Solar sail progress is difficult to assess

Different materials for solar sails with wide variation in capability are all in development. The lighter the sail then the faster it will accelerate.
This link has a table which shows the different speeds possible with different accelerations.

The carbon nanotube sail has the highest potential. 1 square kilometer 30 kg or 0.03 grams per square meter

Other work is for rudimentary metal sail with low size (70 square meter sail) and high weight (thus low performance with 20 g per square meter.)

Size and weight make a huge difference in performance.

From 2000 there was what seemed like a promising and simple approach.

Thicker carbon but still 5 grams per square meter

The New Energy systems material is now 3 grams per square meter. The New Energy system material has the advantage of being stiffer and able to support itself and hold a shape.

If you have a nanofactory or anything close that means the top end of the carbon nanotube solar sail performance should fall out as a precursor capabilitity.

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