Hubble’s successor WEBB’s road to history of cosmos

The history of the James Webb Space Telescope (JWST) began in the 1980s when engineers and astronomers discussed scientific and technical issues that should be addressed in the future at the Next Generation Space Telescope Workshop. The main output was a proposal for the technical capabilities of the observatory, which should follow the Hubble Space Telescope. Discussions at this conference led in 1996 to a formal recommendation that the telescope operates at infrared wavelengths and be equipped with a mirror larger than four meters.

After eight years, a decision was made on the design of the device to start its construction in 2004, with the understanding that it should be launched into space in 2007. The European rocket Ariane 5 will get it into space was agreed in 2005. In addition to the European Space Agency (ESA) and the US National Aeronautics and Space Administration (NASA) are also involved in the Canadian Space Agency (CSA). The cost was then estimated at three billion US dollars. Gradually, however, there were various delays and thus an increase in costs, and so the deadline was constantly postponed.

The Great Depression came in 2010 because the project drained NASA of a relatively large amount of money and threatened to stop it altogether. At the time, according to an internal study, the launch and operation of the James Webb telescope was to cost about six and a half-billion dollars. That’s more than double the cost.

However, the crisis was overcome and by 2011 all eighteen mirror segments had been manufactured and later tested. Between 2012 and 2013, individual parts of Webb’s mirror, constructed in various locations, were gradually transported to NASA’s Goddard Space Flight Center in Greenbelt. It was already clear that the start in 2014 and the one planned for 2015 will not be met.

In 2013, the construction of individual layers of the sunshield was started. This was followed by a phase of testing JWST devices, including resistance to high temperatures or vibrations. It was already the year 2016 and the work on the optics of the telescope was also over.

In 2017, the assembly of the telescope and a package of scientific instruments was completed, which were integrated into one unit and subjected to vibration testing of mechanical integrity. Then everything went to NASA’s Johnson Space Center in Houston, Texas, where a comprehensive test of optical properties took place in a giant vacuum chamber and at a very low temperature.

Everything was on the right track, even though the start date was constantly postponed. In 2018, the assembly of the telescope and instruments was transferred to Northrop Grumman, where the base and sun visor was built and tested. The following year, the two halves were merged.
The final tests continued until the composition of the JWST and its final connection to the Ariane 5 rocket in 2021.

The first shots of the summer

In space, JWST will travel one and a half million kilometers from Earth, almost five times as far as the Moon. It will be located at the second Lagrange point, the place where the gravitational influences of the Earth and the Sun balance. As a result, the telescope will be able to maintain a stable orbit and at the same time stay in the shadow of our planet from the sun’s rays.
But before that, it will have to decompose to its full size, which is a relatively challenging task that may encounter some problems. That’s why JWST is equipped with a system that allows it to vibrate, similar to shaking an object to free some jammed space.

The JWST will be located so far that it will not be possible to bring robotic or human repairmen to it, as was possible with the Hubble Telescope.

Once the observatory arrives at its designated location, its systems will await a series of scientific and calibration tests, including the development of a screen shield the size of a tennis court, telescope setup, and instrument activation. According to experts, the best images could start appearing about half a year after launching into space.

Webb’s telescope will be the most powerful space telescope yet. It should oversee the beginnings of the existence of our universe when the first stars and galaxies formed thirteen and a half billion years ago. According to NASA, it will directly observe a hitherto unseen part of space and time. The device is designed to “see” the infrared radiation that is now heading towards us due to the shift in this form from the most distant objects. This shift is due to the expansion of the universe, in which very distant objects have a large redshift (their light is shifted towards the redder part of the spectrum), and therefore infrared telescopes are needed to study them.

“While Hubble was able to look into the toddler’s years of space, JWST can show his infant years,” NASA scientists say. It will be about four hundred million years before Hubble formed the first stars to form galaxies.

But “Webb” will also be used by scientists to study planets and other bodies in the solar system, to study their origin and evolution, and to compare them with exoplanets, or planets orbiting other stars. At the same time, the telescope will monitor exoplanets, which are located in the so-called habitable zones, and there could be liquid water on their surface.

To carry out these tasks, the observatory has a giant mirror six and a half meters in diameter, four scientific instruments and a shield twenty-one by fourteen meters large, which will protect the apparatus from the heat of sunlight and keep them in the necessary deep cold. The devices in the equipment are the NIRCam infrared camera, the NIRSpec infrared spectrograph, the

MIRI infrared device and the infrared display with the NIRISS spectrograph. The large primary mirror consists of eighteen smaller hexagonal mirrors, every 1.3 meters in diameter and weighing twenty kilograms. Each is made of beryllium and coated with a gold layer. Beryllium scientists chose this metal because of its lightness and strength. In addition, it maintains its shape even in the low-temperature conditions that the telescope instruments need for proper operation. Gold was chosen for the top layer due to its extremely high light reflectance, over a wide range of wavelengths.

The JWST mission is now scheduled for five years but may be extended. It also depends on how long the telescope lasts for the fuel to move and stay in place.

Webb mission launched

This year, the launch was scheduled to take place in March, but due to the covid-19 pandemic, it was postponed to November and then to December 18. However, the incident in preparation of the telescope for connection to the launch vehicle required an inspection to ensure that the equipment was not damaged, and thus a postponement to 22 December. Two more delays, on December 24 and then on December 25, were caused by communication problems between the telescope and the Ariane rocket launch system and unfavorable weather forecasts.