Detecting satellites and space debris with the MWA
Dr Paul Hancock Curtin 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
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? SSA in Australia
Optical LIDAR systems: Canberra + Exmouth C-Band RADAR systems Exmouth + Yatharagga SSA in Australia
Pew pew!
Optical LIDAR systems: Canberra + Exmouth C-Band RADAR systems Exmouth + Yatharagga 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
North (m) North
East (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
FM broadcast stations
Time
Frequency (MHz) International Space Station Tingay et al 2013 - MWA 32T
ISS easily detected
Simulations performed for smaller objects r=10m
A spherical cow at 1000km would be ~1σ
Flux density (Jy) r=1m (1sec x 50kHz image)
r=0.2m
Distance (km) Palmer 2017 - MWA 128T
MWA in VCS mode observe direct and reflected signals by forming two beams
International Space Station Palmer 2017 - MWA 128T
ISS
elevation Doppler = velocity
Delay = distance azimuth
Correlate spatially ⇒ az/el images Correlate in time/freq ⇒ d/v images Palmer 2017 - MWA 128T
Doppler = velocity Doppler = velocity
Delay = distance Delay = distance
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
Comet Reflection
Asteroid
Meteoroid - in space Receive Transmit
Meteor - in the atmosphere
Fireball - a bright meteor
Meteorite - a fallen meteor
Not to scale LWA detects fireball emission
Narrow band → reflection of terrestrial RFI
Broadband → emission
Normalized power
Obenberger et al. 2015JGRA..120.9916O MWA project
LWA-1
The MWA should be able to detect emission from Fireballs LWA-SV
Bright/Rare Faint/Common events events
MWA
Obenberger et al. 2016JGRA..121.6808O Obenberger et al. 2016JGRA..121.6808O Detecting Fireballs (Zhang et al. 2018)
Meteors reflect RFI
Obenberger et al. 2016 ⇒ Emission Emission Project: use the MWA to verify Reflection Transmit emission Receive
Not to scale Our setup
Radio - MWA Optical - Desert Fireball Network AstroCam DFN camera
Credit: Paul Hancock Credit: Natasha Hurley-Walker Zhang et al. 2018: no Meteors
Found lots of satellites (multiple times)
● DUCHIFAT 1 Milk carton size ● UKUBE 1 ● ALOUETTE 2 Beach ball size ● ALOS Bus size ● ISS (ZARYA, Soyuz, Cygnus)
Broadband emission must have a spectral index steeper than -3.7 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 Not to scale
● Alouette 2 ● 1m spherical cow Canadian ● Duchifat 1 research sat. ● Cubesat launched 2014 by Israeli ● Launched 1965, derelict since HS students 2013 ● Antenna for 145 MHz downlink / ● Orbit is 501-2638 km altitude 435 MHz uplink ● Orbit is ~600 km altitude Future plans
1. Enhance the MWA as a monitor of space debris 2. Develop MWA into a detector of space debris 3. An ongoing monitoring program with the MWA