Is laser space propulsion practical?: review

In this paper, we review practical limitations to laser space propulsion that have been discussed in the literature. These are as follows: (1) thermal coupling to the propelled payload, which might melt it; (2) a decrease in mechanical coupling with number of pulses, which has been observed in some cases; and (3) destruction of solar panels in debris removal proposals that might create more debris rather than less. Previously, lack of data prevented definite assessments. Now, new data on multipulse vacuum laser impulse coupling coefficient Cm on several materials at 1064 nm, at 1030 nm, and at 532 nm are available. We are now able to compare the results for single and multiple pulses on materials that have been considered for laser ablation space propulsion (LASP), or that are likely space debris constituents, and decide whether LASP is a practical idea. Laser space propulsion and debris removal concepts depend on thousands or hundreds of thousands of repetitive pulses. Repetitive pulse mechanical coupling as well as thermal coupling (which can melt the target rather than propel it) are both important considerations. Materials studied were 6061T6 aluminum, carbon-doped polyoxymethylene (POM), undoped POM, a yellow POM copolymer, and a mixture of Al and POM microparticles combined and pressed, containing a 50%/50% mixture of the two materials by mass. We address 6 and 70 ps pulses because of the availability of data at these pulse durations. We also briefly consider continuous wave (CW) laser propulsion. Finally, we consider a recent paper concerning solar panel destruction froma positive perspective. (C) 2021 Optical Society of America