Detecting Extraterrestrial Interstellar Probes

Instrument Technologies for the Detection of  Extraterrestrial Interstellar Robotic Probes

Scot L. Stride
Jet Propulsion Laboratory
California Institute of Technology
Pasadena, CA, USA
January 24, 2001

Technological Manifestations of ETI

  • Matter Markers
  • Robotic Probes and Artifacts
  • Relativistic or Fast Flyby’s
  • Ancient Artifacts
  • “Drift-Through’s” swept up by the solar systems galactic orbit
  • Asteroid Belt Artifacts
  • Heliocentric Orbits
  • Elliptical or Earth-Crossing
  • Self-Reproducing Automata
  • (aka Von Nuemann probes)
  • Libration Points
  • Earth-Moon-Sun Parking Orbits
  • Geocentric Orbits
  • High, Low, Cislunar, Transient
    Lunar Orbiters or Artifacts
  • Messenger Probes
    Dyson Sphere’s or O’Neill Colonies
  • Robotic Probe Launches

detection of extraterestal probes


Searching for Interstellar Robotic Probes

Proposed Search Process Steps

1. Decide what robotic robotic probe features to search for.
2. Establish a bounded search volume, artifact size and limiting
3. Study the available instruments, sensors, computers, software.
4. Match detectable probe features with the available instruments.
5. Develop a set of design requirements and specifications for an
automated or robotic observatory.
6. Select a data management and analysis strategy.
7. Derive experimentally testable hypotheses.
8. Design and build the observatory and begin the search.

Searching for Interstellar Robotic Probes

  • Define a Robotic Probe Search Space, Size and Limiting Magnitude
  • Search volume very large – must be satisfactorily bounded
  • Maximum search distance (d) to sphere of 50 AU solar radii
  • Large artifacts, high albedo
  • Possible but very expensive
  • Cislunar 70,000 Km < d < 384,000 Km • Exosphere d > 500 Km
  • Stratosphere to Ionosphere 0 Km < d < 350 Km–Possible, preferred and practical with ground based observatories∗
  • Limiting Artifact Size (S
    < 10 m [Freitas and Valdes] – Based on collision survival, weathering and communication ∗ Limiting Magnitude (M L ) • -12 >
  • ML[Wide FOV, staring array, megapixel CCD, large aperture area]
  • Make a study of the available Instruments and Sensors∗
  • Understand the strengths and weaknesses of existing technologies
  • Match detectable probe manifestations with available instrument
    and sensor technologies
  • Choose the correct instruments and sensors for the task
  • Develop design requirements for an observatory platform
  • Observatory functionally designed for unattended autonomous or
    robotic operation
  • Why Robotic Observatories?
  • Follows current trends in astronomical observing programs
  • Allows optimal use of scheduling and observing time
  • Minimizes researcher fatigue, stress and boredom
  • Automated data acquisition is more reliable and repeatable
  • Observatory can be used for other (non-SETI) scientific research

Searching for Interstellar Robotic Probes

  • Derive experimentally testable hypotheses, for example:
  • Establish a governing set of protocols and procedural documents
  • Data Management and Analysis
  • Observatory raw data must be properly fused, organized and coded
  • Construct a database of information for mathematical analysis
  • Proof is not Real-Time


Scientifically acceptable proof of robotic probe technology will depend on
using statistical methods on a large set of

Utilizing Commercial-Off-The-Shelf

  • What is COTS?
  • Off-The-Shelf Instruments, Sensors, Computer Hardware and
  • Mandate established in 1991 to help resolve military hardware
    obsolescence, supply problems and life-cycle costs
  • A mechanism for rapidly integrating the newest technologies

What does COTS mean for SETI?

  • Variety, Affordability, Flexibility, Modularity, Ruggedization
  • Systems designed for Performance and Reliability
  • Emphasis on System Functional Test and Validation
  • Reduced Customization
  • Lower Maintenance, Replacement and Operational costs
  • Experiments can be replicated by other SETI researchers using the same basic hardware

COTS Instruments

cots probes instruments

  • Instrumentation for Robotic Observatories
  • Automated Weather Station
  • Localized geophysical and meteorology measurements
  • GPS Receiver
  • Position-location, time-code, clock reference signals
  • Optical Telescopes
  • Light gathering and magnification of optical sources
  • Integrated with electronic imaging sensors
  • Spectrometer or Spectroradiometer
  • Gather wavelength and intensity data on emission spectra
  • Motorized positioner mounts for optical instruments
  • Pointing or steering of telescope optics and/or sensor arrays
  • Power Systems
  • Generate portable stand-alone power for the observatory
  • Pan-and-Tilt
  • Positioners
  • Meteo
  • COTS Instruments
  • rology
  • Instruments
  • Spectroradiometers
  • Telescope
  • Optics
  • GPS Time and
  • Frequency
  • Receivers

cots for space probes

  • Electromagnetic Spectrum Sensors
  • CCD (Charge Coupled Devices)
  • Scientific grades, Large apertures, Back-illuminated, High
  • Quantum Efficiency, UV/Visible/NIR Imaging
  • CMOS APS (Active Pixel Sensor)
  • “Camera-on-a-chip”, Digital Output, High Dynamic Range
  • Microbolometers
  • IR Staring Focal Plane Arrays
  • Cooled and Uncooled, IR Imaging
  • QWIPs (Quantum Well Infrared Photodetectors)
  • IR Staring Focal Plane Arrays,
  • < 12 μ m, Narrow or Double-band, Cooled and Uncooled, IR Imaging
  • Temperature and Vibration Sensors
  • Thermocouples, RTD, PRT, Thermistor, Semiconductors
  • Miniature accelerometers to monitor platform vibrations SLS – 18 OSETI-III COTS Sensors Microbolometers CMOS APS QWIPs CCD Sensors SLS – 19 OSETI-III COTS Computer Hardware
  • Modular and Embedded Computing Components
  • Large Commercial and Military Market
  • Affordable, Reliable Electronic ComponentsSignificant Processing Power and Data Throughput
  • Multiprocessing Computation Capability > 1 Gflop/Sec
  • High Sustained and Burst Data Throughput > 1GB/Sec
  • Mature, Standard, Modular Bus Architectures and Interfaces
  • VME, cPCI, PC/104+ Bus Interfaces
  • USB, IEEE 1394, RS232/422 Serial Peripheral Interfaces
  • Embedded Processors
  • 8 and 16-bit microcontrollers perform instrument functions
  • Ruggedized Chassis for Extreme Environments
  • Robust thermal management and control, low EM emissions

cots probes software

COTS Computer Hardware

  • Ruggedized VME Chassis
  • Single Board Computers
  • QUAD DSP VME Board
  • Device Controllers

COTS Computer Software

  • Operating Systems
  • RTOS – Real Time Operating System
  • Deterministic, low latency, low jitter
  • POSIX (Portable Operating System Interface) Compliant
  • VxWorks Tornado™, Linux (Real Time Linux)
  • Why Real-Time?
  • Reliable response to trigger events or sensor generated interrupts
  • Instrument Control and Interface Software
  • LabVIEW™
  • Peripheral Device Drivers
  • Signal Processing Software
  • Analysis Software
  • Utility Software

The software is the single most critical part of the robotic observatory!

A Robotic Observatory Platform

robotic observatory for probe detection


  1. 1. Robotic probes and artifacts are one possible technological manifestation of Type II & III extraterrestrial civilizations.
  2. Robotic probes will possess observable manifestations.
  3. The search should focus on electromagnetic emissions.
  4. The search space, artifact size and limiting magnitudes must all be bounded parameters.
  5. A robotic observatory platform can be designed and built with COTS instruments, sensors, computer HW and SW.
  6. Data collected from observatories can be used to test derived hypotheses using statistical methods.
  7. A search for robotic probe visitation will require time and patience and determination.
  8. SETV is a scientific search for interstellar robotic probes.