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In late 2017, a mysterious object tore through our solar system at breakneck speed. Astronomers scrambled to observe the fast moving body using the world's most powerful telescopes. It was found to be one quarter mile (400m) long and very elongated – perhaps 10 times as long as it was wide.
Researchers named it 'Oumuamua, Hawaiian for "scout". 'Oumuamua was later confirmed to be the first object from another star known to have visited our solar system. While these interstellar objects (ISO) originate around a star, they end up as cosmic nomads, wandering through space.
They are essentially planetary shrapnel, having been blasted out of their parent star systems by catastrophic events, such as giant collisions between planetary objects. Astronomers say that 'Oumuamua could have been travelling through the Milky Way for hundreds of millions of years before its encounter with our solar system. Just two years after this unexpected visit, a second ISO – the Borisov Comet – was spotted, this time by an amateur astronomer in Crimea.
These celestial interlopers have given us tantalising glimpses of material from far beyond our solar system. But what if we could do more than just watch them fly by? Studying ISOs up close would offer scientists the rare opportunity to learn more about far off star systems, which are too distant to send missions to. There may be over 10 septillion (or ten with 24 zeros) ISOs in the Milky Way alone.
But if there are so many of them, why have we only seen two? Put simply, we cannot accurately predict when they will arrive. Large ISOs like 'Oumuamua, that are more easily detected, do not seem to visit the solar system that often and they travel incredibly fast. Ground- and space-based telescopes struggle to respond quickly to incoming ISOs, meaning that we are mostly looking at them after they pass through our cosmic neighbourhood.
However, innovative space missions could get us closer to objects like 'Oumuamua, by using breakthroughs in...
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