Satellites

1 satellite · one orbital plane

ORBITAL GEOMETRY

Network coverage

Ground stations, satellite passes and transfer routes.

Drag to orbit · Scroll to zoom

Allocated linkVisible / waitingPossible optical link

SIMULATED TIME

Day 1 · 00:00:00

250 km · 89.4 minute orbitSimulated orbit

GROUND → SPACE RELAYS → GROUND

Inter-satellite links

Spacecraft & optical links

Acquire each new link

What the links can change

Messages can travel through several satellites before coming down. The planner compares this route with keeping the whole payload on one spacecraft and uses the earliest completed delivery. Ground visibility and the ground radio rate still limit service.

Cyan lines show possible optical pairs within the selected range and above a 100 km Earth-limb clearance. A bright moving link shows the scheduled hop. Two steerable terminals are allocated per spacecraft; one payload and one hop transmit at a time. Each receiver stores the complete payload before forwarding it.

Optical rates are study net caps: 100 Mbps for the compact option, 1,000 Mbps for the long-range option. These are below the manufacturers’ advertised channel rates. The model includes the selected acquisition allowance, one second of processing per forwarding step and crosslink light-travel time. It assumes pointing access and omits Sun exclusion, jitter, body blockage, failures and competing traffic. Range envelopes are not validated optical link budgets.

The long-range candidate is TESAT SCOT80. The compact SCOT30 is a development option with manufacturer availability targeted for 2028. Supplier quotes are required; no terminal purchase price is assumed.

CONSTELLATION DESIGN · 1–10 SATELLITES

Make every orbit count.

Optimization goal

Compare all 10 optimized sizes

Select a row to view its constellation. Times include waiting; all results are simulated.

Search method & design limits

Coverage priority minimizes the area- and time-averaged wait for usable contact while retaining at least 99% of the original layout’s average usable contact time and payload capacity. It tests balanced allocations across 1–N orbital planes, 180° / 360° plane spreads and up to four relative phasings. One-satellite designs test 16 orientations.

Search: 96 equally weighted, approximately equal-area globe samples at 180-second intervals. Up to 11 finalists, including the original layout, are evaluated on 384 samples at 60-second intervals over days 1–7. Waiting is capped at the end of this window. Coverage and capacity are spatial averages for one uncongested terminal; they are not total network throughput or guarantees for every town.

Transfer priority tests up to 107 orientations per constellation size, including the original, the coverage design, source-centred passes and local refinements. Each larger fleet also tests the preceding size’s best route: its relay orientation in radio-only mode, or its full layout plus one satellite when crosslinks are enabled. It minimizes the selected payload’s completion time at the captured start time using the ground contact planner and the selected optical routing model. Choosing a result restores that captured start time. A different route, payload or start time can have a different best design. This goal can trade worldwide coverage for faster delivery on one route.

These are the best tested designs in a bounded search, not a proven global maximum. Altitude, 97.6° inclination, the selected spacecraft configuration, ground antennas, and radio profiles stay fixed during the search. Applying a layout changes a design scenario; moving real spacecraft between planes is not simulated. Launch allocation, orbit maintenance and collision avoidance need mission design.

WORLDWIDE LINK PLANNING

Test any place.

Find a city, or place a pin for your town.

Find a city

Add your own town or site

—Usable rate now · both directions

—Predicted ground receive power

Added places are saved in this browser. Estimates use satellite geometry and the radio settings below; terrain, buildings and local interference are not included.

SPACECRAFT

Spacecraft assemblies

80 kg crosslink spacecraft study. Select an assembly.

Spacecraft configuration

Open covers

Separate assemblies 0%

Download crosslink spacecraft (.glb)

The model contains 16 subsystem assemblies, including optical terminals, routing electronics and the power/thermal upgrade. Electronics and fasteners show their planned positions. Production dimensions and component selections remain open.

Transfer simulator

SIMULATION

Send from Deliver to

Payload size MB

100 MB payload · decimal MB

Playback

1 satellite · same radio settings per spacecraft

Choose your locations and start a transfer.

Delivery by constellation size

Satellites	Delivery time	Net average

Same locations, payload, start time and radio settings for every row. Net average includes all waiting. Uses the active design for each size. Improvements need not be uniform.

Transfer assumptions & contacts

Payload sizes: editable text, a 5 MB picture or a 100 MB video by default. MB means 1,000,000 bytes. The selected radio rate is a net payload cap. Adaptive mode steps through 0.1, 0.5, 1, 2, 5 and 10 Mbps as signal allows, up to that cap. Each profile uses the same assumed 6 dB Eb/N₀ threshold plus 3 dB reserve; these profiles require hardware validation.

Speed depends on slant range, dish size and the assumed weather allowance. A location has zero usable rate outside a supported contact. The planner chooses the earliest completed delivery among the selected satellites. The whole payload uploads to one satellite, can move through optical relays, then downloads from its final carrier. Interrupted ground legs resume with the same carrier. Each optical hop requires a continuous contact long enough for acquisition and the entire payload. One transfer gets exclusive radio access; no competing queues, storage limit or retries are modeled. Ground contacts use five-second conservative samples. Optical contact windows are solved analytically for these equal-height circular orbits. Each forwarding decision has a one-second processing allowance; optical hops also include acquisition and light-travel time. Ground acquisition and ground propagation are not separately added.

The constellation has 1–10 identical satellites at 97.6° inclination and the selected altitude. Coverage and transfer designs can use several orbital planes with independently optimized orientation and phasing. The original single-plane layout remains available in the optimization menu. Optical links follow the selected spacecraft option. A ground terminal tracks one spacecraft at a time. More satellites provide more contact opportunities; the per-link rate cap stays unchanged.

Overview playback compresses waiting time and radio activity. Byte counts, orbit position and elapsed time follow the simulation. No real messages or files are transmitted.

Satellite link planner

Calculation frequencies: 14.25 GHz uplink and 11.95 GHz downlink. Channel assignments, polarization and interference coordination remain part of the RF design.

Altitude

Minimum elevation

Dish diameter

Rate cap / link

Weather allowance

Adapt payload rate to signal

What does dBi mean?

dBi describes the antenna’s directional gain, not electrical amplifier power. A larger dish concentrates the beam more tightly. This model assumes 60% aperture efficiency. Uplink: 14.25 GHz; downlink: 11.95 GHz. These are unassigned calculation frequencies. Spacecraft peak gain uses a 160 mm square aperture and 45% assumed efficiency. Ground transmit power is 5 W; target spacecraft output is 2 W linear per chain. Antenna scan/structure loss is 6 dB. A Starlink terminal is tied to its own network; this custom relay needs a matching Ku radio, waveform and tracking antenna.

Sandy Hook · NL01

—Azimuth · true north

—Elevation

—Slant range · km

—Headroom at rate cap · dB

Read the link calculation

Headroom is above a 6 dB payload Eb/N₀ threshold plus a 3 dB reserve. Assumptions: 5 W ground transmitter; 2 W space transmitter per active chain; two 160 × 160 mm aperture allocations at 45% efficiency; 6 dB spacecraft scan / structure allowance; 600 K space and 180 K ground receivers. The corresponding peak gains are about 25.1 dBi uplink / 23.6 dBi downlink. Actual equipment has not been selected.

Compare test locations

Compare the 18 reference stations and your added places using the selected orbit and radio settings.

Contacts are sampled every 10 seconds. Usable minutes count contact with any satellite once, choosing the best usable rate at each sample. Passes count individual spacecraft. These are capacity estimates before radio scheduling and antenna acquisition.

Reference & added locations

Reference stations identify proposed planning areas. Added cities and towns are simulation points, with no station assumed to be installed. Local spectrum and operating approvals are required.

Technical white paper

Network architecture, orbit selection, RF budgets, ground terminals and programme costs.

Read white paper Download PDF

Version 2.0 · 28 September 2026 · 36 pages

Optical relays, measured 1–10 satellite comparisons, 18 reference stations, worldwide locations, revised mass/power allocations and the complete 56-entry procurement register.

Engineering notes

Geometry, scale and scheduling

Spherical Earth radius 6,371 km; circular orbit; inclination 97.6°. Earth rotates at the sidereal rate. The original orbital phase passes directly over Sandy Hook; optimized designs use the orbital planes and phases returned by the search. No actual epoch, J2, drag, terrain, site weather or exclusion-zone schedule is applied. Weather attenuation is a sensitivity input, not a regional forecast. The five orbits are not all sun-synchronous.

Earth and orbital height share a real scale. Satellites, nodes and link strokes are enlarged for visibility. The footprint marks the geometric access boundary at the selected minimum elevation. Each satellite can allocate up to two visible stations in simulated 60-second radio slots; a station tracks at most one spacecraft at a time. The transfer simulator reserves the radio for the selected payload and shows its active link; it ignores other queues. Usable capacity also depends on radio allocation, equipment performance and authorized operation.

Network ownership and resilience

Nodes can own their computers, antennas, storage and encryption keys. One spacecraft is still a shared point of failure. Independent command teams, transparent allocation, additional operators and additional spacecraft are needed for stronger resilience. Radio licences and interference constraints still apply.

Sources & credits

City catalog: GeoNames cities15000, 25 September 2026, CC BY 4.0. 34,149 records across 244 countries and territories, including cities over 15,000 people and capitals / administrative seats. City centres are approximate; source coverage is not guaranteed. Names, coordinates, country and administrative fields have been reformatted.

Street map: © OpenStreetMap contributors. Street tiles require internet access. Outline map: Natural Earth, public domain. Leaflet 1.9.4 (BSD-2-Clause). Map data credits · Report a map issue.

Earth texture: NASA Blue Marble, Reto Stöckli / Robert Simmon. Rendering: Three.js r160 (MIT). Design reference: Northlink Satellite 360. Revision 2 allocates a 400 Wh / 300 W base and 500 Wh / 600 W optical variants. Mass, power, thermal and optical pointing closure remain open. Original prices checked 25 September; optical additions checked 28 September 2026 (UTC).

NASA: store-and-forward networking · ESA: same-plane satellite phasing example. ESA: multiple orbital planes. The constellations here are Northlink planning assumptions, not models of those missions.

Bundle Protocol v7 · BPSec · ITU propagation methods

Download reference Earth model (.glb)