SORA-Q

JAXA / TOMY Company / Sony Group Corporation / Doshisha University.

Overview

SORA-Q, formally Lunar Excursion Vehicle 2 (LEV-2), is a spherical nano-rover that opens into a two-wheeled running configuration on the lunar surface [1]. It was developed jointly by JAXA, TOMY Company, Sony Group Corporation and Doshisha University [1], and flew inside the SLIM lander, which was launched on 7 September 2023 and landed on 19 January 2024 UTC [4]. TOMY entered the program through a 2016 JAXA request for proposals aimed at building an inexpensive insect-scale robot from consumer toy technology; Sony joined in 2019 with responsibility for control boards and sensors, and Doshisha University joined in 2021 on mechanism design alongside TOMY [3].

Specifications

Parameter	Value	Source
Stowed form	sphere, 78 mm diameter	[2]
Mass	228 g	[2], [3]
Deployed configuration	two hemispherical shells opened into wheels, tail stabilizer, cameras	[3]
Wheel drive	eccentric wheel rotation, to limit sinkage in soft regolith	[2]
Cameras	two, one forward, one aft	[3]
Control and image-processing hardware	Sony Semiconductor Solutions Spresense smart sensing processor board, a consumer IoT part	[1]
Autonomy	full, no ground commanding	[1], [2]
Communications	short-range wireless link to LEV-1, which relays to Earth	[1]

No rated drive speed, gradeability, obstacle height, battery capacity or operating temperature range is published on the JAXA pages.

Mission profile

Parameter	Value	Source
Launch	H-IIA F47 from Tanegashima, 7 September 2023	[2]
Separation from SLIM	15:19:52 UTC, immediately before touchdown, 19 January 2024	[4]
Surface imaging success	20 January 2024 JST	[2]
SLIM landing mass	about 200 kg	[4]
SLIM landing accuracy	better than 10 m
Documented surface operating time	at least 108 minutes	[2]
Onboard image-processing runs executed	240
Images returned from the lunar surface	2
Estimated standoff from SLIM when the front-camera image was taken	5.08 m
Distance driven between the two images	about 0.13 m
Rotation between the two images	about 180 degrees

SLIM lost most of the thrust from one of its two main engines during descent. Because the two engines were mounted with a slight tilt, the surviving thrust still passed roughly through the center of gravity and attitude control held, but the previously canceled lateral component drove an eastward drift, and SLIM touched down about 60 m east of the target with its solar panels facing west instead of at the zenith [4]. LEV-1 and LEV-2 had already separated at that point.

Mobility

The vehicle stows as a sphere 78 mm across and deploys by opening its two hemispherical shells outward into wheels, extending a tail stabilizer and raising the cameras [3], [2]. Locomotion uses an eccentric wheel rotation mechanism, chosen so that the small wheels do not bury themselves in soft lunar regolith. Sinkage of a small wheel in soft ground is the stated design driver.

Flight evidence of mobility comes from image analysis rather than odometry. A rock appears in both of the two returned surface images. Registering the two on that rock gives about 0.13 m of travel and about 180 degrees of rotation between the exposures, which confirmed that the transformation mechanism and the eccentric wheel rotation both worked in the real lunar environment [2]. That the vehicle had deployed from its stowed sphere and driven at all was already established in January 2024 from the first returned image [1]. During surface driving the vehicle detected an attitude anomaly and executed a posture-recovery sequence.

Power and energy

The vehicle runs on internal batteries; no generation source is described in the JAXA material. Documented surface operating time is at least about 108 minutes [2]. Energy efficiency and lifetime extension were among the toy-derived technologies named as the basis of the development [3].

Thermal

No thermal design values for LEV-2 are published.

Compute and avionics

Sony led development of the control system and the image-processing software, built around the Sony Semiconductor Solutions Spresense smart sensing processor board, a commercial IoT part [1]. JAXA’s stated result from that choice is a demonstration that consumer devices can be used in the space environment.

The image-processing chain ran 240 times on the lunar surface [2]. Telemetry analysis confirmed that the onboard processing correctly recognized the lander in the imagery it took.

Autonomy

Autonomy was complete: after separation the vehicle powered up, deployed, righted itself, moved away from the lander while imaging, chose which of the images to send, and transmitted them, with no commands from the ground [2], [1]. Image selection was done by an onboard algorithm that picked frames in which SLIM was well framed. The design premise was a communication environment too constrained for teleoperation. Anomaly detection and self-recovery functions also ran autonomously, and the attitude anomaly encountered during driving was handled onboard.

Communications

LEV-2 has no direct link to Earth. It transmits over a short wireless link to LEV-1, which carries a 90 g transmitter and returns the data direct to Earth from the lunar surface [5]. The first surface image was returned through that path and confirmed the LEV-1 to LEV-2 inter-robot link working [1]. Both returned images suffered data dropouts in transmission: the front-camera image is partially missing, and only the left portion of the rear-camera image was reconstructed [2].

Payload and instruments

Two optical cameras, one facing forward and one facing aft [3]. Their purpose is imaging the spacecraft and the surrounding environment. The front camera returned the image in which onboard processing detected SLIM [2]; the rear camera returned the second image, released in June 2026, whose surviving left portion carries the rock used to establish that the vehicle had moved.

Modes of operation

The published sequence is stowed transit inside SLIM, separation, automatic deployment from sphere to running configuration, attitude righting, drive and image, onboard image selection, transmission to LEV-1 [2]. Anomaly detection and a posture-recovery sequence sit alongside these as an off-nominal branch, and were exercised in flight.

Ground operations

There were no ground operations during the surface phase. Analysis was retrospective: the walking log and other data were still being processed when the first results were published in January 2024 [1], and the second image and the telemetry-derived operating time, image processing count and posture-recovery result were released with the Science Robotics paper in June 2026 [2].

Technologies developed

The program’s stated result is that a palm-sized robot built substantially from consumer toy and IoT technology can carry out an autonomous surface exploration sequence, and JAXA names three directions it opens: operating several small robots at once to cover ground efficiently, pairing small robots with a large rover, and reaching terrain such as caves and steep slopes that has been inaccessible [2]. The Spresense-based control system is cited as evidence for consumer parts in the space environment [1].