Unintended consequences with laser nudging or re-entry of satellites

We measured the impulse coupling coefficient Cm (target momentum per joule of the incident laser light) and ejecta velocity vE with glass-covered Si solar (photovoltaic) cells following the irradiation by repetitive 71 ps, 1064 nm laser pulses at fluence of order 10 J/cm2 in vacuum. We measured high Cm values up to 600 N/MW, but very low specific impulse Isp = vE/go of order 10 s. Thousands of glass particles 20–1500 μm in size were ejected and found on the floor of the vacuum chamber close to the target. At lower fluences, larger pieces were ejected. While pulsed laser coupling data exist on typical metals used for satellite construction, to our knowledge, this is the first data on solar arrays which comprise a large fraction of the total area exposed to a laser pulse intended to nudge or re-enter a satellite. On bare Si, Cm was about two orders of magnitude lower, and no large pieces were dislodged. The consequence of these data are that lasers for nudging or re-entering defunct satellites should be focused carefully on the metal parts, avoiding solar arrays, to avoid creating a cloud of microscopic debris, enhancing rather than ameliorating the space debris problem. Further, data on MLI (multi-layer insulation) and other complex layered structures should be obtained to guarantee against other unintended consequences.