Rashid

MBRSC.

Overview

Rashid is a 10 kg four-wheeled micro-rover built by the Mohammed Bin Rashid Space Centre as the first vehicle of the Emirates Lunar Mission, a program intended to fly a series of rovers named Rashid to different lunar sites with different science objectives [1], [8]. Its prime objective was to traverse a mid-latitude landing site and return high-resolution imagery of the surface, with the vehicle itself framed as a technology demonstrator carrying a substantial instrument suite.

It was carried on the ispace Hakuto-R Mission 1 lander, which failed to land on 25 April 2023 UTC, and no payload could be operated after the landing attempt [5].

Specifications

Parameter	Value	Source
Mass	about 10 kg	[1]
Wheels	4
Slope capability	20 degrees
Rock height capability	10 cm maximum
Navigation cameras	2 wide-field
Power	solar panels mounted at a fixed angle chosen to maximize collection
Communications channels	2
Wheel tread	grousers	[3]
Science instruments	4 plus 2 cameras	[3], [8]

MBRSC does not publish the rover’s dimensions, drive speed, battery capacity or operating temperature range on its current pages.

Mission profile

Parameter	Value	Source
Launch	11 December 2022, on Hakuto-R Mission 1	[5]
Landing attempt	25 April 2023 UTC, 26 April JST
Design traverse	several hundred meters over one lunar day	[3]
Landing site class	mid-latitude	[1]
Outcome	lost with the lander; no post-landing payload operation	[5]

The lander began its descent sequence at 00:40 Japan Standard Time on 26 April 2023 from about 100 km altitude and completed the entire planned deceleration, reaching the target speed of less than 1 m/s in a vertical attitude [5]. Operation matched expectations until about 01:43, the scheduled landing time, at which point the lander’s own altitude estimate read zero while it was in fact about 5 km above the surface. It continued descending slowly until the propulsion system ran out of propellant, after which the controlled descent stopped and the vehicle is believed to have free-fallen to the surface.

The root cause was in software. As the lander navigated to the planned landing site, the altitude measured by the onboard sensors rose sharply when it passed over a cliff about 3 km in elevation that was determined to be a crater rim, producing a larger discrepancy between measured and pre-set estimated altitude than the software expected [5]. A filter designed to reject altitude measurements differing greatly from the lander’s own estimate, included to keep the lander operating stably in the event of a sensor hardware fault, concluded that the sensor reading was abnormal and intercepted all subsequent measured altitude data. A contributing factor was a decision to change the landing site after the critical design review completed in February 2021, which affected the verification and validation plan; prior landing simulations did not adequately represent the lunar terrain along the navigation route [5]. ispace concluded that Mission 1 Success milestones 9 and 10, completion of the lunar landing and establishment of stable post-landing conditions, could not be achieved and that customer payloads could not be operated [5].

Mobility

Four wheels, designed to climb slopes of 20 degrees and rocks up to 10 cm high [1]. The wheels carry grousers, and the wheel-terrain interaction of the design was modeled and measured under MBRSC support using a single-wheel test rig in a lunar soil simulant [3].

Measured and simulated single-wheel performance for the Rashid wheel from that rig:

Slip ratio	Drawbar pull, simulated	Drawbar pull, measured	Normal force, simulated	Normal force, measured	Sinkage, simulated	Sinkage, measured
0.00	5.34 N	5.2 N	59 N	62 N	0.011 m	0.010 m
0.25	9.26 N	10.10 N	58.7 N	62.3 N	0.016 m	0.0158 m
0.50	17.2 N	16.77 N	59.1 N	62.1 N	0.0175 m	0.0169 m
0.75	23.6 N	24.1 N	60.2 N	62.1 N	0.0208 m	0.0192 m

Drawbar pull is set predominantly by slip: as the resisting load in the direction of travel rises, required drawbar pull rises proportionally and wheel slip rises with it [3]. Normal force is close to constant across slip, and sinkage and slip are proportional. Of the terrain parameters, the internal friction angle is the most influential on slip, with softer terrain, meaning lower friction angle, producing more of it.

The modeling used the Reece pressure-sinkage relation rather than Bekker or Wong-Reece, because Bekker-derived formulations are inaccurate for wheels below 500 mm diameter on very loose terrain, and the Reece form was modified to represent the grousers as a sinusoidal component added to the pressure-sinkage response with amplitude and frequency set by grouser geometry and count [3]. The soil parameters fitted for the simulant were a frictional modulus of sinkage of 80, a shear deformation modulus of 0.036 m, a sinkage exponent of 1, a weight density of 13,734 N per cubic meter, an internal friction angle of 28 degrees and zero cohesion, giving a highly compressible soil with low internal friction and low motion resistance.

Power and energy

Solar panels are mounted at a fixed angle chosen to maximize energy collection; after collection and battery charging, regulated voltages are distributed to the subsystems [1]. No generation figure or battery capacity is published.

Thermal

No rover thermal design values are published. A lunar night recovery phase was planned for, and one of the two communications channels was reserved for it [1].

Compute and avionics

No processor part, memory or radiation tolerance approach for Rashid is published.

Autonomy

Rashid was driven remotely by an operator, with two wide-field cameras used for navigation and to increase the operator’s awareness of the environment during driving [1]. No onboard autonomous navigation is published.

Communications

Two channels are used. The primary channel carries the mission traffic, giving high bandwidth at low power draw on the rover, and depends on the lander [1]. The secondary channel draws more power and is slower but does not depend on the lander, which is why it serves both as the backup and as the link for the lunar night recovery phase.

Payload and instruments

Instrument	Function	Source
CAM-M microscopic imager	regolith particle size distribution and surface structure at microscopic scales	[8]
LNG Langmuir probe system	electron density profile of the surface sheath, its behavior through the lunar day and its dependence on topography
CAM-T thermal imager	low spatial resolution thermal imaging
MAD	in-situ testing of the adhesive and abrasive properties of various materials against lunar regolith
Main and secondary cameras	surface imaging and navigation	[1]

The science program covers both fundamental science and engineering questions aimed at enabling later missions to the lunar surface and to other airless bodies [8]. The intended investigations were lunar geology, surface alteration mechanisms, the interaction of the soil with the solar wind, and the suitability of materials for future lunar missions [1].

Modes of operation

The published operating phases are surface driving under remote command with imaging, science measurement, and a lunar night recovery phase served by the secondary communications channel [1]. The rover never reached the surface.

Ground operations

Operations were to be run by MBRSC with the rover driven remotely [1]. No planning cycle or tooling detail is published.

Technologies developed

The vehicle’s stated purpose was to be a technology demonstrator guiding the next generation of lunar missions and solar system exploration for the UAE program [1]. The transferable engineering results published so far are the validated wheel-terrain interaction model for a sub-500 mm grousered wheel on very loose simulant, built on a grouser-modified Reece pressure-sinkage relation and matched against single-wheel test rig measurements across slip ratios from 0 to 0.75 [3], and the two-channel communications architecture in which the backup link is deliberately made independent of the lander so that it can also serve lunar night recovery.

The program continues. MBRSC is building Rashid 2 to the same series definition, with objectives covering the geological and thermal properties of the surface, mapping the electrical charging process and the formation of the electron sheath across the lunar day, and science and engineering experiments in materials, mobility and terramechanics [9].