A Brane Craft is an ultra-thin spacecraft (~55 microns)
• It weighs about 80 grams, yet can deorbit up to 2 kg
• It may be mass-produced
• Potential 100X decrease in orbit cleanup costs
• Many other potential uses:
– Asteroid inspectors
– Asteroid re-directors (multiple per asteroid, dock or high speed impact)
– Planetary and lunar orbiters
• Significant technology development is required in NASA NIAC Phase II
An initial concern was that thin-film solar cells and electronics could not provide a radiation tolerance of up to 10 megarads total integrated dose (TID). Thin film Copper Indium Gallium Selenide (CIGS) solar cells and thin film carbon nanotube and ZnO transistors have the required TID radiation tolerance. The transistors are also fast enough to enable an 8 million instruction-per second microprocessor using a 10-micron fabrication process. Concerns over small-particle penetration rates dropped the minimum feature size to 5 microns to reduce the impact probability of the 8 MIPS processor to below 10% per month. The solar cell strings are impact-tolerant.
The basic Brane Craft design has distributed arrays of nano-electrospray thrusters that use an ionic liquid propellant. About 1 cm2 of electrospray thruster area is required to process the 180 W of DC power for propulsion generated by thin film solar arrays deposited over most of the 1-square meter surface. Ionic liquids have essentially zero vapor pressure, and the propellant is stored in the ~10-micron gap between two sheets of Kapton®. This Brane Craft design could generate a total of 8.2 millinewtons of thrust at 4000 s specific impulse under full sunlight at 1 astronomical unit (A.U.) from the sun. At 45-grams mass Brane Craft could accelerate at 0.18 m/s2; at least 100 times faster than a conventional electrically-propelled spacecraft.
Later versions of Branecraft could be thinner, have higher power (with beamed power) and have ion thrust up to 58,000 seconds.