detecting satellites and space debris with the mwa · astrocam dfn camera. zhang et al. 2018: no...

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