Spacebot v1.0 - Free-flying Robot

Tools & methods

• Mechanical CAD
• Cold-gas propulsion sizing
• Battery and mass budgets
• Docking interfaces
• Mission and thermal analysis

Project overview & mission architecture

I developed Spacebot v1.0 as a reusable free-flying robotic platform for local inspection, component positioning, tool transfer, and anchored assembly or servicing in low Earth orbit. The October 2026 product document defines the mechanical configuration, subsystem interfaces, engineering budgets, and planned operation.

A dedicated station supplies recharging, nitrogen replenishment, and orbital transfers. The station matches the target orbit before releasing robots for local work; robots remain secured during station transfers. The operating region is 400–600 km LEO, with a nominal station altitude of approximately 500 km.

The project is an engineering design. The specifications, calculations, CAD, and animations define the intended system; they do not establish verified in-orbit performance.

My design scope

The product document identifies me, S. R. Perera, as its author at the University of Ruhuna, under supervisor Mrs. M. S. D. Nimali. The design work connects the structural assembly, gas storage and propulsion, battery packaging, docking interfaces, and operational budgets.

The documented scope includes subsystem selection and packaging, preliminary performance calculations, mass and energy allocation, service interfaces, manufacturing considerations, operational states, and verification requirements. Flight software, fleet coordination, and service-station implementation require separate development.

Core configuration & mechanical packaging

Tank supports, battery mounts, and docking hardpoints transfer loads into the primary frame. Removable panels provide access for battery removal, valve inspection, routing, and sensor alignment.

The design identifies a packaging constraint: a centred 360 mm tank in a 500 mm cube leaves 70 mm at each face centre, while the proposed pack depth is 80 mm. Offset placement or revised cell trays must close that clearance in CAD.

Nitrogen propulsion & gas budget

The gas circuit comprises a refill coupling, isolation valves, pressure vessel, pressure and temperature sensing, regulator, filter, manifold, and individually controlled nozzle branches. The design uses 1 N nominal thrust per jet, with an approximately 5 bar chamber-pressure sizing basis and 66 s specific impulse.

At the 50 kg reference mass, ideal balanced four-jet translation provides 4 N and 0.080 m/s². Approximately 56.5 m/s routine equivalent velocity change is a calculated ideal budget, with attitude control, braking, geometry, and plume constraints reducing useful translation.

Battery architecture & energy planning

Four independently protected 8S3P packs supply a common bus. Each pack has 24 reference cells; together the installation has 96 cells. Pack isolation, monitoring, balancing, precharge, and reverse-current protection support fault containment and controlled connection.

The 6–8 hour target requires an average delivered load of roughly 111–83 W. These are planning calculations; thermal conditions, battery behaviour, and feasible return trajectories also constrain a sortie.

Docking, navigation & control

Six face docking positions support attachment, tool exchange, power, and data. Docking loads pass through reinforced hardpoints. A separately qualified nitrogen service coupling handles refilling.

Navigation combines IMU, camera, ranging, and inertial attitude sensing. Relative sensing establishes target pose and closing motion; the star tracker supplies an inertial attitude reference. The propulsion allocation uses a 6 × 24 matrix of nozzle force vectors and their moments about the current centre of mass.

The document sets a provisional 0.05 m/s final-contact speed and requires latch confirmation before enabling services or tool loads. Plume direction, sensor visibility, failure cases, and retreat paths constrain approach and actuation.

Candidate electronics include Xiphos Q7S, ADIS16495, ST-16RT2, and other navigation and communications references. Their power, environmental suitability, interfaces, and qualification remain integration work.

Illustrative eight-hour mission

The product document gives an energy-planning example built around intermittent anchored work. It uses 635 Wh over eight hours, leaving about 28.6 Wh of routine headroom and a separate recovery allowance.

This is a calculated mission example. Continuous high-power tools shorten endurance; gas use, thermal feasibility, and the reserved return path require separate checks.

Thermal design, manufacture & station servicing

The thermal design considers internal dissipation, sunlight, Earth infrared, albedo, radiators, conductive spreaders, and multilayer insulation. The document's ideal radiator estimate excludes external heating and is not a final area selection.

The proposed assembly sequence integrates the frame and hardpoints, pressure hardware, batteries, docking fittings, avionics, thermal paths, and harnesses before panel closure. It then checks routing, nozzle alignment, sensor views, access, and mass properties.

After station capture, latch verification and thrust inhibition precede charging and gas servicing. Charging depends on battery temperature and health; refuelling requires pressure, temperature, leak, and inventory checks before release.

Design status & verification priorities

Spacebot v1.0 establishes the system architecture, CAD arrangement, and preliminary engineering budgets. Final mass and inertia, pressure-vessel qualification, nozzle performance, battery packaging, interface loads, thermal behaviour, and control authority still require verification.

Verification priorities include docking and latch demonstrations, battery isolation, fault injection, leak and service-interface tests, thrust allocation with plume restrictions, mission-return simulation, and structural retention testing. The document treats manipulators and mission tools as additional modules outside the reference wet-mass sizing.

The supplied videos illustrate the intended operation sequence. They are design animations rather than evidence of a built or flown orbital system.

Planned sortie sequence

An overview of the documented project scope.

1. 01Release & transit
2. 02Approach & capture
3. 03Anchored work
4. 04Return & replenish

Operation animations

Project resources

The October 2026 product document defines the Spacebot v1.0 baseline. The supplied CAD views and operation animations illustrate the design.