JWST is Ready for Launch, But the Weather Not So Much

JWST is Ready for Launch, But the Weather Not So Much

Launch of the $10 billion James Webb Space Telescope will have to wait another day. This afternoon NASA, ESA and launch services provider Arianespace declared the telescope and rocket ready for launch, but just hours later had to announce a one-day delay due to poor weather at the launch site in French Guiana. That pushes the launch to Christmas Day.

Following today’s successful Launch Readiness Review, a final technical milestone in launch preparations, weather seems to be the only thing standing in the way of this much anticipated launch. JWST may be years late and billions over budget, but almost giddy excitement about what it may reveal about the universe continues to shield it from harsh criticism.

JWST in its folded configuration at the Arianespace processing facility in Kourou, French Guiana before being encapsulated into the Ariane 5 rocket fairing in preparation for launch. Credit: NASA

About two hours after NASA and Arianespace officials finished a teleconference with reporters to share the news that everything was on track for launch on December 24, ESA issued a press release explaining that the weather would not cooperate that day.

Another forecast is awaited tomorrow evening to confirm December 25’s weather will be acceptable. The launch can slip day-by-day as long as Arianespace has not begun fueling the rocket. If the rocket is fueled, two days are needed in order to produce more propellant (liquid oxygen and liquid hydrogen).

JWST’s launch is not driven by planetary alignment windows like some NASA missions. It can launch almost any day. The exceptions are when the Moon is in the way of its trajectory to the Sun-Earth Lagrange Point-2 (SEL-2). Hopefully it will be well on its way before the first of those black-out periods arises from January 9-13. They recur with every 28-day lunar cycle.

JWST is a cooperative program among NASA, ESA and the Canadian Space Agency. ESA is providing the launch at no cost to NASA on Europe’s Ariane 5 rocket, which launches from Kourou, French Guiana, on the northeast coast of South America.

ESA also provided one of the science instruments, the Near-Infrared Spectrograph (NIRSpec). JWST’s Near-Infrared Camera (NIRCam) was provided by the University of Arizona. The Mid-Infrared Instrument (MIRI) was provided jointly by NASA and the European Consortium (led by the U.K.) with ESA. Canada provided the Fine Guidance Sensor/Near InfraRed Imager and Slitless Spectrograph (FGS/NIRISS). NASA is providing the spacecraft that houses all of those instruments. Northrop Grumman is the prime contractor.

NASA estimates its share of the JWST development cost at $8.8 billion, with another $900 million for five years of operations once it is launched, a total of $9.7 billion. In a June 1, 2021 ESA media briefing, CSA’s Director General for Space Exploration Gilles Leclerc said Canada has spent $200 million Canadian ($160 million U.S.) on JWST and ESA’s Director of Science, Günther Hasinger, said ESA’s cost is about 700 million Euros ($860 million). Hasinger emphasized that is not directly comparable to NASA’s figure because ESA member states contribute individually as well as through ESA.  Scientists’ salaries also are paid by their home institutions, not ESA.

But overall the cost for JWST, excluding operations, is about $10 billion.

The telescope has survived many hurdles already with repeated schedule delays and cost overruns, but the next month will determine literally whether it lives or dies.

Not only must launch go perfectly, but it then begins a 29-day period where the complex telescope must unfold itself and make several course changes to get to its destination a million miles from Earth.

The first two critical events happen the first day. The telescope’s solar panels must deploy 33 minutes after launch (L+31) or it will have no power for the remaining 29 Days on the Edge. Then 12.5 hours after launch is the first Mid-Course Correction (MCC) trajectory change to send it to SEL-2.

Over the course of the next two weeks, the telescope’s five-layered sunshield must deploy as well as its gold-plated mirror and many other pieces of equipment so that it morphs from that folded configuration in the Arianespace processing facility into this elegant formation ready to study the universe in infrared wavelengths.

Illustration of JWST in its deployed configuration, with the sunshield at the bottom protecting it from the heat of the Sun, and the gold-plated mirror searching the universe for infrared signatures using its extremely cold instruments. Credit: NASA

The deployment sequence for the spacecraft is shown in an October 2021 presentation by JWST Program Scientist Eric Smith. The many steps in Spacecraft Commissioning may be somewhat difficult to decipher, but the point is clear — it’s complicated.  NASA also has an interactive version of the deployment steps.

This shows solar array deployment 31 minutes after launch (L+31) but the interactive website says 33 minutes and a NASA official recently also said 33 minutes.

Mike Menzel, NASA’s Lead Mission Systems Engineer for JWST, said at November 2 press briefing that there are 344 single points of failure in the observatory. Of those, 80 percent are associated with deployment, mostly mechanical release mechanisms. Because they could be single point failures, meaning there are no redundant systems to kick-in if they fail, they have been tested especially rigorously.

NASA Administrator Bill Nelson said today that the agency has “always known this was a risky endeavor” but if “you want a big reward, you usually have to take a big risk.”

At the moment, that next big risk is launch on Christmas Day.

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