TENACIOUS

ispace, inc.

Overview

TENACIOUS is a 5 kg four-wheeled lunar micro rover designed, manufactured and assembled by ispace-EUROPE in Luxembourg, carried on the ispace RESILIENCE lander as the surface element of HAKUTO-R Mission 2 [9], [8]. Development was co-funded by the Luxembourg Space Agency through a European Space Agency contract under the Luxembourg national space program LuxIMPULSE. Its task was to drive around the landing site, image it, and scoop lunar regolith whose ownership would then transfer to NASA [10].

RESILIENCE launched 15 January 2025 and made a hard landing at Mare Frigoris on 5 June 2025 [9], [12]. TENACIOUS was never deployed.

No peer-reviewed or conference publication on this vehicle was located. Every vehicle number below comes from ispace material [9], [8]. Mission figures come from ispace and from reporting of the ispace failure investigation [12], [11].

Specifications

Parameter	Value	Source
Mass	approximately 5 kg	manufacturer [9], [8]
Length	54 cm	manufacturer [8]
Width	31.5 cm	manufacturer [9], [8]
Height	26 cm
Payload capacity	maximum 1 kg	manufacturer [9]
Structure	carbon fiber reinforced plastic frame	manufacturer [8]
Wheels	four, profiled for stable travel on regolith
Camera	forward-mounted HD camera
Sampling	shovel for surface regolith
Command and data path	via the lander to mission control

The CFRP frame is specified against launch and transit vibration rather than against surface loads [8]. Drive speed, slope limit, obstacle height, power, battery capacity, thermal limits, processor and radio parameters are not published.

Mission profile

These describe the lander mission rather than the rover.

Parameter	Value	Source
Lander	ispace RESILIENCE	[9]
Lander mass	approximately 1000 kg wet, 340 kg dry
Lander size	2.3 m high, 2.6 m wide with legs extended
Lander payload capacity	up to 30 kg
Launch	15 January 2025, NASA KSC
Transit	low-energy trajectory, about five months	[12]
Lunar orbit insertion	7 May 2025	[9]
Landing attempt	5 June 2025, Mare Frigoris	[9], [12]
Success milestones achieved	8 of 10	[9]
Impact velocity	42 m/s	[11]

Descent proceeded from about 100 km to 20 km altitude with the main engine firing as planned, and telemetry was lost less than two minutes before the scheduled touchdown [12]. The failure investigation attributed the hard landing to the laser range finder, which was slow to return valid distance measurements, so the lander did not decelerate to the required landing speed and struck the surface at 42 m/s [11]. Installation error was considered and judged unlikely, since no anomaly appeared in testing or in the earlier descent phases, which left in-flight performance deterioration of the range finder as the leading explanation. The mission achieved 8 of its 10 declared success milestones, missing only the landing itself and post-landing system stability [9].

RESILIENCE was ispace’s second lunar landing attempt, and both ended in an altitude sensing failure without reaching the surface intact, but by different mechanisms. Mission 1 flew its deceleration profile correctly to under 1 m/s vertical speed while its filter rejected a correct altimeter reading as faulty after a crater rim crossing made the sensed altitude jump, so the lander coasted on a stale zero-altitude estimate until it ran out of propellant about 5 km up and fell, and its payloads, including the UAE’s Rashid rover, were never operated, the same outcome TENACIOUS met on Mission 2 [1]. Mission 2’s failure was a different sensor behaving differently, a laser range finder slow to return valid readings during descent rather than a filter rejecting a good measurement, so the two failures share only their outcome and their sensing modality, not a cause [11].

Sampling and the regolith contract

The regolith scoop exists to execute a contract rather than a science investigation. In December 2020 NASA selected four companies to collect lunar material and transfer ownership to the agency: Lunar Outpost at $1, ispace Japan at $5,000, ispace Europe at $5,000, and Masten Space Systems at $15,000, totaling $25,001 [10]. Payment is 10 percent on award, 10 percent on launch, and 80 percent on successful completion. Transfer of ownership is in place, on the surface, following receipt of imagery and location data, after which the material is the sole property of NASA under the Artemis program. ispace Europe’s award named the lunar south pole in 2023 as the collection site; the flight that carried its rover went to Mare Frigoris in 2025 instead [9].

TENACIOUS carried a shovel to gather surface material and the forward HD camera to photograph it [8]. The rover therefore never needed to return or store a sample: the contract is satisfied by collecting, imaging and locating it.

Mobility

Four wheels, rigid, with no suspension in the published configuration [9], [8]. The wheels are described only as shaped so that the rover traverses regolith stably, and the flight model photograph shows rigid spoked rims with slotted circumferential grousers. Speed, slope limit and obstacle capability are not published, and no mobility test results have been released for TENACIOUS itself.

The grouser geometry places TENACIOUS in the same wheel class as other micro-rover designs sized in the low tens of kilograms or under [6]. A single-wheel testbed and discrete element model of a Rashid-1 style 100 mm radius grousered wheel found that traction coefficient and tractive efficiency measured at full load in 1 g sand changed little when the same model was extrapolated to lunar gravity, while tractive force and resistive torque both dropped by about a sixth, and that the wheel’s grouser trace pitch tracks slip ratio independently of load or gravity, which makes it a candidate visual slip odometer [3]. None of those results were measured on TENACIOUS or its wheels; they establish only that a rigid grousered micro-rover wheel of similar scale is testable on Earth with a quantified, not eliminated, gap to lunar conditions.

Astrobotic’s CubeRover line, an American micro-rover product sized in the same few-kilogram to low tens-of-kilograms range and pitched at lunar surface mobility as a service, ran over 150 wheel-set trials in a 120 ton regolith simulant bin at NASA Kennedy, reporting slope climbs to 30 degrees and successful point turns in deep simulant for some wheel sets without publishing which sets or by what criterion [4], [5]. The vendor’s own product sheet lists a 4 cm/s nominal driving speed and an 8 Earth day mission duration for the largest variant, an offered specification rather than a demonstrated result, and no CubeRover has driven on the Moon [6], [7]. The comparison is a statement about the design class TENACIOUS belongs to, not a claim about TENACIOUS’s own mobility.

Power and energy

A body-mounted solar panel closes the top of the chassis, visible in the photograph above. Generation capacity, battery capacity and night survival are not published. The mission was planned inside a single lunar day, which ended at the landing attempt [9], [12].

Thermal

The chassis is wrapped in multi-layer insulation over the CFRP frame [8]. No temperature limits, radiator area or heater strategy have been published.

Compute and avionics

No processor, memory or radiation tolerance information is published.

Autonomy

None is claimed. Commands and data pass between mission control and the rover through the lander [8], which makes the vehicle a teleoperated one working inside lander communication range.

Communications

Through the lander only [8]. Band, data rate and range are not published.

Payload and instruments

The forward HD camera is the only instrument named [8], alongside the regolith shovel [10]. Rover payload capacity is a maximum of 1 kg [9] against a 5 kg vehicle, so a hosted payload can be a fifth of the rover mass.

Ground operations

Operated from ispace mission control through the lander [8]. No planning cycle, tooling or operations concept has been published.

Technologies developed

The vehicle is the first European designed, manufactured and assembled lunar rover to fly [9], [8]. Because it was never deployed, no operational result exists. What the program established outside the hardware is the legal path: an ispace-EUROPE mission authorization under Luxembourg’s space resources law, coupled to a NASA contract that transfers ownership of collected material in place on the lunar surface [10].

Two failed ispace descents against one successful Japanese precision landing on the same terrain type frame how narrow the design margin is for a small lander carrying a rover this size. SLIM, a separate Japanese lunar lander with no ispace involvement, reached the surface inside 10 m of its target by cutting mass elsewhere: a tank that doubled as primary structure, film solar cells bonded to that tank, and crushable metal legs used with a deliberate two-step tip-over landing rather than sprung suspension, flown with almost no sensor redundancy on the argument that redundancy had not saved an earlier lander from loss within a 20-minute descent [2]. TENACIOUS never reached a surface on which any of its own design choices could be tested against that kind of margin.

What is not established

No independent test report, flight anomaly log or peer-reviewed publication on TENACIOUS has been located; every published vehicle number comes from ispace and ispace-EUROPE’s own promotional and mission material [9], [8]. Mass budget, drive speed, slope and obstacle limits, power generation and storage capacity, thermal survival range, processor, radiation tolerance, and communications band and data rate are all unpublished. No mobility, thermal vacuum or vibration test result for the flight unit has been released, and because the rover never deployed, none can now be generated by the mission itself. The regolith transfer contract that motivated the shovel and camera was written against a 2023 south pole landing site and executed, when it was executed at all across the four awardees, against different sites and outcomes than planned [10], [9].