Fifty miniature satellites weighing one kilogram each will soon be launched to the International Space Station (ISS) and deployed into orbit to explore the region above Earth known as the thermosphere.

The "cubesats"—part of the Von Karman Institute's QB50 initiative, funded by the European Union—will carry out measurements of the region that lies between 200 km and 380 km above Earth. QB50 invited universities worldwide to participate in the project, and the satellites have been designed and built by young engineers, supervised by university staff and guided by the QB50 project through reviews and feedback.

“This region is poorly understood and hard to measure,” says Andrew Dempster, director of the Australian Centre for Space Engineering Research at the University of New South Wales, which will deploy two research satellites. He says the region is where much of the ultraviolet and X-ray radiation from the Sun collide with the Earth and generate auroras and potential hazards that can affect power grids and communications.

Cubesat satellites are 10 x 10 x 10 cm and weigh one kilogram. Image credit: UNSW.Cubesat satellites are 10 x 10 x 10 cm and weigh one kilogram. Image credit: UNSW.The cubesats will be launched to the ISS in December 2016 by an Orbital ATK Antares rocket from Wallops Island, Virginia, inside a Cygnus cargo freighter. They will be deployed from the ISS about a month after arrival and drift down to the target region, where they will explore the lower thermosphere for 3-12 months before they re-enter the atmosphere and burn up.

The miniaturized satellites (10 x 10 x 10 cm) offer many of the functions of a standard-sized satellite: attitude determination and control, uplink and downlink telecommunications, power subsystem including a battery and body-mounted solar panels, on-board data handling and storage by a CPU and either a technology package or a small sensor or camera. And while individual cubesats are too small to carry sensors for significant scientific research, combining a large number of them with identical sensors into a network can help address fundamental scientific questions that otherwise would be unattainable.

Space agencies are not pursuing a multi-spacecraft network for in-situ measurements in the lower thermosphere because the cost of a network of 50 satellites built to industrial standards would not be justifiable given the limited orbital lifetime. Obtaining such measurements can only be realized using low-cost satellites, backers say, and cubesats are viewed as the best option.

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