HydroGNSS
From Wikipedia, the free encyclopedia
HydroGNSS 2: 2025-276AH
.jpeg) | |
| Mission type | Earth observation satellite |
|---|---|
| Operator | ESA |
| COSPAR ID | HydroGNSS 1: 2025-276AG HydroGNSS 2: 2025-276AH |
| Website | hydrognss.org |
| Mission duration | 4 months, 10 days (in progress) |
| Spacecraft properties | |
| Manufacturer | Surrey Satellite Technology |
| Start of mission | |
| Launch date | 28 November 2025, 18:44 UTC |
| Rocket | Falcon 9 Transporter-15 |
| Launch site | SLC-4E |
| Orbital parameters | |
| Reference system | Geocentric |
| Regime | Sun-synchronous |
| Altitude | 550 km |
 ESA insingia | |
HydroGNSS (Hydrological Global Navigation Satellite System) is an Earth observation satellite mission by the European Space Agency (ESA) consisting of two identical small satellites carrying GNSS reflectometry instruments. The mission is using satellite navigation signals reflected from the Earth surface to monitor various Essential Climate Variables related to the hydrological cycle.[1][2][3][4][5][6][7][8] It was launched in November 2025 on a Falcon 9 rocket.[9]
HydroGNSS is designed to deliver data on four hydrological parameters aligned with Essential Climate Variables:[10]
- soil moisture
- inundation or wetlands
- freeze/thaw state
- above-ground biomass
The mission's secondary objectives are to measure wind speed over the ocean and sea-ice extent.[10]
Background
The project builds upon previous GNSS reflectometry satellite missions—the CYGNSS constellation by NASA and the TechDemoSat-1 demonstrator by ESA and UKSA. Surrey Satellite Technology Ltd., the prime contractor for HydroGNSS, was involved in both these missions.[11]
HydroGNSS is launching as the first mission of ESA's Scout series of missions, within the FutureEO programme, although it bears the designation Scout-2.[2] That is because the Scout-1 mission CubeMAP was cancelled before its launch due to budgetary constraints.[12][13] ESA requires each Scout mission to move to launch within three years after kick-off and with a budget under €35 million.[14]
Project history
In March 2021, ESA has decided to implement HydroGNSS as the second of its new Scout series of missions within the FutureEO programme.[15] In October 2021, ESA has signed a contract with Surrey Satellite Technology to build the mission.[16][17] In March 2023, ESA has decided to build two HydroGNSS satellites instead of just one.[18][19]
In August 2025, the two satellites have passed their Flight Acceptance Review.[20] In September 2025, the two satellites have been transported to California for launch on Falcon 9 later that year.[21][11] After testing, propellant loading, battery charging, and launch adapter integration, the two spacecraft were pronounced ready for launch by ESA in November 2025.[14]
The two satellites were launched on 28 November 2025 at 18:44 UTC from Vandenberg Space Force Base on the SpaceX Falcon 9 Transporter-15 rideshare mission[22][23][14][24][10] and separated from the rocket less than 90 minutes after liftoff. At 21:45 UTC, Surrey Satellite Technology confirmed that they had received first signals from the satellites.[9]
On 19 December 2025, SSTL reported that both HydroGNSS satellites were already collecting Delay Doppler Maps of reflected GNSS signals. One example dataset was collected by HydroGNSS 2 over Central Africa on 5 December 2025, 7 days after launch.[25] In March 2026, SSTL reported that the two spacecraft, still in their commissioning phase, were successfully collecting "promising early measurements" and published a video of the mission's Delay Doppler Maps generated over France, the Mediterranean Sea, and north and east Africa.[26]
See also
References
- ↑ Gutierrez, Peter (2025-01-20). "GNSS Reflectometry Project HydroGNSS to Launch in 2025". Inside GNSS - Global Navigation Satellite Systems Engineering, Policy, and Design. Retrieved 2025-09-24.
- 1 2 "HydroGNSS/Scout-2 - eoPortal". www.eoportal.org. Archived from the original on 2025-08-23. Retrieved 2025-09-24.
- ↑ "About HydroGNSS".
- ↑ "HydroGNSS (Earth Scout 2)". Gunter's Space Page. Retrieved 2025-09-24.
- ↑ "HydroGNSS | Small Satellite supplier | Surrey Satellite Technology Ltd | SSTL". www.sstl.co.uk. Retrieved 2025-09-24.
- ↑ Unwin, Martin J.; Pierdicca, Nazzareno; Cardellach, Estel; Rautiainen, Kimmo; Foti, Giuseppe; Blunt, Paul; Guerriero, Leila; Santi, Emanuele; Tossaint, Michel (2021). "An Introduction to the HydroGNSS GNSS Reflectometry Remote Sensing Mission". IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing. 14: 6987–6999. doi:10.1109/JSTARS.2021.3089550. hdl:10261/254026. ISSN 1939-1404.
- ↑ admin (2024-06-20). "HydroGNSS – two small satellites measuring soil moisture over the globe - Space4Climate". Retrieved 2025-09-30.
- ↑ "UK and ESA-funded climate mission HydroGNSS showcased to international space experts – Centre for Earth Observation Instrumentation". ceoi.ac.uk. Retrieved 2025-09-30.
- 1 2 "ESA's HydroGNSS mission launched to 'scout' for water". www.esa.int. Retrieved 2025-11-28.
- 1 2 3 "Watch: HydroGNSS, IRIDE and Greek mission satellites launch". www.esa.int. Retrieved 2025-11-18.
- 1 2 "HydroGNSS: ESA's first Scout begins launch preparations". www.esa.int. Retrieved 2025-09-29.
- ↑ "GomSpace and ESA cancel next phase of climate observation mission". Space Daily. Retrieved 2025-09-30.
- ↑ "CubeMAP mission development halted". www.esa.int. Retrieved 2025-09-30.
- 1 2 3 "ESA's HydroGNSS Scout satellites ready for launch". www.esa.int. Retrieved 2025-11-06.
- ↑ "Second Scout gets the go-ahead". www.esa.int. Retrieved 2025-09-29.
- ↑ "Contract secures build for HydroGNSS Scout mission".
- ↑ "Contract secures build for HydroGNSS Scout mission". www.esa.int. Retrieved 2025-09-29.
- ↑ Parsonson, Andrew (2023-03-22). "ESA HydroGNSS Earth Observation Mission Doubles in Size". European Spaceflight. Retrieved 2025-09-30.
- ↑ "HydroGNSS twice as good". www.esa.int. Retrieved 2025-09-29.
- ↑ "HydroGNSS passes Flight Acceptance Review". www.esa.int. Retrieved 2025-09-29.
- ↑ Harrison, Kerry (2025-09-30). "Europe's HydroGNSS Mission Arrives In California For Launch". Orbital Today. Retrieved 2025-09-30.
- ↑ "ESA's HydroGNSS mission lifts off". www.esa.int. Retrieved 2025-11-28.
- ↑ "Transporter 15 | Falcon 9 Block 5 | Next Spaceflight". nextspaceflight.com. Retrieved 2025-11-06.
- ↑ "HydroGNSS (Earth Scout 2)". Gunter's Space Page. Retrieved 2025-11-06.
- ↑ "Latest News | Small Satellite supplier | Surrey Satellite Technology Ltd | SSTL". www.sstl.co.uk. Retrieved 2025-12-26.
- ↑ "ESA's HydroGNSS on track to scout for water". www.esa.int. Retrieved 2026-03-14.
| |||||||||||||||||||||||||||
Future missions in italics
| |||||||||||||||||||||||||||
