Dust science from the Lunar Gateway

Various dust populations reside in the solar system. Depending on their origin, we can distinguish between interplanetary dust particles (IDP) and interstellar dust (ISD). Besides the sporadic interplanetary dust, there are IDP populations with special dynamical properties: nanodust is easily influenced by magnetic fields, beta-meteoroids are pushed away from the Sun through the solar radiation pressure and become interstellar, and larger cometary dust forms streams that slowly deviate from the orbit of the parent body.

Interstellar dust is assumed to enter the solar system from the direction of motion of the Sun with respect to the interstellar medium. Dust grains acquire a charge in a space environment and are hence sensitive to magnetic fields. While large micron-sized ISD grains are nearly unaffected, small nanometer-sized ISD grains can therefore not enter the solar system. Every 11 years, at the minimum of the solar cycle, mid-sized ISD gets alternately focused or defocused from the ecliptic plane through the influence of the solar wind magnetic field on the charged dust trajectories. Last but not least, impacts on the lunar surface generate a lunar dust cloud through the impact-ejecta process. The Lunar Gateway is a space station concept orbiting the Moon in a near-rectilinear halo orbit with periapsis about 1’500 km and apoapsis about 70’000 km above the lunar surface. The Lunar Gateway offers a platform to perform in-situ measurements of various dust populations at 1 AU in the vicinity of the Moon and in the free solar wind, an environment much more pristine than the environment near to the Earth. The Lunar Gateway should be operative in the 2030s, simultaneously with the next focusing phase of interstellar dust, which only occurs every 22 years.

We present the science case of a dust detector package on the Lunar Gateway, and the expected dust fluxes of the different dust populations. To conclude, we show which instrumentation could be used to achieve the science goals.