Structural disturbances of the lunar surface caused by spacecraft

Abstract

From the lunar surface survey performed with a narrow angle camera of the Lunar Reconnais sance Orbiter (LRO) spacecraft, the distributions of the phase ratios of the Apollo 11 and 12 landing sites and the Ranger 9 impact site were mapped. In the acquired images, the traces of the structural disturbances of the lunar regolith layer caused by the jet flows are seen. In the Ranger 9 impact site, one can see the crater of about 15 m across with a ray system, which is hardly noticeable in the brightness picture, but has a high contract in the phase ratio picture. The character of the photometric anomaly of the rays of this crater shows that they are formed by the ejected stones composing the rugged relief, which induces a strong shadow effect. At the same time, the influence of jet flows from the rocket engines smooths the relief and leads to the photometric anomaly of the opposite sign. The estimate of the maturity degree of the lunar regolith in the Apollo 11 and 12 landing sites obtained from the SELENE spectral survey suggests that the depth of the influence of the rocket engines on the soil is small, and the surface of the impact crater formed by the Ranger 9 spacecraft con tains a large amount of the immature soil.

Extensive Lunar Surface Disturbance at the Chang'e‐5 Mission Landing Site: Implications for Future Lunar Base Design and Construction

“…The initial blast zone, formed by rocket plumes during the powered descending procedure, is approximately circular in outline, with some small marginal lobes (Figure 7b). The circular shape of this landing blast zone is similar to those of the Apollo missions (Clegg et al., 2014; Kaydash & Shkuratov, 2012; Kaydash et al., 2011) but differs from the elongated Chang'e‐3 blast zone (Clegg‐Watkins et al., 2016). The elongation of the Chang'e‐3 blast zone has been interpreted as the result of maneuvering during the hovering and obstacle avoidance stage at a height of ∼100 m (Clegg‐Watkins et al., 2016).…”

Comparing Rocket Exhaust Effects across Lunar Landing Sites Using LRO Narrow Angle Camera images

“…Areas of increased reflectance are seen at all landing sites, and we interpret them as areas disturbed by rocket exhaust (Kaydash et al, 2011;Kaydash et al, 2012;Clegg et al, 2014a). Plotting blast zone area versus lander dry mass, we find that the Apollo, Luna, and Surveyor BZ areas scale exponentially with lander mass (Figure 4).…”

Understanding and Mitigating Plume Effects During Powered Descents on the Moon and Mars

“…Observations of morphological changes (erosion in clods, surface smoothing) and changes in grain size occurring in the landing zone (Metzger et al, 2011;Kaydash et al, 2011;Clegg et al, 2014), and of the disturbance of surface regolith extending up to hundreds of meters away from the spacecraft, elevate the need for surface mobility by rovers or crew as essential for gathering pristine surface soil samples. Although the Apollo exhaust plumes only excavated regolith to a depth of a few centimeters (Kaydash and Shkuratov, 2012), it is important to consider surface alterations when planning missions that will take samples or study surface features in the immediate vicinity of the lander. The plume also injects volatiles into the local environment, some of which could migrate into cold traps and be measured by instruments that are directed at understanding the volatile distribution in permanently shadowed regions (PSRs) (Shipley et al, 2014).…”