When a camera takes a selfie, and reveals a star
In 2022, NASA's Near Infrared Camera took its own selfie for "engineering and alignment purposes.” Will the wonders of this space explorer never cease?
On March 16, 2022, NASA uploaded a selfie taken by the Near Infrared Camera (NIRCam) on the James Webb Telescope on its Flickr handle. This selfie was achieved using a specialised pupil imaging lens inside the camera that was designed to take images of the primary mirror segments instead of images of the sky. In the image, all of Webb’s 18 primary mirror segments are seen collecting light from the same star in unison. The US space agency clarified that the configuration was not used in scientific operations – it was simply done for "alignment and engineering purposes". In other words, just like why the rest of us take selfies.
“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, following the completion of the critical mirror alignment steps.
The telescope completed its first anniversary of observing the universe on July 12, 2023.
As a gift to followers around the world, it offered a new image that gave a detailed view of the closest star-forming region to Earth, the Rho Ophiuchi cloud complex.
In the image, one sees jets bursting from young stars, travelling across the image and impacting the surrounding interstellar gas, while lighting up molecular hydrogen, shown in red.
The detailed, impressionist image feels right out of a Jean "Moebius" Giraud comic panel, whose remarkable work influenced and informed science fiction design and the imagined landscapes in movies, comics and animation.
The NIRCam, which took the image, is the only near-infrared instrument with coronographic and time-series imaging capabilities, making it one of the most sensitive infrared cameras ever built.
Just like how we use sun visors in cars to block light, NIRCam's coronagraphs (a telescopic attachment) are designed to block direct light from a star, making it possible to view the dimmer object nearby. Measuring wavelengths of light from 0.6 to 5 microns, it was created to detect the earliest star clusters, galaxies and young stars in the Milky Way, and objects in the Kuiper Belt.
Essentially, the NIRCam is an instrument that holds up a mirror (or rather several mirrors) to our very beginnings, capturing the light from the first stars and galaxies in the cosmos.
Space Imagery: From Hubble to Webb
On April 24, 1990, the Hubble telescope was launched into space by the Discovery shuttle above Earth’s atmosphere, which gave it a better view of the universe than those deployed at the ground level.
The first major optical telescope to be placed in space, Hubble's launch marked the most significant advance in astronomy since Galileo's telescope in 1609. The Wide Field Camera 3 (WFC3) is Hubble’s main camera, which studies everything from the formation of distant galaxies to planets in the solar system. The NIRCam on the Webb has a mirror that is 2.75 times larger in diameter than Hubble, letting it gaze farther back in time than Hubble.
It’s not entirely fair to compare the two telescopes because they observe different wavelengths, but the Webb is a sure successor to the Hubble.
The NIRCam has been built, keeping a host of stability and predictability requirements on its primary mirror, simply because it’s not possible to send a crew there to fix glitches. Unlike the Hubble Space Telescope, which orbits Earth, the Webb Telescope orbits the Sun, a million miles away.
Stretching roughly four to five light-years, the “Pillars of Creation” (three towers of gas and dust, standing light-years tall, give birth to new stars, buried within their dusty spires) are a fascinating but relatively small feature of the Eagle Nebula, which is a cluster of young stars and a region of active star formation, about 5,700 light years from Earth.
The Hubble Telescope, in 2014, brought back a beautiful, detailed image, showing the pillars engulfed in blazing ultraviolet light from a cluster of young stars located just outside the frame. The winds from these stars are seen eroding the towers of gas and dust.
In October 2022, the James Webb Telescope revealed its image of the “Pillars of Creation”, showing remarkable details as compared to the Hubble image from 2014.
One can see new stars forming within dense clouds of gas and dust, and the three-dimensional pillars appear like distinguished rock structures.
Other than being Instagram-worthy, this new image will help researchers revamp their models of star formation by identifying far more precise counts of newly formed stars, along with the quantities of gas and dust in the region, NASA has stated.
Next up for the NIRCam is dark matter, which is an invisible form of matter with mass but doesn’t interact with ordinary matter in space. The camera won’t be able to detect dark matter of course, but by observing how dark matter behaves around galaxies, scientists can eventually learn more about its properties and understand its nature.
Looking out has only taken us closer to looking in.
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