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Beyond thehorizon.

Where lunar exploration meets mission intelligence.

Explore the Moon's south pole, visualize the Sun and Earth's position against its unforgiving terrain, and discover the conditions that shape the next generation of lunar missions.

Explore ShadowlineDiscover the Mission
Sun elevation
+1.6°
Grazing the horizon
Earth visibility
+6.4°
Above horizon, in line of sight

Conceptual preview. Procedurally generated terrain and illustrative values, not mission telemetry or LOLA-derived data.

A world where every degree matters.

At the south pole the Sun never climbs more than about a degree and a half above the horizon. A ridge a few hundred metres high can decide whether a site sits in near-constant light or in permanent shadow, and whether Earth is in view at all.

  • Sun +1.5°shadow

    01

    Extreme lighting

    The Moon's south pole experiences unusual lighting conditions. Small differences in elevation and terrain can dramatically influence sunlight availability.

  • Earthblockedclear

    02

    Communication constraints

    Earth visibility depends on the geometry between the lunar surface, Earth's apparent position, and surrounding terrain.

  • sunlight →Earth visibility →ABC

    03

    Complex decisions

    Mission planners must balance solar availability, communication windows, and terrain when evaluating candidate landing locations.

Diagrams are schematic and not to scale.

See the mission from the surface.

Shadowline turns complex lunar environmental data into a place you can stand in. Instead of reading tables of angles, you look across the terrain from a candidate landing site and see the Sun, the Earth and the ridges between them.

shadowline / explore / site-a
Concept interface
Candidate site
Site A · rim crest
Placed by the user
Horizon profileIllustrative
Example horizon profile for Site ATerrain elevation angle around a site plotted against azimuth. The Sun's path is lit where it rises above the terrain and blocked where the terrain is higher. Earth sits near 182° azimuth. Values are illustrative.0°90°180°270°360°0°2°4°
Concept of the planned simulator. Terrain is procedural and every readout is computed on an illustrative horizon profile, not real lunar data.
  1. Step 1

    Place a landing site

    Pick a point on the terrain and stand on it. The surrounding ridges and crater walls become your horizon.

  2. Step 2

    Read its horizon

    See where the Sun and Earth travel against that horizon, and where the terrain cuts them off.

  3. Step 3

    Judge the conditions

    Turn the geometry into mission terms: how long the site stays lit, and when it can talk to Earth.

Three ways to explore.

Learn the environment step by step, roam the terrain on your own, or put candidate sites side by side. Each mode has its own space in Shadowline.

  • 01In development

    Guided Mission

    Understand the environment.

    An interactive tutorial that teaches you how to read the lunar south pole the way a mission planner does.

    • Solar elevation
    • Terrain obstruction
    • Earth visibility
    • Communication windows
    • Mission lighting conditions
    Begin Tutorial
  • 02In development

    Free Exploration

    Discover your own landing site.

    Select coordinates, move across the terrain, change the simulation date and analyse your own candidate landing locations.

    Explore the Moon
  • 03In development

    Mission Comparison

    Find the strongest candidate.

    Compare multiple landing sites and dates side by side with synchronised 3D views and mission viability metrics.

    Compare Missions

Built on real lunar data.

Near the pole, latitude tells you very little. What matters is the horizon each site actually sees: the crater walls and distant massifs that decide when sunlight arrives and whether Earth is in view. Shadowline is designed to compute that horizon from measured terrain, then present it as something you can see.

The horizon mask

One site, every direction, one line.

Illustrative horizon maskTerrain elevation angle around a site plotted against azimuth. The Sun's path is lit where it rises above the terrain and blocked where the terrain is higher. Earth sits near 182° azimuth. Values are illustrative.0°90°180°270°360°0°2°4°
Terrain mask Sun path, unobstructed Sun path, blocked by terrain EarthIllustrative values
  1. Step 1

    Sample the terrain

    Read elevations around the site from LOLA polar digital elevation models.

  2. Step 2

    Build the horizon mask

    For every compass direction, find the highest angle at which terrain blocks the sky.

  3. Step 3

    Test the Sun and Earth

    Compare their apparent positions from JPL Horizons against the mask, moment by moment.

Data sources

  • Lunar Orbiter Laser Altimeter (LOLA)

    Polar digital elevation models for terrain geometry and horizon computation.

    Planned integration

  • JPL Horizons (Horizons)

    Ephemerides for the apparent position of the Sun and Earth from a lunar surface site.

    Planned integration

What it will analyse

  • Lunar topography and horizon obstruction

    Crater rims and massifs, not latitude alone, decide what a site can see.

  • Solar elevation and illumination

    Whether the Sun's disc clears the local horizon, and for how long.

  • Earth visibility and line of sight

    Whether Earth stands above the terrain for direct-to-Earth communication.

The visuals on this page are illustrative. Real terrain and ephemeris data have not been integrated yet.

Read the methodology

Your mission starts at the horizon.

Explore the lunar south pole. Discover the challenges. Find your landing site.

Launch Freeplay