The journey to make the James Webb Space Telescope a reality has been long and difficult. Finally, after years of planning, delay, cost overruns and work, the next generation space telescopes are ready for launch. Even though the telescope is currently traveling secretly by cargo ship to the ESA launch site in French Guiana for its next generation of space telescopes, all involved in the JWST project know that a successful launch will not be the last victory.
Post launch is where the real action begins. While the Mars rover teams undergo Seven Minutes of Terror to land their spacecraft on the Red Planet, the JWST teams will have more than 30 days of excruciating, slow-motion terror as the telescope embarks on its month-long-day, 1.5-million-kilometer (million-mile) journey out to the second Lagrange point (L2).
JWST will continue to unfold to its intended configuration with over 40 major deployments. It will require hundreds of actuators to fire, hold mechanisms to release and cables to unwind, joints to work, and electrical systems to activate.
The mission will be a 30-day-long make-or-break operation. All this takes place in space with the telescope alone. There could be 30 days of terror and 30 nights of sleepless nights for all involved.
Artist conception of James Webb Space Telescope. NASA Credit
It all begins with the launch, which is a terror by itself.
Heidi Hammel, an interdisciplinarian scientist and vice president of Association of Universities for Research in Astronomy, stated that we were putting this precious resource on top of controlled explosions. Although it's scary, rocket science is what is. A successful launch will bring relief.
The deployment terror/excitement will begin about 30 minutes after the flight if all goes according to plan. JWST will travel approximately 10,400 km on its journey thanks to the thrust provided by the Ariane 5 rocket. It will be powered by Ariane 5. Webb will seperate the Ariane 5's second stage from JWST after the second stage cutoff.
Massimo Stiavelli (head of Webbs mission office, Space Telescope Science Institute) said that this will cause the solar arrays in orbit to begin to deploy within 30 minutes. This is vital because we require power. This is just one of many important deployments that will lead to L2.
Stiavelli is awake at night because of the next event. The Ariane will direct JWST to L2, but without orbiting Earth first, but a critical thruster firing will ensure that the telescope is heading in the right direction.
He said that we need to switch on the observatory's rocket engine in order to get us to the L2 orbit. Mid Course Correction 1 (MCC1) may take place around 12. 5 hours after launch. This is the most important mission burn.
Hammel stated that JWST must be launched into orbit at L2 because that is how the mission was designed. The mission will be abandoned if the thrusters don't fire.
Another important moment is the deployment and release of the high-gain antenna. This will allow communication to the telescope and the transmission of all the science data back to Earth.
Webb's second trajectory correction maneuver will take place within Webb's first week in space. Next, there are several major deployments that require nearly 200 actuators to function, just in time to allow JWSTs sunshield process to unfold. This includes the deploying and releasing of radiators and booms.
Engineers and technicians deployed all five layers on the sun-shield of the James Webb Space Telescopes during a test. Image credit: NASA/Chris Gunn
This is where the real nail-biting begins. Over 150 release mechanisms are required to properly fire the sunshield, which is about the size of a tennis court. It takes three days.
Helmut Jenkner is a STScI long-standing scientist who said that the number of unexploded actuators can cause a bit of headache because they all have to work. You can get a pretty hair-raising number, even though you have a reliability of over 99.9%.
There are approximately 7,000 parts to the sunshield installation, including 400 pulleys and many cables, as well as eight motors. The sunshields deployment is essential to shield the telescope from heat and light from the Sun, Earth, Moon, and to keep the telescopes' infrared components as cool as possible. JWST will be able to detect faint signatures from distant objects in the universe by this method. While the telescope and other scientific instruments will cool quickly in the sunshield's shade, it will take several weeks before they cool down enough to be stable.
The telescope will start to shape in the second week following launch. First, it will be ready for secondary mirror deployment. The JWSTs6.5 primary mirror will then unfold. The 18 gold-plated segments of beryllium will begin to unfurl starting with the sides wings. The 132 small actuators push or pull each segment of the mirror into a micron-precise alignment. This will bring the primary mirror into focus. Everything must work flawlessly.
The first month of deployment is the most difficult. However, it will take six to six months for all instruments to be calibrated, turned on and commissioned. Scientists will then see the first light through the telescope.
Hammel acknowledged that there are many ways things could go wrong. We have been testing this telescope and every system in every possible way over the past 20+ years and more recently the past 5+ years. This includes shaking it, thermal cycling and putting it under zero pressure. It has been thoroughly tested to discover all possible problems and ensure a successful mission.
You can learn more about JWST on the NASA website or at STScI.
