Australian Centre for Space Photonics
Andrew McGrath
Anglo-Australian
Observatory
This Presentation
Interplanetary communications
problem
 Long term solution
 Historical Australian involvement
 Further Australian involvement
 Making it happen

Exploration of Mars
Highlights the communications
problem
 Long term and substantial past and
continuing international investment

Exploration of Mars

1960 Two Soviet flyby attempts
 1962 Two more Soviet flyby attempts,
Mars 1
 1964 Mariner 3, Zond 2
 1965 Mariner 4 (first flyby images)
 1969 Mariners 6 and 7
 1971 Mariners 8 and 9
 1971 Kosmos 419, Mars 2 & 3
 1973 Mars 4, 5, 6 & 7 (first landers)
 1975 Viking 1, 1976 Viking 2
Exploration of Mars

1988 Phobos 1 and 2
 1992 Mars Observer
 1996 Mars 96
 1997 Mars Pathfinder, Mars Global Surveyor
 1998 Nozomi
 1999 Climate Orbiter, Polar Lander and Deep
Space 2
 2001 Mars Odyssey
Planned Mars Exploration






2003 Mars Express
2004 Mars Exploration Rovers
2005 Mars Reconnaissance Orbiter
2007+ Scout Missions 2007
2009 Smart Lander, Long Range Rover
2014 Sample Return
Interplanetary Communication
Radio (microwave) links, spacecraft
to Earth
 Newer philosophy - communications
relay (Mars Odyssey, MGS)
 Sensible network topology
 25-W X-band (Ka-band experimental)
<100 kbps downlink

Communications Bottleneck
Current missions capable of
collecting much more data than
downlink capabilities (2000%!)
 Currently planned missions make the
problem 10x worse
 Future missions likely to collect evergreater volumes of data

Communications Bottleneck

Increasing downlink rates critical to
continued investment in planetary
exploration
Communications Bottleneck

NASA's perception of the problem is
such that they are considering an
array of 3600 twelve-metre dishes to
accommodate currently foreseen
communications needs for Mars
alone
Communications Energy Budget
Consider cost of communications reduced to
transmitted energy per bit of information
received
Communications Energy Budget
Assumptions:
• information proportional to number of photons
(say, 10 photons per bit)
• diffraction-limited transmission so energy density at
receiver proportional to (R/DT)-2
• received power proportional to DR2
• photon energy hc / 
So:
Cost proportional to R2 / (DT2DR2)
Communications Energy Budget
Cost proportional to R2 / (DT2DR2)
X-band transmitter  ~ 40 mm
Laser transmitter  ~ 0.5-1.5 m
Assuming similar aperture sizes and
efficiencies, optical wins over microwave
by > 3 orders of magnitude
Long-term Solution
Optical communications networks
 Advantages over radio
 Higher modulation rates
 More directed energy
 Analagous to fibre optics vs. copper
cables

Lasers in Space
Laser transmitter in Martian orbit
with large aperture telescope
 Receiving telescope on or near Earth
 Preliminary investigations suggest
~100Mbps achievable on 10 to 20
year timescale
 Enabling technologies require
accelerated development

Key Technologies
Suitable lasers
 Telescope tracking and guiding
 Optical detectors
 Cost-effective large-aperture
telescopes
 Atmospheric properties
 Space-borne telescopes

An Australian Role - till now
History of involvement
 Launch sites
 Development of early satellites
 Communications

– Deep Space Network
– Parkes, ATNF
– Continuing involvement
An Australian Role - in the future


Australian organisations have unique
capabilities in the key technologies
required for deep space optical
communications links
High-power, high beam quality lasers
 Holographic correction of large telescopes
 Telescope-based instrumentation
 Telescope tracking and guiding
The University of Adelaide

Optics Group, Department of Physics
and Mathematical Physics
– High power, high beam quality, scalable
laser transmitter technology
– Holographic mirror correction
– Presently developing high power lasers
and techniques for high optical power
interferometry for the US Advanced
LIGO detectors
Anglo-Australian Observatory
Telescope technology
 Pointing and tracking systems
 Atmospheric transmission (seeing,
refraction)
 Cryogenic and low noise detectors
 Narrowband filter technology

Macquarie University

Centre for Lasers and Applications
– Optical communications
– Transmitter technology
A Proposal

Use the ARC 'Centre of Excellence'
programme to link these
organisations to capitalise on
Australia's strategic advantages to
become an indispensable partner in
the world-wide scientific space
exploration effort
Australian Centre for Space Photonics

To expand unique Australian capabilities
and experience to progress research
into key technologies for an
interplanetary high-data rate optical
communications link that are synergistic
with near term space communication
needs.
Australian Centre for Space Photonics
Manage a portfolio of research
projects in the key technologies for
an interplanetary optical
communications link
 Work in close collaboration with
overseas organizations such as
NASA and JPL

Australian Centre for Space Photonics

An Australian foothold into the wellestablished `big science' investment
of the leading space agencies
Australian Centre for Space Photonics

Closer ties to leading space agencies
and their current and planned
missions
Australian Centre for Space Photonics

Australia's continued long term
participation in the Deep Space
Network
Australian Centre for Space Photonics

Attract and retain the best Australian
students and staff in optics and
photonics
Australian Centre for Space Photonics

Creation of photonics and space
technology IP for commercial
development
Australian Centre for Space Photonics
Take advantage of unique Australian
capabilities
 Australian technology becomes
critical to deep space missions
 Continued important role in space

FOR MORE INFO...
http://www.aao.gov.au/lasers