HOUSTON—Nearly four years after launching its Kepler space telescope to search for worlds outside our solar system, NASA officials confirmed Tuesday they had yet to find a planet with sufficient resources to support the space-exploration agency and its 18,000 employees. “While the discovery of Earth-like exoplanets continues at an encouraging pace, we have so far been unsuccessful at locating one with the proper financial climate and abundant liquid assets necessary to allow an agency of our size and scope to survive,” said agency administrator Charles Bolden, noting that only a relative handful of planets had been found in the so-called NASA Goldilocks Zone, an area of space in which water, moderate temperatures, and $20 billion in annual funding might exist. “There are billions of planets in our galaxy, so we’re very hopeful that one of them might harbor life-forms that actually have an interest in space and science more generally. We haven’t found one yet, but we believe they’re out there.” While Bolden stated that the Kepler mission had found 2,700 exoplanets to date, every one of them appeared to be facing crippling budget shortfalls.