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GaAs PV assist Mercury spacecraft
THE MESSENGER probe which incorporates gallium arsenide multi- junction solar cells is able to operate in extreme temperatures and will orbit 730 times around Mercury for a year.
Key technologies and hardware developed by Northrop Grumman Corporation gave the first spacecraft to orbit Mercury a power system that works to its maximum even in the searing heat that surrounds the planet closest to the sun.
The company also perfected a fully robotic welding process to assemble the photovoltaic cells before they were bonded to the solar array panel. The work was done under the pressure of meeting a launch window that was so tight that missing it would have meant a year-long wait until the next launch opportunity.
“When it launched in 2004, MESSENGER was the first Northrop Grumman program to use these advanced solar cells, electrical designs
and welding processes that now are the baseline for all our major programs, including the James Webb Space Telescope and the Defence Weather Satellite System,” said Tim Frei, vice president, system enhancements and product applications for Northrop Grumman Aerospace Systems. “Our depth of talent and the processes we developed enabled us to perfect the technology needed for spacecraft to perform under very harsh conditions.”
Solar array performance is critical – if it fails, so does the mission. Two single- sided solar panels are MESSENGER’s main source of electrical power. They are two-thirds mirrors and one-third solar cells. The mirrors reflect the sun’s energy and keep the panels cooler. The panels also rotate away from the sun to get the required power and maintain an operating temperature of about 300 F.
Since its launch, MESSENGER has completed one swing past Earth, two Venus flybys and three Mercury flybys. By using the gravity of each planet to
gain speed and alter its trajectory, MESSENGER was able to conserve the fuel it will need during its mission orbiting a planet that is only 29 million miles from the sun, about two thirds closer to the sun than Earth.
At Mercury’s equator, temperatures become hot enough to melt lead. The spacecraft’s fast, elliptical orbit allows it to approach Mercury, gather data and swing out far into space to cool down.
MESSENGER is a NASA Discovery program spacecraft designed and built by the Johns Hopkins University Applied Physics Laboratory, Laurel, Md. The probe completed a six-and-a-half-year journey prior to its March 17 insertion into orbit around the planet closest to our sun. MESSENGER will orbit 730 times around Mercury for a year.
Changelight receives 2 000th Aixtron MOCVD system
AIXTRON SE has installed its 2 000th MOCVD system at LED and solar cell company Changelight in China.
Bastian Marheineke, Vice President Sales at Aixtron, took the opportunity to congratulate DianMing Deng, President Changelight, personally. “We are extremely pleased to be able to share this historic occasion with such an important customer. Changelight was the first customer to use the AIX 2800G4 in China. Their AlGaInP LED epitaxial wafers and chips are amongst the best at the domestic level in terms of scale, output and sales. In 2010, multiple Aixtron G3 and G4 systems were installed at the Xiamen facility with others at the Yangzhou site.”
“The vast majority of systems we sold in 2010, almost 95%, are used for the manufacture of LEDs. In the first quarter of 2011, around 90% of Aixtrons
Aixtron team since our foundation in February 2006. Today, our facilities are based exclusively on Aixtron MOCVD equipment which has been pivotal in our becoming the biggest supplier of high-quality AlGaInP Red Orange Yellow (ROY) HB LED chips in China.”
revenues were generated by sales into Asia; almost 90% of systems sold are for the manufacture of LEDs. China will undoubtedly be our biggest market in 2011,” concludes Marheineke.
DianMing Deng, President Changelight, adds, “We feel deeply honoured that Aixtron supplied its 2 000th system to Changelight. Development from our initial private enterprise to the present listed company is inseparable from the great support we have enjoyed from the
“The new systems form part of our expansion plans in Yangzhou. I see our strategic cooperation partnership with Aixtron will become deeper and broader. We send our best wishes for the company´s further success. Hopefully with the delivery of the 3000th and 4000th MOCVD system in China, too.”
The 2,000th system is part of a multiple tool order for 60x2-inch AIX 2800G4-R systems for advanced optoelectronics devices and will be installed and commissioned by the local Aixtron service team at the Changelight production facilities.
July 2011
www.compoundsemiconductor.net 7
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