detecting satellites and space debris with the mwa · astrocam dfn camera. zhang et al. 2018: no...
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Detecting satellites and space debris with the MWA
Dr Paul HancockCurtin Institute for Radio Astronomy
Space debris is bad
No Mir + Space debris impact
Most objects in space are junk
Spatial distribution
Space Situational Awareness - Global
?
?
SSA in Australia
Optical LIDAR systems: Canberra + Exmouth C-Band RADAR systemsExmouth + Yatharagga
SSA in Australia
Optical LIDAR systems: Canberra + Exmouth C-Band RADAR systemsExmouth + Yatharagga
Pew pew!
High-power laser + advanced AO ⇒ De-orbit debris!
MWA to the rescue
Large FoV ~1000sq.deg @154MHz
Fast scanning ⇒ <8s repointing
70-300MHz operating frequency
128 Tiles = 1 Interferometer
2 modes: correlator or voltage capture
MWA to the rescue
East (m)
Nor
th (m
)
MWA is not a radar
No local transmitter!
How can we use MWA as a radar?
Passive radar
Tingay et al 2013 - With MWA 32T
International Space Station
FM broadcast stations
Frequency (MHz)
Tim
e
Tingay et al 2013 - MWA 32T
ISS easily detected
Simulations performed for smaller objects
A spherical cow at 1000km would be ~1σ(1sec x 50kHz image)
r=10m
r=1m
r=0.2m
Distance (km)
Flux
den
sity
(Jy)
Palmer 2017 - MWA 128T
MWA in VCS mode
observe direct and reflected signals by forming two beams
International
Space Station
Palmer 2017 - MWA 128T
Correlate spatially ⇒ az/el images Correlate in time/freq ⇒ d/v images
azimuth
elev
atio
n
Delay = distance
Dop
pler
= v
eloc
ity
ISS
Palmer 2017 - MWA 128T
Delay = distance
Dop
pler
= v
eloc
ity
Delay = distance
Dop
pler
= v
eloc
ity
Aircraft Meteor trail
Meteor Trails
Meteors “burn up” in the atmosphere
Gas is heated/compressed
Excited gas glows
Really excited gas turns to plasma
Plasma trails are visible to radio telescopes
fireballsinthesky.com.au
Fireballs + Radio observations
Meteoroid - in space
Meteor - in the atmosphere
Fireball - a bright meteor
Meteorite - a fallen meteor
Asteroid
Comet
Not to scale
Receive
Reflection
Transmit
LWA detects fireball emission
Narrow band → reflection of terrestrial RFI
Broadband → emission
Obenberger et al. 2015JGRA..120.9916O
Nor
mal
ized
pow
er
MWA project
The MWA should be able to detect emission from Fireballs
Obenberger et al. 2016JGRA..121.6808O
MWA
LWA-1
LWA-SV
Bright/Rare eventsFaint/Common
events
Obenberger et al. 2016JGRA..121.6808O
Detecting Fireballs (Zhang et al. 2018)
Not to scale
Receive
ReflectionTransmit
Emission
Meteors reflect RFI
Obenberger et al. 2016 ⇒ Emission
Project: use the MWA to verify emission
Our setup
Radio - MWA Optical - Desert Fireball Network
Credit: Natasha Hurley-WalkerCredit: Paul Hancock
AstroCam DFN camera
Zhang et al. 2018: no Meteors
Broadband emission must have a spectral index steeper than -3.7
Found lots of satellites (multiple times)
● DUCHIFAT 1● UKUBE 1● ALOUETTE 2● ALOS● ISS (ZARYA, Soyuz, Cygnus)
Milk carton size
Beach ball size
Bus size
Satellites?
Location of known satellites in difference image
Satellites?
Location of known satellites in difference image
Satellites?
Location of known satellites in difference image
Satellites?
Location of known satellites in difference image
Satellites!
Location of known satellites in difference image
Satellites!
Location of known satellites in difference image
First detections
● Duchifat 1● Cubesat launched 2014 by Israeli
HS students● Antenna for 145 MHz downlink /
435 MHz uplink● Orbit is ~600 km altitude
● Alouette 2● 1m spherical cow Canadian
research sat.● Launched 1965, derelict since
2013● Orbit is 501-2638 km altitude
Not to scale
Future plans
1. Enhance the MWA as a monitor of space debris
2. Develop MWA into a detector of space debris3. An ongoing monitoring program with the MWA