PROBING THE ATMOSPHERE WITH METEORS

Scott Palo – University of Colorado Boulder

Credit Игорь Матвеев

Meteor Radar History

• First published radio observations Nagaoka 1929

• Meteor Winds Manning et al, 1950

Ablation and Ionization

2014 Lyrid Meteor Shower – Babek Tafeshi

2015 Geminids Meteor Shower – abcnews.com

q(z) = k1 tion rair(z) Sf s(z) CD

4.0 h

M(z)

rMET V4(z)

2/3

5

Ceplecha et al, 1998

Cumulative meteoroid flux rate

> 1kg

~10x more meteoroids

that are 10x smaller

Implies 100,000

meteorites with mass >

1kg impact the Earth

each year

Total daily mass

deposition estimated to

be 40-240 metric

tons/day

log10 m + log10 N = 5

Meteor Trail Scattering

a – elevation angle

Meteor trail

bi br

Specular reflection bi=br

Forward Scatter

Colocated Tx/Rx

Monostatic backscatter

Meteor Radar

g=90o

Backscatter

f(t)

s(t) = (re q)2 sin2(a) exp(-8p2 r02 l-2) exp(-32p2 D t l-2 ) Rl/2

Ambipolar diffusion ~ f(T,r) Initial trail radius Fresnel contribution

electrons and ions diffuse at the same rate Electron scatters

as Hertzian Dipole

• Scattering throughout the HF and VHF bands • Preferred radar operating frequencies 30-50MHz • Meteors can be observed on SuperDARN and MF radars • Meteor head echoes can be observed at VHF and UHF • Meteor RX can be used as a riometer

Meteor Trails

A monostatic system can only see backscattered meteor trails, many other trails are missed.

Monotstatic system

TX/RX

Multi-static system

A multistatic system can see many more trails than the monostatic system while still using a single transmitter.

Rx Rx Rx

Meteor Ground Illumination Pattern

Advantages of Multistatic System

Enabling Advances • MIMICs • High rate ADCS • GaN amplifiers • Increase processing power • Increased data storage • Increased capacity • GPS disciplined oscillators

A coarse network of transmitters

Atlanta Little Rock

Durham

Ann Arbor

Lubbock Flagstaff

Platteville

Bear Lake

Eugene

Sioux Falls

State College

Seattle

A continental network of HF to UHF receivers • SDR type system

• On board meteor detection

• GPS disciplined oscillator

• LBA antennas 10-90MHz

• 5-10 antennas per RX site for direction finding

• $5K per RX site,1000 sites across the US = $5M

• 10-50 low power CW transmitters @ $100K ea = $1M - $5M

• Also consider Antarctica as a potential location

• Mesoscale network provides the lower boundary condition for the SAIR