DARPA Moire Project Seeks Real-Time Space Imaging

by edward wright

Hollywood loves to imagine military systems with all sorts of capabilities that do not exist in the real world. One of their favorites is the satellite that’s able to hover over a target and rely high-resolution images back to a ground station on Earth.

This is not possible in the real world because current imaging satellites are in Low Earth Orbit, move on fixed flight paths, and see only a small part of the Earth at any given time.

That’s not to say that warfighters wouldn’t like to have something resembling those fictional abilities. DARPA’s SeeMe project (Space Enabled Effects for Military Engagements) is currently attempting to develop such a capability using a constellation of small, low-cost imaging satellites that can be deployed in large numbers. The US Army Space and Missile Defense Command is trying a similar approach in three small satellite programs, Kestrel Eye, NanoEye, and SATS.

An alternative approach would place an imaging satellite in geosynchronous orbit. A geosynchronous imaging satellite would have a clear advantage in providing constant wide-area coverage. It would also be a difficult target for antisatellite (ASAT) weapons. Technically, however, a geosynchronous satellite presents a major challenge. Because of its much higher altitude, a geosynchronous imaging satellite would need a very large primary aperture to get good-resolution images.

A conventional mirror or lens with required diameter would be too heavy and too big to launch from Earth, in addition to being expensive to fabricate. DARPA’s Membrane Optic Imager Real-Time Exploitation (MOIRE) project is attempting to develop an alternative: a lightweight membrane etched with a diffractive pattern that is used to focus light on a sensor. This new technology promises to be four to five times lighter than a conventional object with the same area. A membrane optic could also fold for launch within a payload shroud, which is difficult to do with a conventional optic.

The MOIRE project is working on a ground-based demonstration than could lead to a future geosynchronous system. The project seeks to develop technologies for manufacturing diffraction membranes up to 20 meters in diameter, large structures to hold the membrane flat, and secondary optical elements to create a complete wide-bandwidth imaging device.

The MOIRE project is now in Phase 2 which seeks to manufacture a section of a five-meter primary optic, along with the required secondary optics for ground tests. In addition, MOIRE will perform an on-orbit test of a small-scale membrane optical system through the United States Air Force Academy’s FalconSAT-7. Last summer, Air Force Academy personnel demonstrated the FalconSAT-7 membrane deployment system during a microgravity flight on a Boeing 727. FalconSAT-7 is scheduled for launch in 2014.

by edward wright

Edward Wright is chairman of the United States Rocket Academy and project manager of Citizens in Space. You can find more articles by Mr. Wright at the Citizens in Space web site.

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