Drills and Sampling Actuators

Mechanisms that break, cut, abrade or lift planetary surface material and deliver it to an instrument or a container. The classes separate by how the cutting force is produced and how the reaction is absorbed: rotary augers, rotary-percussive drills, piezoelectric hammering actuators, pneumatic lift, and scoops, rasps and brushes.

Two constraints govern the selection and neither is about the cutter. The first is reaction force. A rotary corer must be held against the rock, and the preload does not come free: reacting 50 N of weight on bit at Itokawa by lander weight alone would need a 500,000 kg lander, which is the argument for anchoring or for a mechanism that needs almost no preload [18]. An Enceladus lander study set the allowable reaction transmitted to the vehicle at 8 N [23], while the Perseverance arm preloads its corer stabilizer at about 300 N on rock and up to 600 N against the rover docking assembly for a bit exchange [25]. The second is cuttings. The InSight HP3 mole reached 37 cm of vertical tip depth against a 3 to 5 m requirement because the cohesive duricrust supplied no lateral pressure and therefore no hull friction to balance the 5.4 N recoil of its own hammer [19], and TRIDENT bound in low-permeability targets where rock powder behaves as a nearly incompressible working fluid at 100 to 200 N of weight on bit [5]. Percussion is carried for the same reason in most of the entries below: rotary-only drilling of Arctic ground ice took days per meter against under an hour with percussion, a field observation cited as the justification for carrying a percussor rather than a measurement [4].

Rotary and rotary-percussive drills

Part	Builder	Used by	Status	Source
MSL coring drill	JPL	curiosity	Flown 2012	[1]
Mars 2020 percussion mechanism	JPL	perseverance	Flown 2021	[2][25]
IMSAH Sample Acquisition Tool	JPL	none	Ground test	[3]
TRIDENT	Honeybee Robotics	trident (PRIME-1), viper	Flown, no hole drilled	[4][5][6]
Icebreaker-3	Honeybee Robotics	none	Field analog	[9]
Chang’e-5 class coring auger	Harbin Institute of Technology	chang-e-5-sampler (test unit)	Ground test	[7]
Compact Drilling and Sample System	JPL, American Technology Consortium	none	Ground test	[8]
Microspine-anchored corer	JPL	none	Ground test	[18]

Ratings and qualification results

• MSL coring drill, JPL: a rotary-percussive sample acquisition device with four actuated mechanisms, the spindle, a ball-lock chuck, a voice coil percussor and a ball screw translation stage [1]. Ratings: 120 N weight on bit held by the translation mechanism against a dual bridge force sensor, 1800 blows per minute at a commandable 0.05 to 0.8 J per blow, a 15.9 mm bit, and 50 mm of sampling depth in rock from clays to massive basalt. The life requirement is 81 samples [1], effectively doubled in depth because each sample is preceded by a dilution cleaning pre-sample. Peak impact force under the bit reached 6 kN on the MSL force dyno [2], and bits were changed only when worn rather than exchanged routinely as on Perseverance [25]. Qualification: -70 to +70 C for most components, with the percussor, contact sensor and bit assembly qualified colder; the translation mechanism demonstrated 10,012 N of retraction force at -70 C, and axial drag during acquisition stayed below 5 N across the qualification range. Development testing found that the drill cannot dead-pull a bit stuck at 40 percent of the worst case load, which is loss of all wheel friction on a 20 degree slope with the bit locked in rock; the mitigation is hammering the bit end to exploit a stick-slip effect that the source reports as an expectation rather than a demonstrated result [1]. The paper predates landing, so it carries no delivered-sample statistics and no rate of penetration.
• Mars 2020 percussion mechanism, JPL: a base-driven spring hammer on a triple Scotch yoke turned by a brushless DC gear motor, selected over the MSL voice coil so that only steel lumps and springs carry the shock [2]. Ratings: 200 g hammer, 11 N/mm total spring rate, 5 mm crank throw and about 9 mm static anvil gap, giving first impact near 25 Hz and operation to 40 Hz at impact velocities of 0.5 to 3 m/s. Peak force under the hammer is about 40 kN on the percussion dyno, measured with a Kistler 9041A load washer sampled near 200 kHz over a typical 50 microsecond impulse, and about half of it survives the percussive chain to deliver more than 15 kN under the bit against 6 kN measured for MSL [2]. Weight on bit saturates: 80 to 100 N was sufficient preload and more gave no benefit. Qualification: more than 7.2 million impacts on a dedicated life test unit across -70 to +70 C, a 3x demonstration against a 2.3 million impact nominal life derived from 43 planned cores and 74 abrasions [2]. The cold start drove the lubrication of the crank pin bearings, covered on Gearing and Actuators. The claimed factor of five or greater advantage in rate of penetration over MSL in equal strength rock is asserted without the supporting data.
• IMSAH Sample Acquisition Tool, JPL: three brushless motors driving a linked spindle and percussion mechanism, a magnetic chuck, a core break-off wedge and a coring bit, coring directly into a sealed tube [3]. Ratings: 121 g striker, 500 rpm spindle, cores about 10 mm in diameter by 50 mm long, and a passive bit release at 100 N at the bit tip. Rate of penetration is dominated by bit outer diameter: cutting the bit face area by 16 percent, from 0.96 to 0.89 inch outer diameter at a fixed 0.39 inch core diameter, took Saddleback basalt from 2.4 to 7.9 mm/min, volcanic breccia from 1.3 to 2.7, siltstone from 6.3 to 27.9, Santa Barbara limestone from 26.2 to 59.6 and kaolinite from 49.3 to 162 mm/min, all with relatively unworn bits at ambient laboratory temperature and pressure [3]. Qualification: none. Sample tube retention flexures failed by fatigue under percussive loading because they had been analyzed statically only, and the linked spindle and percussion mechanism removed the tuning freedom needed to diagnose anomalies. Weight on bit and tool power draw are not stated anywhere in the source, and the diameter sensitivity rests on two points.
• TRIDENT, Honeybee Robotics: a 1 m class rotary-percussive ice mining drill built in two identical flight units, one for the PRIME-1 payload on Intuitive Machines IM-2 and one for VIPER [4]. Ratings: 26.5 kg total, of which 19.5 kg is drill hardware and 7 kg the avionics box; 25.4 mm percussive-grade carbide bit; cam-spring percussor at 2 J per blow to 972 blows per minute, nominally 729 bpm for 8.1 blows per revolution at 100 rpm; auger nominally 90 to 100 rpm within a commandable 10 to 120; 100 N nominal weight on bit within a commandable 0 to 500 N; 1.25 mm/s feed into fresh material; 50 W nominal rotary power [4]. The concept of operations is bite sampling in 10 cm increments, commandable from 1 cm, which sets the depth resolution of the delivered cuttings. Qualification: the engineering unit drilled nearly 30 m cumulatively over 337 bites and more than 30 hours, in lunar regolith simulants and in rock of 4 to 120 MPa unconfined compressive strength, at temperatures below -100 C and pressures below 1e-4 torr for the simulant work, with no measurable dust-ingress effect on actuator no-load currents [4]. The icy targets were NU-LHT-2M and LSP-2 doped to 0, 4.1 and 8.5 weight percent water rather than ice formed by a lunar-relevant process, the rock holes were at ambient pressure and temperature apart from one 1 m vacuum hole, and the source is written by the drill’s builder. Flight: the Athena lander came to rest on its side at 84.7906 S, 29.1957 E on 6 March 2025, so no hole was drilled [4]. The roughly 20 minute checkout released the launch locks, ran the rotation and percussion actuators, extended the deploy stage to 35 cm and the feed stage to 100 cm, and read out both drill string temperature sensors with the drill horizontal and buried in regolith thrown up at landing [4].
• Icebreaker-3, Honeybee Robotics: a 1 m class rotary-percussive Mars drill, three to five times lighter than the prototypes preceding it [9]. Ratings: 30 to 40 W during 5 to 10 minute drilling sequences and 200 W maximum, both quoted from earlier campaign reporting rather than measured. Field results: more than 5 m across six boreholes in Arctic impact breccia permafrost at Haughton Crater in August 2014, more than 2 m of it in ice or ice-consolidated material, without the melt-refreeze and binding faults that had stopped the predecessor LITA drill in the same ground the previous year; the fixes were a stiffer drillstring, more auger torque, reverse rotation for extrication, and a bit temperature sensor to watch frictional heating approach the water triple point [9]. At Rio Tinto in 2015 the drill reached only 2.4 m in five holes after the auger torque motor shorted on the first full day and the replacement spare failed the same way with the wrong control software installed, which the authors state leaves nothing about drill capability concludable from that campaign. No penetration rate and no bit wear data are reported for either site.
• Chang’e-5 class coring auger, tested at Harbin Institute of Technology: a hollow stratified-coring drill tool with a 32 mm auger radius, 10.53 mm flight thickness, 2 mm flight height and a 14 degree helix angle, with four radially mounted Kentanium blades of 10 mm width at a 90 degree rake [7]. Ratings: rotary speed held below 200 r/min, against a general planetary practice of staying under 300. Ground test: in pozzolana simulant compacted to 2.14 g/cm3 and 98 percent relative density, with a 35.1 degree friction angle and 2.85 kPa cohesion, weight on bit at 85 mm/min penetration was 72.1 N at 60 r/min, mean of five runs spanning 61.6 to 83.6 N, and 7.8 N at 200 r/min, mean of five spanning 6.6 to 10.0 N; rotary torque at the 60 r/min condition was 1.31 N m, mean of five spanning 1.13 to 1.45 [7]. Screw conveyance and chip extruding, the dominant terms of the conventional models, come out three orders of magnitude too small to account for the measured loads, and the model that follows underpredicts rotary torque by about 20 percent at every condition while tracking weight on bit closely. The control result is the ratio of penetrating to rotary speed: below 1 the loads rise smoothly and above 1 the conveying density rises, the bit jams and the loads climb sharply [7]. All of it is 1 g, ambient, one simulant at one compaction state [7].
• Compact Drilling and Sample System, JPL with American Technology Consortium: a 2.0 kg two-motor rotary-percussive drill on a keyed acme lead screw, intended to sample comet, asteroid or Mars material at the sample’s own bulk temperature in vacuum [8]. Ratings: 25 W maximum electrical power, a 1.2 m lead screw extensible by adding segments, a 15 mm bore bit with an internal chamber of about 400 mm3, and a spring-cam percussor striking 5 times per revolution; the design case is -165 C for the cometary target and about -100 C for Mars. All are design values with no measured counterpart. Component testing at cryogenic vacuum is the substance of the source: tungsten disulfide coated maraging Vascomax C250 planetary gears ran 1.5 hours before the coating wore through and the steel galled, having performed well at ambient, and Ferro-Tic titanium carbide pins and bushings galled in 1.5 minutes as installed because insufficient polishing left the steel matrix in contact [8]. A split-tip bit at a 15 degree rake and 10 degree relief was the best of eight styles across six materials, three rotation rates and two thrust forces, and drilling rate correlated inversely with three-point bend strength rather than with compressive strength, qualitatively and with no coefficient reported. This document is an unfinished draft: its conclusion is the two words “In conclusion,”, its temperature performance section gives the winding resistance as “TBD ohms” at both ambient and -165 C, and its abstract advertises autonomous operation and percussive drilling that the body contradicts by stating the sequences are still being integrated and that percussion did not improve drilling performance in most materials [8]. Nothing here supports a drilled depth, a rate, a sample mass or a bit life, and the drill was never flown.
• Microspine-anchored corer, JPL: an omnidirectional microspine anchor carrying a repackaged Bosch hammer drill, which supplies and reacts its own weight on bit [18]. Ratings: the anchor held more than 160 N tangent to consolidated rock, more than 180 N normal and more than 150 N at 45 degrees, and survived more than 100 engage and release cycles without damage. Ground test: cored inverted into vesicular basalt to 83 mm depth in a 20 mm borehole, retaining a 12 mm core in three to six stratigraphy-preserving pieces, in 3 to 10 minutes per hole [18]. Anchor testing used strong consolidated rock only; friable rock, which is the regolith-covered case at most small bodies, is untested, and weight on bit, power draw and bit wear are not reported. Inverted drilling in Earth gravity is offered as a proxy for microgravity and does not reproduce dust behavior or the absence of a settling force.

What the cuttings do, and what the telemetry shows

Cuttings removal decides whether a 1 m drill reaches 1 m. TRIDENT penetrated unconsolidated and cuttings-permeable material easily in the 2023 Haughton Crater and Bishop Tuff campaigns, drilling 7.80 m across eight holes at Haughton with five recovered fault states, 2.4 m of that in ice or ice-cemented impact breccia below an active layer about 67 cm thick, but choked and bound in low-permeability microporous targets, exceeding its safety torque limits at Bishop and needing a pipe wrench to free the auger [5]. The demonstrated fix was operational rather than mechanical, cutting the bite from the nominal 10 cm to 1 to 2 cm so that cuttings are bailed more often. In porous pumice at the same campaign a single 40 cm bite ran without cuttings buildup [5]. The MSL bit likewise carries two spare assemblies in passive boxes on the rover front panel, and a clogged bit can be jettisoned [1].

Drill telemetry alone identifies the material the bit is in. Across fifteen Antarctic boreholes at Schirmacher Oasis and Lake Untersee in January 2026, the TRIDENT engineering unit’s torque, weight on bit, rate of penetration and auger angular velocity marked an ice-rock transition at about 62 cm at one site and a frozen subsurface boundary at 20 cm at another, with a weight-on-bit drop at about 50 cm in the Lake Untersee ice cover matching published bubble content peaking at 54 cm [6]. None of the three was confirmed by core logging or independent stratigraphy. A subspace change-point detector running online at 40 Hz separated faulty from non-faulty drilling with a Cohen’s D of -1.58 on torque score and 1.33 on penetration rate score, against 0.89 and 1.14 for the same score in the laboratory and at Haughton Crater; the source’s text claims every stream but torque value exceeded 0.8, which its own table contradicts for auger angular velocity at 0.26 and 0.25 [6]. Only the last eight of the fifteen holes were monitored, because an over-the-air software update failed, and the fault labels come from handwritten observer notes.

Hardware life in this class is short enough to be a mission constraint. The cam-spring percussive head of that engineering unit broke on the second day of Antarctic operation after roughly 80 to 90 m of cumulative drilling since 2016, and was replaced from spares in the field the following day; Honeybee test-to-failure runs put the fatigue life of the head at 2 to 3 days of continual percussive drilling, an order of magnitude above the flight cumulative drilling requirement [6]. That unit is an engineering model with a long and partly degraded service history, so it is not evidence about flight hardware.

Ultrasonic and piezoelectric hammering actuators

A piezoelectric stack drives an ultrasonic horn; a free mass between the horn tip and a non-rotating bit converts the ultrasonic drive into sonic hammering. The bit does not rotate, so there is no reaction torque on the platform, and the required preload is set by the impact rather than by a cutting edge [10].

Part	Builder	Used by	Status	Source
Ultrasonic/Sonic Driller-Corer (USDC)	JPL, Cybersonics	none	Ground test	[10][11]
High-temperature USDC, bismuth titanate	JPL	none	Ground test	[12]
Piezoelectric Rotary Hammer Drill	JPL	none	Ground test	[13]
Auto-Gopher-1	JPL	none	Field analog	[14]
Auto-Gopher-2	JPL, Honeybee Robotics	none	Field analog	[15]

Ratings and qualification results

• Ultrasonic/Sonic Driller-Corer (USDC), JPL with Cybersonics: a piezoelectric stack, a three-layer stepped titanium horn and a free-floating bit, with a 20 to 23 kHz drive converted at the tip into a 60 to 1000 Hz sonic hammering wave [10]. Ratings: preload below 10 N, stated to be independent of rock hardness, with the review of the family giving as low as 10 N preload and 2 to 3 W average power for a 400 g device [11]. Ground test: the one instrumented pair is 5.3 W average electrical power at 0.1 mm/s in construction brick, with a 2.75 mm tungsten carbide steel rod and a 4 g free mass at laboratory ambient, a single trace with no repeats; a 14 cm hole through sandstone was demonstrated with the device mounted on a Sojourner-class chassis on the bench [10]. Those two numbers give a specific energy near 8900 J/cm3, one to two orders above conventional rock drilling, so the low power is bought with a low removal rate. No power-versus-rate pair is reported for basalt, granite or diorite, and the conventional-drill baseline the source argues against, 20 to 30 W at 150 N and over 30 N m of reaction torque, is carried with no source at all [10]. The device’s own impedance data are inconsistent with its text: 35 kHz is assigned to two different modes in consecutive sentences and appears nowhere in the plotted spectrum, whose peaks sit near 22, 40 and 45 kHz [10]. There is no vacuum, thermal, dust, life or duty cycle result. The family review adds a modeled floor of about 4 to 5 mm on the smallest intact core a percussive mechanism can cut in medium to hard rock, from an isotropic model at 10 GPa Young’s modulus, and reports the Ultrasonic/Sonic Gopher reaching 1.76 m in lake ice at Lake Vida, Antarctica, in 2005 with a 6.4 cm bit [11]. The same review’s claim of demonstrated operation from -200 to 500 C is an actuator statement with no test description, duration or indication of whether a complete drill or a bare transducer was tested.
• High-temperature USDC, bismuth titanate, JPL: a breadboard sampler built for the Venus surface, where the ambient is 460 C at about 90 atm [12]. Ratings: 400 Vrms at 0.69 A for 276 VA apparent and 26 W real, a power factor of 0.094, with 20 N weight on bit and a 17 N free-mass preload at a 0.5 s per second duty cycle near 21 kHz. Ground test: 25 mm through a 26 mm brick at 460 C in a furnace in air at 1 atm, in 21 accumulated active minutes for an average of 1.2 mm/min, after a 1 mm starting hole cut at room temperature [12]. The bit was rotated by hand at 4 to 5 rpm from outside the furnace, so the self-rotating mechanism the design depends on was not what was tested. Screening results from the same campaign [12]: Y-cut LiNbO3 single crystal has a 1150 C Curie point and showed no measurable change in electromechanical properties after 1000 hours at 500 C, sputtered platinum electrodes survived 500 C where sputtered gold degraded severely, and CPM-3V hardened steel bit teeth degraded at 500 C and were replaced with WA-2 tungsten carbide. The source’s Table 1 is captioned as maximum drilling rates and gives 1.27 mm/min for the 1 inch LiNbO3 sampler at 500 C, while the paragraph below it states about 1.4 mm/min during the first minute, exceeding the stated maximum by 10 percent; the conflict is not resolved in the document [12]. Venus pressure was not reproduced, the supercritical CO2 atmosphere and the sulfuric acid chemistry are absent, every result is a single run of a single breadboard, and the 460 C headline was drilled in brick rather than in basalt.
• Piezoelectric Rotary Hammer Drill, JPL: one piezoelectric stack producing both hammering and rotation, by driving a horn whose angled cuts twist the tip as it extends so that it transfers torque to a keyed free mass by friction at impact, with repelling magnets replacing the preload spring [13]. Ratings: six PZT ceramics prestressed to 15 MPa, a first resonance measured at 11,972 Hz against 12,217 Hz predicted, and a second mode at 22.4 kHz that turns the bit the other way. Ground test: 8 mm/min in limestone at 100 W input, 3 lb weight on bit, 4 lb magnetic preload and 80 percent duty cycle over ten minutes, on the bench at room temperature and pressure [13]. That is one row of one table, on one prototype, with no repeat and no uncertainty anywhere in the document. The transducer’s measured electromechanical coupling is 0.07 against the 0.2 to 0.4 the report gives as typical of USDC horns [13], a value accepted knowingly so that fabrication could begin inside an internship, so this is not a representative member of the horn family. Two of its stated conclusions are not supported: the claim that all data show bit rotation speed rising with input power is contradicted by its own figure, where one series reads about 40 rpm at 122 W, about 160 rpm at 140 W and about 140 rpm at 192 W; and the largest single performance change reported, a fourfold rise from 2 to 8 mm/min when the free mass was cut by 25 percent, is given in one sentence with no controlled comparison [13].
• Auto-Gopher-1, JPL: a wireline rotary-percussive corer combining a piezoelectric percussor at 5250 Hz with electric motor bit rotation, anchoring against the borehole wall with three compliant shoes rated to 1600 N and screwing itself down [14]. Ratings: 71 mm borehole, 60 mm by 100 mm core, 15.5 N m of bit torque at 100 rpm from a 360 W rotary drive, 22 kg and 150 cm long. Field results: 3.07 m and 32 cores over three days at a gypsum quarry near Borrego Springs, California, in about 40 MPa rock at ambient terrestrial temperature and pressure [14]. Percussion buys both rate and energy: 180 cm/hr at 100 percent percussive duty cycle against 40 cm/hr rotary-only, and 220 Wh/m against 350 Wh/m for the same pair, with 250 to 280 Wh/m at 50 percent duty cycle depending on the on-off period; a 5 s on, 5 s off cycle gave 80 cm/hr while 1 s on, 1 s off at the same duty cycle recovered the full rate. The authors warn that continuous percussion risks overheating the piezoelectric stack. Nothing was tested cold or in vacuum despite the Europa and Enceladus framing, bit life and core recovery quality are unreported, and the energy per meter is extrapolated from that 3.07 m hole [14]. A companion source states in its abstract that this campaign averaged 100 to 150 W at about 2.4 m/hr, which its own figure contradicts: no plotted point exceeds about 165 cm/hr at any power to 255 W, and at 100 to 150 W of percussive power the measured points lie between 60 and 95 cm/hr [16]. Take the 3.07 m and the duty-cycle series from the primary record [14], not the 2.4 m/hr.
• Auto-Gopher-2, JPL with Honeybee Robotics: the wireline successor, with core break-off against an internal wedge, core capture and ejection, embedded electronics and a hill-climbing controller that tracks the transducer’s drifting resonance [16]. Ratings: 65 kg, 3.7 m long, under 500 W peak, with a 5.2 kHz piezoelectric percussor and a flight-like umbilical [15]. Field result: 7.52 m in a Borrego Springs gypsum quarry of 39 plus or minus 2 MPa over a campaign of more than a week, more than twice the drill’s own length. The subsystem checks that preceded it used Cordova Cream limestone at 25 MPa as the soft case and Indiana limestone at 40 MPa to approximate the field site [15]. The outcome record is a slide deck: no rate of penetration, no telemetry, no bit wear and no energy per meter for the 7.52 m hole, and the mass and power are for a terrestrial field unit rather than a flight design. Cryogenic ice testing is asserted and not reported, and the authors list length, mass and automatic bit unloading as unsolved.

Bit geometry

Bit outer diameter and tooth condition move the rate of penetration more than most drive parameters do. On the IMSAH tool a 16 percent reduction in bit face area doubled to tripled the rate in every one of five analog rocks [3]. For a percussive coring bit the number and spacing of teeth on the bottom annulus sets a specific energy minimum, reached once adjacent chip zones meet, which one analysis places at a spacing-to-depth ratio of about 5 to 6 under a Coulomb-Mohr wedge model and 4 to 6 under tensile splitting, giving an optimum of about 4 teeth at a 90 degree wedge and 6 at 120 degrees for a 0.625 inch bit in limestone [17]. That analysis was validated by pressing four bits into one limestone block on a servohydraulic frame under load control, with no ultrasonic or percussive drive present at all, and its stated conclusion that the 12-tooth bit consumed more energy than the 6-tooth bit is contradicted by its own table, where the 12-tooth bits took 9.5448 and 7.5545 kN mm against 21.1678 and 14.1573 for the 6-tooth bits; the claim holds for energy per gram of cuttings and not for total energy [17]. The clearest measured effect in that experiment is the cost of a dull edge: 31.08 kN mm/g against 17.18 for the same 6-tooth 60 degree geometry sharp, one unrepeated comparison on one rock.

Percussive penetrators, pneumatic samplers and rasps

Part	Builder	Used by	Status	Source
HP3 mole	DLR	insight-mole	Flown 2018, 37 cm reached	[19]
LISTER pneumatic drill	Honeybee Robotics, Texas Tech	lister	Flown 2025	[20][30]
Lunar PlanetVac	Honeybee Robotics	lunar-planetvac	Flown 2025	[21]
Phoenix scoop and rasp	JPL	phoenix-arm	Flown 2008	[22]
Dual-Rasp sampling system	JPL	none	Development, TRL 5	[23]
Counter-rotating brush-wheel sampler	JPL	none	Proposed, not selected	[24]

Ratings and qualification results

• HP3 mole, DLR: a self-hammering penetrator, 0.85 kg in total with a 0.46 kg suppressor, a 0.11 kg hammer and a 0.28 kg casing, driven by a spring storing 0.7 J per stroke at 0.27 Hz [19]. Ratings: forward stroke impact force of 1180 to 1350 N over under 0.1 ms, equal to 2.1 to 2.4 MPa across the 27 mm mole diameter, and a recoil of 5.4 N nominal into plastically deformable soil rising to 6.9 N against a hard elastic surface, which must be balanced by hull friction. Flight result: 37 cm of vertical tip depth at Homestead hollow, about 43 cm along the mole axis at a final 30 degree inclination, against a 3 to 5 m requirement, and only with robotic arm assistance [19]. The cohesive duricrust supplied no active lateral pressure and therefore no hull friction, and the 2 kg support structure weighed only 7.4 N on Mars, barely above the 30 plus or minus 2 N of its own friction springs, so hammering lifted it during at least the first 77 strokes. The hammer mechanism itself did not degrade over the 12,000 strokes it ran on Mars [19]. Penetration resistance exceeded 5 MPa at 31 to 37 cm tip depth, inferred from the penetration rate and stroke energy rather than measured with a penetrometer, against 0.2 to 0.5 MPa at equivalent overburden in the DLR Bremen Deep Penetration Testbed, and the Mars rate of 0.11 mm/stroke fell an order of magnitude below the 2.4 mm/stroke seen in quartz sand on Earth [19]. The transferable finding for every hammering penetrator is the atmosphere: 1 bar of ambient pressure puts 57.3 N on the mole back cap when recoil opens a low-pressure cavity at the tip, far above the 6.9 N maximum recoil, and in cohesive simulant the proto-flight mole stops penetrating below 60 to 100 mbar while showing no pressure dependence at all in cohesionless quartz sand.
• LISTER pneumatic drill, Honeybee Robotics with Texas Tech: a heat flow probe on 6.4 mm stainless coiled tubing that jets gas to displace regolith, flown on Firefly Blue Ghost Mission 1 [20]. Ratings: under 9 kg for the drilling and sensor mechanism against a 15 kg instrument allocation, a 32 x 33 x 43 cm envelope, a 2.8 cm by 2.8 mm platinum resistance needle sensor pushed into undisturbed bottom-hole regolith at each stop, 33 W quiescent and 88 W drilling average power, and a 2 m threshold penetration with a 3 m objective set to escape insolation-driven thermal waves. Ground test: 2.2 m in an ideal fines-only simulant and 1.35 m in a bed with about 33 percent by volume small rocks, both in a 1 g vacuum chamber [20]. Only those two simulant conditions are reported, with no distribution across repeated runs. Flight: the drill reached 0.98 m at Mare Crisium in March 2025, short of both the threshold and the chamber depths, downward progress having slowed at 0.94 m as clasts and pebbles too large to be blown out gathered at the hole bottom [30].
• Lunar PlanetVac, Honeybee Robotics: a pneumatic sampler that lofts regolith with a gas burst into a collection container, operated at Mare Crisium on 3 March 2025 [21]. Flight result: 6.5 cc collected against a 1 cc requirement in a five second sequence, with lofted material reaching the container in under a second, and a second gas burst sorting particles either side of a 1 mm dividing wall in the capture chamber [21]. The sampling hood appears to have been aggressively angled and may not have been touching the surface, so the volume cannot be attributed to a known standoff and is not a nominal-configuration figure. It is one event at one site, and a companion abstract from the same team reports 13 grams collected including 5 grams of rocklets [21], a mass that neither document reconciles with the volume quoted here.
• Phoenix scoop and rasp, JPL: a 2.4 m, 4 DOF arm with a scoop carrying primary and secondary blades, a rasp on the back, a camera and a thermal probe [22]. Flight result: 53 dig sequences across 10 trenching areas over more than 150 sols, and 18 samples delivered, 6 to TEGA, 4 to the wet chemistry laboratory and 8 to the optical microscope [22]. An indurated icy layer sat 3 to 10 cm below the surface across almost the whole workspace, detected by increased joint torques, surface accommodation mode entry and motion-impeded events rather than by a calibrated force measurement, and it sloped deeper toward the lander; the deepest trench reached 18 cm. Icy soil was the hardest acquisition: sixteen rasp holes in a 4 by 4 grid yielded about 2.5 cc, cut early in the morning to keep the scoop cold, and the first two delivery attempts failed with the sample congealing in the scoop before the third succeeded [22]. No placement accuracy, repeatability, force or torque figure is quantified anywhere in the source, and delivery counts carry no denominator of attempts except for that icy case.
• Dual-Rasp sampling system, JPL: two counter-rotating rasp cutters throwing a collimated stream of cuttings into an ellipsoidal guide, with the rasps at one focus and a sample cup entrance at the other, for a landed Enceladus mission [23]. Ratings: an 8 N limit on reaction load transmitted to the lander, derived from a stability study at about 1 percent Earth gravity; a design envelope to 10 MPa cone penetration strength over 40 to 95 percent porosity; sampling within 10 mm of the surface for the freshest material and to 30 mm for stratigraphy; 1 to 5 cm3 per transfer with at least ten transfers; and sample kept below 100 K from acquisition to delivery. Transfer is pneumatic and closed: the guide rotates into place as the cup lid and a helium tank blows the sample down rigid tubing through passive rotary unions at both arm joints. Status: TRL 5 development, with system assembly in progress and the pneumatic transfer subsystem not yet integrated [23]. The reduced-gravity tests on the November 2020 parabolic campaign were run at 50 to 70 torr, roughly Mars surface pressure and some eight orders of magnitude above the Enceladus surface, at ambient temperature, six tests in total; the one quantitative result is a particle speed of 1.17 m/s traced from high speed video against a 1.05 m/s cutting head tangential speed. The 8 N requirement is argued from the Phoenix rasp having worked below 10 N preload at under 30 W [23], which does not establish a capability below 8 N, and no collected mass, cutting rate, power draw or rasp wear is reported.
• Counter-rotating brush-wheel sampler, JPL: a head on a deployable boom carrying two counter-rotating wire brush wheels that sweep loose regolith into a container during a touch-and-go contact of about a second, proposed for the Gulliver Deimos sample return Discovery proposal in 2003 [24]. The counter-rotation cancels net angular momentum and net mass-flow thrust so the sampler does not fight the spacecraft attitude control system, which lets acquisition run open loop. Requirements set 10 kg of collected regolith at an assumed 1.5 g/cc, rocks accepted to 3 cm [24], and a worst case contact at 1.0 m/s vertical and 0.5 m/s horizontal. The single measurement is 250 cc of play sand collected against a 130 cc geometric engagement volume, on a bench rig driven by two hand drills at 1 g, which is about 375 g at the deck’s own density assumption and roughly 4 percent of its own requirement [24]. Nothing was built beyond that mock-up, nothing was tested in vacuum, in reduced gravity or in simulant, and the proposal was not selected. The deck also carries a 5 m boom in its requirement and mass basis against 8 meters in the operations concept on the facing slide [24].

Surface preparation and what happens after acquisition

Abrading a rock face is the same actuator problem with a different endpoint. The MER Rock Abrasion Tool was 687 g in an 85 mm by 128 mm envelope, spinning a grinding wheel at 3000 rpm offset 11.11 mm from the tool axis so that a 23.37 mm paddle path swept a 45 mm circle, at 10 to 100 N of arm preload with an abort below 5 N [25]. Its MSL successor brushed rather than ground, on pivoting brushes with up to 30 degrees of hardstop travel after fixed bristles wore and flexed unacceptably in testing, required to clear 70 percent of sub-500 micron particles by area from a 45 mm patch and qualified to 300 operations against a 150 operation need. Mars 2020 dropped brushing entirely: the brush would have shared the spindle motor already committed to coring and core break, whose torque-speed curve could not reach the roughly 2.5 times coring speed a brush needed, and a three-speed transmission was not possible, so a compressed nitrogen tool sized for a minimum 888 puffs took its place [25]. The abrading bit is 50 mm with three tungsten carbide teeth and must cut up to 16 mm from the highest point to guarantee a 2 mm minimum depth over 10 mm of unabraded topography. Flight results are individual targets rather than a distribution: 7 mm at Dourbes on sol 256, with about 12 minutes to start and abrade the hole and about 6 minutes of gas clearing, and 8 mm at Guillaumes on sol 160 [25]. Seven abrasion patches were cut over the first crater floor campaign, sols 100 to 379 [29].

Acquisition is only the first station. On Perseverance a 3 DOF sample handling assembly inside the rover belly moves tubes between a nine-bit carousel, a volume assessment station, a sealing station whose ram generates over 20 kN across 16 mm of stroke, 39 storage sheaths and 49 hermetic seals [27]. Its force control is the published difficulty: filter lag between the motor controller and the flight software added 17 N of overshoot in Fz and 3 N in Fxy, and a motor detent keepout between roughly 20 and 100 rpm, which the profiler accelerates through and dwells above, added 15 N and 2 N more, which cost force limits and station clearance margin. In flight the same force path produced a fault on sol 687 of the depot campaign when an improper tare accumulated non-real force across consecutive dropoffs until the 23 N axial limit tripped [26]. That campaign dropped ten sample tubes at Three Forks over sols 652 to 693, driving 207.93 m and parking between 9.6 and 48.8 cm radially from the optimum drop point, with all ten tubes coming to rest horizontal so the contingency arm sequence for a toppled tube was never needed [26]. Not every core is a core: at the Roubion target on sol 164 the engineering telemetry was nominal and the tube sealed successfully, and the tube was empty, the rock judged too weak and assessed to have disintegrated during coring, found only by imaging and the volume probe [29].

Powdered sample then has to move without clogging or cross-contaminating. A piezoelectric flextensional shaker fluidizes powder through the CHEMIN funnel, sieve and 2.7 mm inlet tubes, driven at 7 V peak swept 11 to 12 kHz over 5 seconds and repeated to 300 seconds [28]. Cross contamination between alternating quartz and corundum stayed below 1 percent and below 0.5 percent respectively by weight at Mars ambient pressure in CO2, values at the X-ray diffraction detection limit and therefore bounds. The failure found was thermal: severe powder layering on the funnel chimney appeared at -32 C and not at Earth ambient temperature at either pressure, implicating water freezing to the wall, and three days of bake-out at 105 C reduced it without removing it [28]. The first design put the actuators in the load path supporting the funnel mass and random vibration and pyro shock delaminated the polymer bond in the shims, so the redesign moved them offset out of that path and raised the blocked-free resonance from 1.4 to 2.5 kHz.