Which Exoplanet to Visit?

by Ian Crawford

Project Icarus is tasked with designing an interstellar spacecraft capable of exploring nearby stars and studying their planetary systems up close. The unmanned space vehicle—inspired by nuclear pulse propulsion studies by the British Interplanetary Society in the 1970s—will ideally reach its target star within 100 years after launch.

So the Icarus spacecraft is planned to take us beyond our solar system to neighboring stars, where should it go first?

The specific target star has not yet been selected, but its choice will be narrowed by a number of factors.

Given realistic propulsion options, and the requirement that the spacecraft can slow down to orbit its target, the target star cannot be more than 15 light-years from Earth. However, given that the project ideally wishes to complete the mission in much less than 100 years, it follows that the actual target will probably have to be significantly closer than 15 light-years.

Within 15 light-years of the sun there are approximately 56 stars, in 38 separate stellar systems. I say approximately for several reasons.

Firstly, at the outer boundary the uncertainties on the distances can amount to a few tenths of a light-year, which could mean that some stars notionally just beyond 15 light-years might actually be closer (and vice versa).

Secondly, not all stars within this volume may yet have been discovered, although this is only likely for the very dimmest red or brown dwarf stars.

Thirdly, perhaps surprisingly, there are still slight discrepancies between the catalogs of nearby stars. Probably the most authoritative recent compilation, and the one on which my number of 56 stars is based, is published by the Research Consortium on Nearby Stars.

Star Candidates

The scientific objectives of Icarus include studies of the interstellar gas and dust lying between the sun and the target star, studies of planets orbiting the target star, and, most exciting of all, studies of any life forms that may have evolved on these planets.

Read more: Which Exoplanet to Visit? | Icarus Interstellar.

Home           Top of page