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Researchers Find a Safer, Cheaper Way to Retire Satellites

Researchers Find a Safer, Cheaper Way to Retire Satellites

by Samburaj DasSeptember 2, 2015

Spanish researchers at the University of La Rioja have come up with an improved way to safely obliterate satellites after their re-entry into the atmosphere.

The published paper, named “End-Of-Life Disposal of High Elliptical Orbit Missions: The Case of INTEGRAL” can be found here.

A new methodology for retiring satellites, developed by researchers at the University of La Rioja has proven to improve mission safety while lowering risks and costs, reports Phys.

The method involves the use of an ‘evolutionary algorithm’ that helped solve the quandary of a mathematical optimization problem involving several variables and objectives.

Objectives including reducing the risk of collisions of other satellites; reducing the likelihood of an uncontrolled re-entry into the earth’s atmosphere; simulating the evolution of piece of debris or an orbiter over a 100 year stretch, among others, had to be fulfilled.

Deadly Space Debris

deadly space debris

Space Debris

Space debris poses a substantial problem facing engineers, primarily due to the ever-present threat of striking a satellite, thereby forming more space debris. The need for the safe disposal of defunct satellites in ‘highly elliptical orbits’ (HEO) was entirely necessary, and members of the Scientific Computing Group (GRUCACI) at the University have found the answer.

HEO orbits are unconventionally eccentric, thanks to the gravitational field and its effects by the Earth’s bulge at the equator. Gravitational forces working from the moon and the sun also affect satellites in these higher orbits.

In such circumstances, there is an increased possibility that these high-orbiting satellites intrude on two other ‘protected regions’ – lower earth orbits (LEO) and geostationary orbits (GEO) over extended periods of time. Satellites in conflicting orbits could result in disaster.

“Our research has focused on taking advantage of the same gravitational effects that affect HEO orbits so as to reduce the cost of eliminating the satellites once they have reached retirement,” explains Roberto Armellin, co-author of the published work.

Some propellant needs to be reserved to perform the satellite disposal maneuvers, so it cannot be used to extend mission duration, which makes it more expensive. So we have developed a methodology aimed at reducing the amount of propellant needed, and hence the associated cost.

A Real Field Test

The European Space Agency’s INTEGRAL mission, a gamma-ray space observatory launched in 2002, is the first satellite to be tested with the new method.

Researchers used their advanced algorithms to make an orbit-propagating software that was put to use on INTEGRAL.

“The simulation results suggest maneuvers allowing the INTEGRAL satellite to re-enter the Earth’s atmosphere and subsequently disintegrate during the period of time from September 2028 to July 2029, in a controlled way and with a cost which is reduced by the amplification of natural gravitational effects,” Armellin claims.

The ESA’s original strategy to take out INTEGRAL involved firing up its engines four times this year and coincided with the new solution offered by the Spanish researchers.

Furthermore, the research and study of the GRUCACI team confirms the very real possibility of selecting safe regions on earth by latitudes. Such insight could help ensure the lowest risk to populated areas on earth during satellite re-entry.

Images from Shutterstock.

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