The observatory, a joint project of NASA, ESA and the CSA, which has cost more than 10 billion dollars, is designed to look deep into the early universe.
The James Webb Space Telescope, located 1.5 million kilometers from Earth, at the second Lagrange point, L2, has already completed a critical stage: the telescope’s 6.5-meter-wide primary mirror is now fully aligned. . And it has released its first fully focused image to celebrate this milestone.
The protagonist of this image is precisely a star: 2MASS J17554042+6551277 , a fairly ordinary star that serves an extraordinary purpose. This bright object, about 2,000 light-years distant from us, is just over 16 times brighter than the Sun. A red filter was used to optimize visual contrast; and, although the telescope is only focusing on the star, its instruments are so sensitive that they have also been able to see background stars and galaxies.
“It’s kind of a generic average star in our galaxy,” Marshall Perrin, an astronomer at the Space Telescope Science Institute, said at the news conference. “This star is one of many stars that we use during the Webb start-up process…usually they are not chosen because they are special stars, but because they are the right brightness in the right parts of the sky for our tests. of engineering”.
After performing a series of critical steps to align the main mirror, the telescope is almost ready to obtain much more precise images of stars, planets and galaxies once the telescope begins science operations in the coming months.
NASA says the image is so good that Webb’s optical performance “will be able to meet or exceed the scientific goals for which the observatory was built.”
“More than 20 years ago, Webb’s team set out to build the most powerful telescope anyone has ever put in space and came up with a bold optical design to meet demanding science goals,” said Thomas Zurbuchen, NASA associate administrator.
The next step?
The telescope’s mirrors are still misaligned by hundreds of microns or so from their desired locations. So over the next six weeks, the team will proceed with the remaining alignment steps before final preparations for the science instrument. They will further align the telescope to include the near-infrared spectrograph, mid-infrared instrument, near-infrared imager, etc.
As the telescope progresses through the next phases of its deployment, the star images it returns will become sharper, more focused, and brighter.
During these times, an algorithm will evaluate the performance of each instrument and calculate the final corrections needed to achieve a well-aligned telescope across all science instruments. Will it be the last? Almost. This is when Webb’s final alignment step will begin and the engineers will adjust for any small residual positioning errors in the mirror segments.
The plan is for all aspects of the optical telescope alignment to be ready by early May, or even earlier ; then it will begin about two months of preparation of scientific instruments before we begin to see the cosmic wonders that Webb will reveal to us.
Reference: NASA JAMES WEBB
