CIMON

NASA. Public domain (NASA / US government work).

Overview

CIMON, the Crew Interactive MObile companioN, is a free-flying artificial intelligence crew assistant operated in the European Columbus module of the International Space Station. The project was commissioned by the German Space Agency at DLR to explore human-robot interaction on long-duration missions, and the hardware was developed by Airbus [1]. Working in confined and extreme environments over a long mission is a risk to crew performance and wellbeing, and CIMON is the technology demonstrator aimed at that risk [2]. Its purpose is to reduce astronaut workload and stress, give hands-free access to procedures and data, and serve as a research subject for human-AI teaming [1]. Unlike the task-oriented free-flyers alongside it on the station, its core function is to interact, converse and demonstrate a form of emotional intelligence. In operation it acts as a database, a computer and a camera, showing the equipment required for a task on its screen, presenting directions for conducting experiments, searching for objects and taking inventory [2].

CIMON-2, Int-Ball2 and Astrobee are the intra-vehicular free-flyers currently resident on the station [2].

Specifications

Parameter	CIMON-1	CIMON-2
Shape and size	32 cm sphere	32 cm sphere
Mass	approx. 5 kg	approx. 5 kg
Mobility	12 propelling fans, about 120 mN maximum in x	same
Navigation	stereo camera VSLAM with IMU fusion	same
Imaging	1280 x 1024 at 25 fps	same
Processor	Pokini F WIFI (AMD A4-6700T), two units	same
Software	Ubuntu with ROS	same
Power	Li-ion, crew replaceable, or wired input	same
Endurance on batteries	2 h	3 h
Data communication	wired connection, WLAN, Bluetooth	same
Payload interface	2 x USB, Bluetooth	same
Ground operations	ground station remote connection plus AI server	same

Source: [1].

Mission profile

Parameter	Value	Source
Host	International Space Station, Columbus module	[1]
CIMON-1 on orbit	2 July 2018 to 27 August 2019	[6]
CIMON-2 launch	5 December 2019, 18:29 CET, SpaceX CRS-19 from Cape Canaveral	[5], [6]
CIMON-2 planned duration	up to three years aboard the station	[5], [6]
Users and science subjects since 2018	more than five nations	[1]

CIMON-1 was developed by about 50 people over two years from August 2016, and CIMON-2 by 20 people in under a year [6]. Airbus in Friedrichshafen and Bremen built the hardware, and the DLR Space Administration funded and oversaw the project with German Federal Ministry for Economic Affairs and Energy money, IBM supplied the artificial intelligence, Ludwig Maximilian University Munich was the scientific partner and Biotesc at the University of Lucerne provided ground support [6].

Mobility

CIMON moves and rotates in all directions on internal battery-powered fans, which provide both attitude control and translation within the module [1]. It has no external moving parts and the body is largely produced by 3D printing [4]. Published fan counts conflict: the program summary text gives 14 internal fans [1] while its own comparison table gives 12; the review of intra-vehicular free-flyers records 14 on CIMON and 12 on CIMON-2 [2]; DLR states twelve [4]. Thrust is deliberately limited to between 0.03 and 0.12 N across the three axes for safety [2], with a maximum of about 120 mN in the x direction [1]. The spherical form is the choice made across intra-vehicular free-flyers to limit the consequences of a collision with crew or cargo [2].

Power and energy

CIMON runs on lithium-ion batteries that the crew replaces, and it can also take a wired power input [1]. Endurance is 2 hours on CIMON-1 and 3 hours on CIMON-2, an increase of about 30 percent in the battery-powered autonomy [2], [6]. There is no docking station: CIMON requires crew for setup, unlike Astrobee and Int-Ball2, which reach a dock by themselves [1]. The Astrobee team made batteries available to the CIMON project in orbit until CIMON received its own items, which is the argument the joint operations teams make for a common pool of batteries, chargers, navigation markers and onboard computing across free-flyer projects. No battery capacity in watt-hours is published. The shift from consumables to rechargeable batteries across intra-vehicular free-flyers dates from the AERCam, Personal Satellite Assistant and SPHERES projects, and autonomous recharging is listed as one of the capabilities essential for any free-flyer tasked with maintaining an orbiting station [2].

Thermal

No thermal control design is published. CIMON carries temperature sensors [1] and operates in the pressurized cabin. All of these free-flyers use the existing infrastructure of the ISS for power supply, heat rejection and communications rather than providing their own.

Compute and avionics

Onboard computing is two units of Pokini F WIFI single-board computers built around an AMD A4-6700T, running Ubuntu with ROS, backed by an AI server on the ground [1]. The split is architectural rather than incidental: onboard software handles autonomous navigation and flight control by visual odometry and motion planning, while the language understanding runs on Earth. Both Astrobee and Int-Ball2 place their vision loop on a separate processor or core for the same reason, and time-critical modules such as propulsion take the highest priority across all of these designs [2].

Autonomy

The artificial intelligence is IBM’s Watson platform running on Earth servers. Spoken commands are transmitted to the ground, processed by Watson, and the responses sent back to the robot [1]. CIMON is not self-learning; its knowledge base must be pre-loaded and trained by human operators. The cloud-dependent architecture was chosen for demonstration purposes and contrasts with systems designed for onboard autonomy. The consequence is operational: a continuous link is a core constraint on when CIMON can be used.

That constraint is the reason CIMON appears in the case for offline assistants. It is cited as an intelligent personal assistant limited by predefined, inflexible responses drawn from specific structured data sources, rule-based and requiring constant online connectivity [3]. One-way Mars communication delay reaches 24 minutes, which removes the ground-processing option entirely for a deep-space equivalent.

Navigation is vision-based. A dual 3D camera collects depth information and the relations between features to build a map with SLAM algorithms [2], fused with the IMU [1]. Directional microphones localize the sound source so the robot turns toward the speaker, and the front camera then establishes and maintains eye contact [2]. Ultrasound sensors handle collision avoidance [2], [4]. CIMON uses its own visual fiducials as an absolute localization reference, independent of the marker sets used by Astrobee and Int-Ball2 [1].

Communications

CIMON has a wired connection, station WLAN and Bluetooth [1], the widest link set of the three current intra-vehicular free-flyers [2]. Because the language model runs on the ground, the WLAN path carries the interaction loop rather than telemetry alone, and the requirement for a continuous link is treated by the operations teams as the defining CIMON constraint [1].

Payload and instruments

The sensor set is a crew camera, an infrared camera, an IMU, ultrasonic sensors and temperature sensors [1]. The optical suite as described by the program comprises stereo cameras for 3D vision and navigation, an infrared camera, two side cameras supporting augmented reality tasks and a high-resolution camera for documenting experiments. The manufacturer’s description of CIMON-2 lists a stereo camera for orientation, a high-resolution camera for facial recognition and two lateral cameras for photo and video documentation [6]; DLR describes two cameras for facial recognition plus five others for orientation and video documentation [5]. Imaging is 1280 x 1024 at 25 fps [1], against Int-Ball2’s 1920 x 1080 at 30 fps and 4056 x 3040 at 15 fps. The eyes on the front face are two of the cameras and are used for facial recognition [5].

The audio system uses multiple microphones to perform directional sound source localization, which is what lets the robot turn and face the astronaut who is speaking [1]. CIMON-2 carries eight directional microphones plus one additional directional microphone dedicated to speech recognition [6], [5], and a loudspeaker for speech and music [4], along with cameras and software for facial recognition, orientation and video documentation.

Two USB ports and Bluetooth are available as a payload interface [1], and the laser pointer and USB ports are hardware that has not yet been activated in flight.

Modes of operation

The crew interface is an LCD monitor showing an animated face that conveys operational status, a speaker, status LEDs, a laser pointer, on-off and microphone-mute buttons, and IMU-based physical contact detection [1]. The animated face is the status display, and the design intent is a more natural interaction than a text readout. CIMON acts as a database, a computer and a camera in the crew’s workflow rather than as a manipulator: of the free-flyers on the ISS only Astrobee carries an arm, and that is a perching arm [2].

Crew privacy is handled in hardware: CIMON provides a mechanical offline button [1]. Int-Ball2 indicates data acquisition with LEDs and Astrobee uses a set of visual cues, and in all three cases the crew are informed before any activity so they know video may be downlinked.

CIMON-2 can analyze emotion in language and show empathy when interacting with the crew [6]. Teleoperation from the ground remains the fallback for fault detection and recovery on every intra-vehicular free-flyer regardless of the autonomy level reached [2].

Ground operations

CIMON is operated over a ground station remote connection working alongside the AI server [1]. Ground verification used software simulations, ground model testing, an Elegant Bread-Board and hardware-in-the-loop simulation. Some performance variances are found only on orbit, which is why every one of these programs pairs simulation with hardware test articles. Building a prototype before the official design review accelerated development, which the joint operations teams list as a lesson common to all three ISS free-flyer programs. Early alignment with the Human Safety board supported a smooth development phase and control of all hazards.

Anomaly resolution across these programs runs tiered: reproduce the fault on identical ground hardware, attempt remote recovery by power cycle or software patch, then crew replacement of hardware on orbit, then down-mass for ground repair [1]. CIMON took the replacement route, substituting an upgraded robot rather than repairing the flown one, as the Int-Ball project also did; Astrobee’s Honey was instead returned to the ground for repair. Ground support for CIMON operations is provided by Biotesc at the University of Lucerne [6].

Technologies developed

CIMON established that a verbal and visual interface is a usable additional tool for daily work in a crewed exploration environment, and most users gave positive feedback [1]. It was built to reduce crew workload and emotional stress, and it is the free-flyer whose declared product is the interaction itself rather than a camera view or an algorithm testbed [2]. Users and science subjects from more than five nations have interacted with the system since 2018, performing different and comparable tasks, which is the basis on which precise system requirements for a successor can be identified [1].

The program’s own stated limitation is the constraint imposed by its setup and its dependencies on external services, which traces to the 2016 mission goal of fielding an early-available technology demonstrator [1]. The stated next step is a hardware update increasing autonomy and availability, including a docking station and permanent deployment, together with on-premises AI services based on large language models and agentic AI. Offline assistants built from knowledge graphs, retrieval-augmented generation and language models are being designed for exactly that case, to run without a link to Earth [3].

Software interoperability turned out to be the transferable result. In 2025 CIMON and Int-Ball2 exchanged data in real time in the ICHIBAN activity, which was possible because both run ROS as their middleware [1]. Modular software architecture on ROS was adopted independently by Astrobee, CIMON and Int-Ball2, and the joint teams identify shared middleware as the route to sharing sensory and computational resources between free-flyers in a resource-constrained environment.

References