Phil Chu

Robotic Drill Systems for Planetary Exploration

The objective of the systems described in this report was to demonstrate that lowpowered drill systems could be fully autonomous in capturing subsurface samples, handing off samples to science instruments, and drilling. Two drills were designed with a logically selected suite of sensors and hardware which allowed for data to be collected both above and below the surface. Information received from these sensors was fed back to an intelligent drill control system to enable autonomy. Testing of these two drills at Mars analog sites demonstrated that fully autonomous drilling is possible with low-powered drill systems.

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.

Prototype rotary percussive drill for the Mars Sample Return mission

Since 1990s Honeybee Robotics has been developing and testing surface coring drills for future planetary missions. Recently, we focused on developing a rotary-percussive core drill for the 2018 Mars Sample Return mission and in particular for the Mars Astrobiology Explorer-Cacher, MAX-C mission. The goal of the 2018 MAX-C mission is to acquire approximately 20 cores from various rocks and outcrops on the surface of Mars. The acquired cores, 1 cm diameter and 5 cm long, would be cached for return back to Earth either in 2022 or 2024, depending which of the MSR architectures is selected. We built a testbed coring drill that was used to acquire drilling data, such as power, rate of penetration, and Weight on Bit, in various rock formations. Based on these drilling data we designed a prototype Mars Sample Return coring drill. The proposed MSR drill is an arm-mounted, standalone device, requiring no additional arm actuation once positioned and preloaded. A low mass, compact transmission internal to the housing provides all of the actuation of the tool mechanisms. The drill uses a rotary-percussive drilling approach and can acquire a 1 cm diameter and 5 cm long core in Saddleback basalt in less than 30 minutes with only ∼20 N Weight on Bit and less than 100 Watt of power. The prototype MSR drill weighs approximately 5 kg1,2.

Mars drill for the Mars sample return mission with a Brushing and Abrading bit, regolith and powder bit, core PreView Bit and a coring bit

The first mission in the Mars Sample Return campaign is the 2018 Mars Astrobiology Explorer-Cacher (MAX-C) rover. Its goal is to acquire rock cores and regolith samples, hermetically seal them inside a cache, and leave the cache to be collected at a later stage. To help analyzing of rock samples in-situ before returning them to earth, we have developed five bits: a combined Brushing and Abrading Tool (BAT), a core PreView Bit, a Powder and Regolith Acquisition Bit (PRAB), and finally the Caching bit for acquiring rock cores ~ 1 cm diameter and 5 cm long for sample return. The BAT uses the same approach as the Rock Abrasion Tool on the Mars Exploration Rovers to brush and abrade rocks. The PreView bit acquires a 2.5 cm long core which can be viewed through the slot inside the bit or placed onto an observation tray. The PRAB acquires rock powder during the drilling process or regolith sample. The sample can be stored for sample return or dispensed into an instrument cup. The PRAB has integrated sieves and can either acquire particles below certain diameter or retain particles above certain diameter. All the bits are deployed using the same drill. This paper reports on the development and testing of these bits as well as trade study investigating optimum core dimension.

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.

Mobile In-Situ Water Extractor (MISWE) for Mars, Moon, and Asteroids In Situ Resource Utilization

In-Situ Resource Utilization (ISRU) facilitates planetary exploration by drawing needed resources, such as water, from the local environment. This work presents a 3-step in-situ water recovery approach: 1) mining the soil using deep fluted auger, 2) extracting the water from soil within the flutes, and 3) discarding the soil before transporting the water to a main storage facility. Drilling in icy soil and ice has already been demonstrated in vacuum chambers by the authors. This paper focuses on the second critical step: water extraction from the icy soil or ice within the deep flutes. This paper reports on tests demonstrating efficient collection of water from ice-bearing soil under Mars conditions. The water recovery Mobile In Situ Water Extractor (MISWE) breadboard collected as much as 92% of the water initially present in the soil, and required as little as 0.9 Whr/g of energy (80% efficient compared to theoretical). The extraction process took approximately 40 min.

Development of the Brushing, Abrading, Regolith, Core PreView and the Coring Bits for the Mars Sample Return Mission

The National Aeronautics and Space Administration (NASA) and the European Space Agency (ESA) are developing a Mars Sample Return Mission (MSR) campaign of three missions starting with the 2018 Mars Astrobiology Explorer-Cacher (MAX-C) mission. The MAX-C would acquire rock cores and regolith samples into a cache, and leave the cache on the ground. At a later stage this cache would be collected and returned to Earth by another mission. In order to select the most suitable sets of rocks for sample return, the rocks have to be analyzed in situ (as is done on MER). To aid this process, we have developed five bits: a brushing bit, an abrading bit, a core preview bit, a powder and regolith acquisition bit, and finally the core bit for acquiring rock cores ~ 0.7-1 cm diameter and 5-10 cm long for sample return. All these bits would be deployed from the same drill. This paper presents development stages of these bits and testing them with a drill deployed from a robotic arm and inside a Mars chamber. The test rocks used were Kaolinite, limestone, and basalt.

Mars2020 sample acquisition and caching technologies and architectures

The goal of the Mars2020 mission is to acquire up to 28 rock/regolith samples and 3 blanks (or 34 rock/regolith samples and 3 blanks), and cache these for the future sample return mission. Honeybee Robotics investigated three architectures; however only two showed promise. In the One Bit One Core (OBOC) architecture, individual drill bits with core samples are cached. This is the least complex architecture and results in the total mass (cache+bits+rocks) of less than 2 kg and Orbital Sample diameter of 19 cm for the 31 cores case and slightly more (<;2.4 kg cache and 20 cm OS) for the 37 cores. In the One Breakoff System One Core (OBSOC) architecture, the breakoff tube and the sleeve with cores are removed from the drill bit and cached. The architecture also uses one time use bit assemblies (plus spares). This architecture results in the lowest cache mass and OS diameter but the trade is complexity and sampling system mass. The OBSOC cache mass is ~1.5 kg and ~1.86 kg for the 31/37 cases respectively, while the OS diameter is 17 cm and 17.5 cm for the 31/37 cases respectively. All architectures use SLOT bit that allows inspection of rock samples along their lengths prior to caching. The paper also introduces several key technologies developed by Honeybee Robotics over the past 15 years, including the SLOT caching bit, the Powder and Regolith Acquisition Bit, Rock Abrasion and Brushing Bit (RABBit), PreView Bit, Percussive and Core Breakoff technologies.

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.

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.