he ones taken by our probes in our own solar system. Consider that there are 4088 stars located within 100 light-years of Earth, implying that there could very easily be tens of thousands of planets that could be imaged at such high resolutions.
Toward a Telescope Cloud
The impact of such a powerful observational tool on our knowledge of alien solar systems would be nothing short of revolutionary. There is only one serious obstacle to obtaining this bounty: such a telescope can only observe one target at a time, because the telescope, the sun, and the target have to all be in a line. To observe another target, it must change its position so that it is aligned with the sun and the other target. To observe a target on the opposite end of the sky, the telescope will have to travel to the opposite end of the solar system, which since it needs 542 AU or more of distance from the sun, requires a trip of at least 1100 AU, or six light-days.
This distance would take months for even the most advanced near-future propulsion technology (nuclear pulse) to traverse. Instead of accepting months of downtime, it would be far more efficient to have multiple telescopes stationed at different ends of the solar system, perhaps starting with a pair at opposite ends of the sun and filling in different slices of the sky from there. In this way the maximum travel distance could be cut to hundreds of AU, then down into tens of AU, which as outlined in my post on colonizing the Oort cloud is a manageable distance with nuclear pulse propulsion. At 1g of constant acceleration 20 AU can be traversed in twelve days; the required maximum speed of 1.8% of light is easily attained by nuclear pulse. Keep in mind that this would be the maximum travel distance; most repositionings would, when the sphere of space telescopes at >542 AU is fully built out, take only from a few hours to a few days to complete.
Repeated and long-term observations of distant targets are possible and would surely be done extensively when this infrastructure is created. In fact, it isn’t hard to imagine a time when this region of the solar system may be the preferred place to conduct astronomical observations of not only extrasolar planets, but an array of distant objects. Thus, the innermost parts of the Oort cloud may not become economically or demographically important, but they may well become scientifically important for this reason alone.
Considering that the concept for a mission of this type is already being promoted by Claudio Maccone and being talked about at NASA, the innermost Oort cloud may be penetrated by space telescope arrays sooner than almost anyone even suspects. The build-out of such an infrastructure (one might call it the “telescope cloud”) is hardly imminent, but it wouldn’t be surprising if it was built up at roughly the same time humans establish colonies in the outer solar system. The same level of propulsion technology that can get you from Earth to Saturn in a few weeks can also get you to the gravitational lensing distance in a few years.
An Oort Cloud Gold Rush?
Gravitational lens telescopes may not be a driver of human settlement like the reasons explored in the previous post on colonizing the Oort cloud, since telescopes can be operated autonomously, especially with the sort of technology likely to be available in the near future. The fact that a round-trip transmission takes a week, however, may compound any errors that occur, making human servicing so frequently necessary that it may be easier to simply station people on-site or on a more mobile spaceship nearby that roams the region checking up on the telescopes. Visits for servicing will likely be needed from time to time in any case, though this wouldn’t be a driver of permanent settlement.
The very fact of week-long round-trip transmission times, however, might stimulate some scientists and scholars to station themselves on-site in order to access and analyze observational data faster than would otherwise be possible. In a scenario where detailed observations are needed with multiple-step dec