German cubesats to showcase formation flight technology
Update: This article was updated Oct. 1 at 4:31 pm Eastern time with additional information on technology that keeps NetSat cubesats in formation.
SAN FRANCISCO – The four-satellite NetSat mission launched Sept. 28 on a Russian Soyuz rocket is designed to showcase technology for formation flight.
NetSat’s four cubesats will “demonstrate formation flight in a three-dimensional configuration,” Klaus Schilling, University of Wurzburg robotics and telematics chair, told SpaceNews by email. “This promises huge potential for innovative approaches to future satellite systems in Earth observation and telecommunications.”
In addition, the NetSat mission may reveal collision avoidance strategies, added Schilling, who is also the NetSat principal investigator.
The Wurzburg Center for Telematics worked with German startup Smart Small Satellite Systems GmbH to develop the three-unit NetSat cubesats.
The cubesats rely on intersatellite links to exchange navigation and control information. Each four-kilogram cubesat also is equipped with a single electric thruster and reaction wheels to point the thruster in the appropriate direction, Schilling said.
Prior to launch, the Center for Telematics won contracts to apply its formation-flying technology to Telematics Earth Observation Mission, an Israeli-German effort to generate 3D maps of Earth’s surface features, and to CloudCT, a campaign to collect detailed images of the external and internal structures and properties of clouds.
The NetSat cubesats traveled to orbit alongside three Russian Gonets telecommunication satellites and more than a dozen small satellites. Exolaunch coordinated shipment of the satellites to launch site, as well as integration and deployment in orbit.
It’s not rare for two satellites to fly in formation like the U.S.-German Gravity Recovery and Climate Experiment and the University of Toronto Institute for Aerospace Studies Space Flight Laboratory’s two-satellite Canadian Advanced Nanospace eXperiment-4 and -5.
It is rare, though, for four satellites to operate in a three-dimensional formation. NASA’s Magnetospheric Multiscale (MMS) mission has observed magnetic reconnection in Earth’s magnetosphere with four satellites launched in 2015 that fly in tetrahedral formation thanks to commands sent from ground stations.
“Typically, we perform maneuvers every few months to clean up the formation, resetting it to optimize science,” Trevor Williams, MMS flight dynamics lead at the NASA Goddard Space Flight Center, told SpaceNews by email. “We have carried out a total of over 600 maneuvers.”
NetSat, in contrast, relies on intersatellite links, relative navigation measurements and networked control to correct deviations whenever satellites stray from their intended orbital positions without waiting for commands from the ground, Schilling said.
“The new feature of the Netsat formation is self-organisation of the 3D configuration directly in orbit,” he added.