Science Goal
Science Objective
Key Observations
Measurement Requirements
Mirror & Instrumentation Requirements
Instrument
Property
Value
Understand Black Hole Formation
(B-Q1, AstroDecadal 2020)
Constrain mass, spin, and Eddington ratio of Sgr A* & M87 (B-Q1a)
Time-resolve Sgr A*'s accretion flow:
Accretion disk of M87:
Constrain the mass and spin of Sgr A* & M87 to >10% of the ground truth by temporally resolving accretion disk on sub-ISCO timescales
Radio
Antenna
+
Primary
Receiver
Diameter
Receiver Frequency
Angular resolution
Surface Accuracy
Enable multi-messenger astronomy on astrophysical transients
(B-Q2, AstroDecadal 2020)
Directly image nHz-frequency binary black hole targets at 86 GHz
Constrain orbital dynamics and jet P.A. precession of OJ 287 system to <10% ground truth
Radio
Antenna
+
Primary
Receiver
Mass
Areal
Density
Aperture
Efficiency
Pointing Accuracy
Understanding Accretion Flow Dynamics and Relativistic Jets (B-Q3, AstroDecadal 2020)
Enable parameter estimation on quasars and blazar targets
Estimate mass, spin, luminosity, and polarization distribution of AGN targets hosting SMBHs
Directly image BL Lac radio targets of luminosity , angular size
timescales (for transients) and brightness temperature
Radio
Antenna
+
Primary
Receiver
SEFD
System
Temperature
Field of View
(FOV)
Thermal
Noise
Detection of 12-year period optical outburst from OJ 287:
Science Goal
Science Objective
Key Observations
Measurement Requirements
Instrumentation Requirements
Instrument
Property
Value
Understand Black Hole Formation
(B-Q1, AstroDecadal 2020)
Constrain mass, spin, and Eddington ratio of Sgr A* & M87 (B-Q1a)
Time-resolve Sgr A*'s accretion flow:
Accretion disk of M87:
Constrain the mass and spin of Sgr A* & M87 to >10% of the ground truth by temporally resolving accretion disk on sub-ISCO timescales
Radio
Antenna
+
Primary
Receiver
Diameter
Receiver Frequency
Angular resolution
Surface Accuracy
Enable multi-messenger astronomy on astrophysical transients
(B-Q2, AstroDecadal 2020)
Directly image nHz-frequency binary black hole targets at 86 GHz
Constrain orbital dynamics and jet P.A. precession of OJ 287 system to <10% ground truth
Radio
Antenna
+
Primary
Receiver
Mass
Areal
Density
Aperture
Efficiency
Pointing Accuracy
Understanding Accretion Flow Dynamics and Relativistic Jets
(B-Q3, AstroDecadal 2020)
Enable parameter estimation on quasars and blazar targets
Estimate mass, spin, luminosity, and polarization distribution of AGN targets hosting SMBHs
Directly image BL Lac radio targets of luminosity , angular size
timescales (for transients) and brightness temperature
Radio
Antenna
+
Primary
Receiver
SEFD
System
Temperature
Field of View
(FOV)
Thermal
Noise
Detection of 12-year period optical outburst from OJ 287:
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
Spaceflight Heritage
SBUDNIC
PVDX
EQUiSat
BHEX Mini
BHEX Mini
Event Horizon Telescope
(2019)
Event Horizon Telescope (EHT)
Event Horizon Telescope
(2019)
Event Horizon Telescope (EHT)
Spaceflight Heritage
EQUiSat
SBUDNIC
PVDX
Spaceflight Heritage
SBUDNIC
PVDX
EQUiSat
BHEX Mini
BHEX Mini
Imaging a Black Hole
"Metrics and Motivations for Earth–Space VLBI: Time-resolving Sgr A* with the Event Horizon Telescope" Palumbo et. al. ApJ 2019
Size
Weight
Power
Power
Cost
SEFD
USO
Data
Orbit
SEFD
USO
Data
Orbit
SEFD
USO
Data
Orbit
SEFD
USO
Data
Orbit
SEFD
USO
Data
Orbit
SEFD
USO
Data
Orbit
SEFD
USO
Data
Orbit
SEFD
USO
Data
Orbit
SEFD
USO
Data
Orbit
SEFD
USO
Data
Orbit
SEFD
USO
Data
Orbit
SEFD
USO
Data
Orbit
SEFD
USO
Data
Orbit
SEFD
USO
Data
Orbit
SEFD
USO
Data
Orbit
SEFD
USO
Data
Orbit
SEFD
USO
Data
Orbit
SEFD
USO
Data
Orbit
SEFD
USO
Data
Orbit
SEFD
USO
Data
Orbit
SEFD
USO
Data
Orbit
SEFD
USO
Data
Orbit
SEFD
USO
Data
Orbit
SEFD
USO
Data
Orbit
SEFD
USO
Data
Orbit
SEFD
USO
Data
Orbit
SEFD
USO
Data
Orbit
SEFD
USO
Data
Orbit
Aspera
Pandora
StarBurst
PUEO
(Galaxy Evolution via UV)
(Exoplanet Explorer)
(Neutron Stars via Gamma Rays)
(Particle Physics via High-Energy Neutrinos)
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
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)
"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
30 min
60 min
90 min
24 hr
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 radiation environment in LEO vs. MEO
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!
Size
Weight
Power
Power
Cost
Size
Weight
Power
Power
Cost
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
Jan 2025
Jan 2025
Jan 2025
Jan 2025
Feb 2025
Jan 2025
Feb 2025
Mar 2025
Rick Fleeter
Jan 2025
Feb 2025
Mar 2025
Apr 2025
Ben Hudson
Luke Anderson
Jan 2025
Feb 2025
Mar 2025
Apr 2025
May 2025
Jeffrey Olson
Jun 2025
Jul 2025
Todd Ely
Joseph Lazio
Eric Burt
Jan 2025
Feb 2025
Mar 2025
Apr 2025
May 2025
Jun 2025
Jul 2025
Feb 2025
Mar 2025
Apr 2025
May 2025
Jun 2025
Jul 2025
Aug 2025
Science
Leadership
Engineering
Leadership
BHEX Mini
Team
Advisors
Inner
circle
Inner
circle
Engineering
Leadership
Advisors
BHEX Mini
Team
Inner
circle
Science
Leadership
Engineering
Leadership
Advisors
BHEX Mini
Team
Engineering
Leadership
Inner
circle
Science
Leadership
Advisors
BHEX Mini
Team
Inner
circle
Science
Leadership
Engineering
Leadership
Advisors
BHEX Mini
Team
Inner
circle
Science
Leadership
Engineering
Leadership
BHEX Mini
Team
Inner
circle
Science
Leadership
Engineering
Leadership
Advisors
BHEX Mini
Team
Inner
circle
Science
Leadership
Engineering
Leadership
Advisors
Inner
circle
Science
Leadership
Engineering
Leadership
Advisors
BHEX Mini
Team
🕒 Prospective Timeline
June
July
August
September
🕒 Prospective Timeline
June
July
August
September
🕒 Prospective Timeline
June
July
August
September
🕒 Prospective Timeline
June
July
Aug
September
🕒 Prospective Timeline
June
July
Aug
Sep
💰Funding Deadlines
June
💰Funding Deadlines
$5,000
July
💰Funding Deadlines
$5,000
$175,000
Aug
💰Funding Deadlines
$5,000
$175,000
>$4M
Sep
💰Funding Deadlines
$5,000
$175,000
>$4M
Oct
💰Funding Deadlines
$5,000
$175,000
>$4M
>$400,000