Optical Detection of Submillimeter and Millimeter Debris in LEO

Mike [email protected]

Submillimeter and millimeter debris in LEO

Optical detection of submillimeterOptical detection of submillimeter and millimeter debris in LEO

Mike GruntmanDepartment of Astronautical Engineering

University of Southern California

Future In-Space Operations (FISO) SeminarFebruary 25 2015

Acta Astronautica,v. 105, 156-170, 2014

FISO Series February 25, 2015 USC/VSOE Astronautics 1/19

February 25, 2015 10.1016/j.actaastro.2014.08.022



Orbital Detection of ... Debris in LEO

orbital debris in LEO

observational gap and limitations of current techniques

LODE (Local Orbital Debris Environment) concept

photon-counting time-tagging imaging sensor debris detection

LODE example and performance characteristics

ti i t d l b f d b i t /d t ti anticipated annual number of debris events/detections

mission and CONOPS




Orbital Debris in LEOOrbital Debris in LEO

range from tiny (10 m) to very l (10 )

Large debris: > 710 cm (34)large (10 m)

pose threat to spacecraft loss of spacecraft d d ti d l f

tracked and cataloged by U.S. SSN ~ 19,000 active satellites can avoid collisions

degradation and loss of capabilities (incl. mission ending) of subsystems and payloads

(in principle) by maneuvering Space Fence will improve tracking

capabilities

Small debris: < 5 cm (2) characterized statisticallyU.S. National Space Policy, 2010

increase understanding of the cannot be avoided by maneuvers 1 mm 10 cm: estimated >107 < 1mm: estimated >1012

increase understanding of the current and future debris environment




Observational Gap< 0.1 mm can be experimentally characterized by

bringing exposed surfaces back to Earth from orbit (LDEF, SMM, EURECA, Space Shuttle) Models (ORDEM and MASTER) orbit (LDEF, SMM, EURECA, Space Shuttle)

> 5 cm tracked/cataloged by radar

( )disagree (order of magnitude) in the 0.110 mm range

Focus of this work: 0.1 10 mmsubmillimeter (0.1 1.0 mm) andmillimeter (1 10 mm) debris

too small to be detected by radar or optically too few to be measured by studying exposed

surfaces h t l d li one has to rely on modeling

damage to spacecraft and payloads ranges from surface degradation to loss of


spacecraft or its components and payloads Figure: Krisko et al., IAC-14-A6.2.8, 2014



Accumulation of DebrisAccumulation of Debris

d it f d b i > 1

atmospheric drag effectively removes debris below 600 km 1 mm sphere at 400 km altitude

density of debris > 1 mm

1-mm sphere at 400-km altitude reenters the atmosphere within a couple weeks

debris accumulate above 700 kmdebris accumulate above 700 km solar radiation pressure could

decrease lifetime of large area-to-mass ratio debris

maximum density at ~ 800 km




R d d O ti l Li it tiRadar limitations radar detection ~R-4

radar cross section (RCS)NASA Haystack and Goldstone can detect debris down to several mm at

Radar and Optical Limitations

radar cross section (RCS) RCS area (d2) for d > 3

RCS drops precipitously with decreasing size for d < (1/3) (Rayleigh scattering)

can detect debris down to several mm at altitudes of 400 km

Haystack and Haystack Auxiliary (HAX) demonstrated detection up to 800 km

most radars operate in S band ( = 615 cm) and X band ( 3 cm)

atmospheric absorption fundamentally limits increase of radar frequencies

p

German TIRA radar detected 1 2 cm debris at altitudes uplimits increase of radar frequencies

beyond X band detected 12 cm debris at altitudes up

to 1000 km

Optical observations a number of feasibility studies for observingOptical observations ground- and space-based telescopes

primarily observe large GEO objects space-based optical sensors observe

a number of feasibility studies for observing millimeter and (primarily) centimeter size debris in LEO by space-based sensors

all based on CCDs in focal plane


large objects in LEO (e.g., MSX) nobody looked at submillimeter debris



Local Orbital Debris Environment (LODE) SensorLocal Orbital Debris Environment (LODE) Sensor

Observation-validated models of d b i i t ti l f

Local Orbital Debris Environment (LODE)debris environment essential for optimal design and safe operations of satellites models disagree (0.110 mm)

to measure debris near satellite orbit based on passive optical photon-counting

time-tagging imaging system t l th b ti l

g ( ) even if they were in agreement,

important to validate

a way to close the observational gap

NASA Handbook 9719.4, 2008From the safety and the satellite operations perspective, there is an immediate need for a large

This work:top-level

feasibilityan immediate need for a large and dedicated meteoroid and orbital debris sensor to monitor and update the populations between 0 1 and 1 0 mm

feasibility study

(unfunded)

Acta Astronautica


between 0.1 and 1.0 mm. Acta Astronauticav. 105, 156-170, 2014



LODE ConceptLODE Concept

focal plane detector of a small telescope photon-counting time-tagging imaging system

(position-sensitive detector based on microchannel plates PSD based on MCP)

essentially different from frame detectors (CCDs)essentially different from frame detectors (CCDs)

PSDs used since 1970s laboratory and space MG:

review open type (electrons, ions, EUV, X-rays) and sealed with photocathode (optical)

numerous space instruments (plasma and energetic particle analyzers; EUV and X-ray

review article

in major physics journalg p y ; y

spectrometers and imagers) optical: ground-based telescopes (very few) optical: currently operational in two instruments

(COS d STIS) H bbl S T l

journal in 1984


(COS and STIS) on Hubble Space Telescope



Position Sensitive Detector (PSD) based on MCPPosition-Sensitive Detector (PSD) based on MCP

incident particle (photon) converted into an l h (106 108) f l t

Siegmund et al., SPIE-8033, 2001

avalanche (106108) of electrons different types of readout schemes determine: coordinates (x,y) and detection time (t)

of each registered photon in real time

sensitive area: 2020 mm to 100100 mm

of each registered photon in real time image built up (accumulated) in computer memory

sensitive area: 2020 mm to 100100 mm spatial resolution: up to 20002000 pixels time (tagging) resolution: ~1 ns max count rate (total): up to 106 s1 max count rate (total): up to 106 s 1

max count rate (point source): 10100 s1

PSDs essentially differ from


frame detectors (CCDs)



Detection of Debris Crossing FOVDetection of Debris Crossing FOV

Prior studies of optical space-based f d b i d t ti

LODE debris detectionsensors for debris detection CCD in focal plane debris passage across FOV during a

frame accumulation time interval results

debris passage across FOV forms3D debris trajectory in (the focal plane plus time) (x,y,t) 3D space

requires detection of only severalframe accumulation time interval results in a streak across a pattern of fixed stars and diffuse background

forms 2D debris trajectory in focal plane ( ) 2D space

requires detection of only several photons to extract the rare event disadvantage: smaller photon detection efficiency than by CCDs

plane (x,y) 2D space 20 or more photons are needed for

signal above noise in a single CCD pixel reliable detection of a rare streak

significantly smaller (than for CCD-based frame detector) number of debris-reflected photons should enter the sensor higher sensitivityreliable detection of a rare streak

requires multiple lightened-up pixels at least a few hundred debris-

reflected photons should enter the sensor

opens a way for detecting smaller (submillimeter) debris

MCP-based PSDs have been never considered for detection of small debris


sensor considered for detection of small debris



D t ti f D b iDetection of Debris

bright stars:

Siegmund et al., SPIE-8033, 2001

Ph t gmust be avoided (small fraction of the sky) PSD intrinsic noise: significantly smaller

than diffuse background count ratet i f t ( ) li it d b

Photo-cathode

(S-20)efficiency

sensor spectral range

sensor geometric factor (00) limited by sky light background

assume (simplified)p g visible: 400850 nmlight background Zodiacal light

( p ) antisolar pointing

(e.g., sun-synchronous dawn-dusk orbit) velocity of debris V0 = 10 km/sec

l i f th FOVg

integrated starlight of unresolved stars diffuse galactic light typical background intensity:

normal crossing of the sensor FOV isotropic (2) scattering of solar light by

debris with albedo = 0.15 M debris-scattered photons to be


500 S10S 21 mag/arcsec2 8.0 kRM debris scattered photons to be registered for debris event detection



D t ti f D b iDetection of DebrisMaximum distance hM for debris (size a) FOV crossing detection

Effective debris detection area S(a) 0

a debris diameterV0 debris velocity debris albedod0 sensor aperture diameter photon detection efficiencyCM maximum count ratef0 sky diffuse backgroundFS solar photon fluxM number of debris-scattered

A passage of an object larger in size and/or closer to the sensor would result in a larger average number of registered


photons photons and consequent event detection



LODE E lLODE Exampled0 = 6 cm (sensor aperture diameter)CM = 104 s1 (maximum count rate)

0 = 5.35106 sr (solid angle)0 = 0.15 (plane angle) M minimal number of debris-reflected

f O

mV = 7.6 and brighter to be avoided

photons to be registered for FOV crossing by a debris)

necessary to determinea probability that random background photons produce a pattern of registered photons indistinguishable

25,000 stars1.1% of the sky

registered photons indistinguishable form a true debris detection

PSD (in the focal plane)1525 mm (diameter)


128128 pixels (resolution)



Mi i l N b f R i t d Ph t MMinimal Number of Registered Photons M

example:it takes t = 1 ms for a debris to cross the selected FOV at the h = 3.8 km distance

One would consider photons registered (accumulated) during such a time interval ofduring such a time interval of (t = 1 ms) for search of events of debris passage at this distance (h) or closer t, ms

1 false event per year




Maximum Distance and DetectionMaximum Distance and Detection Area

actually, effective y,maximum detection distance and effective detection areas are larger (a

1 false event per year

g (factor of ~2 for area) because of the Poissonian nature of detected photons 1 false event per year

size 0.15 mm 0.3 mm 1.0 mm 3.0 mm 10 mmM 4 4 5 6 7

p

hM 15.6 m 62 m 0.55 km 4.2 km 40 kmt 0.004 ms 0.016 ms 0.14 ms 1.1 ms 10 ms S 0 32 m2 5 1 m2 400 m2 0 023 km2 2 0 km2


S 0.32 m2 5.1 m2 400 m2 0.023 km2 2.0 km2



1 mm at 0 55 km 3 mm at 4 2 km 10 mm at 40 km

LODE FOV

1 mm at 0.55 km 3 mm at 4.2 km 10 mm at 40 km

Crossing by DebrisDebris

blue dotsb k dbackground

photons

red dotsdebris

reflected




A l N b f D b i E tAnnual Number of Debris EventsOrbitaltitude800 kmi li ti

flux density per 0 1 mm bin m2 yr 1

detection rate per 0 1-mm bin yr 1inclination

98.5

MASTER

per 0.1-mm bin, m2 yr 1 per 0.1-mm bin, yr

MASTERpredicts fewer debris than ORDEM

total annual number (0.2 10.0 mm) 1400 3.8 events per daysubmillimeter (0.2 1.0 mm) 780 2.1 events per day(large) millimeter ( 6 10 mm) 465 1.3 events per day




Mi i d CONOPSMission and CONOPS

Instrument/experiment challenges Spacecraft and mission detection of smallest debris closest to

the instrument capture of a burst of 1015 photons

within 1 microsecond

small satellite or hosted payload no major challenges to

spacecraft or CONOPSwithin 1 microsecond deadtime < 50 ns

raising the minimal debris size to 0.3 mm (from 0.2 mm) will substantially

exception: high-data rate

Narrow-FOV LODE concept is complementary to radar (Haystack and ( ) y

relax the requirements to the detector

data rate 1 Mbps 1011 bit/day (raw)

HAX) and wide-FOV CCD-based optical instruments constrain uncertainties of

measurements by various techniques challenging for a small sat

real-time processing on board straightforward for short time intervals

( ll d b i )

y q

could be used for measuring debris in GEO, GTO, and dust in lunar environmentmicrometeoroid fluxes


(smallest debris) micrometeoroid fluxes

Thank you for your attention!



About the Author

Mike Gruntman is Professor of Astronautics at the University of Southern California (USC); he is the founder of the USC Astronautics Program and served the founding chairman of the Department of Astronautical Engineering from 20042007. His research interests include astronautics, space physics and instrumentation, rocketry and propulsion, and satellite design and technologies. He is Co-I on current NASA missions IBEX and TWINS. Mike authored and co-authored 270 publications including 85+ journal articlesMike authored and co-authored 270 publications, including 85+ journal articles and book chapters and 3 books. He served on the editorial board of the journal Review of Scientific Instruments and on various government advisory panels. Mike teaches courses in spacecraft design (1100 graduate students during the l t 10 ) d ft l i H l t h h tlast 10 years) and spacecraft propulsion. He also teaches short courses (AIAA, ATI) to industry and government. Web site: astronauticsnow.com email: [email protected]


Optical Detection of Submillimeter and Millimeter Debris in LEO

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