Planetary Resources will be putting up hundreds of inexpensive space telescopes with 9 inch mirrors, 2 meter resolution and sub-arcsecond pointing. The passive constellation method for boosting image resolution could achieve centimeter resolution. When Planetary Resources adds some fine station keeping capabilites, they will be able to create massive space telescope interferometers. They will add some starshade satellites and be able to image exoplanets. 1 kilometer resolution would be a hypertelescope array about 10,000 miles across. That would mean a 100 million pixel image of an exoplanet (planets in solar systems up to about 10 light years away). They would be able to look even further at somewhat lower resolution.
We have already made the case that super cheap space telescopes will capture a large part of the satellite imaging and space data industry. By using passive and then active arrays of space telescopes, the resolution will increase beyond the current best larger satellites. Planetary Resources will have a multi-billion business as they disrupt the satellite imaging and near earth satellite businesses. They will do this before they mine anything. I predict Planetary Resources will be a multi-billion company in value and revenue before 2020.
Passive telescope arrays with the Arkyd 100 Series
Efficient, Passively Orbiting Constellations for High Resolution Imaging of Geosynchronous Objects
Over the past several years, much progress has been made in the development of the Intensity Correlation Imaging approach to ultra-fine resolution imaging. In this paper, we consider the design of a LEO-based observatory of small telescopes using the Intensity Correlation Imaging technology to achieve 1 centimeter resolution imaging of objects in geosynchronous orbit. We formulate the system Modulation Transfer Function (MTF) and then seek to optimize u-v plane coverage by the design of passive, LEO orbits. An adaptive random search technique is used to find constellation designs that offer twice the rate of u-v coverage as earlier results.
Within the context of Intensity Correlation Imaging based on the Brown-Twiss effect, we considered the design of a LEO-based observatory of small telescopes capable of 1 cm resolution imaging of objects in geosynchronous orbit. We formulated the effective system Modulation Transfer Function (MTF) and then sought to optimize u-v plane coverage by the design of passive, LEO orbits. An adaptive random search (ARS) technique was used to find constellation designs that offer twice the rate of u-v coverage as earlier results. The ARS algorithm proved to be an effective approach to obtaining suboptimal but greatly improved solutions to this complex, non-convex optimization problem. This method also offers the flexibility to incorporate additional constraints, such as minimum inter-satellite approach distance. Such extensions are the object of on-going work.
In previous work, we explored the possibility of using intensity correlation techniques, based upon the Hanbury Brown-Twiss effect to perform fine resolution imaging in the service of exoplanet astronomy. Here we consider a multi-spectral variant of the Hanbury Brown-Twiss technique. At each of a number of independent, light-gathering telescopes photodetection data encompassing each of a set of frequency channels are obtained and then are communicated to some convenient computational station. At the computational station, the correlations among the photodetections in each of the frequency bands are time averaged and then further averaged over the various frequency channels to arrive at measurements of the mutual coherence magnitude for each pair of telescopes. From these statistics, imaging data are, in turn, computed via phase retrieval techniques. Here, within a modern quantum optics framework, we examine the signal-to-noise characteristics of the coherence estimates obtained in this way under a variety of non-ideal conditions. We provide step-by-step derivations of the statistical quantities needed in a largely self-contained treatment. In particular, we examine the effects of partial coherence on a scene typical of exoplanet imaging and show how partial coherence can be used to greatly attenuate the parent star. We find that the multispectral version of intensity interferometry greatly improves the signal-to-noise ratio in general and dramatically so for exoplanet detection. The results also extend the analysis of signal-to-noise to a wider variety of practical conditions and provide the basis for multispectral intensity correlation imaging system design.
Hypertelescopes with the Arkyd 200 series as nodes
Laser Driven Hypertelescope
Feasibility of a laser-driven hypertelescope flotilla at L2 (28 page presentation)
• Many small mirrors better than few large ones
• But how small ? Minimum size about 30mm for tolerable beam spread
• 40,000 mirrors of 30mm for same area as JWST ? …
. Laser-trapped flotilla ?
Planetary resources with mass produced space telescopes is making the telescope nodes for a hypertelescope array. Assuming they get to Arkyd 200 (telescopes with propulsion) by about 2020 they will be able to use the hundreds of space telescopes at L2 to create a massive hypertelescope array to image exoplanets. Resolution could get to the kilometer level. They will be able to image neutron stars at 10 meter resolutions (more photons to gather from stars).
* 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.
EXO-EARTH IMAGER (EEI)
* visible “portraits” of exoplanets can be obtained in 30 minutes of exposure, using a 150 kilometer hypertelescope with 150 mirrors of 3 meters.
* 10 km resolution at 4.37 Light years. That’s about what our satellite photos took back in the 1960’s. Certainly high enough resolving power to image landforms, islands, forests, whatever else is going on. This would require a hypertelescope array that is 1,500 miles across.
1 kilometer resolution would be a hypertelescope array about 10,000 miles across. That would mean a 100 million pixel image of an exoplanet.
* To resolve 30 foot 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]