A 'smart ruler' could help swarms of space telescopes image exoplanets

We've talked plenty of times here about the infeasibility of launching a mirror big enough to directly image exoplanets using current rocket fairings-at least as long as we're not sending them 500-plus AU away to a gravitational lensing point. We've also talked at length about the potential solution to that problem-interferometry, where multiple smaller satellites link up precisely but are spaced far enough apart to act as one gigantic mirror. The problem is, from a technical standpo...