Membrane spacecraft with 7.7 kW/kg power-to-weight ratio and 4000 ISP

A ‘brane’ is a dynamical object that can propagate through spacetime. Flattening a spacecraft into a membrane, or 2-brane, can produce a low mass vehicle with ultra-high power-to-weight ratio (7.7 kW/kg using thin film solar cells). If most of this power is used by an array of thinned, distributed electrospray thrusters with a specific impulse of 4000 s, a Brane Craft could start in low Earth orbit, land on Phobos, and return to low Earth orbit.

Other possible targets include any near-Earth asteroid and most main belt asteroids. Propellant is stored as a liquid within a 10-micron wide gap between two Kapton sheets that form the main structure of the Brane Craft.

This NASA NIAC project will study how to design an ultra-light dynamic membrane spacecraft, with 3-axis attitude determination and control plus navigation, that can significantly change both its shape and orbit. Conventional sensors like star trackers will have to be replaced by 2-dimensional alternatives. Estimated mass is about 35 grams for a 1 square meter Brane Craft.

The target application is removal of orbital debris in low Earth orbit (LEO) through rendezvous, contact, conformal wrapping, and application of thrust. Sending conventional spacecraft, even 1-to-5 kg CubeSats, to each of the thousands of 10-cm or larger debris objects for active deorbiting becomes prohibitively expensive.

With current CubeSat launch costs of ~$250,000 for a 3U CubeSat with ~kilometer/s delta-V propulsion and 3-axis attitude control, the U.S. would spend close to billion dollars in launch costs alone to remove 4 thousand debris objects. Brane Craft could significantly reduce that cost and enable removal of more objects.

Brane Craft rendering
During the last decade, researchers at The Aerospace Corporation have pioneered the development of nano­satellites (1–10 kilo­grams) and picosatellites (0.1–1 kilo­grams). These ultra-small spacecraft can be fabricated quickly and launched into space for less than $100,000 as secondary payloads. They are ideal platforms for flight-testing micro- and nano­technologies, new materials and sensors, and advanced spacecraft software.



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