Direct Imaging Black Holes from LEO
Ref Bari, Brown University
Physics MS, Brown
Analysis of Binary Black Holes via Neural Networks (under Prof. Brendan Keith, Brown)
Funded under NSF Neural DynAMO Grant
“Nitrogen Outgassing from Water Worlds” (R.Bari et. al., under review, The Astrophysical Journal 2025)
“Reflection from Relativistic Light Sails” (R. Bari, The Astronomical Journal 2024)
“Simulating the Action Principle in Optics” (R. Bari, The Physics Teacher 2023)
Spin Qubit CNN Researcher at the Meriles Condensed Matter Lab
“A Path Integral Derivation of Hawking Radiation” (MS Thesis)
Physics MS, Brown
Analysis of Binary Black Holes via Neural Networks (Prof. Brendan Keith, Brown)
Brown Space Engineering
Spaceflight Heritage
EQUiSat
SBUDNIC
PVDX
Spaceflight Heritage
SBUDNIC
PVDX
EQUiSat
Event Horizon Telescope
(2019)
Event Horizon Telescope (EHT)
Event Horizon Telescope
(2019)
Event Horizon Telescope (EHT)
Event Horizon Telescope
(2019)
Event Horizon Telescope (EHT)
Black Holes: An Intro
(2031)
Black Hole Explorer Satellite (BHEX) Mission
Imaging a Black Hole
(The black hole explorer: Motivation and vision, Johnson et. al., 2024)
Spaceflight Heritage
EQUiSat
SBUDNIC
PVDX
Spaceflight Heritage
SBUDNIC
PVDX
EQUiSat
BHEX Mini
BHEX Mini
Imaging a Black Hole
Todd Ely
Joseph Lazio
Eric Burt
Ben Hudson
Luke Anderson
Rick Fleeter
Partner Satellite to BHEX
Stand-alone Satellite
Pathfinder Mission
Partner Satellite to BHEX
Stand-alone Satellite
Pathfinder Mission
Supplement (u,v) coverage at 86 GHz
Enable parameter estimation of Sgr A*/M87
Achieve Space-Space VLBI
Partner Satellite to BHEX
Stand-alone Satellite
Pathfinder Mission
Supplement (u,v) coverage at 86 GHz
Enable parameter estimation of Sgr A*/M87
Achieve Space-Space VLBI
Pathfinder Mission
Partner Satellite to BHEX
Stand-alone Satellite
Supplement (u,v) coverage at 86 GHz
Enable parameter estimation of Sgr A*/M87
Achieve Space-Space VLBI
Supplement (u,v) coverage at 86 GHz
Enable parameter estimation of Sgr A*/M87
Achieve Space-Space VLBI
Survey of >25 AGN+BH Targets @86 GHz
Enable Population Modeling of SMBHs
Enable real-time imaging of dynamical accretion disk around Sgr A*
Enable multi-messenger gravitational astronomy w/ LIGO + LISA
Partner Satellite to BHEX
Stand-alone Satellite
Pathfinder Mission
Supplement (u,v) coverage at 86 GHz
Enable parameter estimation of Sgr A*/M87
Achieve Space-Space VLBI
Supplement (u,v) coverage at 86 GHz
Enable parameter estimation of Sgr A*/M87
Achieve Space-Space VLBI
Survey of >25 AGN+BH Targets @86 GHz
Enable Population Modeling of SMBHs
Enable real-time imaging of dynamical accretion disk around Sgr A*
Enable multi-messenger gravitational astronomy w/ LIGO + LISA
Enable low-cost Space-Ground & Space-Space VLBI
Sub-milli arcsecond angular resolution
Dual short and long baseline lengths
Rapid coverage of (u,v) plane
Decreased signal loss from LEO
Decreased radiation environment in LEO vs. MEO
Sub-milli arcsecond angular resolution
Dual short and long baseline lengths
Rapid coverage of (u,v) plane
Decreased signal loss from LEO
Decreased radiation environment in LEO vs. MEO
Prospects of Detecting a Jet in Sagittarius A* with VLBI (Chavez et. al., ApJ 2024)
Sub-milli arcsecond angular resolution:
Dual short and long baseline lengths
Rapid coverage of (u,v) plane
Decreased signal loss from LEO
Decreased radiation environment in LEO vs. MEO
Sub-milli arcsecond angular resolution:
Dual short and long baseline lengths
Rapid coverage of (u,v) plane
Decreased signal loss from LEO
Decreased radiation environment in LEO vs. MEO
Sub-milli arcsecond angular resolution:
Dual short and long baseline lengths
Rapid coverage of (u,v) plane
Decreased signal loss from LEO
Decreased radiation environment in LEO vs. MEO
Metrics and Motivations for Earth–Space VLBI: Time-resolving Sgr A* with the Event Horizon Telescope (Palumbo et. al., ApJ 2019)
Sub-milli arcsecond angular resolution:
Dual short and long baseline lengths
Rapid coverage of (u,v) plane
Decreased signal loss from LEO
Decreased radiation environment in LEO vs. MEO
Metrics and Motivations for Earth–Space VLBI: Time-resolving Sgr A* with the Event Horizon Telescope (Palumbo et. al., ApJ 2019)
Sub-milli arcsecond angular resolution:
Dual short and long baseline lengths
Rapid coverage of (u,v) plane
Multifrequency Black Hole Imaging for the Next-generation Event Horizon Telescope (Chael et. al., 2023, ApJ)
Sub-milli arcsecond angular resolution:
Dual short and long baseline lengths
Rapid coverage of (u,v) plane
Decreased signal loss from LEO
Decreased radiation environment in LEO vs. MEO
Sub-milli arcsecond angular resolution
Dual short and long baseline lengths
Rapid coverage of (u,v) plane
Decreased signal loss from LEO
Decreased radiation environment in LEO vs. MEO
Sub-milli arcsecond angular resolution
Dual short and long baseline lengths
Rapid coverage of (u,v) plane
Decreased signal loss from LEO
Decreased radiation environment in LEO vs. MEO
Maximum data transmission rate (in bits per second); How fast can you send data from BHEX Mini to the earth?
Sub-milli arcsecond angular resolution
Dual short and long baseline lengths
Rapid coverage of (u,v) plane
Decreased signal loss from LEO
Decreased radiation environment in LEO vs. MEO
Power of Transmitted Signal: Strength of downlink signal in Watts (i.e., shouting louder to be heard further away!)
Sub-milli arcsecond angular resolution
Dual short and long baseline lengths
Rapid coverage of (u,v) plane
Decreased signal loss from LEO
Decreased radiation environment in LEO vs. MEO
Transmitter Gain: How well-focused your signal is when it leaves the satellite
(i.e., shouting into a megaphone instead of into the wind)
Sub-milli arcsecond angular resolution
Dual short and long baseline lengths
Rapid coverage of (u,v) plane
Decreased signal loss from LEO
Decreased radiation environment in LEO vs. MEO
Receiver Gain: How effectively the ground station collects and concentrates the incoming signal (i.e., ALMA's big dish listening to our incoming signal)
Received Power: How strong is the signal once it hits the ground receiver? (after traveling through empty space)
Sub-milli arcsecond angular resolution
Dual short and long baseline lengths
Rapid coverage of (u,v) plane
Decreased signal loss from LEO
Decreased radiation environment in LEO vs. MEO
Receiver Gain: How effectively the ground station collects and concentrates the incoming signal (i.e., ALMA's big dish listening to our incoming signal)
Distance: How much distance did the signal travel through free space? (LEO vs. MEO!)
Sub-milli arcsecond angular resolution
Dual short and long baseline lengths
Rapid coverage of (u,v) plane
Decreased signal loss from LEO
Decreased radiation environment in LEO vs. MEO
Receiver Gain: How effectively the ground station collects and concentrates the incoming signal (i.e., ALMA's big dish listening to our incoming signal)
Sub-milli arcsecond angular resolution
Dual short and long baseline lengths
Rapid coverage of (u,v) plane
Decreased radiation environment in LEO vs. MEO
Sub-milli arcsecond angular resolution
Dual short and long baseline lengths
Rapid coverage of (u,v) plane
Decreased signal loss from LEO
Decreased radiation environment in LEO vs. MEO
Decreased ISM scattering at LEO than MEO
Decreased ISM scattering at LEO than MEO
Orbit design for mitigating interstellar scattering effects in Earth-space VLBI observations of Sgr A* (Aditya Tamar, Ben Hudson, Daniel C.M. Palumbo, A&A, 2025)
Decreased ISM scattering at LEO than MEO
Intrinsic Gaussian Source
Decreased ISM scattering at LEO than MEO
ISM Scattering
Decreased ISM scattering at LEO than MEO
BHEX Mini Visibility Amplitude Advantage
Regardless of Source Flux Density!
Antenna
Receiver
Cryocooler
Cryocooler
HiPTC Heat Intercepted Pulse Tube Cooler
Solar Panels
Ultra-Stable Oscillator
Ultra-Stable Oscillator
Phase Error
Ultra-Stable Oscillator
Ultra-Stable Oscillator
Allan Deviation
ABRACON SMD OCXO
Digital Backend
Original Analog Radio Signal
Sample the Signal every Unit Interval
Nyquist-Shannon Sampling Theorem
Retain only the samples and record the sign of the voltage for each sample
Reconstruct the original signal
Quantization Efficiency: how much of the analog SNR is retained after digitization
SNR: Signal to Noise Ratio
Data Generation Rate: In Bits per Second
Cross-Correlation
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💰Funding Oppurtunities
June
$3,000
💰Funding Oppurtunities
July
$175,000
$3,000
$175,000
💰Funding Oppurtunities
Sep
$175,000
$3,000
$250,000
💰Funding Oppurtunities
Oct
$175,000
$3,000
$250,000
💰Funding Oppurtunities