Spacecraft controllers have started turning on NASA's James Webb Space Telescope's four cutting-edge sensors in preparation for the observatory's first observations of a target star.

HD 84406 is a star in the constellation Ursa Major, the Great Bear, that is 241 light-years away from Earth. The photographs will not be used for science, but rather aid ground personnel with aligning the 18 golden segments of Webb's main mirror, which is 21 feet wide (6.5 meters).

Webb's Near Infrared Camera (NIRCam) will capture the photos, which must first cool to its operating temperature of minus 244 degrees Fahrenheit (minus 153 degrees Celsius).

"At the beginning, we will have 18 individual blurry images," Mark McCaughrean, a scientist at the JWST Science Working Group and senior advisor at the European Space Agency (ESA), who is familiar with the process, told Space.com. "At the end, we will have one nice sharp image."

While Webb's optics experts reposition the mirror segments in nanometer-scale stages to create a flawlessly smooth surface, NIRCam will continue to stare at HD 84406. Work on this project is planned to extend until the end of April. Individual science equipment will only begin completely training their eyes on objects in the near and distant universe after that. The first proper photographs are scheduled to be released in late June or early July to the general audience.

None of the other three equipment, according to McCaughrean, could take NIRCam's place in assisting to position the mirror. The success of the telescope is dependent on NIRCam, therefore it cannot fail.

"If NIRCam failed, we wouldn't be able to align the mirror," said McCaughrean. "That's why it's essentially two cameras in one. There is full redundancy. If one fails, we still have the other."

The Mid-Infrared Instrument (MIRI) is the only remaining instrument that has been partially turned on throughout the telescope's month-long journey to its destination. The heaters that kept the other two warm throughout the cruise phase have now been turned off on the Near Infrared Spectrograph (NIRSPec) and the Fine Guidance Sensor/Near Infrared Imager and Slitless Spectrograph (FGS/NIRiss).

These heaters allowed the instruments to gently release trapped air, preventing water condensation and ice formation.

The devices will require weeks to attain their operating temperatures. This temperature is barely 10 degrees Fahrenheit (5.5 degrees Celsius) above absolute zero (minus 460 degrees F or minus 273 degrees C), the coldest temperature at which atoms (which are the universe's source of heat) stop moving. The spectrographs can work at temperatures as low as minus 393 degrees Fahrenheit (minus 236 degrees C).

Webb's ability to do scientific activities is dependent on these extremely low temperatures. The telescope was built to observe the universe's oldest stars and galaxies, which originated hundreds of millions of years after the Big Bang. The light emitted by these galaxies, however, is only observable at infrared wavelengths due to the expansion of the universe (a result of the so-called redshift). Because infrared light is essentially heat, if the telescope itself radiated any warmth, the faint signal would be undetectable.

While the cameras, such as NIRCam and MIRI, will generate spectacular views of stars and galaxies, McCaughrean explained that the spectrographs would reveal comprehensive information about the chemical composition of those far away objects.

On January 24, the James Webb Space Telescope arrived at its final destination, the Lagrangian Point 2 (L2). L2 is a sun-Earth axis point approximately 930,000 miles (1.5 million kilometers) distant from the sun. L2 is a popular place for astronomy missions because to the gravitational interaction of the two bodies, which creates stable circumstances. A spacecraft in this location orbits the sun in lockstep with Earth (in practice, the James Webb Space Telescope orbits the sun in circles as it follows Earth around the sun).

After a decade of delays, the James Webb Space Telescope was launched on Dec. 25. The $10 billion expedition, conceived by astronomers in the early 1990s, stretched the technological envelope. Webb is expected to transform several fields of astronomy once its mirrors are aligned and equipment calibrated. Webb will contribute to the study of exoplanets, star formation, dark matter, and even the solar system and its asteroids, in addition to the first stars and galaxies.