NASA’s Kepler spacecraft hunting for Earth-like planets around other stars has found 706 candidates for potential alien worlds while gazing at more than 156,000 stars packed into a single patch of the sky.
Kepler will continue conducting science operations until at least November 2012, searching for planets as small as Earth, including those that orbit stars in a warm, habitable zone where liquid water could exist on the surface of the planet. Since transits of planets in the habitable zone of solar-like stars occur about once a year and require three transits for verification, it is expected to take at least three years to locate and verify an Earth-size planet. The expectation is that Kepler should be able to identify at least 60 habitable earthlike planets in its 500 light year range.
The new estimate is that there are 100 million habitable worlds in the Galaxy. Some may feel negative about this. What about the Fermi Paradox? If there are so many habitable worlds then why haven’t some of them had aliens come visit us.
Hypertelescopes and World imaging space Telescope Arrays are Needed to Follow Up
Once control techniques for a flotilla of space mirrors will be mastered, it will perhaps not take many years to expand their size from hundreds of meters to hundreds of kilometers. This is the size needed to obtain well resolved visible images of an exo-Earth within a few parsecs . Simulation 37 have shown that visible “portraits” of such planets can be obtained in 30 mn of exposure, using a 150 km hypertelescope with 150 mirrors of 3 meters.
a 100-pixel image of a planet twice the width of Earth some 16.3 light years away would require the elements making up a space telescope array to be more than 43 miles apart. Such pictures of exoplanets could make out details such as rings, clouds, oceans, continents, and perhaps even hints of forests or savannahs. Long-term monitoring could reveal seasonal shifts, volcanic events, and changes in cloud cover.
* To resolve 30 foot (9 meter) objects looking 4.37 light years away the elements making up a telescope array would have to cover a distance roughly 400,000 miles wide, or almost the Sun’s radius. The area required to collect even one photon a year in light reflected off such a planet is some 60 miles wide. To determine motion of 2 feet per minute — and that the motion you’re seeing is not due to errors in observation — the area required to collect the needed photons would need to be some 1.8 million miles wide. [NOTE – I do not think there would be enough photons coming off of such a small object at light year distances. This is why the hypertelescope expert talks about massive telescope arrays to resolve neutron stars. They are small but are emitting enough photons for an image
Adaptive Intelligent Interferometric Imaging Systems
Develop new technology to improve our ability (and reduce the cost) to perform high resolution imaging of distant astronomical targets such as exo-solar systems and protoplanetary disks. These high resolution imaging tasks will be addressed by using multi-spacecraft interferometric imaging systems (MSIIS). Such systems synthesize a large optical aperture by interfering the light collected by smaller aperture telescopes carried by the component spacecraft of such systems. The state of the art for the maneuver design of such systems attempts to uniformly fill the Fourier/u-v plane of the image. However, such maneuvers lead to an exceedingly wasteful expenditure of resources since the Fourier plane of any image is quite sparse. The new methodology proposed here is intended to reduce that waste, and thereby substantially reduce the cost of achieving ambitious goals in astronomical imaging. Intellectual merit of proposal: The intelligent imagining methodology is formulated as a stochastic adaptive control problem. It consists of: (a) intensity correlation interferometry based on the Hanbury-Brown-Twiss (HB-T) quantum optic effect; (b) forming a constant probabilistic estimate of the image using noisy interferometric measurements made by the component spacecraft; and (c) utilizing this probablilistic estimate of the image to guide the motion of the component spacecraft such that most of the resources of the system are utilized in exploring the “information rich” areas of the u-v plane. Intensity correlation interferometry (ICI) based on the HB-T effect results in relaxation of the precision control requirements by several orders of magnitude. The image estimation problem will be addressed by a new methodology grounded in frequentist statistics. The motion planning of the spacecraft is proposed to be solved using approximate dynamic programming (ADP) utilizing the probabilistic estimates of the image content from the estimation algorithm. Broad impact of proposal: This new technology should permit the development of high resolution imaging systems with effective aperture sizes that are heretofore unheard of. For example, it may make it far more feasible and affordable for us to detect the spectral signature of plant life in earth-sized planets within 100 to 100 light years of earth