Nordic multi-static space debris radar architecture

Daniel Kastinen Johan Kero

Sari Lasanen Marko Leinonen Tomi Teppo

Tom Grydeland Liliana Macotela Bård Kårtveit

Final presentation

Agenda

Introduction
User consultation
Use cases
The NOSTRA Mission
System requirements
Feasibility study
Conclusions

Introduction

Introduction

Introduction

Introduction

Tri-static high-latitude high-power large-aperture phased-array radar

Mono-static radar = 5-15 seconds per trajectory measurement
Tri-static radar = 0.1 seconds for initial orbit determination
(50-150 increase in efficiency)
High-latitude = optimal for observing the majority of LEO/MEO space objects and observing them often
High-power large-aperture = higher sensitivity and better resolution
Phased-array = rapid pointing anywhere in the field of regard, both tracking and surveillance possible simultaneously
Every site has transmitter and receiver = system is resilient and versatile

Introduction

Introduction

Introduction

Agenda

Introduction
User consultation
Use cases
The NOSTRA Mission
System requirements
Feasibility study
Conclusions

User consultation

User consultation

Key findings from Norwegian user consultation

Potential cornerstone of national space traffic management system
Build national capability and competence
Commercial-sector usage primarily through EU SST
Dual-use role foreseen from the outset
Norwegian participation to open for insider access to EU SST

User consultation

Key use cases from Norwegian user consultation

Ensure clear space ahead of launch activity
Tracking in the face of jamming/spoofing
Protecting assets from collisions, especially with larger objects (5 cm or larger)
Avoid secondary impacts (i.e. fragmentation of primary object(s))
Earlier and more precise collision warnings
Planning and de-risking maneuvers
Improving the quality of warnings and predictions from existing tools and systems (EU-SST)
Tracking during early phases of re-entry
For academic: Access to radar data, and at least sensitivity for 10 cm size objects

User consultation

Key requirements from Norwegian user consultation

Timely orbit updates
Earlier and more precise collision warnings (strictly decreasing uncertainties)
Academic users concerned about having access to data
Exclusivity not an issue, widespread dissemination considered positive
Coordination/synergy with other systems
One respondent very concerned if were thinking seriously enough about site security

User consultation

Swedish use cases derived from user consultation

Support mission planning
Support launch and orbit (LEOP)
Support research and education
Support societal sectors
Build national capabilities and competences
Participating in international SSA exercises
Size distribution in LEO down to 1 cm
Usage primarily through EU-SST

Verify quality of catalogue data
National space traffic management system
Fragmentation analysis
Early warnings and rapid fragmentation survey
Determine configuration of specific objects
Determine sources of jamming / interference
Measurements of objects in High Level Airspace

User consultation

Swedish requirements derived from user consultation

Track all objects larger than 100 cm
Dynamic list of high accuracy prioritised objects
Performance sufficient for EU-SST
Compatible with EU-SST COPLA system
Provide catalogue updates
Usable for national emergency response systems
Possibility for security classified control
No need for field of regard down to horizon

Typical replies from non-academic users:
“We need to do a broader analysis to answer these questions"
"First of all, we need ready-made data products, not to do our own analyses”

User consultation

Swedish priorities derived from user consultation

Full operational capacity within the next 5 years. If anything is to be prioritised, reaching full operational capability is most important. It needs to be good enough to contribute to the EU-SST as soon as possible.
Survey of some priority space objects via alignment with previously known orbital elements, in order to get an updated position and possibly other parameters on it compared to the public catalogues.

User consultation

Finnish use cases derived from user consultation

Support research and education
Participating in international SSA exercises
Usage primarily through EU SST
Maintaining of catalogues
Collision avoidance
Support for debris removal
Planning for future missions
Maneuver warnings
Fragmentation model improvements
Fragmentation survey
Measure (smaller than) 1m objects in MEO/GEO)

User consultation

Finnish requirements derived from user consultation

Performance sufficient for EU SST
Compatible with EU SST COPLA system
EU SST data via FSSAC
Use space data standards and formats
Provide catalogue updates
Dual use
Observe 2cm objects at 500km (up to 1000km)
Observe (smaller than) 1m objects in MEO

User consultation

Finnish priorities derived from user consultation

First modular stage already measures orbital parameters
Prefer low cost over measuring MEO/GEO objects
EU SST data via FSSAC in Finland
Civilian infrastructure

Agenda

Introduction
User consultation
Use cases
The NOSTRA Mission
System requirements
Feasibility study
Conclusions

Use cases

Pool of all use cases from users
Prioritize high impact and common use cases
Select use cases where NOSTRA can be effective

Selected used cases for the Mission

Use cases

Selected used cases for the Mission

EU SST
Launch and Early Orbit Phase support
Collision avoidance
Fragmentation events
Mission planning and support
Re-entry
Manoeuvre detection
Catalogue maintenance and quality

Population modelling
Debris removal and in-orbit servicing operations
Research and education
Jamming and interference
Attitude and spin
High Level Airspace
Meteors, meteoroids and Near Earth Objects
International collaboration

Use cases

Use case contribution

The impact NOSTRA would have on a specific use case

Performance metrics

A generalized metric affecting many use case contributions

Use cases

Performance metrics

SNR as a function of range and target size
Dimensionality of each simultaneous measurement set, and observable physical characteristics
Range and velocity accuracy for each measurement as a function of SNR
Instantaneous solid angle coverage of system (for transmitting and receiving) and temporal resolution
Object separation limits / system resolution
System re-configuration time and availability

Agenda

Introduction
User consultation
Use cases
The NOSTRA Mission
System requirements
Feasibility study
Conclusions

The mission of NOSTRA is to establish a Nordic capability for routine monitoring of space debris and satellites, serving civilian, dual-use, and academic needs.
Adding unique observations, tracking, and cataloguing to monitoring frameworks strengthens collision avoidance, space safety, and strategic autonomy.
In parallel, the programme will foster academic research, education, and long-term industrial and scientific competence across the Nordic region.

Agenda

Introduction
User consultation
Use cases
The NOSTRA Mission
System requirements
Feasibility study
Conclusions

System requirements

System requirements need to describe how an implementation will achieve the mission requirement within the context in which it is to be operated. [Fro24]

expressed as verifiable statements
shall (mandatory), should (desirable) and will (operational context)
traceable to mission requirements

System requirements

System Governance & Constraints
Functional Requirements
Performance Requirements
Operational Requirements
Interfaces & External Data Requirements
Reliability, Availability, Maintainability (RAM)
Security & Safety

System requirements

System Governance & Constraints

State-controlled
F-SSAC in Finland
On-site integrity tagging and classification

Functional Requirements
Performance Requirements
Operational Requirements
Interfaces & External Data Requirements
Reliability, Availability, Maintainability (RAM)
Security & Safety

System requirements

System Governance & Constraints
Functional Requirements

LEO detections 2 cm at 1000 km
MEO detections 1 m (10 cm optional)
Beam-park mode
99% detection rate for 1 m objects in fence mode
Tracking mode
User-defined scan mode
False alarm rate < 10^-6
Tracking multiple simultaneous targets
Angles at least 45° off boresight
Rapid time series for ablation processes
Independent IOD
Position 1-σ < 300 m
Calibrated RCS time series for size/shape/material ch'n
Provinance tracking for product validation

Performance Requirements
Operational Requirements
Interfaces & External Data Requirements
Reliability, Availability, Maintainability (RAM)
Security & Safety

System requirements

System Governance & Constraints
Functional Requirements
Performance Requirements

Pointing 1-σ < 0.1°
(D) Tristatic orbit accuracy/precition better than current EU SST radars
F-SSAC messages within 30 min, and high-priority within 5 min
Availability > 95%

Operational Requirements
Interfaces & External Data Requirements
Reliability, Availability, Maintainability (RAM)
Security & Safety

System requirements

System Governance & Constraints
Functional Requirements
Performance Requirements
Operational Requirements

Graceful degradation and fault recovery
Automated scheduler with configurable performance metrics
Support for high-inclination launch from Esrange

Interfaces & External Data Requirements
Reliability, Availability, Maintainability (RAM)
Security & Safety

System requirements

System Governance & Constraints
Functional Requirements
Performance Requirements
Operational Requirements
Interfaces & External Data Requirements

Standard formats
Controlled interfaces for authorised access to raw data

Reliability, Availability, Maintainability (RAM)
Security & Safety

System requirements

System Governance & Constraints
Functional Requirements
Performance Requirements
Operational Requirements
Interfaces & External Data Requirements
Reliability, Availability, Maintainability (RAM)

Regular calibration
Staged development
100-year environmental conditions

Security & Safety

System requirements

System Governance & Constraints
Functional Requirements
Performance Requirements
Operational Requirements
Interfaces & External Data Requirements
Reliability, Availability, Maintainability (RAM)
Security & Safety

Archive and catalogue
dual-use product lines with access control
Rich metadata for all products
End-to-end security

Agenda

Introduction
User consultation
Use cases
The NOSTRA Mission
System requirements
Feasibility study
Conclusions

Feasibility study

Background
General framework
Hardware components
Performance
ROM

Background

Electronically scanning arrays (AESA) for SST built during recent years

GESTRA built 2014-2023 by Fraunhofer
S3STR built 2015-2019 by Indra
Space Fence built 2014-2020 by Lockheed-Martind
UHF Planar DRA radar built 2023-2024 by LeoLabs

GESTRA

Frequency 1.28-1.38 GHzs, Power 1kW x 256
Quasimonostatic (distance 100m) pulsed radar
Transmits with a single and receives in dual polarization
Aperture diameter 3m
256 active cavity-backed stacked patch antennas surrounded by 64 dummy elements
Track with prior and Track-while-Scan modes

S3STR

Frequency L-band 1215 to 1400 MHz
Quasimonostatic modular radar
TX antennas circular stacked patches inside a cavity. RX antennas printed bow ties
Cooling with liquid cold plates
Digitized by direct undersampling.
Pneumatic calibration towers
Track-while-Scan mode
Mean FoR 180 degrees in azimuth towards South and 60 degrees in elevation
Revisit time less than 10s

Space Fence

Frequency S-band. Radiated power 2.69MW peak and 0.81MW average.
Quasimonostatic
65000 transmitter elements and 217000 receiver elements
Liquid cooling
LEO/MEO/GEO objects
Element-level beamforming (instead of subarray-level)

UHF Planar DRA radar

UHF Planar DRA radar

Frequency UHF
Monostatic
Elements inverted vee-dipoles (probably)
Elevated platform with groundplane
Calibration towers
Next LeoLabs radar S-band DRA to detect 2cm debris

Critical quantities for design

Center frequency (L or S band)
Power (order of hundreds of kWs to MW)
Duty cycle (up to 25%)
Bandwidth (100-200 MHz) and Range accuracy (8m @11dB@SNR)
Pointing accuracy (0.6° @11dB SNR)
Beamwidth (0.5° to few degrees) and Directivity (over 30dB)
Field-of-Regard (FoR)
Revisit time (e.g. survey)

Choosing frequency

1.3 GHz (wavelength 23 cm)
2.7 GHZ (wavelength 11 cm)
3.2 GHZ (wavelength 9 cm)

Choosing the frequency

Scattering for a perfectly conducting sphere with diameter of 2cm
RCS becomes larger for higher frequencies

Choosing the frequency

Scattering for a perfectly conducting sphere with diameter of 10cm
RCS is large. In resonance regime.

Radar equation and Link budget

Received power is $$ P_{R} = P_T \frac{G_{T}G_{R}\lambda^2 \sigma}{(4\pi)^3 R_{T}^2 R_{R}^2 L} $$ where the losses are originate e.g. from
- Impedance mismatch
- Polarization mismatch
- Resistive heat loss
- Resistive heat loss

Polarization

RCS depends on polarizations
The ratio $$ R = \frac{P_{LHCP}}{P_{RHCP}+P_{LHCP}} $$ divides objects roughly to three categoriries:
- Sphere-like objects: R ~ 1
- Plate-like objects: R ~ 0.5-1
- Corner reflectors: R < 0.5
Usual choice: dual polarization in reception