SPACEResearchCentre

SPACE Research CentreSchool of Mathematical and Geospatial Sciences

RMIT University, Australiawww.rmit.edu.au/space

RMIT SPACE Research Centre – overview of past and present research endeavours

Robert Norman

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Outline

• RMIT SPACE Research Centre

• RMIT ASRP project

• CRC-SEM (Space Environment Management) - SERC

• Brief overview of the project

• Ray tracing techniques based on geometrical optics

• Summary

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RMIT SPACE Research Centre

SPACE – Satellite Positioning, Atmosphere, Climate and EnvironmentResearch Centre was officially launched on Friday, 19th November 2010The centre focuses on the development of platform technologies for Space,

Atmosphere and Climate, including new methods, new algorithms and frontier technologies in:

• space situational awareness (including space object/debris monitoring and tracking)

• space weather,• weather and climate,• atmospheric mass density,• ray tracing based on geometrical optics • satellite positioning, navigation and timing

Prof Kefei Zhang leads the SPACE research centre6 researchers & 10 PhD students & centre manager

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The RMIT ASRP project

Platform Technologies for Space, Atmosphere and Climate

• $7.5m (~50% cash, $2.85m from Australian government)

• To make a significant contribution to our space industry, particularly in space situational awareness, satellite navigation, positioning and timing, space debris tracking, atmospheric modelling, radiowave propagation, weather and climate monitoring and space weather.

Consortium members • Prof Kefei Zhang / Robert Norman, RMIT University (Leading)• Prof Peter Teunnisen, CUT (Federation Fellow)• Prof Chris Rizos, HoS of SSI, UNSW (President of IAG)• Prof John Le Marshall / Y Kuleshov, Bureau of Meteorology • Dr Jizhang Sang / Craig Smith, EOS Space Systems Pty Ltd • Mr Graeme Hooper, GPSat Systems Australia Pty Ltd• Prof Yue-an Liou, National Central University, Taiwan• Mr Howard Diamond, World Data Center for Meteorology/NOAA

Domestic vs international: 6+2

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GPS Radio Occultation

>2000 occultations/day

GPS altitude ~20,200 kmLEO altitude ~ 800 km• Global coverage • High vertical resolution• Temperature, pressure, refractivity, electron density and humidity profiles of the atmosphere • COSMIC – Constellation Observing System for Meteorology, Ionosphere, and Climate

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RO and RS coverage

The 1744 F3C RO locations for 2nd March 2009.

(Image courtesy of UCAR).

Location of radiosonde weather stations.

(Image courtesy of World Meteorology Organization

(WMO)).

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CRC for Space Environment Management• Managed by the Space Environment Research Centre (SERC)

• Established to build on Australian and international expertise in measurement, monitoring, analysis and management of space debris and to develop technologies to preserve the space environment

• The goal is to remote maneuver space debris using photon pressure from a ground based laser.

• Partnerships– Essential: EOS, RMIT University, ANU– Other: Lockheed Martin Corp., Optus, National Inst. of Info and

Comms Tech [NICT]/Japan– Affiliates: NASA, ESA, Japanese Space Agency [JAXA]– Funding: A$60M for 5 years (cash + in-kind)

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CRC-SEM

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Space debris

• Since the Sputnik launch in 1957–Approximately ~28,000 payloads, rocket

bodies, and mission related objects have been deployed via ~ 4,500 launches

–About 66% of launched mass has re-entered the Earth’s atmosphere

• 200+ known break up events– E.g. explosions, collisions, etc.

• Current environment– 19,000+ objects >10 cm– 500,000 objects >1 cm– Tens of millions of objects <1 cm– In-orbit mass: 5,900 tons – 1,000+ operational satellites Vanguard-1, one of the oldest known pieces

of space debris (launched in 1958)

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Space is getting polluted

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The Problem

Chinese ASAT

Iridium-Cosmos collision

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Large debris objects in Low Earth Orbit (LEO)

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Collisional Cascading: The Kessler Syndrome

Projected amount of orbital debris resulting from the Kessler Syndrome if spaceflight is stopped for the next 200 years. Image Credit: NASA

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RP1: Identification of Space Objects and Preservation of the Space EnvironmentThis program is developing solutions for reliable and accurate observation and tracking of space objects, better monitoring and cataloguing of space debris, using adaptive optics and lasers.

RP2: Orbit Determination and Predicting Behaviours of Space ObjectsThis program is developing new tools to improve the accuracy and reliability of orbit predictions, including the development of new models for atmospheric mass density.

RP3: Space Asset ManagementThis program focuses on developing techniques, algorithms and databases to predict and avoid potential collisions in space. To develop a global space catalogue and distribution system having conjunction analysis and threat warnings.

RP4: Space SegmentThis program will engage space objects using photon pressure with a view to establishing momentum transfer and force models for the interaction between the space objects and the propagated energy. Up to 3 dedicated satellites will be designed and launched into orbit to serve as instrument platform targets.

Research Programs (RPs)

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22-Oct-16 Conference Name / Author 18

WP1: Atmospheric mass density modelling

WP2: Ray tracing – Signal Propagation

WP3: Precise orbit determination for controlled objects

WP4: Debris ROD using sparse observational data

WP5: Semi-analytic Satellite Theory (SST) for fast and accurate orbit propagation

In total 45 research tasks

RP2 Work Packages (WP’s)

Dr Robert Norman, Dr Brett Carter, Alea Yeasmin, Tim Kodikara, Changyong He

Dr Robert Norman, Ara Cate (VC scholarship), Andong Hu

Dr Yang Yang, Changyong He, Han Cai

Dr Steve Gehly, Michael Afful, Yang Zhao, Adam Harris, Samantha Le May

Dr Jérôme DaquinCentre manager: Sarah BarterNDRGS: Dr Suqin Wu, Xiaoming Wang

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Ray Tracing Techniques

Numerical ray tracingGenerally requires a form of the Haselgrove equations which are a form of Hamiltons equations. These equations are integrated at each step along the ray path.

Analytical ray tracingAnalytical ray tracing as its name suggests uses explicit equation to represent the ionosphere and lower atmosphere as well as the ray parameters.This technique is generally much quicker than numerical ray tracing.

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Numerical Ray Tracing

• Traces ray tubes

• Involves integrating 18 differential equations simultaneously at each step along the ray path

• International Reference Ionosphere (IRI) model

• Can trace ordinary (O), extraordinary (X) as well as the no field (NF) ray paths

• Homing-In capability

• Able to trace ray paths and determine group path, phase path, range, height, transmitted and received elevation and azimuth angles as well as the divergent signal strength.

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Analytical ray tracing

• Quasi-cubic segment ionospheric model

• 2-D SMART

• 3-D SMART

• Inversion techniques, VI ionograms, BSI, Superdarn radars

• Mapping/Modeling Es

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3D-SMART

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Summary

• A brief overview was given of the following:

– SPACE Research Centre– RMIT’s ASRP project– RMIT’s involvement in the CRC-SEM

• The numerical ray tube technique is ideally suited to simulate the laser signal path and signal strength at the target location.

• The numerical and analytic ray tracing techniques are completely different in their design. Having two completely independent methods for simulating the electromagnetic signal (e.g., laser signal) will be important in validating our results.

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