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 ? ? 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.