Direct active measurements of movements of lunar dust: Rocket exhausts and natural effects contaminating and cleansing Apollo hardware on the Moon in 1969

Abstract

Dust is the Number 1 environmental hazard on the Moon, yet its movements and adhesive properties are little understood. Matchbox‐sized, 270‐gram Dust Detector Experiments (DDEs) measured contrasting effects triggered by rocket exhausts of Lunar Modules (LM) after deployment 17 m and 130 m from Apollo 11 and 12 LMs. Apollo 11 Lunar Seismometer was contaminated, overheated and terminated after 21 days operation. Apollo 12 hardware was splashed with collateral lunar dust during deployment. DDE horizontal solar cell was cleansed of nominally 0.3 mg cm−2 dust by 80% promptly at LM ascent and totally within 7 minutes. A vertical cell facing East was half‐cleaned promptly then totally over hundreds of hours. Each cell cooled slightly. For the first time lunar electrostatic adhesive forces on smooth silicon were directly measured by comparison with lunar gravity. Analyses imply this adhesive force weakens as solar angle of incidence decreases. If valid, future lunar astronauts may have greater problems with dust adhesion in the middle half of the day than faced by Apollo missions in early morning. A sunproof shed may provide dust‐free working environments on the Moon. Low‐cost laboratory tests with DDEs and simulated lunar dust can use DDE benchmark lunar data quickly, optimising theoretical modelling and planning of future lunar expeditions, human and robotic.