Image sensors find use in space applications

Essex-based e2v is a leading supplier of high-sensitivity image sensors to the global space sector. Launched into orbit with satellite missions, e2v's sensors transmit back to Earth detailed images of new scientific discoveries. These include the detection of new extra-solar planets, findings from investigations into black holes and detailed astronomical information on significant environmental climate changes. Custom sensor designs and packaging from e2v are recognised for their technical excellence by the world's major space agencies, including NASA, ESA, JAXA and CSA. In April, e2v's high-performance imaging sensors were launched into space on board the European Space Agency's (ESA) Albert Einstein spacecraft, the fourth Automated Transfer Vehicle (ATV) to be sent to the International Space Station (ISS). The e2v CCD47-20 imaging sensors were selected by instrumentation company Sodern as part of the two key systems it delivered for the ATV: These were an SED16 star tracker, an optical device used for determining the orientation of the spacecraft by measuring its position relative to stars, and a Videometer, which is the primary rendezvous and docking sensor for the spacecraft. Built under Astrium prime contractorship, the first three ATVs (Jules Verne, Johannes Kepler and Edoardo Amaldi) were also equipped with these e2v imaging sensors and successfully completed their missions in 2008, 2011 and 2012 respectively. The Albert Einstein ATV was carried into orbit on board an Ariane 5 rocket from French Guiana and hauled almost 7 tonnes of cargo to the ISS 360km above the Earth. The spacecraft is the most powerful automatic spaceship ever built and is equipped with its own propulsion and a high-precision navigation system. e2v imaging sensors will automatically guide it into dock at the ISS, playing a key part in the approaching and docking manoeuvres that are so precise that, when 249m away from the ISS, the ATV will slow down to 7cm/sec. The ISS relies on frequent deliveries of equipment, fuel, spare parts, food, air and water for its permanent crew. The unmanned ATV is essential in delivering supplies to the ISS and will stay attached to the station, providing reboost and attitude control. Once undocked, it will be commanded to burn up in the atmosphere over an uninhabited area of the southern Pacific Ocean. e2v's marketing manager, Jon Kemp says: "Albert Einstein is the fourth ATV to have been launched into space. e2v's imaging sensors are a key component in enabling the ATV to successfully dock with the ISS and provide essential wet and dry cargo to the astronauts on board." More recently in May, e2v sensors were launched into space on board Proba-V, an Earth observation microsatellite operated by ESA that has been specifically designed to chart global vegetation. The satellite was carried into orbit from French Guiana by VERTA 1, the second Vega launcher.  For almost 15 years the instruments on board the Spot 4 and 5 Earth observation satellites have monitored and mapped worldwide vegetation, providing essential information on crops, droughts, desertification, changes in vegetation and deforestation. These instruments will become unavailable later this year and, whilst ESA's Sentinel 3 satellites will eventually take over the supply of this information, they will not be operational in time to take over.  ESA has therefore specifically designed Proba-V, which is equipped with a miniature version of the vegetation sensor that is on board Spot 5, to chart global vegetation every two days and provide a continuity of service to the community of more than 10,000 users. Proba-V's instrument is equipped with an e2v AT71547 Charged Coupled Device (CCD) image sensor. This particular sensor is made up of four lines of 6000 pixels each and benefits from a long space heritage, having been used in a number of Earth observation missions. e2v provided a custom solution for this mission by mounting and positioning the window on the image to meet the stringent requirements of this multispectral application.