Philip Chu

Percussive digging systems for robotic exploration and excavation of planetary and lunar regolith

A percussive digging system has been demonstrated to decrease the amount of downforce needed to penetrate a given soil, thus reducing the required reaction loads and robot mass. Preliminary testing of a percussive digging system in compacted lunar regolith simulant, JSC-1A, has demonstrated a 15x (fifteen times) reduction in the downforce necessary to penetrate the regolith. Downforce reductions of this magnitude are sufficient to enable robotic exploration system architectures that would not otherwise be feasible.

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.

Novel method of regolith sample return from extraterrestrial body using a puff of gas

Future sample return missions to the Moon, asteroids, and in particular, Mars seek reliable and inexpensive methods of returning uncontaminated samples back to Earth. Sample return from the Moon has already been demonstrated in the 1960s and 1970s by US Apollo and Soviet Luna missions; study of these samples in earth laboratories resulted in a quantum leap in planetary science. As opposed to sample return from the Moon, sample return from Mars presents much greater challenges mainly because of the presence of the atmosphere, and sheer distance from the Earth. To reduce a mission complexity and cost, we propose a novel, low risk and actuator-free sample return of Martian regolith, dust and atmosphere. In the proposed scheme, a sample of regolith is acquired directly into a return vehicle using a pneumatic system1 2. We envisage 3 pneumatic tubes to be embedded inside the 3 legs of the lander (for redundancy). Upon landing, the legs will bury themselves into the surface and the tubes will fill up with regolith (and ice, if present). With one puff of gas injected at the base of the tubes, the sample will be lofted into a sampling chamber onboard the return vehicle. An additional chamber can acquire atmospheric gas and dust. The sample return will require only 1) a mechanism to open/close a sampling chamber and 2) a valve to open a gas cylinder.

The Phoenix Mars Lander Robotic Arm

The Phoenix Mars Lander Robotic Arm (RA) has operated for 149 sols since the Lander touched down on the north polar region of Mars on May 25, 2008. During its mission it has dug numerous trenches in the Martian regolith, acquired samples of Martian dry and icy soil, and delivered them to the Thermal Evolved Gas Analyzer (TEGA) and the Microscopy, Electrochemistry, and Conductivity Analyzer (MECA). The RA inserted the Thermal and Electrical Conductivity Probe (TECP) into the Martian regolith and positioned it at various heights above the surface for relative humidity measurements. The RA was used to point the Robotic Arm Camera to take images of the surface, trenches, samples within the scoop, and other objects of scientific interest within its workspace. Data from the RA sensors during trenching, scraping, and trench cave-in experiments have been used to infer mechanical properties of the Martian soil. This paper describes the design and operations of the RA as a critical component of the Phoenix Mars Lander necessary to achieve the scientific goals of the mission.

Pyramid Comet Sampler (PyCoS)

Future sample retuns missions from comets and small bodies require a sample acquisition system that can deal with a range of material strength and still satisfy a mimimum sample volume. To address these two requirements, Honeybee Robotics developed a piercing-style sampling system called Pyramid Comet Sampler (PyCoS). PyCoS falls into a family of sample capture systems that use piercing blades. Such systems could potentially include 2 or more blades. The ‘piercing blades’ systems are used every day as posthole diggers and tree spades. During our research we investigated a number of blade designs for 3 (Tetrahedron) and 4 blade (Pyramid) geometries. We designed and built experimental fixtures for a single shot and percussive approach of driving blades into subsurface. Test results demonstrate that it is possible to penetrate >10 cm depth in materials as strong as 4 MPa with energies per blade that can be generated by a Rosetta harpoon pyrotechnic device. Percussive systems, on the other hand, cannot penetrate 4 MPa materials with 2.5 J/blow hammer energy. Therefore, a single, high energy impact is the most robust approach to sample capture using piercing blades approach.

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).

Dust-tolerant mechanism design for lunar & NEO surface systems

NASA has grand goals including exploring extraterrestrial bodies such as near-earth objects (NEOs) in order to better understand our origins as well as protect Earth from space-based threats.1 Robotic precursor missions and eventually manned exploration will require advanced dust-tolerant mechanisms if long-life and low-risk missions are to be attained.

Dust-Tolerant Connector Development for Lunar Surface Systems

Honeybee Robotics Spacecraft Mechanisms Corporation is currently developing quickdisconnect (QD) utility connectors that tolerate and mitigate lunar dust accumulation. Dust, especially lunar dust, has been identified as a significant and present challenge in future exploration missions. Development is currently focused on two applications including: (1) a manual utility connector for the Constellation Program (CxP) configuration two spacesuit’s battery recharge; and (2) an autonomous utility connector for small pressurized rover battery recharge. A myriad of additional lunar surface systems would benefit equally from this technology including cryogenic fluid connections for in-situ resource utilization and autonomous tool-change for robotic platforms. Prototype dust-tolerant connectors have been tested in the presence of JSC-1AF lunar simulant at 1 torr; resulting in design validation as well as design revisions. In addition, Honeybee is also developing an environmental test chamber capable of simulating the conditions on the lunar surface. To be operational in 2010, the DUsty environment Simulation Test (DUST) chamber will be rated to 10 torr and have capabilities including high-temperature bake-out, plasma cleaning, and residual gas analysis to sufficiently prepare and monitor lunar simulant conditions. A dusttolerant utility connector for CxP lunar surface systems is an enabling technology that is broadly applicable; bridging the gap between mission/systems planning, and actual capabilities. The dust-tolerant technologies that Honeybee is developing will enable extended surface operations; advancing our ability to obtain meaningful science during initial manned missions and extended crew stays at the planned lunar outpost.

Pneumatic Drilling and Excavation in Support of Venus Science and Exploration

Venus is considered to be Earth’s sister planet hence we can learn a lot about Earth by investigating Venus tectonics, volcanism, and atmosphere. As opposed to Mars which lost most of its atmosphere but retained a lot of water, Venus has extremely dense and hot, carbon dioxide atmosphere (95 % CO2, >90 atm pressure, and ~480 °C temperature) and lost most of its water. One day Earth could end up looking just like Venus or Mars. Mars has been mapped by multitudes of spacecraft and we learn more about that planet each year. In comparison, understanding of Venus is relatively poor. The science objectives for Venus exploration are expressed in various reports by the Venus Exploration Analysis Group (Vexag 2014).

Field Testing of a Pneumatic Regolith Feed System During a 2010 ISRU Field Campaign on Mauna Kea, Hawaii

Lunar In Situ Resource Utilization (ISRU) consists of a number of tasks starting with mining of lunar regolith, followed by the transfer of regolith to an oxygen extraction reactor and finally processing the regolith and storing of extracted oxygen. The transfer of regolith from the regolith hopper at the ground level to an oxygen extraction reactor many feet above the surface could be accomplished in different ways, including using a mechanical auger, bucket ladder system or a pneumatic system. The latter system is commonly used on earth when moving granular materials since it offers high reliability and simplicity of operation. In this paper, we describe a pneumatic regolith feed system, delivering feedstock to a Carbothermal reactor and lessons learned from deploying the system during the 2010 ISRU field campaign on the Mauna Kea, Hawaii.