How long ago was Ikaros designed? I've been a member of the Planetary Society since I was a child and this has been talked about since at least the early 90s, i

How long ago was Ikaros designed? I've been a member of the Planetary Society since I was a child and this has been talked about since at least the early 90s, iirc. This has been a major goal of the Planetary Society for years and years and years, finally overcoming the setbacks with a successful crowdfund. I don't doubt Ikaros may have been conceived much earlier, considering how spacecraft design takes time.