Book reviews

Teaching/Communication/Extension/Profession,

A space-based laser system for the deflection and manipulation of near Earth asteroids

Abstract Analysis gained from a series of experiments has demonstrated the effectiveness of laser ablation for the low thrust, contactless deflection and manipulation of Near Earth Asteroids. In vacuum, a 90 W continuous wave laser beam has been used to ablate a magnesium-iron silicate sample (olivine). The laser operated at a wavelength of 808 nm and provided intensities that were below the threshold of plasma formation. Olivine was use to represent a rocky and solid asteroidal body. Assessed parameters included the average mass flow rate, divergence, temperature and velocity of the ejecta plume, and the height, density and absorptivity of the deposited ejecta. Experimental data was used to verify an improved ablation model. The improved model combined the energy balance of sublimation with the energy absorption within the Knudsen layer, the variation of flow with local pressure, the temperature of the target material and the partial re-condensation of the ablated material. It also enabled the performance of a space-based laser system to be reassessed. The capability of a moderately sized, conventional solar powered spacecraft was evaluated by its ability to deflect a small and irregular 4 m diameter asteroid by at least 1 m/s. Deflection had to be achieved with a total mission lifetime of three years. It was found to be an achievable and measurable objective. The laser (and its associated optical control) was designed using a simple combined beam expansion and focusing telescope. The mission study therefore verified the laser’s proof-of-concept, technology readiness and feasibility of its mission and subsystem design. It also explored the additional opportunistic potential of the ablation process. The same technique can be used for the removal of space debris

Light-touch2 : a laser-based solution for the deflection, manipulation and exploitation of small asteroids

This paper presents the preliminary mission and system analysis of a small-scale, light-weight system for the deflection, manipulation and exploitation of small size asteroids. The system proposed in this paper, called Light-Touch2, uses lasers to ablate the surface of an asteroid and induce a low thrust modification of its orbit. The system is applied to the deflection of a small size asteroid, 2-4 m in diameter, 130 tons in mass. It will be demonstrated that a laser system powered by conventional solar arrays can produce enough thrust to change the velocity of the asteroid by 1 m/s in less than 3 years. The current mission and system design to implement the Light-Touch2 concept envisage the use of a small class spacecraft, called AdAM (Asteroid Ablation Mission), which will fly in formation with the asteroid and apply laser ablation for a suitably long time. In the paper, the Light-Touch2 concept is compared against other known contactless deflection systems. Assessed qualities include momentum coupling and mass efficiency. The system and mission analysis will also be complemented by navigation analysis. A combination of ground-based and onboard optical measurements will be used to provide the required accuracy to fly in formation with the asteroid and to measure the deflection. The paper will therefore present the preliminary spacecraft system analysis and the preliminary transfer and navigation analysis

A Novel Penetration System for in Astrobiological Studies

Due to ultraviolet flux in the surface layers of most solar bodies, future astrobiological research is increasingly seeking to conduct subsurface penetration and drilling to detect chemical signature for extant or extinct life. To address this issue, we present a micro-penetrator concept (mass < 10 kg) that is suited for extraterrestrial planetary deployment and in situ investigation of chemical and physical properties. The instrumentation in this concept is a bio-inspired drill to access material beneath sterile surface layer for biomarker detection. The proposed drill represents a novel concept of two-valve-reciprocating motion, inspired by the working mechanism of wood wasp ovipositors. It is lightweight (0.5 kg), driven at low power (3 W), and able to drill deep (1-2 m). Tests have shown that the reciprocating drill is feasible and has potential of improving drill efficiency without using any external force. The overall penetration system provides a small, light and energy efficient solution to in situ astrobiological studies, which is crucial for space engineering. Such a micro-penetrator can be used for exploration of terrestrial-type planets or other small bodies of the solar system with the minimum of modifications

Planetary micro-penetrator concept study with biomimetric drill and sampler design

Due to ultraviolet flux to the surface layers of most solar system bodies, future astrobiological research is increasingly seeking to conduct subsurface penetration, drilling and sampling to detect chemical signature of extant or extinct life. To seek a compact solution to this issue, we present a micro-penetrator concept (mass < 10 kg) that is suited for planetary deployment and in situ investigation of chemical and physical properties. To draw inspiration from nature, a biomimetic drill and sampler subsystem is designed as a penetrator instrument based on the working mechanism of a wood wasp ovipositor to sample beneath the sterile layer for biomarker detection. One of the major limitations of sampling in relatively low gravity environments (such as asteroids, Mars, etc) is the need for high axial force when using conventional drills. The ovipositor drill is proposed to address this limitation by applying a novel concept of reciprocating motion that requires no external force

A novel penetration system for in situ astrobiological studies

Due to ultraviolet flux in the surface layers of most solar bodies, future astrobiological research is increasingly seeking to conduct subsurface penetration and drilling to detect chemical signature for extant or extinct life. To address this issue, we present a micro-penetrator concept (mass < 10 kg) that is suited for extraterrestrial planetary deployment and in situ investigation of chemical and physical properties. The instrumentation in this concept is a bio-inspired drill to access material beneath sterile surface layer for biomarker detection. The proposed drill represents a novel concept of two-valve-reciprocating motion, inspired by the working mechanism of wood wasp ovipositors. It is lightweight (0.5 kg), driven at low power (3 W), and able to drill deep (1-2 m). Tests have shown that the reciprocating drill is feasible and has potential of improving drill efficiency without using any external force. The overall penetration system provides a small, light and energy efficient solution to in situ astrobiological studies, which is crucial for spac

A space-based laser system for the deflection and manipulation of near Earth asteroids

bstract Analysis gained from a series of experiments has demonstrated the effectiveness of laser ablation for the low thrust, contactless deflection and manipulation of Near Earth Asteroids. In vacuum, a 90 W continuous wave laser beam has been used to ablate a magnesium-iron silicate sample (olivine). The laser operated at a wavelength of 808 nm and provided intensities that were below the threshold of plasma formation. Olivine was use to represent a rocky and solid asteroidal body. Assessed parameters included the average mass flow rate, divergence, temperature and velocity of the ejecta plume, and the height, density and absorptivity of the deposited ejecta. Experimental data was used to verify an improved ablation model. The improved model combined the energy balance of sublimation with the energy absorption within the Knudsen layer, the variation of flow with local pressure, the temperature of the target material and the partial re-condensation of the ablated material. It also enabled the performance of a space-based laser system to be reassessed. The capability of a moderately sized, conventional solar powered spacecraft was evaluated by its ability to deflect a small and irregular 4 m diameter asteroid by at least 1 m/s. Deflection had to be achieved with a total mission lifetime of three years. It was found to be an achievable and measurable objective. The laser (and its associated optical control) was designed using a simple combined beam expansion and focusing telescope. The mission study therefore verified the laser’s proof-of-concept, technology readiness and feasibility of its mission and subsystem design. It also explored the additional opportunistic potential of the ablation process. The same technique can be used for the removal of space debris