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Space-Smash simulation when satellites collide



Satellite collisions cause debris; See this video for more information. Credit: ESA / ID & Sense / ONiRiXEL, CC BY-SA 3.0 IGO, CC BY-SA 3.0 IGO

Satellites orbiting the Earth move at many miles per second ̵

1; so what happens when their paths cross? Satellite collisions are rare and their consequences are poorly understood. A new project tries to simulate them in order to better predict future space junk.

So far, only four such collisions have occurred in space history – most of the space debris comes from explosions of leftover fuel tanks or batteries – but they are likely to become more common.

"We want to understand what happens when two satellites collide," explains ESA 's structural engineer Tiziana Cardone, who oversees the project.

"So far many assumptions have been made about how the very high collision energy would dissipate, but we do not have a solid understanding of the physics involved

" We want to be able to visualize in detail how the satellites are broken and how many debris are produced to improve the quality of our models and forecasts. "[19659005] The total energy is orders of magnitude higher than the space-typical building technology that focuses on sustaining the force of the launch." This is a really unknown area, "adds

"We need to understand this because we are currently working on expensive demolition strategies based on our understanding of debris," explains Holger Krag of ESA's Space Debris Office, "We project the development of the debris environment up to 200 Years ahead.




Space … Clean and untouched, right? At least from afar. But we are looking more closely at the orbits around our own planet of garbage: dilapidated satellites and rocket stages and smaller pieces chasing around at hypersonic speed Since 2012, ESA's Clean Space Initiative has been working to make space as safe, clean and accessible as possible for the future Keeping our space activities throughout their lifecycle, from the first planning to the end of their lifecycle, keeps generations clean, because the clean path is the way to go. Source: ESA (Genevieve Porter) – Marianne Tricot (Ecole Estienne Paris)

Of the four known clashes, only one of them took place as we had expected, with both satellites crashing catastrophically and creating debris clouds. The others were very different, so something is missing in our picture.

"By executing many different collision variants, we hope to understand what happened in the actual collisions to substantiate our modeling."

Two different types of software simulations are performed: at the German Fraunhofer Institute for Short-Term Dynamics and at a consortium led by the Center for Studies and Activities for Space at the University of Padua, Italy.

The first approach is based on a sophisticated method Numerical method for simulating the deformation and fragmentation processes in a collision. The colliding objects are modeled with realistic structural and mechanical properties represented by a "finite element mesh".

Snapshot of a simulated collision between a model of the LOFT (Large Observatory For X satellite and a 12-unit CubeSat moving at a relative speed of 11 km / s and in an angle of 32 degrees LOFT is an ESA candidate for an ESA mission that competes for a launch opportunity in the early 2020s At the Fraunhofer Institute for Short-Term Dynamics, colliding objects at the material level are simulated with realistic structural and mechanical properties, represented by a "finite element mesh." These elements are converted into discrete particles as structural fragments, allowing the simulation of the structural response of a satellite to collisions and predicting the cloud of impact generated fragments and their evolution over time.Credit: ESA / Fraunhofer Institute for Short-Time Dynamics

These elements are converted into discrete particles as satellite fragments. This allows the simulation of the structural response of the satellites to the collision as well as the generation of the fragment cloud and its temporal evolution.

The second approach treats the spacecraft as consisting of larger elements, such as fuel tanks or solar systems connected to physical connections. When the energy transfer of the collision takes place, these connections are disconnected and the elements are fragmented. A library of past simulations and empirical data is used to show how these elements fragment under the force of impact.

An alternative simulation method using a 5 cm aluminum alloy ball shows Loft Loft (a large observatory for X-ray timing) satellites at a speed of 8.5 km / s and an impact angle of 45 degrees. LOFT is an ESA candidate for an ESA mission that is competing for a launch opportunity in the early 2020s. This component-level approach, undertaken by a consortium led by the Center for Space Studies and Activities at the University of Padua, Italy, treats the spacecraft with larger elements such as panels, payloads, fuel tanks or solar cells along with physical connections. When the energy transfer of the collision takes place, these connections are disconnected and the elements are fragmented. A library of past simulations and empirical data is used to show how these elements fragment under the force of impact. Credit: ESA / Center for Studies and Activities for Space

The two types of simulation, working at the material and component level, should give new insights into the underlying physics of collisions, but have begun to mimic the effects of a single piece of debris – the type of collision that will be simulated can physically be used in terrestrial laboratories.

Once these simulations double the observed reality, they are used to reproduce the total impact of satellites on a 500 kg scale.

Simulating a hyperspace impact from a sphere on a satellite surface. At the Fraunhofer Institute for Short-Term Dynamics, the deformation and fragmentation process of the collision is simulated using a sophisticated numerical method. This approach allows for a physically consistent simulation that fits very well with experimental results. Credit: ESA / Fraunhofer Institute for Short-Term Dynamics

The first known collision took place in 1991, when Kosmos was hit in Russia in 1934 by a piece of Cosmos 926. In 1996, the French satellite Cerise was hit by a fragment of an Ariane 4 rocket. In 2005, a US upper school was hit by a third-tier fragment of a Chinese missile. In 2009, an iridium satellite collided with the Russian Cosmos-2251.


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Source:
European Space Agency


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