[아하! 우주] Incomparable quality… James Webb vs Spitzer Space Telescope

<!—-> ▲ Part of the Large Magellanic Cloud, taken by the Spitzer Space Telescope (left) and the James Webb Space Telescope. Photo = NASA/JPL-Caltech, NASA/ESA/CSA/STScI

As the James Webb Space Telescope (JWST, herefollowing referred to as Webb Telescope) has finally completed the mirror alignment work, expectations for the ‘work’ to be released by Webb Telescope are growing even higher. On the 9th (local time), the NASA James Webb operation team announced that the Webb telescope will be ready for full operation from July.

The preparations for the Web telescope, unveiled at the press conference on this day, are progressing steadily as planned. “The Webb telescope is currently undergoing test imaging, and the images obtained here give us hope,” said Michael McElwayne, a scientist at NASA’s Goddard Space Flight Center Webb Telescope Project. It can be observed,” he said.

Among the images released by NASA that day, the most interesting one was the performance comparison between the Webb telescope and the Spitzer Space Telescope, which was launched in 2003 and observed the universe in infrared until it was retired in 2020. The subject of comparative photography was the Large Magellanic Cloud, which is the closest neighbor to the Milky Way. Part of the Large Magellanic Cloud, photographed by the Spitzer Space Telescope, appears somewhat hazy, although celestial shapes are revealed. In contrast, the Webb telescope’s images of the same area were so clear that the difference in resolution was evident.

▲ Star 2MASS J17554042+6551277 captured by the James Webb Space Telescope in March. The focus was on this star, but the optics were too sensitive to capture the galaxy and other stars in the background. Photo = NASA/STScI

For this reason, some criticized that the Spitzer Space Telescope is a CRT-class, while the Webb Telescope is UHD.

The Webb telescope, which contains the dream of mankind to see the universe right following the Big Bang 13.5 billion years ago, was launched on December 25, last year, aboard the Ariane 5 rocket from French Guiana. After that, the Webb telescope flew 1.6 million km, regarding four times the Earth-Moon distance, and arrived safely at L2, where the gravity of the sun and the earth are balanced. Since then, the Webb telescope has successfully completed all of the complex seven-step alignment process to determine the success of the mission, and is currently taking test shots and finally checking its operation.

▲ An image of the James Webb Space Telescope in action

The Webb Telescope is a space telescope that is completely different from the existing Hubble Space Telescope. The main mirror, made by connecting 18 hexagonal mirrors in the form of a honeycomb, has a diameter of 6.5m, which is more than twice the size of Hubble, which is 2.4m, and has more than 7 times the light collecting power.

The 18 hexagonal mirrors are made of beryllium with a thin gold coating. In addition, the Webb Telescope is a telescope specialized in infrared observation, and when observed with long-wavelength infrared rays, even objects hidden behind dust in space can be clearly seen. Taking these characteristics together, the observation capability of James Webb is estimated to be 100 times greater than that of the Hubble Telescope.

By Park Jong-ik, staff reporter [email protected]