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How to approach an asteroid
New model describes how objects orbit fast-moving space rocks
Asteroids have the potential to destroy our planet with little or no notice. The paths of these giant balls of rock and ice that hurtle around space are difficult to predict, and researchers are investigating the way they move and how objects move around them. Now, a new paper in Communications in Nonlinear Science and Numerical Simulation sheds some light on how objects move around fast-rotating asteroids.
Xiyun Hou and a team from Nanjing University in China didn't just study one object orbiting an asteroid, however. They looked at families of objects using a computer simulation that more closely resembles what happens in real life.
The team found that the dynamics of how an object interacts with a fast-rotating asteroid can’t be described using the classical ‘two-body problem’ that is often used to predict how two objects interact. The two-body problem describes two objects with similar mass interacting only with each other. Due to gravity, these would orbit each other, such as in the Earth-Moon system.
They showed instead that the orbits of objects around fast-rotating asteroids are irregular and unstable. “The phase space structure around fast-rotating, irregular asteroids is completely different from that described using the two-body problem, and the orbital motion of objects around these asteroids is generally unstable,” says Hou.
This means that, unlike the Moon orbiting our planet, these objects are much more likely to lose their orbit. They may either escape their orbit and leave the asteroid or collide with the asteroid itself.
Understanding how objects move around asteroids is important for the future of space research. Recently, a few space missions have approached asteroids closely, one even landing and sampling material from the surface. In the future, one possibility is that soil from asteroids (known as regolith) could be mined for astronauts to use, to make things such as shields for space radiation, for example.
This new information will also help space mission designers plan how they approach asteroids. “Our study can help researchers to locate regions where possible natural objects around the asteroid can be found, design safe trajectories for the probe and analyse the fate of ejected regolith,” says Hou. “We provide people who design space missions with the information they need to plan orbits.”
Hou, X. et al.: "Genealogy and stability of periodic orbit families around uniformly rotating asteroids," Communications in Nonlinear Science and Numerical Simulation (2017)