Magnus Hedlund

Novel Approaches to Drilling and Excavation on the Moon

The extraction of top surface and also of highly compacted material on the lunar surface is critical to the success of long term utilizat ion of resources for the production of oxygen, water and other consumables needed for propulsion and life support systems as well as for other ‘civil’ engineering applications such as building berms, roads, trenches. In-Situ Resource Utilization (ISRU) will become even more critical if the lunar polar craters are found to contain water ice. Apollo data clearly indicates highly compacted soil at shallow depths on the lunar surface, for which there is no existing experience in effective excavation under the vacuum and partial gravity environment. In this paper, we discuss two novel approaches for regolith excavation and transport. These include pneumatic and percussive systems. The main advantage of the pneumatic system is in efficient regolith transport (with 1 gram of gas at 3 psia over 6000 grams of soil can be lifted) while the main advantage of the percussive system is in reducing excavation fo rces by up to 40x. Both systems offer many advantages when used alone but also can be combined into a single highly synergistic system. For example, a percussive scoop could be integrated with the pneumatic lift of particles and the nozzle of the pneumatic excavator could be integrated with the percussive mechanism to enhance its deeper excavation capabilities.

Pneumatic Excavator and Regolith Transport System for Lunar ISRU and Construction

In this paper, we discuss our initial experimental results and preliminary theoretical model for transporting fine regolith particles as would be found in planetary environments (lunar or Mars) using high Mach number excitation, low pressure gases in tubing. This technique, coined “vacuum jet-lift method” selectively excites particles through transfer of gas momentum into the particles in the vicinity of a gas injection head. The resultant dustygas flow is subsequently transported along a tube containing the particles as the gas attempts to ultimately escape into the low pressure environment (controlled exit port to local atmosphere). At the gas injection point, a “leaky” seal between the injector and regolith or soil is permitted that allows some gas loss. The head loss through this leaky seal must be much greater than head loss through the rest of the transport system. We discuss experimental tests in ~5 torr atmosphere demonstrating regolith-mass-to-gas-mass transport efficiencies exceeding 1000:1 utilizing this technique. We also describe a theoretical model for scaling that demonstrates much higher efficiencies are achievable with lower pressure gases. Once the particles are entrained in the gas, the carrier gas can also be used to efficiently heat the particles as compared to attempting to drive heat flow directly through the highly insulating regolith.

Five-Step Parametric Prediction and Optimization Tool for Lunar Surface Systems Excavation Tasks

NASA systems engineers require an accurate assessment of excavator mass, power and energy requirements to correctly design lunar surface systems’ overall architecture. In order to properly determine excavator mass and energy for various excavation tasks, we recommend a 5-step process. It starts with selection of appropriate soil that is analogous to lunar regolith. The second step refers to soil preparation methods; the desire is to make the soil’s relative density similar to in-situ lunar regolith’s relative density. The third step requires measuring excavation forces by deploying instrumented digging end effectors in carefully prepared soil bins and preferably in vacuum. After forces are measured, they need to be scaled for lunar gravity. The scaling factor varies depending on soil properties (cohesion and friction angle) and also on the size of an excavating blade/scoop. Once the forces are scaled they can be used to accurately estimate excavators’ parameters for various tasks. This paper describes in detail all of the 5 steps mentioned above.

Investigating the Efficiency of Pneumatic Transfer of JSC-1a Lunar Regolith Simulant in Vacuum and Lunar Gravity During Parabolic Flights

Pneumatic (gas-driven) particle transfer is widely used in terrestrial applications for moving fines and coarse particulates. Its major advantage is the lack of moving parts, which otherwise would clog or jam, and ease of guiding the dusty gas stream across long distances and variable trajectories. Because lunar soil is highly abrasive, this transfer system is especially desirable in applications such as feeding regolith to the Oxygen reactor in alunar In Situ Resource Utilization plant. In this paper, we report on the experiments performed in vacuum and at lunar gravity during parabolic flights, to determine whether a pneumatic lift system could be feasible for lunar applications. We found that with 18 milligrams of Nitrogen gas at 3 psia, almost 100 grams of soil was successfully lifted at high velocity. This represents a mass efficiency of 1:5500. The required gas could be supplied in the form of Helium widely used as a pressurant in a lander’s propulsion system or a lander’s residual propellant could be burned in a small rocket thruster to provide hot gasses. The gas could also be recycled and in turn enhance the systems’ efficiency.

Asteroids: Anchoring and Sample Acquisition Approaches in Support of Science, Exploration, and In situ Resource Utilization

The goal of this chapter is to describe technologies related to asteroid sampling and mining. In particular, the chapter discusses various methods of anchoring to a small body (a prerequisite for sampling and mining missions) as well as sample acquisition technologies and large scale mining options. These technologies are critical to enabling exploration, and utilization of asteroids by NASA and private companies.

Sample Acquisition and Caching Architectures for the Mars 2020 Rover Mission

We present two architectures for sample acquisition and caching for the upcoming Mars 2020 rover mission. Both architectures use a ‘one bit one core’ caching approach whereby each rock core sample is acquired with a new bit and subsequently cached with that bit. The sampling system has as many bits as the required number of returnable samples (plus extras). Hermetic seals are achieved by screwing the bit into a sleeve within the cache. In the first architecture, one drilling system is used in conjunction with a number of detachable tools. These tools include a Rock Abrasion and Brushing Tool (RABBIT) for brushing and abrading of rocks in a similar manner as Rock Abrasion Tool (RAT) on Mars Exploration Rovers (MER), a Preview Bit for viewing of cores in situ, a Powder and Regolith Acquisition bit (PRABit) for acquisition of rock powder/regolith for instruments and for sample return, and a SLOT bit for acquisition of returnable core samples. The SLOT bit allows observing and analysis of the core sample along its length and estimation of its volume. If deemed to be of high enough scientific value, the SLOT bit with the sample can be deposited in a cache and hermetically sealed. The second architecture uses a standalone RAT, similar to the RAT on the MERs, and a drill system with the SLOT bit and the PRABit. To capture regolith for sample return, the PRABit can be used as before.

Axel rover NanoDrill and PowderDrill: Acquisition of cores, regolith and powder from steep walls

This paper describes development and testing of low-mass, low-power drills for the Axel rover. Axel is a two-wheeled tethered rover designed for the robotic exploration of steep cliff walls, crater walls and deep holes on earth and other planetary bodies. The Axel rover has a capability to deploy scientific instruments and/or samplers in the areas of interest to scientists currently inaccessible by conventional robotic systems. To enable sample recovery, we developed two drills: NanoDrill for acquisition of 25 mm long and 7 mm diameter cores and PowderDrill for acquisition of either in situ regolith/soil or drilled cuttings from depths of up to 15 mm. Both drills have been successfully tested in laboratory in limestone and sandstone rocks and on-board the Axel rover in the Mars Yard at NASA JPL. The drills managed to acquire limestone and sandstone cores and powder, with an average power of less than 5 Watts. The penetration rate of the NanoDrill was ~2 mm/min and of the PowderDrill it was ~9 mm/min. After sample acquisition, both drills successfully ejected of the acquired samples (cores and powder).

Moon and Mars Analog Mission Activities for Mauna Kea 2012

Rover-based 2012 Moon and Mars Analog Mission Activities (MMAMA) scientific investigations were recently completed at Mauna Kea, Hawaii. Scientific investigations, scientific input, and science operations constraints were tested in the context of an existing project and protocols for the field activities designed to help NASA achieve the Vision for Space Exploration. Initial science operations were planned based on a model similar to the operations control of the Mars Exploration Rovers (MER). However, evolution of the operations process occurred as the analog mission progressed. We report here on the preliminary sensor data results, an applicable methodology for developing an optimum science input based on productive engineering and science trades and the science operations approach for an investigation into the valley on the upper slopes of Mauna Kea identified as “Apollo Valley.”

Resource prospector drill performance during the integrated payload tests

The goal of the Lunar Resource Prospector (RP) is to capture and evaluate volatile species within the top meter of the lunar regolith. The RP drill has been designed to 1. Generate cuttings and place them on the surface for analysis by the Near InfraRed Volatiles Spectrometer Subsystem (NIRVSS), and 2. Capture cuttings and transfer them to the Oxygen and Volatile Extraction Node (OVEN) coupled with the Lunar Advanced Volatiles Analysis (LAVA) subsystem. The drill auger is designed to capture cuttings as opposed to cores. The lower auger section has deep and low pitch flutes for retaining of cuttings. The upper section has been designed to efficiently move the cuttings out of the hole. The drill uses a “bite” sampling approach where samples are captured in ~10 cm intervals. The drill has been integrated with the NASA JSC RP rover prototype and tested in the summer of 2015. This paper describes the drill and test results.

PlanetVac: Pneumatic regolith sampling system

This paper describes a PlanetVac mission concept utilizing a pneumatic system for sample acquisition and delivery, and the design and testing of a prototype system. The lander uses sampling tubes embedded within each lander foot pad. Each tube can deliver in excess of 20 grams of regolith and small rocks directly into science instruments or a sample return spacecraft for earth return. To demonstrate this mission approach, a small lander with four legs and two sampling tubes has been designed, built, and tested. Testing has been performed in vacuum chamber and with two planetary simulants: Mars Mojave Simulant (MMS) and lunar regolith simulant JSC-1A. One sampling system was connected to an earth return rocket while the second sampling system was connected to a deck mounted instrument inlet port. Demonstrations included a drop from a height of ~50 cm onto the bed of regolith, deployment of sampling tubes, acquisition of regolith into an instrument (sample container) and the rocket, and the launch of the rocket. In all tests, approximately 20 grams of sample has been delivered to the regolith box and approximately 5 grams of regolith has been delivered into a rocket. The gas efficiency was calculated to be approximately 1000:1; that is 1 gram of gas lofted 1000 grams of regolith.