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Europe completes second instrument for James Webb Space Telescope

Paul Sutherland, News Editor
08 September 2013, 12:09

Sen— The European Space Agency (ESA) has completed the second of two instruments it is contributing to the next great orbiting observatory, the James Webb Space Telescope.

It is called the Near-Infrared Spectrograph, or NIRSpec, and was assembled for ESA by aerospace giant Astrium GmbH in Germany. Last year, the first European contribution, the Mid InfraRed Instrument (MIRI) was finished and delivered to NASA.

They are two of four state-of-the-art devices that will be fed light gathered by the JWST’s vast 6.5-metre mirror to help make new discoveries about the Universe after it is launched by an Ariane 5 rocket from French Guiana in 2018.

NIRSpec will be sensitive enough to pick out the light from the earliest stars and galaxies to form in the Universe, only about 400 million years after the Big Bang happened 13.8 billion years ago.

It will split infrared light from these objects into a spectrum, helping astronomers to find out their chemical make-up, physical properties, age and distance. NIRSpec will be able to carry out its observations on up to 100 such objects at a time.

Demonstrating its versatility, NIRSpec will also study the early stages of starbirth across our own Milky Way galaxy, and analyse the atmospheric properties of exoplanets orbiting other stars, checking the potential for life to exist there.

Following rigorous testing in Europe, NIRSpec will be transported to NASA later this month where it will be integrated into JWST’s instrument module, ready for further tests and calibration as the whole observatory is assembled.

Eric Smith, NASA’s Acting Program Director for JWST, said: “We are delighted to acknowledge the completion of ESA’s NIRSpec and excited to have it join the other Webb science instruments at NASA’s Goddard Space Flight Center.”

NIRSpec instrument for the JWST

The NIRSpec instrument for the JWST in its assembly room. Credit: Astrium

Europe’s other instrument for the JWST, MIRI, was handed over to NASA’s Goddard Space Flight Center in May last year following ten years of development by more than 200 engineers.

MIRI is so sensitive that it could pick out a candle at the distance of Jupiter’s moons. It is one of four main experiments that will fly on the JWST later this decade.

More than 200 engineers spent over ten years working on MIRI. It was declared ready at a ceremony in London by the consortium that has built it.

Made up of a camera and a spectrometer, it will observe at infrared wavelengths at the extremely low temperature of -266°C – just 7°C above absolute zero.

Alvaro Giménez, ESA’s Director of Science and Robotic Exploration, marked the latest landmark event for the new telescope by saying: “The formal handover of NIRSpec from Astrium to ESA marks an important and exciting milestone in Europe’s contribution to the JWST mission.

“Along with the delivery of MIRI to NASA last year, we are thrilled that European engineers and scientists are playing a key role in this important international mission.”

The JWST, a joint project of NASA, ESA, and the Canadian Space Agency, is a telescope that will focus on the infrared region of the spectrum with its instrumentation. These “heat-seeking” devices will be able to detect distant galaxies but also see through the dust that blocks visible light from newborn stars.

An animation of the Near-Infrared Spectrograph rotating. Credit: NASA

Apart from NIRSpec and MIRI, the other two instruments will be a near-infrared camera (NIRCam) and a combined fine guidance sensor and near-infrared imager and slitless spectrograph (FGS-NIRISS).

A giant sunshield will keep the observatory and its instruments chilled to -233 degrees C to allow them to operate for up to ten years.

The JWST has become a controversial instrument because costs have greatly overrun the initial budget. Many scientists complain that money for other NASA missions has had to be cut back to support it.

But it is set to be a mighty successor to Hubble when it reaches its remote place in space 1.5 million km (miles) beyond Earth’s own orbit around the Sun at a gravitationally stable point known as L2.