Introducing ESA Scout HydroGNSS

SSTL entered a contract with ESA on 11th October 2021 to provide under the new Scout small scientific satellite programme a mission called HydroGNSS to measure climate change variables using GNSS Reflectometry. SSTL is working on the project with scientific partners from Sapienza, IEEC, FMI, Tor Vergata, CNR/IFAC, NOC, Nottingham and others.

HydroGNSS satellite selected for ESA Scout mission | SSTL

More information can be found in these links:
Youtube animation

New Orbital GNSS-R Demonstration

GNSS-Reflectometry on DoT-1 Microsatellite

SSTL Demonstrates New GNSS-R Capabilities
Delay Doppler Maps captured in orbit on DoT-1 during test on 13th August 2020

Surrey Satellite Technology Ltd (SSTL) has successfully demonstrated GNSS-Reflectometry (GNSS-R) from its 18kg DoT-1 satellite. SSTL has pioneered the new field of GNSS-R with successful payloads on board TechDemoSat-1 and the CYGNSS constellation, and is continuing to develop the technology and data analysis in pursuit of this new science. The latest GNSS-R payload on-board the DoT-1 satellite is incorporated within the new small form factor Core Avionics module integral to all SSTL’s future satellite platforms. This innovation paves the way for any SSTL satellite that can accommodate a nadir pointing antenna to become part of a GNSS-R small-sat constellation.

More info in press release at:

First GNSS-R Sea Ice Level 2 Product Released

The first sea ice product on MERRByS from the TDS-1 satellite GNSS-R data catalogue has been released, and is now available on the FTP server. Surrey Satellite Technology Limited (SSTL) and the National Oceanography Centre (NOC) recently released v1.0 of the Calibrated Bistatic Radar Equation (C-BRE) processor, which provides a number of new and improved features including a novel GNSS-R Sea Ice Detection Algorithm (GSID). The output from this algorithm has been formatted into a Sea Ice product, and can be found here under “L2_CBRE_v1_0_GSID”. An updated product manual can be found here on the documentation page. We would be keen to hear feedback from users about this new capability.

A month by month availability web page has been set up to allow users to quickly view the historical ice data and can be found here.

Antarctic ice map generated using TDS-1 data between 31/10/2018 - 30/11/2019.
Antarctic ice map generated using TDS-1 data between 31/10/2018 – 30/11/2019.
Arctic ice map generated using TDS-1 data between 31/10/2018 - 30/11/2019.
Arctic ice map generated using TDS-1 data between 31/10/2018 – 30/11/2019.

NOC C-BRE v1.0 L2 Data Released

Cartographic plot showing C-BRE v0.5 and C-BRE v1.0 data availability (NOC 2019)

During an ESA-sponsored study in 2018-2019, Surrey Satellite Technology Limited (SSTL) and the National Oceanography Centre (NOC) have been collaborating to improve the L1B to L2 inversion accuracy for TDS-1 data.

The output of this work is an upgraded Calibrated Bistatic Radar Equation (C-BRE) processor (v1.0). This algorithm has been integrated into MERRByS and used to re-process the back catalogue of TDS-1 measurements.

The improvements over C-BRE v0.5 include:

  • Application of dual on-board / Antarctic radiometric calibration, increasing data coverage
  • An ice detection algorithm allowing data up to ice edges, and a new flag for presence of ice
  • Improved corrections for variation in GPS transmit powers
  • Improved flagging of processor and RFI anomalies

The data is available from the MERRByS FTP server in the data folder labelled “L2_CBRE_v1_0”. This folder can be found here.

An updated product manual describing the new C-BRE v1.0 Level 2 outputs can be found on the documentation page.

TDS-1 Drag Sail Deployment

Image of deployed drag sail taken by TDS-1 on-board inspection camera

The deployment of the Icarus-1 drag sail, which was supplied by Cranfield University, marks the end of mission operations for SSTL’s TechDemoSat-1.  This sail increases the cross-sectional area of the satellite and hence atmospheric drag to speed up reentry.

SSTL posted a press release announcing the deployment. Jonathan Amos from the BBC tweeted with a special mention of the achievements of TDS-1 in GNSS Reflectometry.

Meanwhile SSTL staff members are working on an upcoming satellite mission carrying an opportunistic GNSS reflectometry experiment. We hope to bring you news about this new project very soon.

April 2019 Update from TDS-1

Routine DDM collection from the SGR-ReSI on TechDemoSat-1 ceased in December 2018, and since then, operators have been making preparations for the drag-sail deployment. This has required controlled passivation of the satellite, which includes the slow expulsion of all remaining propellant from the propulsion tanks.

During gaps in this preparation period, we have been able to make a final handful of L0 raw data collections from TDS-1, to add to the collections we have gathered through its 5 year lifetime.

As well as C/A code signals from GPS, we have been targeting E1B/C reflections from the Galileo satellites, and other signals that fall within the SGR-ReSI’s frequency band. The Galileo signals are wider in bandwidth than GPS C/A code, and use BOC modulation. These new signals are somewhat more complex to process, but to a first order, we see similar behaviour in the DDMs to GPS C/A code reflections over ocean, land and ice. This is good news as it shows the practicality of using Galileo alongside GPS reflections in our upcoming GNSS-R missions.

Galileo E1(B+C) Delay Doppler Map from TDS-1 over ocean
Galileo E1(B+C) Delay Doppler Map from TDS-1 over ice

We at SSTL, together with partners from NOC, will be presenting recent results from TDS-1 at the GNSS+R 2019 workshop 20-22nd May 2019 in Benevento, Italy. We look forward to meeting many of you there.