Two weeks after the Christmas launch, NASA’s James Webb Space Telescope completed its self deployment today, and astronomers were happy in the process.
The deployment of the 18 segment, 21.3 foot wide primary mirror of JWST marks the end of the most risky part of the $10 billion telescope mission.
It is more than 300000 miles from its destination, which is a gravity equilibrium point L2 1 million miles from the earth. It still needs to fine tune the orientation of the gold and beryllium parts of the mirror and cool its instrument to a temperature several degrees above absolute zero. However, the mission controller of the Space Telescope Science Institute was able to successfully select nearly 300 potential fault points.
“We have a fully deployed JWST Observatory,” Paul Reynolds of Northrop Grumman announced in a widely watched webcast.
The design sensitivity of JWST is 100 times that of the 32 year old Hubble Space Telescope, and the service life of the Hubble Space Telescope is about to exceed expectations. Once JWST starts scientific operation as early as may, it should bring new mysterious discoveries, from the habitability of alien planets, to the nature of black holes and quasars, and then to the origin of the universe.
After years of development delays and billions of dollars in cost overruns, today’s mirror deployment is regarded by astronomers and senior NASA officials as a landmark success.
NASA Director Bill Nelson said: “NASA is an impossible place.”.
Mark mccaughrean, senior adviser on science and exploration of the European Space Agency, reviewed Winston Churchill’s wartime maxim to describe the moment. “Quoting Mr. Churchill, it’s not over yet,” McCullen wrote on twitter. “This is not even the beginning of the end. However, this may be the end of the beginning. Before the beginning of science, five months of cooling, calibration and commissioning still exist, and the hard work of the relevant teams. But today is a big step.”
It took two weeks to deploy the rigging of the primary mirror and other parts of the JWST, including the hood and secondary mirror, because the telescope was too large to be fully installed in the nose cone of the European Ariana 5 rocket that launched it.
The sunshade, which consists of five layers of ultra-thin coated plastic, must be deployed in space to protect the telescope from solar radiation, which is considered the most dangerous part of the deployment process. Then, the left and right sides of the telescope must be pulled up and locked like the sides of the hanging leaf table. The left side was in place on Friday and the right side was handled today.
“This is arguably the most challenging deployment plan in NASA’s history,” NASA mission systems engineer Mike Menzel said at a post deployment briefing at the Space Telescope Science Institute in Baltimore.
The mission team has developed contingency plans for possible failures, including procedures for shimming spacecraft in space if necessary. But none of these plans need to be used.
“It’s not as easy as it looks, but what you see is relaxed… It’s just a tribute to people,” said Bill oaks, the project manager of the task. “We have experienced, and now I think it is a completely correct test quantity, a completely correct engineering review quantity and a completely correct design adjustment quantity.”
Before launch, the mission manager said that JWST would face 344 potential single points of failure. Moreover, since the telescope is destined to operate outside Earth orbit, there is no opportunity to send a maintenance team to repair any defects – just like the Hubble telescope.
Although the most dangerous part of the mission is over, there are still some risks. The spacecraft will have to launch its thrusters on January 23, enter the orbit near the L2 gravitational equilibrium point, and then enter the conventional orbit in the next few years.
Menzel said, “of the initial 344 single points of failure, 49 were not retired and would not be retired during the mission.”. “These 49 are typical of all tasks – such as propulsion boxes.”
The good news is that things have gone surprisingly well so far. In fact, it is so smooth that the telescope has enough remaining propellant, much longer than the initial expected operating life of 5 to 10 years.
“Roughly speaking, this is about 20 years of propellant,” Menzel said.
Update at 1:10 a.m. on January 9: Eric agol, an astronomer at the University of Washington, plans to use JWST to study the potential habitable exoplanetary system trabist-1, which illustrates the deployment of the telescope in e-mail:
“It is a testament to the careful planning that went into engineering JWST that so far everything has gone without a hitch. That doesn’t mean that we astronomers can relax yet — there are still a lot of things that have to go right for the telescope to work as planned! But so many critical hurdles have been passed that I feel much more optimistic that in six months we will have a working telescope.”