Could we travel to this distant neighbour and what problems would we encounter on the way?
Although Proxima Centauri is sometimes referred to as Alpha Centauri C, we aren’t yet sure how it fits in with Alpha A and B. The stars in the binary system orbit around a common centre of gravity, and range from being 1.67 billion kilometres (1 billion miles) to 5.3 billion kilometres (3.3 billion miles) apart due to the eccentricity of their orbit. They’re relatively similar and Sun-like.
By contrast, Proxima is smaller, redder, weaker and much further from the other two stars. Visually it appears as a faint red star near two very large bright stars – it doesn’t seem to fit. However, Proxima has the same proper motion as Alpha Centauri AB; the angular changes in position over time are the same. Proxima could have been pulled into the system by the older stars, or formed at the same time.
Alpha Centauri and Proxima Centauri in particular, as the closest star to us after the Sun, is theoretically our first stop once we figure out the particulars of interstellar travel. Although it’s close in terms of stars, the distance is the biggest challenge. We could get there, but it’s going to take a long time. Using our current technology, it would take thousands of years. The Voyager 1 space probe has travelled further than any other, and is currently travelling in previously unknown space territory at around 60,000 kilometres per hour (38,000 miles per hour). If it were heading to Proxima, Voyager would take more than 70,000 years to reach the star.
In 2011, NASA’s Ames Research Center and the Defense Advanced Research Projects Agency (DARPA) began collaborating on the 100 Year Starship Project. The purpose was to determine the requirements for meeting the goal of human interstellar travel within a century. Some currently feasible ways of reaching Proxima include ion propulsion engines and solar sails. The former creates thrust by accelerating ions, while solar sails harness radiation pressure of gases to push thin, sail-like mirrors to high speeds. Both concepts have been tested, but have not yet been used as a primary source of power.
There is also a human cost to interstellar travel. If it’s not possible to reduce the amount of time it takes to reach Proxima, we’d need multiple generations of astronauts; children would be born along the way and have to pick up where their parents left off. Even if we could get there in a century, that’s longer than the average human lifetime. Space travel also causes bone and muscle loss, and the cardiovascular system loses some of its efficiency. There’s also the matter of supplying and maintaining a spacecraft for a number of astronauts, for the trip there and back. Distance is just one challenge on our quest to reach the stars.