the first time we have done this with both the actual Webb flight hardware and ground system,” said Amanda Arvai, Deputy Division Head of Mission Operations at the Space Telescope Science Institute in Maryland.

“We’ve performed pieces of this test as the observatory was being assembled, but this is the first ever, and fully successful, end-to-end operation of the observatory and ground segment.  This is a big milestone for the project, and very rewarding to see Webb working as expected.”

The test lasted four days and took place from both the Space Telescope Science Institute and the cleanroom where James Webb is undergoing final assembly at Northrop Grumman’s Redondo Beach, California, facility.

“This was also the first time we’ve demonstrated the complete cycle for conducting observations with the observatory’s science instruments.  This cycle [started] with the creation of an observation plan by the ground system which [was] uplinked to the observatory by the Flight Operations Team,” added Arvai.

“Webb’s science instruments then performed the observations and the data was transmitted back to the Mission Operations Center in Baltimore, where the science was processed and distributed to scientists.”

Speaking to the most recent round of tests, Dr. Eric Smith, James Webb Space Telescope Program Scientist, NASA Headquarters, noted in response to NASASpaceflight questions that, “Running commands from the operations center all the way through the Webb communications network AND getting back the responses we expected is an exciting milestone.”

“This complex system of computer software and commands, spacecraft electronics and communications networks worked beautifully.  Anyone who’s ever written a computer program, or built something, can relate to the joy of seeing it do exactly what you wanted it to.”

Successful testing of the four primary scientific instruments came on the heels of acoustic testing that blasted James Webb with the same amount of sound and acoustic waves it will experience during launch next year. 

Acoustic testing is yet another critical part of pre-flight preparations to ensure satellites can survive the sound environment imparted to them during launch, which is often the most stressful aspect of any mission not just for the satellite but for its control teams and scientists as well. 

The James Webb Space Telescope in final integration earlier this year at Northrop Grumman’s Redondo Beach, CA, facility. (Credit: NASA/Chris Gunn)

What makes James Webb slightly unique in this regard is that the most stressful part of its mission will likely not be the launch to its intended location 1.5 million kilometers (1 million miles) from Earth at the L2 Lagrange point but rather its complex unfolding process thereafter.

A Lagrange point is a specific region of space around two large celestial bodies where the gravity of those two objects cancels each other out, providing a stable platform for observatories like the James Webb Space Telescope while keeping it the same distance from Earth.

Once in space, and due to its complex design, JWST must perform roughly 344 complex — no room for failure — unfolding operations.  These events are all Category 1 failure points, meaning that if any single one does not unfold as designed, the entire mission will be rendered inoperable.

Because of that, great care is being taken to make sure all of those steps are working perfectly on the ground as JWST — unlike Hubble — was not built with human servicing missions in mind given the vast distance from Earth at which it will operate.

To this end, a major upcoming test for JWST is deployment and unfolding of its sunshield, communications arrays, and mirrors to verify that all deployments can occur successful.

Randy Pollema, electrical integration and testing lead for Webb at Northrop Grumman in Redondo Beach, added, “I’ve never seen such … collaboration and cross-organizational efforts to bring so many different teams and people in so many different areas together to execute a common goal so successfully.”

“We have a lot of pride, and feel a lot of personal reward in what we’ve been able to accomplish over the last year in assembling Webb into its final form, and with the completion of this latest systems evaluation we can confidently move forward knowing that the assembly was a success.”

Speaking to the overall importance of the mission and what they are personally most excited for, Dr. Smith told NASASpaceflight that “The commissioning or ‘try-out’ portion of the mission that happens after launch and lasts for six months leading to the normal operations of the mission [is something I’m personally really excited about].”

“This is the period when we ready the observatory for operations in space and has many critical events, but also long periods of waiting for conditions on the observatory (like temperature) to be just right before we can do anything.  We’re working hard on how this will go, but it gets overshadowed by the great images of the observatory itself.”

Dr. Smith noted with pride that “This mission will demonstrate that NASA still does the nearly impossible and represents the pinnacle of government, industry and academic achievement.”

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