New Near-Infrared Detectors Accelerate Euclid Mission

The redesign of Euclid’s NISP pays off. (Source: Euclid Cons. / CPPM / LAM)

Euclid is a pioneering ESA mission to observe and map the 3D distribution of billions of faint galaxies spread across the sky. This will enable scientists to determine in unprecedented detail the properties of the mysterious dark energy and dark matter, which together are thought to make up 95 percent of the universe. The data are expected to revolutionize cosmology by improving our understanding of the evolution of the very fabric of the universe over the past ten billion years.

In order to investigate the invisible dark Universe, Euclid will carry two scientific instruments. Light gathered by Euclid’s 1,2-meter diameter primary mirror will be split and sent to these instruments. The visible imager (VIS) is being built by a consortium of nationally funded institutes led by Mullard Space Science Laboratory (MSSL) in the UK.

The other instrument, NISP, is provided by a consortium of nationally funded institutes led by the Laboratoire d’Astrophysique de Marseille (LAM) in France, with contributions from fifteen countries, including the United States through an agreement between ESA and NASA. Part of the US contribution is the provision of the NISP infrared detectors, an array of sixteen imaging sensors (of the H2RG type) that are paired with sixteen sets of readout electronics.

Originally, both the sensors and the readout electronics were procured from Teledyne Scientific in California, USA. The contract with Teledyne to design the sensors and readout electronics was managed by ESA and was later taken over by NASA prior to initiation of the build phase. The flight hardware, including mercury cadmium telluride sensors, readout sensor chip electronics (SCE), and connecting low resistance cable, were delivered to ESA in April 2017. However, most of the flight readout electronics began to fail after delivery.

The observed failures were the effect of a partial detachment of an application-specific integrated circuit (ASIC) from the board it was mounted on, caused by the very cold temperatures required for the Euclid mission detectors.

The complexity of the issue convinced NASA that the best way forward was to redesign and manufacture a new set of reliable readout electronics in rapid time, rather than attempt to improve the old design. In December 2017, NASA selected a new SCE design that was based on tried and tested materials and processes derived from previous missions.

The new SCE units, sometimes called option B, were still based on the original Teledyne ASIC, but their mounting, circuits and packaging were entirely designed, manufactured, and tested by NASA at its Jet Propulsion Laboratory in Pasadena, California, and Goddard Space Flight Center in Maryland.

The Euclid NISP features new readout electronics. (Source: Euclid Cons. / CPPM / LAM)

After little more than one year later, on 7 February 2019, a NASA / ESA board approved the shipment to Europe of the first four of the newly designed flight-model SCE units, which fully met all specifications.

Three months later, on 10 May, NASA delivered the last batch of flight SCEs to the premises of the LAM in France. This delivery brought the overall total to sixteen flight models plus two spares, paving the way for completion of the full focal plane array of the NISP instrument. Two additional spare units will be shipped to LAM shortly.

”The effort produced by the US partners to redesign the NISP readout electronics and demonstrate that the new design fully meets specifications in all its mechanical, thermal, electrical, and performance aspects, was truly remarkable,” said Paolo Strada, NISP senior instrument engineer at ESA.

”The decision to move to option B was a very challenging one, since the new design for the SCE units and associated development was critical for the completion of NISP and it was consequently driving the mission launch date,” added Giuseppe Racca, ESA’s Euclid project manager. ”NASA managed to dispel all our fears and delivered the new devices in advance of the NISP deadline date. The cooperation between Europe and the NASA centers that were involved was always excellent during this challenging time.” (Source: ESA)

Link: Euclid Mission, European Space Agency, Paris, France

 

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