# Etalon 3D model

> Shape built from published dimensions and pictures; details simplified.

Free 3D model of Etalon, a satellite, built from published dimensions by Space Radar. 13,672 triangles, 100 kB glTF, MIT.

- **Class:** Satellites
- **Mission:** Technology and science
- **Triangles:** 13,672
- **File:** etalon.glb, 100 kB, glTF 2.0 binary (meshopt)
- **Look:** Flat colours
- **Size:** 1.3 m across
- **Made:** Built from dimensions
- **Added:** 2026-10-13
- **NORAD:** 19751
- **Download:** https://raw.githubusercontent.com/Sara-Managed-Projects/space-radar/main/site/models/etalon.glb
- **Mirror:** https://git.sara-agent.org/sara-projects/space-radar/raw/branch/main/site/models/etalon.glb
- **Viewer:** https://www.spaceradar.ai/model/?id=etalon
- **On the live map:** https://www.spaceradar.ai/#at=sat-19751
- **Licence:** MIT (https://github.com/Sara-Managed-Projects/space-radar/blob/main/LICENSE)
- **Credit:** Etalon 3D model by Space Radar (spaceradar.ai), MIT License

Canonical: https://models.spaceradar.ai/etalon/

## How it was made

Built in code from published dimensions and photographs, with no image-to-3D generator and no one else’s mesh. 3D model: built by Space Radar from the published counts of Etalon's 2 146 retroreflectors.

built by this project in code (the private tool model-from-images: assemble.py, from a yaml of primitives), from the cited dimensions and the pictures under `references`; no image-to-3D model was used, and no published mesh

## Dimensions

- Diameter: 1.294 m
- Retroreflectors: 2146

Source: International Laser Ranging Service (NASA-hosted), https://ilrs.gsfc.nasa.gov/missions/satellite_missions/current_missions/eta1_general.html and eta1_reflector.html, opened 2026-10-13: 'Each Etalon satellite is a 1.294 m diameter sphere. The diameter of the sphere touching the corner cube reflector (CCR) faces is 1284 mm'; 'a total of 2140 fused-quartz CCR's (304 arrays 7 CCR's each and 2 arrays 6 CCR's each) plus 6 germanium CCR's.'; 'made of aluminum-titanium alloy with an integral coefficient of diffuse reflectivity 0.7'; the distribution is 'not absolutely uniform'. NOT CITED: where any array sits, the size of a cube's face (drawn 27 mm across, six-sided), the pitch inside an array (drawn 31 mm)

## References

- [Etalon-1 and -2, the ILRS mission page](https://ilrs.gsfc.nasa.gov/missions/satellite_missions/current_missions/eta1_general.html), International Laser Ranging Service; photograph no credit line is given, so it is not relied on (The page's text is NASA-hosted (the International Laser Ranging Service at Goddard); its photograph is NOT FREE: no credit line is given, so it is not relied on)