# TechDemoSat-1 (TDS-1)
*missions*

UK technology demonstration satellite launched July 2014 by SSTL; carried SGR-ReSI GNSS-R instrument from Surrey Space Centre; first spaceborne demonstration of GNSS-R for ocean wind speed retrieval at scale.

## Specifications
- **operator**: surrey-satellite-technology
- **current status**: ended
- **actual launch**: 2014-07-08
- **orbit type**: LEO SSO 635 km
- **tasking supported**: false
- **launch vehicle**: roscosmos-soyuz-2
- **entity type**: mission
- **last verified date**: 2026-06-11
- **verified by**: agency-doc
- **claim status**: unclaimed
- **provider**: surrey-satellite-technology
- **attributes**: {"operator":"surrey-satellite-technology","current_status":"ended","actual_launch":"2014-07-08","orbit_type":"LEO SSO 635 km","tasking_supported":false,"summary":"UK technology demonstration satellite launched July 2014 by SSTL; carried SGR-ReSI GNSS-R instrument from Surrey Space Centre; first spaceborne demonstration of GNSS-R for ocean wind speed retrieval at scale.","launch_vehicle":"roscosmos-soyuz-2"}
- **relevance**: in-scope

## Editorial
TechDemoSat-1 (TDS-1) was a UK technology demonstration satellite built and operated by Surrey Satellite Technology Ltd (SSTL), launched on 8 July 2014 into a sun-synchronous orbit at 635 km altitude. The mission ended in May 2019 following deployment of its de-orbit sail.[^eoport-tds1][^sstl-tds1]

The primary instrument relevant to Earth observation was the SGR-ReSI (Space GNSS Receiver Remote Sensing Instrument), developed by Surrey Space Centre. SGR-ReSI was a 24-channel GNSS reflectometry receiver capable of processing GPS L1 signals and designed for Galileo and GLONASS compatibility, with dual FPGAs enabling real-time delay-Doppler map (DDM) generation. TechDemoSat-1 demonstrated spaceborne GNSS-R ocean surface wind speed retrieval from a dedicated GNSS reflectometry instrument.[^tds1-gnssr-paper][^eoport-tds1]

The methods and hardware validated on TechDemoSat-1 directly informed the design of the CYGNSS constellation (launched 2016) and the SGR-ReSI-Z receiver carried by the HydroGNSS Scout mission (launched 2025). TDS-1 carried a total of fifteen technology demonstration payloads across communications, propulsion, and remote sensing domains.[^sstl-tds1]

## Sources
- [eoport-tds1] | TechDemoSat-1 mission overview, eoPortal | https://www.eoportal.org/satellite-missions/techdemosat-1 | tier=agency-doc | accessed=2026-06-11
- [sstl-tds1] | TechDemoSat-1, SSTL space portfolio | https://www.sstl.co.uk/space-portfolio/launched-missions/2010-2019/techdemosat-1-launched-2014 | tier=operator-marketing | accessed=2026-06-11
- [tds1-gnssr-paper] | Spaceborne GNSS-Reflectometry on TechDemoSat-1, Unwin et al. JSTARS 2016 | https://cygnss.engin.umich.edu/wp-content/uploads/sites/534/2021/06/Unwin-etal_TechDemoSat-Early-Mission-Ops_JSTARS_2016.pdf | tier=peer-reviewed | accessed=2026-06-11

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Source: https://eo-atlas.org/missions/techdemosat-1
Maintainer: SpectraWorks B.V. (CC-BY 4.0)