Spanish Aerospace:
Leaders at Every Altitude

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Space Telescopes

Scientists want to deploy large telescopes into space to probe further into the nature of the universe, explains Diego Rodriguez, director of Sener's space department, but they're constrained by the size of the satellites. The ideal telescope would need to be a long, stiff structure, he points out, "and there's limited room in the launcher… With traditional technology, you can only use a structure that can be retracted and deployed."

A solution to such a challenge is a strategy known as formation flying, where two satellites would be launched and would then fly together; one might house, for instance, the lens of a telescope, and the other its detector.

This technique has already been employed in the aeronautics sector. In such a system, airplanes fly a set distance apart from one another and maintain a distance precisely. In the case of satellites, two satellites would be launched. One would contain an extremely accurate metrology system to monitor the location of the second to within a tenth of a millimeter, ensuring a perfect alignment between the lens on one satellite and the detector on another. "On the second satellite, you incorporate very small thrusters that provide extremely low but very accurate forces to compensate for the satellite's position, maintaining the alignment," continues Rodriguez.

While spacecraft have previously been launched that maintain positions relative to one another, none have yet achieved a sufficiently high degree of accuracy to unite the elements of a telescope.

Developing a successful formation-flying technology is the goal of Proba-3, a research project of the European Space Agency (ESA), and the first ESA mission to be headed by a Spanish company. Sener will lead the mission in primary partnership with GMV, a technology business group whose space headquarters are based in Madrid, and Madrid-based EADS CASA Espacio. (Two other members of the core team are the Belgian companies QinetiQ and Spacebel.) Sener will focus on control systems that will be continuously monitoring the satellites to maintain the appropriate distance. GMV, a top guidance, navigation, and control company, will design and implement the formation-flying system, which includes both onboard and related ground-based systems. EADS CASA Espacio, Spain's leader in the field of launchers, antennas, and satellites, will build one of the two satellites, which will incorporate new elements such as highly sensitive thrusters.

The deployment of two small satellites flying in precise location relative to one another will allow for the launch of much more powerful telescopes, x-ray sensors, or sensors that operate via radio frequency, to explore a variety of sources for information about the universe. Another such project, which the ESA is incorporating into the Proba-3 mission, is the study of the sun's corona, according to Gonzalo Galipienso, EADS CASA Espacio's political affairs director. For such a study, one of the satellites must act in much the same way the moon does during a solar eclipse, that is, it must use an instrument to block the body of the sun so that the second satellite's instruments can record the image of the solar corona.

EADS CASA Espacio recently developed instruments for an ESA research satellite that collects data for a project called SMOS (Soil Moisture and Ocean Salinity). The company is also developing two Earth observation satellites: Ingenio and PAZ. And GMV's work in the space sector has led that technology company to become the world's top supplier of ground control centers for commercial telecommunications operators, and among the leading suppliers of navigation and control systems.

"Formation flying is an extremely challenging technology," says Jorge Potti, general manager of GMV Aerospace. "This will surely enable exciting new missions that today aren't feasible."

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