Contributes to Clean and Sustainable Space
There are more than 29,000 known and tracked pieces of space debris (also known as space junk) orbiting Earth, each traveling at about 27,000 km/h. The space junk pose a risk to future space missions, as even tiny pieces could seriously damage or destroy a satellite or spacecraft.
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Laura Helene SletbakkCommunication Manager
“One approach to remove debris from orbit is to make it re-enter the Earth's atmosphere while we still have some control of it, such that it burns up along the way. However, sometimes the satellite does not completely disintegrate, resulting in a collision with Earth’s surface,“ says Njord Eggen, Project Engineer in the division Space & Surveillance at Kongsberg Defence & Aerospace (KONGSBERG).
Although there has been no recorded confirmed incident of a person being hit by space debris, the increase of satellites and spacecraft orbiting Earth calls for immediate action, according to the European Space Agency (ESA).
According to ESA, the process of ensuring the Agency’s compliance with current and upcoming regulations marks a first step in the process of transitioning its activities to a more sustainable footing through the adoption of cleaner alternatives to current harmful materials and technologies. In addition, future ESA missions will be evaluated in terms of their environmental impact across their entire life cycle.
The need for environmental protection extends to space. The production of space debris will be reduced to protect key orbits, while new technologies will be developed to reduce the current debris population. Even if all space launches stopped tomorrow, the amount of debris will keep on increasing if left alone.
Photo below: Visualization current space debris. Courtesy of NASA ODPO.
DEMISABILITY TESTS
Through ESA’s Clean Space programme, KONGSBERG started an investigation to demonstrate the 'demisability' of a Solar Array Drive Mechanism (SADM). The activity has been supported by ESA, Hyperschall Technologie Göttingen GmbH (HTG) and the German Aerospace Center (DLR).
The SADM is identified as a critical component as it consists of materials such as steel and titanium - materials used and nested structure are some of the factors contributing to this criticality.
“A software modelling of the SADM was done by HTG in order to simulate and analyse the demise. This allowed us to test in a statistically significant way the possible fragmentation scenarios prior to using a representative model in the plasma wind tunnel, “ says Njord.
“One of the explored design changes to enhance demisability was to change the material of some key screws to aluminium with a lower melting temperature in order to trigger an earlier fragmentation, leading to an enhanced demise, “ says Eggen.
A simplified model was manufactured by KONGSBERG for the demisability test. The on-ground test took place in the L3K wind tunnel facility of DLR. DLR performed two tests – the first test on the whole SADM-model, the second test was an assembly of the inner mandrel and crown wheel, main bearing and preload nut.
Photo below: The on-ground test took place in the L3K wind tunnel facility. Credit: DLR
RESULTS
The test predictions obtained through the simulations matched well with the test in the plasma wind tunnel. However, due to some uncertainties, such as material properties and heat flux, the models needed some tweaking to match the tests and to be verified.
“We are satisfied with the test results, and grateful that we were able to carry out this project supported by ESA. The Clean Space’ programme has given us valuable material and design- experience and competence,” says Njord
KONGSBERG is applying for a contractual change notice to expand the scope to include tests for a more compact SADM. The application is expected to be decided in a short time.
Demising a Solar Array Drive Mechanism
Simulating the burn-up during atmospheric reentry of one of the bulkiest items aboard a typical satellite using a plasma wind tunnel.This Solar Array Drive Mechanism (SADM) has the essential task of keeping a satellite’s solar wings trained on the Sun, maintaining mission operations.
As part of a larger effort called Managing the end of life of satellites, ESA is developing technologies and techniques to ensure future low-orbiting satellites are designed according to the concept of ‘D4D’ – Design for Demise.
