This new “selfie” was created using a specialized pupil imaging lens inside of the NIRCam instrument that was designed to take images of the primary mirror segments instead of images of the sky. This configuration is not used during scientific operations and is used strictly for engineering and alignment purposes. In this image, all of Webb’s 18 primary mirror segments are shown collecting light from the same star in unison. Credits: NASA/STScI
Following the completion of critical mirror alignment steps, NASA’s
James Webb Space Telescope team expects that Webb’s optical performance
will be able to meet or exceed the science goals the observatory was
built to achieve.
On March 11, the Webb team completed the stage of alignment known as “fine phasing.” At this key stage in the commissioning of Webb’s Optical Telescope Element, every optical parameter that has been checked and tested is performing at, or above, expectations. The team also found no critical issues and no measurable contamination or blockages to Webb’s optical path. The observatory is able to successfully gather light from distant objects and deliver it to its instruments without issue.
Although there are months to go before Webb ultimately delivers its
new view of the cosmos, achieving this milestone means the team is
confident that Webb’s first-of-its-kind optical system is working as
well as possible.
“More than 20 years ago, the Webb team set out to build the most
powerful telescope that anyone has ever put in space and came up with an
audacious optical design to meet demanding science goals,” said Thomas
Zurbuchen, associate administrator for NASA’s Science Mission
Directorate in Washington. “Today we can say that design is going to
deliver.”
While some of the largest ground-based telescopes on Earth use
segmented primary mirrors, Webb is the first telescope in space to use
such a design. The 21-foot, 4-inch (6.5-meter) primary mirror – much too
big to fit inside a rocket fairing – is made up of 18 hexagonal,
beryllium mirror segments. It had to be folded up for launch and then
unfolded in space before each mirror was adjusted – to within nanometers
– to form a single mirror surface.
“In addition to enabling the incredible science that Webb will
achieve, the teams that designed, built, tested, launched, and now
operate this observatory have pioneered a new way to build space
telescopes,” said Lee Feinberg, Webb optical telescope element manager
at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.
With the fine phasing stage of the telescope’s alignment complete, the team has now fully aligned Webb’s primary imager, the Near-Infrared Camera, to the observatory’s mirrors.
“We have fully aligned and focused the telescope on a star, and the performance is beating specifications. We are excited about what this means for science,” said Ritva Keski-Kuha, deputy optical telescope element manager for Webb at NASA Goddard. “We now know we have built the right telescope.”
Over the next six weeks, the team will proceed through the remaining alignment steps before final science instrument preparations. The team will further align the telescope to include the Near-Infrared Spectrograph, Mid-Infrared Instrument, and Near InfraRed Imager and Slitless Spectrograph. In this phase of the process, an algorithm will evaluate the performance of each instrument and then calculate the final corrections needed to achieve a well-aligned telescope across all science instruments. Following this, Webb’s final alignment step will begin, and the team will adjust any small, residual positioning errors in the mirror segments.
The team is on track to conclude all aspects of Optical Telescope Element alignment by early May, if not sooner, before moving on to approximately two months of science instrument preparations. Webb’s first full-resolution imagery and science data will be released in the summer.
Webb is the world's premier space science observatory and once fully operational, will help solve mysteries in our solar system, look beyond to distant worlds around other stars, and probe the mysterious structures and origins of our universe and our place in it. Webb is an international program led by NASA with its partners at ESA (European Space Agency) and the Canadian Space Agency.
Natasha Pinol / Alise Fisher
Headquarters, Washington
202-358-0930 / 202-617-4977
Natasha.r.pinol@nasa.gov / alise.m.fisher@nasa.gov
Laura Betz
Goddard Space Flight Center, Greenbelt, Md.
240-357-6833
Laura.e.betz@nasa.gov