NASA scientists have given a taste of the power of the James Webb Telescope, the largest and most expensive ever built. The image released by the US space agency shows a preview of the first deep space images captured by the equipment. It was just an appetizer – official images won’t be released until July 12.

On Twitter, the agency claims that “taking glamorous photos is not even the main job” of the telescope – despite spectacular results – and that the image “is among the deepest ever observed in the Universe”.

The main purpose of the equipment is to enable precise scientific measurements. When the sensor captures images, they are not normally stored given the communication bandwidth between the telescope and the Earth.

Just a “straw”

Almost as exciting as the image is to imagine it’s just a small sample of the Fine Guidance Sensor (FGS), the telescope’s orientation sensor. At this point, the space observer is simply trying to ensure that the cameras and mirrors that make up the equipment are properly aligned.

“The resulting engineering test image has some rough qualities. It was not optimized for scientific observation; rather, the data was taken to test the telescope’s ability to lock onto a target, but this suggests the power of the telescope,” the agency says on its official website.

The scientists say that it would be impossible, for example, to study the age of the galaxies contained in this image because, during the test, the FGS did not use color filters, as is usual in other scientific instruments.

However, this does not exclude that the recordings can be useful later.

“When this image was taken, I was thrilled to clearly see all the detailed structure of these faint galaxies. Given what we now know is possible with high-bandwidth guided imaging, perhaps these images, taken in parallel with other observations if possible, could be scientifically useful in the future,” said Neil Rowlands, Webb Fine Guidance Sensor Program Scientist at Honeywell Aerospace.

How were the images made?

According to NASA, the published calibration test image required 32 hours of exposure time (with the lens open, “entering” the light) at several overlapping points in the Guider 2 channel.

The observations did not focus on detecting faint objects, yet the telescope was able to make this type of capture. The wavelength response, from 0.6 to 5 micrometers, made possible the deepest image of the infrared sky.

The resulting “photo” is monochromatic and displayed in color with white, yellow, orange and red, representing the progression from lighter to darker shots.

According to NASA, the star 2MASS 16235798+2826079, appearing on the right edge of the photo, is the brightest on record.

“There are only a handful of stars in this image, distinguished by their diffraction peaks. The rest of the objects are thousands of faint galaxies, some in the nearby Universe, but many, many more in the distant Universe,” the agency said.

With costs in the range of US$10 billion (53.12 billion reais, at current prices), the James Web was born out of a partnership between NASA, the European Space Agency (ESA) and the Canadian Space Agency (CSA).

The main objective of the equipment is to reveal the origins of the Universe and to be able to “go back in time” up to 100 million years after the Big Bang.