European tech for James Webb Space Telescope launch

European tech for James Webb Space Telescope launch

Feature articles |
By Nick Flaherty

After 25 years and nearly $10bn, the James Webb Space Telescope (JWST) launched into space on Christmas Day.

IR HiRel, an Infineon Technologies company, supplied mission-critical radiation-hardened (rad hard) components for the joint venture between the US, European and Canadian space agencies. The company previously provided rad hard power electronics for NASA’s first flagship space observatory, the Hubble Space Telescope, launched in 1990.

Rather than orbiting the Earth, the 8m high, 6,200kg telescope will orbit the L2 Lagrange point between the Earth and the Sun to observe the universe.

“With JWST expected to operate 1.5 million kilometres from Earth, it will face deep space conditions far more extreme than Hubble,” said Chris Opoczynski, Senior Vice President and General Manager of IR HiRel. “The spacecraft bus provides vital support functions for the telescope’s operation, not the least of which is power distribution, command, control and data handling, etc. Using IR HiRel’s rad hard power conversion solutions provides assurance of long-lived, highly reliable performance for this historic mission.”

The JWST project started in 1996 to replace the Hubble telescope and of the $9.7bn project cost, $8.8bn was spent on spacecraft development between 2003 and 2021. The remaining $861m is planned to support five years of operations.

Once operational, the infrared telescope will extend Hubble’s discoveries to help scientists understand all phases of cosmic history and search for signs of possible habitability among thousands of recently discovered exoplanets. The Near InfraRed Spectrograph (NIRSpec) multi-object spectrograph is capable of simultaneously measuring the near infrared spectrum of at least 100 objects with various spectral resolutions down to 0.3 nanometres. The observations are performed over the wavelength range from 0.6 to 5.0 micrometres.

Next: Airbus assembly

The instrument was designed, developed, and integrated on the telescope by a team of more than 70 people at Airbus sites in Ottobrunn and Friedrichshafen, Germany, as well as Toulouse, France, with support from NASA and 17 European subcontractors.

The 6.4m diameter mirror of the telescope operates at 40 Kelvin and uses a highly a-thermal concept (which prevents heat or changes in temperature), with the mirrors, mirror mounts, and optical bench base plate all manufactured out of Silicon Carbide Ceramic SiC 100.

“I am very happy and excited to be still a part of the complete Webb team and to contribute to the greatest science story nowadays from the beginning to the end of commissioning. I am also very proud of the complete Airbus team working together as ONE team to make NIRSpec a success. Working with the complete Webb team all over the world (mainly with NASA) was and is the best experience I ever had,” said Ralf Ehrenwinkler, Head of the NIRSpec Programme at Airbus.

Airbus will support NIRSpec from liftoff to through the space telescope’s end-of-the commissioning phase. This includes monitoring its parameters 24/7 during the critical cool-down phase in space and initial functional testing when the NIRSpec instrument is turned on after the month long journey to the L2 operating point.

JWST carries three other instruments, with the MIRI Mid-Infrared Instrument also developed by Airbus as well as the NIRCam (Near-Infrared Camera), and FGS/NIRISS (Fine Guidance Sensors/Near-InfraRed Imager and Slitless Spectrograph), which are housed in the Integrated Science Instrument Module (ISIM). 

The MIRI has three Arsenic-doped Silicon (Si:As) detector arrays. The camera module provides wide-field broadband imagery, and the spectrograph module provides medium-resolution spectroscopy over a smaller field of view compared to the imager.

The sensor MIRI has to be actively cooled to 7 Kelvin (-266 °C) and the mirrors were a design, development and supply contract for the UK Astronomy Technology Centre (UK ATC) at Cranfield University. Researchers at Cranfield made over 400 mirror surfaces for the instrument in an ultra precision machine that they designed and built.

NIRCam, assembled by Lockheed Martin, uses two identical optical imaging modules and contains focal plane assemblies (FPA) provided by Teledyne Imaging Sensors. The FPA hardware consists of 40 million pixels, and is designed for cryogenic operation at 40 degrees Kelvin. The FPA hardware requires regulated power, output data synchronization, temperature control and operational mode controls as well as image data conditioning, amplification and digitization. The NIRCam focal plane electronics (FPE) and its associated software will provide these functions. The FPE hardware and software also convey the image data to the JWST integrated science instrument module command and data handling computer.

While JWST will only use 1 kilowatt of power, the solar array is capable of generating nearly double that amount to factor in the gradual wear and tear of a harsh space environment. Several spacecraft bus subsystems, such as electrical power, altitude control, communications, and command and data handling, integrate IR HiRel space-grade DC-DC converters, rad hard MOSFETs and other power control products that ensure reliable operation in the harsh deep space environment.

The launch is scheduled for 13.20CET on Christmas Day, 25th December 2021 on an Ariane 5 launcher;;

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