Cowardin, Heather

NASA Technical Reports Server

National Aeronautics and Space Administration
Heather Cowardin, Ph.D.
Orbital Debris Research & Science Operations Manager
ODRSO Lead R&D
JACOBS JETS Contract
In support of the NASA Orbital Debris Program Office
Presented at 37th Meeting of the IADC 
7 to 10 May 2019 Rome, Italy
https://ntrs.nasa.gov/search.jsp?R=20190014044 2019-08-31T13:38:08+00:00Z
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• DebriSat Project Overview
• Status
• Plan Forward
Outline
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DebriSat Project Team
• NASA Orbital Debris Program Office (ODPO)
– Co-sponsor, project and technical oversight, data collection, data analyses, 
NASA model improvements
• AF Space and Missile Systems Center (SMC)
– Co-sponsor, technical oversight
• The Aerospace Corporation (Aerospace)
– DebriSat design support, DebrisLV design & fabrication, data collection, 
data analyses, DoD model improvements
• University of Florida (UF)
– DebriSat design & fabrication, data collection, fragment processing and 
characterization
• AF Arnold Engineering Development Complex (AEDC)
– Hypervelocity impact tests
National Aeronautics and Space Administration
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Brief Intro
• The purpose of the DebriSat project is to replicate a hyper-velocity 
fragmentation event using modern-day spacecraft materials and construction 
techniques to better improve the existing DoD and NASA breakup models
50 cm 50 cm
90 cm
Deployable Solar PanelsMulti-Layer Insulation
30 cmComposite Body Panels
Spectrometer
S-band Antenna X-band Antenna
UHF/VHF Antenna
Divert Thruster
Optical Imager
Sun Sensor
570 g projectile @ 6.8 km/sec
National Aeronautics and Space Administration
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DebriSat Project Motivation
• The need for laboratory-based impact tests was recognized by 
DoD and NASA decades ago
• Key impact test series, Satellite Orbital Debris Characterization 
Impact Test (SOCIT) was conducted by the Department of Defense 
(DOD) and NASA at AEDC in 1992 to support the development of 
satellite breakup models
• Breakup models based on SOCIT have supported many
applications over the years 
• As new materials and construction techniques are developed for 
modern satellites, there is a need for new laboratory-based tests to 
acquire data to improve the existing DoD and NASA breakup 
models and support space situational awareness (SSA) 
applications
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Fragment Characterization Plan
• Collect, measure, and 
characterize all 
fragments, including 
MLI and solar panel 
pieces, down to 
~2 mm in size
• Conduct radar, 
photometric, and 
spectral 
measurements for 
selected fragments
– Support improvements 
to radar and optical 
size-estimation models
National Aeronautics and Space Administration
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DebriSat Project Milestones
Collection-Characterization-Application
• Fragment processing and characterization
2014-present
• Delivery of first set of measurement data
Sep 2016
• Initial data analyses for model improvements
2016-2017
• Fragment radar and optical measurements
2018-2019
• Complete measurement data
Sep 2020
• Debris model and SSA application updates
2018-2020
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Status-Historical
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Status- Recorded/Collected
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Status-2D/3D
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Status- Size
as of 01/23/2019
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Status-Shape as function of Lc
as of 01/23/2019
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Status-Shape as function of Mass
as of 01/23/2019
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Status-Density
as of 01/23/2019
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Plan Forward-
Prepping for Next Measurements
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Next steps- near term
• On-going research focus
– Current data is heavily biased towards CFRP, focus on larger fragments
– Using X-ray imagery to extract number of fragments in intact soft catch panels
– Mass all 3D fragments
– Collect subset of fragments to collect laboratory-based optical measurements and radar 
measurements to compare optical inferred sizes and radar cross sections
– Data will be used in the development of ORDEM 4.0
• Continue investigating non-spherical projectiles with various 
densities improve damage equations 
– HVI test program, in support of the Orbital Debris Progam Office (ODPO), is 
investigating the damage characteristics of non-spherical particle impacts into US 
lab type whipple shields. 
– Projectile = Al 2024-T3 non-spherical projectiles; Velocity = 7 km/s; Impact angle = 0°
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Back-Up
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Previous Laboratory Impact Test
SOCIT vs DebriSat
SOCIT
U.S. Navy Transit 
1960’s era satellite
DebriSat 
Representative modern 
spacecraft in LEO
Target body 
dimensions 46 cm (dia)×30 cm (ht) 60 cm (dia)×50 cm (ht) 
Target mass 34.5 kg 56 kg
MLI and solar 
panel No Yes 
Projectile material
Al sphere Hollow Al cylinder with attached nylon bore-rider
Projectile 
dimension/mass 4.7 cm diameter, 150 g 8.6 cm × 9 cm, 570 g 
Impact speed 6.1 km/sec 6.8 km/sec 
Impact Energy to 
Target Mass ratio 
(EMR) 
81 J/g (2.8 MJ total) 235 J/g (13.2 MJ total) 
Before
See Ausay, E., “A Comparison of the SOCIT and DebriSat Experiments”
Before
National Aeronautics and Space Administration
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Optical Laboratory Data Analyses:
Optical Measurement Center (NASA/JSC) 
• Goal: develop optical size 
estimation model eliminating need 
for assumptions in current 
calculations
R: 36,000 Km
Ag: geometrical albedo=0.175
Ψ (α), Lambertian Phase Function
• Acquire empirical-based bidirectional 
reflectance distribution function 
measurements to eliminate need to 
have aspect angle dependencies
• Upgraded robotic arm with 6 DOF is 
now underway; expected completion by 
end of FY18
Mabs(v) Msun(v)
5.0
0.5
g
 [ ] 2 Rd 10
[ A Ψ(α)]π
+
−⋅= ⋅
⋅ ⋅
• ASD field spectrometer: high-resolution reflectance 
spectrometer . 
• SBIG CCD camera and attached filter wheel, 
which uses Johnson/Bessell BVRI and SDSS g’r’i’z’
• 75 W Xenon arc lamp
• R17 robotic arm (5 DOF)
• Rotary arm with potentiometer
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Radar Facility Data Analyses 
Historical:
• 1990s physical measurements 
acquired (Lc, area, and mass)
• Majority of objects investigated 
were aluminum or steel
• Radar measurements were 
taken at multiple angles in 
order to avoid undersampling 
the RCS aspect angle 
variations
• Data were taken at a wide 
range of frequencies from 2.4 
to 18 GHz (S, C, X and Ku 
bands)
Plan Forward:
• Repeat the 1990s experiment with more 
modern materials, a large frequency 
sweep, and collect RCS measurements 
in various aspect angles ― radar facilities 
are currently being assessed for cost, 
resources, and availability 
• Similar to previous analysis, the physical 
parameters will be compared with RCS 
measurements to investigate the 
relationships for a broader subset of 
materials/shapes
• The DebriSat fragments will provide the 
opportunity to compare optical 
measurements against optical inferred 
sizes and radar cross sections


DebriSat Project Status

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