SAMPLR

Overview

SAMPLR is a lunar robotic arm payload built by Maxar with the Colorado School of Mines and NASA Goddard, selected as one of twelve payloads under NASA’s Lunar Surface Instrument and Technology Payload program for delivery on a Commercial Lunar Payload Services flight [1]. It consists of an arm, a sieve-scoop, a penetrometer and a camera system.

The arm is a second-generation Instrument Deployment Device, an evolution of the arms Maxar built for the Mars Exploration Rovers Spirit and Opportunity, with motors compatible with the lunar environment replacing the Martian ones [1]. The scoop descends from the same company’s scoop built for the canceled 2001 Mars lander and later flown on InSight. The penetrometer is a different lineage, derived from the In Situ Experimental Probe developed at the Colorado School of Mines under NASA’s SSERVI IMPACT team.

The payload’s primary objectives are to demonstrate the next-generation arm on the lunar surface, to capture regolith geotechnical data with the penetrometer, and to demonstrate a sieve-scoop that isolates and delivers particles of a wanted size to a lander or rover [1].

Specifications

Parameter	Value	Source
Degrees of freedom	5, reducible	[1]
Designed arm lengths	1 m and 2 m
Supported mounting height	0.5 to 1 m for the 1 m arm, up to 2 m for the 2 m arm
End effector	force-torque sensor and a turret with up to four radial instrument mounts
Scoop sieves	2, different mesh sizes, in the scoop side walls
Turret positions used	2 of 4, by the penetrometer and the sieve-scoop

Mass, joint torques, tip speed, work volume, power and positioning accuracy are not published, and neither arm length has been selected.

Mission profile

The payload was manifested on Masten Mission One, a CLPS delivery to the lunar south pole that did not fly [1]. No mass, power or accommodation figures from a current assignment have been published.

Mobility

None. The arm is fixed to its host lander and reaches within its own work volume.

Manipulation

Five degrees of freedom is the baseline, with the explicit option of building fewer joints where a mission’s task set allows it, which the designers frame as a mass and cost trade rather than a capability one [1]. The end of the arm carries a force-torque sensor and a turret with as many as four radial mounting locations. Two are taken by the payload’s own tools, and the remaining two are offered to other instruments, which is one of the ways SAMPLR is described as enabling for other payloads.

Arm length is set by the host rather than by the task. Both 1 m and 2 m configurations were designed against mounting heights of 0.5 to 1 m and up to 2 m above the surface, so the arm adapts to whatever deck height the commercial lander provides [1].

Power and energy

Not published.

Thermal

Not published beyond the statement that the motors were updated for compatibility with the lunar environment [1].

Compute and avionics

Not published.

Autonomy

Demonstrating variable autonomy to aid telerobotic missions is listed as a secondary objective [1]. What that means in implementation, and what the arm does without an operator, is not described.

Communications

Through the host lander.

Payload and instruments

The sieve-scoop collects regolith and sieves it. Two sieves of different mesh size are built into the scoop’s side walls, so a particle size can be bracketed between a large and a small cutoff rather than merely capped, and flow through the sieves is induced by rotating and vibrating the scoop [1]. Sample mass is measured with the wrist force-torque sensor rather than with a dedicated instrument. The scoop also removes surface material to expose regolith below it for other instruments, and can move rocks out of the work volume to a limited extent.

The penetrometer uses the arm as its linear translation mechanism and the wrist force-torque sensor as its instrument [1]. From penetration and stress-relaxation forces it yields bulk relative density, cohesive behavior and surface strength. The supporting data published for it is from the predecessor In Situ Experimental Probe rather than from SAMPLR hardware: penetration force curves separating low-density JSC-1A from high-density GRC-3 simulant, and a proposal, cited to that earlier work rather than demonstrated here, that the rates of change of penetration resistance and of stress relaxation can indicate the water ice content of a regolith-ice mixture in a permanently shadowed region.

Modes of operation

Not published as a set. The described activities are work volume mapping with the camera system, scooping, sieving and delivery, penetrometry at the surface and at depth beneath removed material, and imaging of the surrounding terrain and of the lander and its payloads [1].

Ground operations

Not published.

Technologies developed

The program’s engineering result is a reuse argument made concrete. A Mars Exploration Rover arm design, twenty years old and flight proven across two rovers, is re-motored for the lunar environment and offered with a configurable joint count and two lengths, so that the same arm fits landers whose deck heights differ by a factor of four [1]. The scoop follows the same pattern from a different ancestor, the 2001 Mars lander scoop that eventually flew on InSight, modified with two side-wall sieves.

The second result is the pairing of the wrist force-torque sensor with the arm’s own linear motion to make a penetrometer, so that geotechnical measurement costs a probe on a turret rather than a dedicated instrument with its own actuator [1]. Whether it works on the Moon is untested: every published measurement comes from the predecessor probe in simulant.

References