Offloading operations using a Heavy-Lift LSMS

Chariot, LSMS-H, and ESA lunar lander offloading operations.

Sharon A. Jefferies, William R. Doggett
John T. Dorsey, Thomas C. Jones &
Michael E. Haddad
NASA Langley & KSC

Jonathan Chrone, Scott Angster
David A. Helton & Darrell L. Caldwell, Jr.
Analytical Mechanics Associates

This study investigates the feasibility of using a heavy-lift variant of the Lunar Surface Manipulator System (LSMS-H) to lift and handle a 12 metric ton payload. Design challenges and requirements particular to handling heavy cargo were examined. Differences between the previously developed first-generation LSMS and the heavy-lift version are highlighted. An in-depth evaluation of the tip-over risk during LSMS-H operations has been conducted using the Synergistic Engineering Environment and potential methods to mitigate that risk are identified. The study investigated three specific offloading scenarios pertinent to current Lunar Campaign studies. The first involved offloading a large element, such as a habitat or logistics module, onto a mobility chassis with a lander-mounted LSMS-H and offloading that payload from the chassis onto the lunar surface with a surface-mounted LSMS-H. The second scenario involved offloading small pressurized rovers with a lander-mounted LSMS-H. The third scenario involved offloading cargo from a third-party lander, such as the proposed ESA cargo lander, with a chassis-mounted LSMS-H. In all cases, the analyses show that the LSMS-H can perform the required operations safely. However, Chariot-mounted operations require the addition of stabilizing outriggers, and when operating from the Lunar surface, LSMS-H functionality is enhanced by adding a simple ground anchoring system.

Lunar Surface Manipulator System (LSMS) naming conventions.

As we consider returning humans to the Moon with a view towards building an outpost to enable a permanent human presence, it is important to consider the means by which lunar surface system elements and other cargo will be offloaded from the lunar lander as well as handled on the surface. In particular, methods to offload heavy cargos, such as surface habitats, from lunar landers and to manipulate that cargo on the surface of the Moon need to be investigated. Previous studies have focused on using a Lunar Surface Manipulator System1 to offload cargo up to ~ 6 metric tons and the All-Terrain Hex-Legged Extra-Terrestrial Explorer (ATHLETE) for offloading cargos up to the maximum lander capacity. In this study, we investigated the use of a Lunar Surface Manipulator System (LSMS) that has been modified to handle a 12 metric ton payload, which is consistent with the estimated mass of the largest payloads currently used in NASA’s Lunar Campaign Analysis.

This study focused on two key areas: a) identifying necessary design modifications to enable the LSMS to handle the heavier cargo mass and to ensure the LSMS could reach all potential cargos from lander, chassis, and surface mounted locations, and b) analyzing payload handling operations with the Heavy-lift LSMS (LSMS-H) to ensure the operations could safely be performed while avoiding a potential tip over situation. As part of the analysis, preliminary calculations were made to identify the safe operation envelope, or tip over boundaries, for several cargo handling scenarios. These initial calculations helped to identify necessary design modifications to expand the safe-operating zone and reduce the likelihood of tip over. The results were then fed into the Synergistic Engineering Environment (SEE). The SEE was used to simulate each offloading scenario, dynamically calculating the system center of gravity (CG) (assuming a constant gravity field) and comparing the CG location to the tip over boundary.

In addition to the operational focus areas described above, this study also sought to understand the correlation between lunar cargo handling equipment and procedures using their terrestrial equivalents, particularly those that may facilitate remote offloading operations without the presence of crew on the lunar surface. As several of the payload handling operations will potentially occur in preparation for crewed missions, it is essential that payload acquisition and release be as simple and safe as possible to reduce risk to lunar equipment. Several benefits are identified that may be realized by incorporating commonality into the development of lunar and terrestrial flight handling hardware and procedures.

Devices for lifting, translating and precisely placing payloads are critical for efficient Earth-based construction operations. Recent and past studies have demonstrated that devices with similar functionality will be needed to support lunar outpost operations.

Download (PDF) the Study, HERE.

American Institute of Aeronautics and Astronautics

Second Generation ATHLETE lunar vehicle

The second generation ATHLETE lunar vehicle with mock habitat as payload [NASA/JPL].

Matt Heverly, Jaret Matthews,
Matt Frost & Chris McQuin
NASA/JPL/California Institute of Technology

Proceedings of the 40th Aerospace Mechanisms Symposium, (pg. 317-326)
NASA/Kennedy Space Center, May 2010

The Tri-ATHLETE vehicle is the second generation of a wheel-on-limb vehicle being developed to support the return of humans to the lunar surface. This paper describes the design, assembly, and test of the Tri-ATHLETE robotic system with a specific emphasis on the limb joint actuators. The design and implementation of the structural components is discussed, and a novel and low cost approach to approximating flight-like cabling is also presented. The paper concludes with a discussion of the “second system effect” and other lessons learned as well as results from a three week long field trial of the vehicle in the Arizona desert.

In order to establish a continual human presence on the Moon we must develop assisting infrastructure that can carry cargo as well as provide mobility to the astronauts for exploration and the development of a central, but not necessarily fixed, lunar base. The Tri-ATHLETE vehicle system is a new form of two cooperative robotic vehicles that can act individually or physically connect together through a structural pallet to transport and manipulate cargo.

The basis of the ATHLETE (All Terrain Hex Limed Extra Terrestrial Explorer) robot is the wheel-on-limb vehicle concept. This hybrid mobility platform enables the vehicle to traverse at high speeds across benign terrain, as well as enabling walking, by locking the wheels and using them as feet, on extreme terrain. This vehicle architecture also allows for manipulation since the vehicle is stable on three or more wheels. Non-adjacent limbs can be lifted and used to interact with the environment.

A tool mechanism at the end of the limb, attached to the wheel hub, allows for interchangeable tools, such as a gripper or an auger, to be used for manipulation. This unique vehicle design allows for significant weight savings over a traditional planetary roving vehicle that must have large wheels to allow for low ground pressure as well as high torque wheel actuators since the vehicle cannot walk in extremely soft or steep terrain.

Tri-ATHLETE lunar vehicle Michelin Lunar Wheel impacting a 10-cm rock [NASA/JPL].

The ATHLETE project started in March of 2005. The first generation vehicle was completed in October of that same year. This 1000-kg, 2-m tall vehicle was developed rapidly with the intent of providing a hardware platform to aid in the development of the robotic system’s software. This software development vehicle ended up performing five field tests in natural terrain throughout the United States.

These field tests enabled the team to test the vehicle’s capabilities such as traversability over soft terrain, walking, repelling, and manipulation in unstructured environments.

From this first prototype several new capabilities were discovered and several vehicle deficiencies were revealed.

Review the presentation (PDF), HERE.

Popular Science: More on Athlete

The Lunar Habitat Hauler

Popular Science Online has posted perhaps the best, well, "popular" close up look yet at Athlete, under going testing at JPL. A featured video shows off more nifty detail of what is certain to become an iconic and integral part of NASA's nomadic lunar exploration paradigm, now being shown-off to the general public.

Annemarie Conte posted the close-up video presentation at PopSci Tuesday afternoon, April 22.

"The mission-ready robot," she writes, "which will be about twice the size of the prototype pictured here and made of steel, should be able to haul a load of up to 15 tons pretty much anywhere it wants to—as long as it obeys a 3mph speed limit. “That’s about as fast as you can go without risking flipping over because of the low gravity,” explains Brian Wilcox, the primary investigator on the Athlete project...."

"Scientists at JPL hope to rocket Athlete to the moon for unmanned testing as early as 2012. What would come next depends on the success of NASA’s plans for manned space exploration"

Read more HERE.

Athletic Teamwork

More excellent YouTube video of Naval Research Laboratory's Athlete in action, cooperating in heavy lifting

More on NRL's Lunar Athlete Rover

While I've written before of the U.S. Navy's Athlete, a dexterous, long distance and freight-handling robotic walking lunar rover, under development by the Naval Research Laboratory in cooperation with the Massachusetts Institute of Technology, I thought I'd be reading of something quite different when teased by a passing headline a short time ago.

The Athlete test-bed robots are gangly-looking enough, I thought, than to read New Scientist describe them as "giant, six-legged robots," that can "pick up and move a future Moon base thousands of kilometres across the lunar surface.."

They're certainly big, but hardly the 50 Foot Woman, not able to to lift a single-wide mobile home, let along an entire moon base, except perhaps in pieces and many trips.

And whether they are able to handle "thousands of kilometers" even over the course of any one unit's lifetime remains to be seen.

Athlete has been developed with MIT's farside Dark Age Lunar Interferometer, or DALI, which the Institute hopes can be deployed over a thirty-five mile wide area of the Tsiolkovsky, and in relative radio quiet a decade from now. DALI would listening for faint, highly red-shifted wavelengths from the so-called Dark Age, between 200 million years after the Big Bang and the first eras of star formation hundreds of millions of years later, when the structure of the present state of the known Universe began.

As I posted previously, the Naval Research Laboratory shares a $500,000 grant with MIT to design and test the logistics of deploying the proposed array. Plans call for deploying a nearside radio array to perform some actual science and to test the concepts behind DALI and its construction, already well along in planning.

NRL proposes using Athlete to patiently and persistently, as a robot should, haul components from a landing zone and eventual hub to sites clustered over a 50 kilometer wide area in Tsiolkovsky's southeastern third.

Each collector, 250 meters in size, would then need to be deployed and tuned. I've suggested they might then become integral to the full array itself by offering tuning mobility as the rails for the Very Long Baseline Array in Socorro, New Mexico performs, changing the size of a massive virtual aperture.

New Science Robots Special Report

JPL Athlete

AIAA Lunar Architecture (September 2007) - Adobe Reader