Voyager 1 is our most travelled spacecraft to date, clocking up a mammoth 12 billion km during its incredible journey to the edge of our solar system.
However, this long-haul trip has taken over 30 years to complete. What's more, even at speeds of over 35,000 mph, Voyager will take a further 20,000 years to reach the middle of the Oort Cloud, the hazy swarm of comets that surrounds the solar system.
Proxima Centauri, our nearest star, is twice this distance again. Clearly, if we want to explore further than our celestial doorstep, we must find new modes of space travel. From the feasible to the fantastic, here is a run-down of top transport options...
Future Options
Solar Sails
Made from flimsy, fragile material, they could be the next big thing in space travel. Rather than using the wind to push them along, solar sails are propelled by sunlight. A solar sail is a lightweight panel made from reflective material that acts like the sails of a boat. Rather than using wind, however, the sails are actually propelled by light. Unbelievable as it may seem, the stream of light particles (called photons) emitted from the Sun is strong enough to push a mini-spacecraft right out of the Solar System and beyond into interstellar space.
Ion Engines
Instead of burning chemical fuels, ion engines are electrically charged and work by ejecting positive ions from the back of the rocket, propelling the spacecraft forward. Though the thrust is tiny, the ion engine is extremely efficient, allowing the fuel to last far longer than in conventional rockets. Ion powered spacecraft gradually accelerate to extremely high speeds of 35,000 km per hour or more.
Nuclear Power.
One of the most feasible, yet controversial, methods of space transport. Our current chemical rocket engines produce relatively little power. They have to make use of planetary alignments, or 'launch windows', and use the gravity of other planets to catapult them further into space. Nuclear rockets would be more powerful and wouldn't need to take advantage of these chance planetary pattern. There are two types of possible nuclear rocket which rely on different types of nuclear reactions:
- fission, when atoms are split apart
- and fusion, when they join together.
Antimatter Spacecraft.
Antimatter, the alter-ego of matter, is the most efficient fuel possible, converting 100% of its mass into energy. There is a big problem with using antimatter. It takes more energy to make antiparticles than antiparticles produce when they are destroyed. Because of this, only 10 billionths of a gram is produced globally per year. This paltry amount isn't even enough to heat a cup of coffee, let alone travel to another planet. In addition to this, there's also the tricky problem of storage. How do you contain antimatter when it explodes as soon as it comes in contact with matter?
These technical difficulties mean that we won't be jetting off in antimatter rockets in the foreseeable future. Researchers at NASA's Marshall Flight Centre are hoping that the technology will be ready in 30-40 years time.
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