Mar 16, 2018 16:44
Richard Boutilier
Posted on: Centauri Dreams
I am sure this has already been answered in the forum, but, if someone wouldn't mind repeating the answer, I am wondering if the reported "continent"-sized resolution of the probes is based on only the nano-craft's optics or includes using the deformable light-sail as a reflector-style telescope collector dish for the probes?
May 14, 2018 22:41
Breakthrough Initiatives
Posted on: Breakthrough Initiatives
Thank you for your comments. We are considering using less than 1 meter of the deformable sail to image the target planet. When we understand our ability to manipulate the sail we will have a better estimate on how well we can image the target.
- Pete Klupar, Breakthrough Starshot
Sep 13, 2018 16:15
Breakthrough Initiatives
Posted on: Breakthrough Initiatives
Reply:
The angular resolution of images obtainable by cameras aboard the craft will be at best the diffraction limit, roughly the wavelength of the light divided by the size of the camera's aperture. This angular resolution will correspond to a particular length scale proportional to the distance between the planet and the camera at the time the image is captured. If this distance is about the Earth-Sun separation (namely 1 AU), the image is taken with optical light (namely a wavelength of ~700 nm), and the camera's aperture is about 10 cm in size, then the implied resolution of the image at the planet is ~1000 km, namely continent-scale. At this point none of the above-mentioned parameter values are set in stone - a nanocraft may be able to pass much closer to the planet, especially if many of them are sent. The lightsail itself may be usable as a reflecting telescope as you suggest, which would improve the resolution of the image all else equal. Meanwhile the design of the lightsail will likely be set primarily by the requirement that it rides stably on the laser beam without heating up too much in the process, then potentially by its usability as an antenna to aid in transmitting data back to Earth. If it can be used to aid in imaging the planet, all the better, but more research and development is needed before we can say if it will also be useful for the optics of the camera (since the tolerance in the precision of its shape when used a camera aperture depends sensitively on the choice of the transmission wavelength).
- John Forbes and Avi Loeb (Harvard), Breakthrough Starshot
Sep 15, 2020 11:48
rpmhm0@gmail.com
Posted on: Breakthrough Initiatives
Is individual camera resolution the critical issue here? With a cloud of cameras resolution is in theory limited by the diameter of the cloud. We have to solve huge modelling, measurement and communication problems to approach this but these might be easier than sending physical optics?
Sep 17, 2020 17:40
Philip Mauskopf
Posted on: Breakthrough Initiatives
Reply:
To obtain a resolution limited by the diameter of a cloud of "cameras" the probes would have to somehow combine the light they receive in phase. This is potentially possible by using a cloud of reflectors and having a central combiner (see, e.g. papers on ground-based and space-based "hyper telescopes" - https://eandt.theiet.org/content/articles/2020/03/hypertelescope-camera-captures-unprecedented-detail-of-celestial-objects/).
However, this level of coordination both in sending a cloud of probes designed to arrive at the star system at the same time and spaced in a way that would enable beam combining is much more difficult than navigating individual probes to fly by any planets at closer distances. The baseline plan of sending each probe spaced in time with its own camera and optics then gives an opportunity for redundancy and varying the distance of closest approach at launch and during transit.
For example, an approach within 0.1 AU with a 10 cm optic would improve the image resolution from 1000 km to 100 km.
- Phil Mauskopf (Arizona State University), Breakthrough Starshot
