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Illustration of Project Icarus Starfinder, by Adrian Mann. Credit: Adrian Mann Illustration of Project Icarus Starfinder, by Adrian Mann. Credit: Adrian Mann

Alpha Centauri - a prime target for our first mission to the stars

Sen—A new Earth-sized planet found right on our cosmic doorstep at Alpha Centauri is an exciting discovery. It becomes the prime target for mankind's first mission to the stars.

Alpha Centauri was always going to be a high priority because it is the closest star system, made up of three different suns. The presence of planets makes it even more interesting because of the possibility of life.

This particular planet, dubbed Alpha Cen Bb is too hot to be habitable because it is far too close to its home star, being much closer than our innermost planet Mercury is to our Sun. Discovered using a giant European telescope in Chile, its surface is around 1,200 C and likely to be molten lava.

But it is highly likely that there are other planets there which might be orbiting within the habitable zone where conditions are more favourable for life. Those planets must now be our prime target to visit.

However, interstellar travel is not going to be easy. This star system is close in cosmic terms but it is still more than four light-years away - a distance of over 25 trillion miles. From a technological point of view it is not something we could do in the near future. A mission could easily be a century or more away but we are designing it now.

It requires technology that we don't yet have. We would need to send the probe at a speed that was a large fraction of the speed of light. If you could travel at 10 per cent of the speed of light it would still take 44 years to get there!

The fastest man-made space probes so far were the two robotic Voyagers that are just leaving the Solar System after being launched in the Seventies. To get to Alpha Centauri would take them about 80,000 years!

More modern propulsion such as an ion drive, light beam or nuclear power might cut this time down to 17,000 years, but the only way to get there in decades will require a hugely energetic nuclear drive or antimatter or something that we just don't have yet but could possibly develop in the future. So we need to get a lot faster , but that will be a long-term project that could take 100 or more years to develop.

We need to stop within the Alpha Centauri star system and to land instruments on the surfaces of the planets to send back information about them.

ESO illusatration of exoplanet in the Alpha Centauri star system

Illustration of the planet Alpha Centauri Bb and the Alpha Centauri star system. Credit: ESO/L. Calçada/N. Risinger

I think the first interstellar missions will be robotic rather than crew based Star Trek-type exploration. I'm a big advocate of sending astronauts to the Moon and planets, but sending robots to the stars will be hard enough.

If we eventually do send humans, there are currently three options. One is for a sort of world ship where the voyage would take several generations with many being born and dying on the way. The second is for the astronauts to be put into hibernation but we don't yet know if that is practical. The third way is just to go very fast, perhaps at 90 per cent of the speed of light, but the energy requirements to do that would be phenomenal.

I'm working on Icarus, a serious, scientific and technological attempt by the British Interplanetary Society to find out what would be required to fly to the stars. It is a follow-up to Daedalus, an earlier study that was begun more than 30 years ago, and takes account of all the new developments in technology.

My particular involvement is on the astronomy side, choosing targets for a probe and I'd already come to the conclusion that Alpha Centauri is the best target for such a mission. The new planet discovery makes that argument even more compelling.

Professor Ian Crawford, Planetary Science and Astrobiology expert at Birkbeck, University of London

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